More HP on a budget
08-15-2015, 02:53 PM
#1
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
More HP on a budget
I have a 1990 GTA (305 TPI / 4 speed auto) that feels under-powered (not an exciting ride experience) and I would like to perform some upgrades to add a little more pep. Whether the car has always been this way I don't know -- it's second hand and I can imagine mechanically it's seen better days. Probably has original everything and is at 115k miles. I say that I want "a little more pep" because (1) I don't want to put a lot of money into it ($1000 max for now) and (2) It has T-tops and I don't want to twist the frame.
After reading up on the GTA source page I found that it has 215HP (probably less now considering the wear, etc). I looked up the VIN codes and found that it has the LB9 engine. I'm not sure what transmission and heads it has. Although at one point in the past I thought I found it has the 1LE tranny, but can't recall how I figured that -- it's possible that's not correct.
After doing a little research online i believe the best approach for what I want (and keeping budget in mind) is to swap out the camshaft with something "hotter" -- more valve lift, more valve duration, and either (1) machine the existing heads or (2) swap the heads (better flow and larger valve size). From various reading it sounds like I need to upgrade valve springs (but what else would need to be replaced with a new cam? As you probably can tell I'm not a mechanic, but have the drive to learn).
Does anyone know what heads I have? or whether it would be recommended to replace them? One thing, I *think* I would prefer to keep the TPI setup. Are there any nicer heads that I can re-use the TPI system with? Also, if I upgrade cam/heads can I use the same stock injectors/fuel pump? What would you recommend?
I'm guessing this might get the car to about 300HP and hence a more exciting driving experience. I currently have a genesis coupe (306HP) and find it enjoyable to drive power-wise, but am planning to trade it in for a truck one day, so thinking I'll be happy if I can get the GTA up to 300HP.
Still in planning phase of the project... so apologize for rambling.
As state earlier, I'm no mechanic, however I have dabbled in mechanical work before. I have a garage and quite a few tools. I've rebuilt my motorcycle carb and have done some other simple work (replace sprockets, drive chain, brake disc)... so I'd say I'm mechanically inclined and pay special attention to the details. Hopefully this will be enough to dig into the GTA.
Looking forward to your responses.
Thanks!
After reading up on the GTA source page I found that it has 215HP (probably less now considering the wear, etc). I looked up the VIN codes and found that it has the LB9 engine. I'm not sure what transmission and heads it has. Although at one point in the past I thought I found it has the 1LE tranny, but can't recall how I figured that -- it's possible that's not correct.
After doing a little research online i believe the best approach for what I want (and keeping budget in mind) is to swap out the camshaft with something "hotter" -- more valve lift, more valve duration, and either (1) machine the existing heads or (2) swap the heads (better flow and larger valve size). From various reading it sounds like I need to upgrade valve springs (but what else would need to be replaced with a new cam? As you probably can tell I'm not a mechanic, but have the drive to learn).
Does anyone know what heads I have? or whether it would be recommended to replace them? One thing, I *think* I would prefer to keep the TPI setup. Are there any nicer heads that I can re-use the TPI system with? Also, if I upgrade cam/heads can I use the same stock injectors/fuel pump? What would you recommend?
I'm guessing this might get the car to about 300HP and hence a more exciting driving experience. I currently have a genesis coupe (306HP) and find it enjoyable to drive power-wise, but am planning to trade it in for a truck one day, so thinking I'll be happy if I can get the GTA up to 300HP.
Still in planning phase of the project... so apologize for rambling.
As state earlier, I'm no mechanic, however I have dabbled in mechanical work before. I have a garage and quite a few tools. I've rebuilt my motorcycle carb and have done some other simple work (replace sprockets, drive chain, brake disc)... so I'd say I'm mechanically inclined and pay special attention to the details. Hopefully this will be enough to dig into the GTA.
Looking forward to your responses.
Thanks!
08-15-2015, 04:35 PM
#2
Re: More HP on a budget
If you're looking to make more power, especially thinking heads and cam, your budget of $1000 will get you NOwhere. GOOD exhaust will blow that budget. As of now I think you need to reevaluate your ideas. Power isn't cheap. I will try and clear up some of your questions to try to help you learn.
If you're worried about twisting the frame think about sub frame connectors. Big bang for the buck even if it doesn't make you faster. I've never heard someone say they shouldn't have done it.
Your 8th digit of the VIN should be a 'F' for 305 TPI. Doesn't mean someone didn't swap things around ever in it's 25 years of exisistance though. I'll stick to thinking it is original for simplicitys sake.
Your transmissoin is called a TH700R4. Never heard of such thing as a 1LE transmission. I suggest you search more on 1LE but in the mean time I will tell you it was a performance package that didn't change the trans and I'd imagine most were T-5 manual transmissions. There were quite a few 700R4 1LE cars but I don't think they changed any calibrations in the trans itself for the 1LE RPO.
The heads you SHOULD have are 081 heads. Again, search. They're not bad heads for moderate power. At your HP level, I'd stick with them. Yes, you can change them for more but that does get complicated quick so I won't dive too far into it. I'd imagine the TPI will be a choke before the heads.
Changing cams, I'd suggest fresh springs and having a machine shop do the brunt of the work. If they're good, they'll make sure everything is as it should be. Other than seals, a timing chain, push rods, rocker arms and inspect the roller lifters to cover the whole valve train.
Depending on power level, you'll need to change injectors long before pump. The size of injectors depends on power output for the most part.
My suggestion to to keep reading. 1st problem on your car as it sits is the exhaust. Replace that with GOOD parts (ie DON'T CHEAP OUT) and the 305 will breath much easier. 2nd a good axle with a better ratio...3.23, 3.42 will be a huge gain in performance. TPI limits your RPM potential so too steep of gears(4.10) doesn't make you faster, just means the engine will run out of breath. 3rd is those subframe connectors. At that point, you've already blown away your current budget. Hope that clears some things up.
If you're worried about twisting the frame think about sub frame connectors. Big bang for the buck even if it doesn't make you faster. I've never heard someone say they shouldn't have done it.
Your 8th digit of the VIN should be a 'F' for 305 TPI. Doesn't mean someone didn't swap things around ever in it's 25 years of exisistance though. I'll stick to thinking it is original for simplicitys sake.
Your transmissoin is called a TH700R4. Never heard of such thing as a 1LE transmission. I suggest you search more on 1LE but in the mean time I will tell you it was a performance package that didn't change the trans and I'd imagine most were T-5 manual transmissions. There were quite a few 700R4 1LE cars but I don't think they changed any calibrations in the trans itself for the 1LE RPO.
The heads you SHOULD have are 081 heads. Again, search. They're not bad heads for moderate power. At your HP level, I'd stick with them. Yes, you can change them for more but that does get complicated quick so I won't dive too far into it. I'd imagine the TPI will be a choke before the heads.
Changing cams, I'd suggest fresh springs and having a machine shop do the brunt of the work. If they're good, they'll make sure everything is as it should be. Other than seals, a timing chain, push rods, rocker arms and inspect the roller lifters to cover the whole valve train.
Depending on power level, you'll need to change injectors long before pump. The size of injectors depends on power output for the most part.
My suggestion to to keep reading. 1st problem on your car as it sits is the exhaust. Replace that with GOOD parts (ie DON'T CHEAP OUT) and the 305 will breath much easier. 2nd a good axle with a better ratio...3.23, 3.42 will be a huge gain in performance. TPI limits your RPM potential so too steep of gears(4.10) doesn't make you faster, just means the engine will run out of breath. 3rd is those subframe connectors. At that point, you've already blown away your current budget. Hope that clears some things up.
08-15-2015, 07:01 PM
#3
Re: More HP on a budget
I agree with changing the rear out for a posi 3.42 or even 3.23. That's something you'll immediately notice, you Can get a rear from the junkyard for pretty cheap. 4th gen camaros and trans am rears are a good choice, some had posi 3.42s, just make sure you get one with a disc or drum brake set up depending on what your current rear end already has.
08-15-2015, 11:43 PM
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
If you're looking to make more power, especially thinking heads and cam, your budget of $1000 will get you NOwhere. GOOD exhaust will blow that budget. As of now I think you need to reevaluate your ideas. Power isn't cheap. I will try and clear up some of your questions to try to help you learn.
If you're worried about twisting the frame think about sub frame connectors. Big bang for the buck even if it doesn't make you faster. I've never heard someone say they shouldn't have done it.
Your 8th digit of the VIN should be a 'F' for 305 TPI. Doesn't mean someone didn't swap things around ever in it's 25 years of exisistance though. I'll stick to thinking it is original for simplicitys sake.
Your transmissoin is called a TH700R4. Never heard of such thing as a 1LE transmission. I suggest you search more on 1LE but in the mean time I will tell you it was a performance package that didn't change the trans and I'd imagine most were T-5 manual transmissions. There were quite a few 700R4 1LE cars but I don't think they changed any calibrations in the trans itself for the 1LE RPO.
The heads you SHOULD have are 081 heads. Again, search. They're not bad heads for moderate power. At your HP level, I'd stick with them. Yes, you can change them for more but that does get complicated quick so I won't dive too far into it. I'd imagine the TPI will be a choke before the heads.
Changing cams, I'd suggest fresh springs and having a machine shop do the brunt of the work. If they're good, they'll make sure everything is as it should be. Other than seals, a timing chain, push rods, rocker arms and inspect the roller lifters to cover the whole valve train.
Depending on power level, you'll need to change injectors long before pump. The size of injectors depends on power output for the most part.
My suggestion to to keep reading. 1st problem on your car as it sits is the exhaust. Replace that with GOOD parts (ie DON'T CHEAP OUT) and the 305 will breath much easier. 2nd a good axle with a better ratio...3.23, 3.42 will be a huge gain in performance. TPI limits your RPM potential so too steep of gears(4.10) doesn't make you faster, just means the engine will run out of breath. 3rd is those subframe connectors. At that point, you've already blown away your current budget. Hope that clears some things up.
If you're worried about twisting the frame think about sub frame connectors. Big bang for the buck even if it doesn't make you faster. I've never heard someone say they shouldn't have done it.
Your 8th digit of the VIN should be a 'F' for 305 TPI. Doesn't mean someone didn't swap things around ever in it's 25 years of exisistance though. I'll stick to thinking it is original for simplicitys sake.
Your transmissoin is called a TH700R4. Never heard of such thing as a 1LE transmission. I suggest you search more on 1LE but in the mean time I will tell you it was a performance package that didn't change the trans and I'd imagine most were T-5 manual transmissions. There were quite a few 700R4 1LE cars but I don't think they changed any calibrations in the trans itself for the 1LE RPO.
The heads you SHOULD have are 081 heads. Again, search. They're not bad heads for moderate power. At your HP level, I'd stick with them. Yes, you can change them for more but that does get complicated quick so I won't dive too far into it. I'd imagine the TPI will be a choke before the heads.
Changing cams, I'd suggest fresh springs and having a machine shop do the brunt of the work. If they're good, they'll make sure everything is as it should be. Other than seals, a timing chain, push rods, rocker arms and inspect the roller lifters to cover the whole valve train.
Depending on power level, you'll need to change injectors long before pump. The size of injectors depends on power output for the most part.
My suggestion to to keep reading. 1st problem on your car as it sits is the exhaust. Replace that with GOOD parts (ie DON'T CHEAP OUT) and the 305 will breath much easier. 2nd a good axle with a better ratio...3.23, 3.42 will be a huge gain in performance. TPI limits your RPM potential so too steep of gears(4.10) doesn't make you faster, just means the engine will run out of breath. 3rd is those subframe connectors. At that point, you've already blown away your current budget. Hope that clears some things up.
Good to know that I got descent heads already. I'll search around and find out more about them and see if there are any opportunities for HP gains by porting/polishing and increasing valve sizes. With a hotter cam, would you recommend increasing valve size (intake and exhaust)? I've heard heads can generally be improved by grinding down certain areas (such as humps that serve no purpose), and unshrouding the valves to improve flow. This may be an area I can save $ on (as opposed to replacing the heads)
Couple more noob questions:
Can the stock rear-diff be rebuilt to use the better gearing? Or would you recommend replacing the whole thing from a junkyard, as TylerS recommended (sounds like 4th gen rear-diffs are a good bet)? I definitely want better gears than the weak ones it currently has. Can I just buy the gears and drop them into the existing rear-diff?
When replacing the camshaft can I accomplish this with the engine still in the car? On the TBI forum I read that it can be done that way and just need to essentially remove everything in front of the engine (accessories, radiator, etc).
If I decided to get rid of TPI and go with a carb, do you know if there is one that will fit under the stock hood? I'd prefer to not change the body. If so that means injectors are no longer necessary right? I wouldn't be opposed to a carb unless I had to cut the hood.
I'm assuming the transmission needs to be rebuilt tougher to withstand the power gain. Similar to my rear-diff question -- can I reuse the body of the existing transmission and just drop in stronger gears? What's recommended here?
08-15-2015, 11:44 PM
#5
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
I agree with changing the rear out for a posi 3.42 or even 3.23. That's something you'll immediately notice, you Can get a rear from the junkyard for pretty cheap. 4th gen camaros and trans am rears are a good choice, some had posi 3.42s, just make sure you get one with a disc or drum brake set up depending on what your current rear end already has.
08-16-2015, 12:34 AM
#6
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Car: 1988 Camaro
Engine: 355, 10.34:1, 249/252 @.050", IK200
Transmission: TH-400, 3500 stall 9.5" converter
Axle/Gears: Ford 9", detroit locker, 3.89 gears
Re: More HP on a budget
At your 300 HP goal your stock transmission should be fine. Maybe add a trans go shift kit and corvette servo, .500" boost valve.. Full rebuild should not be needed
Many people have used carbs under stock hoods. In fact most of the 82-87 camaro/firebirds was factory carb.
Right Injectors would no longer be needed if you swap to a carb.
Replacing just the gears in your rear end is harder for the back yarder than replacing whole rear end housing... The ring and pinion gears needs special tools and skill to install and set right with contact pattern, back lash, etc.
Start your project off with headers, aftermarket mandrel bent Y pipe and single 3" aftermarket cat back.
Sub frame connectors
Full tune up.. Replace fuel filter, spark plugs, plug wires, dist. cap, air filter, etc... Check and set timing
Posi. 3.42 rear gear/rear end
Then go from there..
Many people have used carbs under stock hoods. In fact most of the 82-87 camaro/firebirds was factory carb.
Right Injectors would no longer be needed if you swap to a carb.
Replacing just the gears in your rear end is harder for the back yarder than replacing whole rear end housing... The ring and pinion gears needs special tools and skill to install and set right with contact pattern, back lash, etc.
Start your project off with headers, aftermarket mandrel bent Y pipe and single 3" aftermarket cat back.
Sub frame connectors
Full tune up.. Replace fuel filter, spark plugs, plug wires, dist. cap, air filter, etc... Check and set timing
Posi. 3.42 rear gear/rear end
Then go from there..
08-16-2015, 09:16 AM
#7
Re: More HP on a budget
Good to know that I got descent heads already. I'll search around and find out more about them and see if there are any opportunities for HP gains by porting/polishing and increasing valve sizes. With a hotter cam, would you recommend increasing valve size (intake and exhaust)? I've heard heads can generally be improved by grinding down certain areas (such as humps that serve no purpose), and unshrouding the valves to improve flow. This may be an area I can save $ on (as opposed to replacing the heads)
Couple more noob questions:
Can the stock rear-diff be rebuilt to use the better gearing? Or would you recommend replacing the whole thing from a junkyard, as TylerS recommended (sounds like 4th gen rear-diffs are a good bet)? I definitely want better gears than the weak ones it currently has. Can I just buy the gears and drop them into the existing rear-diff?
When replacing the camshaft can I accomplish this with the engine still in the car? On the TBI forum I read that it can be done that way and just need to essentially remove everything in front of the engine (accessories, radiator, etc).
If I decided to get rid of TPI and go with a carb, do you know if there is one that will fit under the stock hood? I'd prefer to not change the body. If so that means injectors are no longer necessary right? I wouldn't be opposed to a carb unless I had to cut the hood.
I'm assuming the transmission needs to be rebuilt tougher to withstand the power gain. Similar to my rear-diff question -- can I reuse the body of the existing transmission and just drop in stronger gears? What's recommended here?
Couple more noob questions:
Can the stock rear-diff be rebuilt to use the better gearing? Or would you recommend replacing the whole thing from a junkyard, as TylerS recommended (sounds like 4th gen rear-diffs are a good bet)? I definitely want better gears than the weak ones it currently has. Can I just buy the gears and drop them into the existing rear-diff?
When replacing the camshaft can I accomplish this with the engine still in the car? On the TBI forum I read that it can be done that way and just need to essentially remove everything in front of the engine (accessories, radiator, etc).
If I decided to get rid of TPI and go with a carb, do you know if there is one that will fit under the stock hood? I'd prefer to not change the body. If so that means injectors are no longer necessary right? I wouldn't be opposed to a carb unless I had to cut the hood.
I'm assuming the transmission needs to be rebuilt tougher to withstand the power gain. Similar to my rear-diff question -- can I reuse the body of the existing transmission and just drop in stronger gears? What's recommended here?
You can rebuild your current diff with new gears but that's easier said than done. Swapping out the rear is much simpler but if using a 4th gen axle you'll need to note that the wheel offsets are different and can't use 3rd gen wheels. Personally, I would find a used 3rd gen axle, but that's up to you.
Yes, you can swap camshafts with the engine in the car. Note that if you're doing heads etc at the same time it's easier to setup an engine OUTside the car. Also note since your car it a speed density TPI that the ecm will get the most out of any changes and maybe REQUIRED for it to run correctly. That's a whole other ball of wax. Depending on if you can find a tuner, buy equipment and burn chips yourself, or go EBL-P4 and tune yourself.
If you decide to go carb'd (I do NOT recommend this especially if your car is in nice condition) and you'll have several carb and intake manifold options that'll clear a stock hood.
Transmission can be rebuilt with stronger stuff or you can buy one straight from a vendor. Just needs to be a F body trans. The tail housing is different for the torque arm mount. Then depending on gears, cam and heads, what torque converter do you need. See how quickly the budget goes away.
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08-16-2015, 12:34 PM
#8
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Car: 90 Formula / T-tops
Engine: 305 TPI
Transmission: MD8
Re: More HP on a budget
From what I can gather, to get to 300hp it will take some doing. Along with the exhaust and cam, heads are going to need replaced with something that breaths better, which is going to cost you. Once you get your machine breathing better, you're probably going to have to get into tuning the computer. Not sure if stock 305 injectors will allow 300hp to be developed, haven't researched that far.
Be careful with your differential. You probably have posi right now. I've read starting in 1990 a new, stronger diff was used (28 splines and strong as a 4th Gen). Don't throw it away if you have one. Just something to be cognizant of. Also, I can't imagine a 1990 GTA w/o TPI. Did you double check your VIN ?
If you want to boost your horsepower up on a budget, exhaust and cam/springs are the way to start. I'm guessing you wouldn't need sub-frame connectors for that power boost.
https://www.thirdgen.org/forums/tpi/...ml#post5933683 (some links I found for good reading on heads)
https://www.thirdgen.org/forums/tpi/...ses-cures.html
Read the sticky threads such as this one, tons of good info: https://www.thirdgen.org/forums/tran...-10-bolts.html
Be careful with your differential. You probably have posi right now. I've read starting in 1990 a new, stronger diff was used (28 splines and strong as a 4th Gen). Don't throw it away if you have one. Just something to be cognizant of. Also, I can't imagine a 1990 GTA w/o TPI. Did you double check your VIN ?
If you want to boost your horsepower up on a budget, exhaust and cam/springs are the way to start. I'm guessing you wouldn't need sub-frame connectors for that power boost.
https://www.thirdgen.org/forums/tpi/...ml#post5933683 (some links I found for good reading on heads)
https://www.thirdgen.org/forums/tpi/...ses-cures.html
Read the sticky threads such as this one, tons of good info: https://www.thirdgen.org/forums/tran...-10-bolts.html
Last edited by LiquidBlue; 08-16-2015 at 12:57 PM.
08-16-2015, 11:40 PM
#9
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
At your 300 HP goal your stock transmission should be fine. Maybe add a trans go shift kit and corvette servo, .500" boost valve.. Full rebuild should not be needed
Many people have used carbs under stock hoods. In fact most of the 82-87 camaro/firebirds was factory carb.
Right Injectors would no longer be needed if you swap to a carb.
Replacing just the gears in your rear end is harder for the back yarder than replacing whole rear end housing... The ring and pinion gears needs special tools and skill to install and set right with contact pattern, back lash, etc.
Start your project off with headers, aftermarket mandrel bent Y pipe and single 3" aftermarket cat back.
Sub frame connectors
Full tune up.. Replace fuel filter, spark plugs, plug wires, dist. cap, air filter, etc... Check and set timing
Posi. 3.42 rear gear/rear end
Then go from there..
Many people have used carbs under stock hoods. In fact most of the 82-87 camaro/firebirds was factory carb.
Right Injectors would no longer be needed if you swap to a carb.
Replacing just the gears in your rear end is harder for the back yarder than replacing whole rear end housing... The ring and pinion gears needs special tools and skill to install and set right with contact pattern, back lash, etc.
Start your project off with headers, aftermarket mandrel bent Y pipe and single 3" aftermarket cat back.
Sub frame connectors
Full tune up.. Replace fuel filter, spark plugs, plug wires, dist. cap, air filter, etc... Check and set timing
Posi. 3.42 rear gear/rear end
Then go from there..
Regarding the exhaust, would a H pipe be better than a Y pipe? It seems like Y is popular with these 3rd gens. I'd prefer true dual exhaust for the nice tones, but perhaps there's a good reason to stick with single pipe?
+1 on the tune up... it needs one badly and I'll certainly get to those items before long.
Thanks
08-16-2015, 11:51 PM
#10
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
Having the heads ported etc by a shop can get pricey, depending on what the heads need and what you want done may cost more than new heads. The smaller bore size of the 305 limits what valves can be used so your head choices shrink. I'd say to either just rebuild those heads and not worry about porting OR find a set of TrickFlow 305 heads. http://www.summitracing.com/parts/tf...make/chevrolet
You can rebuild your current diff with new gears but that's easier said than done. Swapping out the rear is much simpler but if using a 4th gen axle you'll need to note that the wheel offsets are different and can't use 3rd gen wheels. Personally, I would find a used 3rd gen axle, but that's up to you.
Yes, you can swap camshafts with the engine in the car. Note that if you're doing heads etc at the same time it's easier to setup an engine OUTside the car. Also note since your car it a speed density TPI that the ecm will get the most out of any changes and maybe REQUIRED for it to run correctly. That's a whole other ball of wax. Depending on if you can find a tuner, buy equipment and burn chips yourself, or go EBL-P4 and tune yourself.
If you decide to go carb'd (I do NOT recommend this especially if your car is in nice condition) and you'll have several carb and intake manifold options that'll clear a stock hood.
Transmission can be rebuilt with stronger stuff or you can buy one straight from a vendor. Just needs to be a F body trans. The tail housing is different for the torque arm mount. Then depending on gears, cam and heads, what torque converter do you need. See how quickly the budget goes away.
You can rebuild your current diff with new gears but that's easier said than done. Swapping out the rear is much simpler but if using a 4th gen axle you'll need to note that the wheel offsets are different and can't use 3rd gen wheels. Personally, I would find a used 3rd gen axle, but that's up to you.
Yes, you can swap camshafts with the engine in the car. Note that if you're doing heads etc at the same time it's easier to setup an engine OUTside the car. Also note since your car it a speed density TPI that the ecm will get the most out of any changes and maybe REQUIRED for it to run correctly. That's a whole other ball of wax. Depending on if you can find a tuner, buy equipment and burn chips yourself, or go EBL-P4 and tune yourself.
If you decide to go carb'd (I do NOT recommend this especially if your car is in nice condition) and you'll have several carb and intake manifold options that'll clear a stock hood.
Transmission can be rebuilt with stronger stuff or you can buy one straight from a vendor. Just needs to be a F body trans. The tail housing is different for the torque arm mount. Then depending on gears, cam and heads, what torque converter do you need. See how quickly the budget goes away.
good to know I have options regarding carb vs keeping the TPI. Perhaps retaining the TPI will do just fine for the mild build I'm after. I'd only go to carb if I needed to, to get the my power goal. I'll need to read up on setting up the chip for proper tuning. Looks like there's a wealth of knowledge on this forum on the topic. Should make for some good reading!
08-17-2015, 12:04 AM
#11
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
From what I can gather, to get to 300hp it will take some doing. Along with the exhaust and cam, heads are going to need replaced with something that breaths better, which is going to cost you. Once you get your machine breathing better, you're probably going to have to get into tuning the computer. Not sure if stock 305 injectors will allow 300hp to be developed, haven't researched that far.
Be careful with your differential. You probably have posi right now. I've read starting in 1990 a new, stronger diff was used (28 splines and strong as a 4th Gen). Don't throw it away if you have one. Just something to be cognizant of. Also, I can't imagine a 1990 GTA w/o TPI. Did you double check your VIN ?
If you want to boost your horsepower up on a budget, exhaust and cam/springs are the way to start. I'm guessing you wouldn't need sub-frame connectors for that power boost.
https://www.thirdgen.org/forums/tpi/...ml#post5933683 (some links I found for good reading on heads)
https://www.thirdgen.org/forums/tpi/...ses-cures.html
Read the sticky threads such as this one, tons of good info: https://www.thirdgen.org/forums/tran...-10-bolts.html
Be careful with your differential. You probably have posi right now. I've read starting in 1990 a new, stronger diff was used (28 splines and strong as a 4th Gen). Don't throw it away if you have one. Just something to be cognizant of. Also, I can't imagine a 1990 GTA w/o TPI. Did you double check your VIN ?
If you want to boost your horsepower up on a budget, exhaust and cam/springs are the way to start. I'm guessing you wouldn't need sub-frame connectors for that power boost.
https://www.thirdgen.org/forums/tpi/...ml#post5933683 (some links I found for good reading on heads)
https://www.thirdgen.org/forums/tpi/...ses-cures.html
Read the sticky threads such as this one, tons of good info: https://www.thirdgen.org/forums/tran...-10-bolts.html
I'm quite sure my rear-diff is POSI... though it seems like it might have done a 1-wheel peel out once before... I was scratching my head when i saw the one burn-track on the ground. Pretty sure most other times it's made 2-wheel marks, so both wheels were spinning. Wish I knew what I had. I'm assuming the gears are 2.73 as it seems very weak on take offs. Guess I'll need to look for a stamped part number to find out for sure. Will try to find out what the price difference is between swapping to a tuffer one vs. a shop rebuilding the existing to better gears (3.42 or 3.5).
It actually has TPI... in previous replies I was pondering if I should change the TPI to carb, as it seems carb will get more performance (more RPM). I'm no expert but I'm pretty sure TPI will be fine for a mild build (300HP), but will require a chip upgrade. Not sure how much burning my own chip will set me back. The current injectors are original I'm quite sure so I'll plan to change those out for some that can provide more go-juice.
Thanks for the links. Will read up on those.
08-17-2015, 12:21 AM
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Car: '88 IROC-Z/'03 Cts/'63 500 XL
Engine: 5.7 tpi/3.2 V6/390 FE
Transmission: 4L60E/Crap!/Ford-o-matic
Re: More HP on a budget
What is the endgame with your car? You want a weekend/track car or a more practical yet fun daily? My Roc is bone stock right now and I want to get more oomph than the 220hp she's got....BUT she is going to be my daily for a while so I don't want HORRIBLE gas mileage, I don't want to have a motor that needs constant tuning and adjusting and I damn sure can't afford to be dropping moogoo bucks into her right now. Therefore a set of headers, true dual exhaust, shift kit and beefing up the rear are all of the mods I will be doing. Tpi's are moody bitches from what I've heard when it comes to messing with their air to fuel ratio.
Maybe consider an engine swap?
Maybe consider an engine swap?
08-17-2015, 01:03 AM
#13
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Car: 1988 Camaro
Engine: 355, 10.34:1, 249/252 @.050", IK200
Transmission: TH-400, 3500 stall 9.5" converter
Axle/Gears: Ford 9", detroit locker, 3.89 gears
Re: More HP on a budget
True dual exhaust on these cars are a pain in the butt to do and to drive/use.
No room under the car to fit 2 exhaust pipes and get them up high enough. Yes it has been done many times before... Yes I have true duals on mine... No, no one that has true duals are 100% happy with the fit and finish.
And really unless you are making 500+ HP there is no point performance wise to run true duals. A good aftermarket Y pipe and single 2.75" to 3.5" pipe will support the power most are making with no loss.
As far as rebuilding a rear end.. Parts will run $300-500 and labor will be about $350-500
A junkyard, part out guy, craigslist, etc rear end will be $100-500
No room under the car to fit 2 exhaust pipes and get them up high enough. Yes it has been done many times before... Yes I have true duals on mine... No, no one that has true duals are 100% happy with the fit and finish.
And really unless you are making 500+ HP there is no point performance wise to run true duals. A good aftermarket Y pipe and single 2.75" to 3.5" pipe will support the power most are making with no loss.
As far as rebuilding a rear end.. Parts will run $300-500 and labor will be about $350-500
A junkyard, part out guy, craigslist, etc rear end will be $100-500
08-17-2015, 07:13 AM
#14
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Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: More HP on a budget
If you do a good 3.42 posi, headers and 3 in exhaust, and a shift kit for that 700r4 it will make your driving experience much better. 300HP..NO, but it will definitely be a good start maybe inside your budget.
08-17-2015, 09:38 AM
#15
Re: More HP on a budget
good to know I have options regarding carb vs keeping the TPI. Perhaps retaining the TPI will do just fine for the mild build I'm after. I'd only go to carb if I needed to, to get the my power goal. I'll need to read up on setting up the chip for proper tuning. Looks like there's a wealth of knowledge on this forum on the topic. Should make for some good reading!
08-17-2015, 11:51 PM
#16
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
What is the endgame with your car? You want a weekend/track car or a more practical yet fun daily? My Roc is bone stock right now and I want to get more oomph than the 220hp she's got....BUT she is going to be my daily for a while so I don't want HORRIBLE gas mileage, I don't want to have a motor that needs constant tuning and adjusting and I damn sure can't afford to be dropping moogoo bucks into her right now. Therefore a set of headers, true dual exhaust, shift kit and beefing up the rear are all of the mods I will be doing. Tpi's are moody bitches from what I've heard when it comes to messing with their air to fuel ratio.
Maybe consider an engine swap?
Maybe consider an engine swap?
08-18-2015, 12:08 AM
#17
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
True dual exhaust on these cars are a pain in the butt to do and to drive/use.
No room under the car to fit 2 exhaust pipes and get them up high enough. Yes it has been done many times before... Yes I have true duals on mine... No, no one that has true duals are 100% happy with the fit and finish.
And really unless you are making 500+ HP there is no point performance wise to run true duals. A good aftermarket Y pipe and single 2.75" to 3.5" pipe will support the power most are making with no loss.
As far as rebuilding a rear end.. Parts will run $300-500 and labor will be about $350-500
A junkyard, part out guy, craigslist, etc rear end will be $100-500
No room under the car to fit 2 exhaust pipes and get them up high enough. Yes it has been done many times before... Yes I have true duals on mine... No, no one that has true duals are 100% happy with the fit and finish.
And really unless you are making 500+ HP there is no point performance wise to run true duals. A good aftermarket Y pipe and single 2.75" to 3.5" pipe will support the power most are making with no loss.
As far as rebuilding a rear end.. Parts will run $300-500 and labor will be about $350-500
A junkyard, part out guy, craigslist, etc rear end will be $100-500
08-18-2015, 10:28 AM
#19
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Car: 87 Monte Carlo SS
Engine: 89 350TPI Transplant
Transmission: 2004r
Axle/Gears: 3.73
Re: More HP on a budget
Certain year f-bodies, not sure of the year, had a dual catalytic converter setup. If you could find one of those I'm sure it would help along with the other member's suggestion of headers and bigger y-pipe.
08-18-2015, 05:42 PM
#20
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Re: More HP on a budget
What kind of emission testing do they do in Albuquerque?
This can affect which direction you should go.
This can affect which direction you should go.
08-18-2015, 11:37 PM
#21
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
How about removing the catalytic converter? Does that decrease efficiency? I think they help ensure the gas is completely burned. Heard that removing it can improve on HP a bit.
08-19-2015, 12:09 AM
#23
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
One more idea... just hypothetical... What all goes into stroking the engine? My understanding (and could be wrong) of stroking is you replace the crankshaft with one that allows longer travel of the piston in the cylinder, thus creating more volume in the original cylinders. Obviously this would require a new crankshaft and longer connecting rods I'd assume (and probably pistons). What else would need to be upgraded? Would this create a design imbalance? Would compression drop so much that it's a bad idea? Or create a whole lot of HP? In a common setup of a stroked 305, how many cubic inches would it end up at?
08-19-2015, 12:45 AM
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Car: 1988 Camaro
Engine: 355, 10.34:1, 249/252 @.050", IK200
Transmission: TH-400, 3500 stall 9.5" converter
Axle/Gears: Ford 9", detroit locker, 3.89 gears
Re: More HP on a budget
At that point swapping to a 350 would be a much better idea and cheaper and give better results.
You are correct on the concept of stroking an engine.. You install a crank with a longer stroke (the length it pushes the rods/pistons up and down)
To do this you will need a new crank, and pistons. Of course new bearings, rings, gaskets as well.
Rod length does not effect the C.I.D of an engine.
Plus you will need to clearance the block (grind) spots where the bigger crank now hits. Like block oil pan rails, bottom of cylinder walls, etc
You will also need to clearance the rods or buy aftermarket "stroker clearanced" rods.
Then have the rotating assembly balanced.
Compression goes up, not down with a stroker due to the increase in stroke length
The common 305 stroker build is bored .030" over and a 3.75" stroke crank added, giving you 334 c.i.d
You can buy a good used 1996-2001 L31 vortec 350 out of a wrecked truck/SUV for $300-800 with 160K miles or less on it. Stock it had 255 HP.
Add a performer rpm vortec intake or summit stage II or III intake, skip white HEI dist., Small cam upgrade, valve springs to match, headers, 600-670 cfm carb and be at 325-350 HP
All for less than what it will cost you to build the 334 short block (short block means no heads or intake)
You are correct on the concept of stroking an engine.. You install a crank with a longer stroke (the length it pushes the rods/pistons up and down)
To do this you will need a new crank, and pistons. Of course new bearings, rings, gaskets as well.
Rod length does not effect the C.I.D of an engine.
Plus you will need to clearance the block (grind) spots where the bigger crank now hits. Like block oil pan rails, bottom of cylinder walls, etc
You will also need to clearance the rods or buy aftermarket "stroker clearanced" rods.
Then have the rotating assembly balanced.
Compression goes up, not down with a stroker due to the increase in stroke length
The common 305 stroker build is bored .030" over and a 3.75" stroke crank added, giving you 334 c.i.d
You can buy a good used 1996-2001 L31 vortec 350 out of a wrecked truck/SUV for $300-800 with 160K miles or less on it. Stock it had 255 HP.
Add a performer rpm vortec intake or summit stage II or III intake, skip white HEI dist., Small cam upgrade, valve springs to match, headers, 600-670 cfm carb and be at 325-350 HP
All for less than what it will cost you to build the 334 short block (short block means no heads or intake)
08-19-2015, 07:13 PM
#25
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
At that point swapping to a 350 would be a much better idea and cheaper and give better results.
You are correct on the concept of stroking an engine.. You install a crank with a longer stroke (the length it pushes the rods/pistons up and down)
To do this you will need a new crank, and pistons. Of course new bearings, rings, gaskets as well.
Rod length does not effect the C.I.D of an engine.
Plus you will need to clearance the block (grind) spots where the bigger crank now hits. Like block oil pan rails, bottom of cylinder walls, etc
You will also need to clearance the rods or buy aftermarket "stroker clearanced" rods.
Then have the rotating assembly balanced.
Compression goes up, not down with a stroker due to the increase in stroke length
The common 305 stroker build is bored .030" over and a 3.75" stroke crank added, giving you 334 c.i.d
You can buy a good used 1996-2001 L31 vortec 350 out of a wrecked truck/SUV for $300-800 with 160K miles or less on it. Stock it had 255 HP.
Add a performer rpm vortec intake or summit stage II or III intake, skip white HEI dist., Small cam upgrade, valve springs to match, headers, 600-670 cfm carb and be at 325-350 HP
All for less than what it will cost you to build the 334 short block (short block means no heads or intake)
You are correct on the concept of stroking an engine.. You install a crank with a longer stroke (the length it pushes the rods/pistons up and down)
To do this you will need a new crank, and pistons. Of course new bearings, rings, gaskets as well.
Rod length does not effect the C.I.D of an engine.
Plus you will need to clearance the block (grind) spots where the bigger crank now hits. Like block oil pan rails, bottom of cylinder walls, etc
You will also need to clearance the rods or buy aftermarket "stroker clearanced" rods.
Then have the rotating assembly balanced.
Compression goes up, not down with a stroker due to the increase in stroke length
The common 305 stroker build is bored .030" over and a 3.75" stroke crank added, giving you 334 c.i.d
You can buy a good used 1996-2001 L31 vortec 350 out of a wrecked truck/SUV for $300-800 with 160K miles or less on it. Stock it had 255 HP.
Add a performer rpm vortec intake or summit stage II or III intake, skip white HEI dist., Small cam upgrade, valve springs to match, headers, 600-670 cfm carb and be at 325-350 HP
All for less than what it will cost you to build the 334 short block (short block means no heads or intake)
Cool - thanks for clarifying the stroke concept. It does indeed sound very involved and expensive.
Perhaps I would consider swapping to a 350 after all. I read up on the 305->350 threads and it sounds like there not much that needs to change (can re-use the same 700R4 and rear diff). Sounds like I mostly just need new sensors and fuel injectors (I'm sure I'm leaving off some items).
Funny I started this thread thinking $1000 budget, now I'm considering a swap to a 350... though in my defense I thought a ton of stuff would need to change for a swap.
Question: what 350 should I use (sounds like many will fit)? What years/vehicles can I get the engine out of and have it install properly (ie: compatible with the 700R4 and TPI for a 1990)? I hear in general it's best to go with the latest model to take advantage of all the modern improvements.
Thanks!
08-20-2015, 12:12 AM
#26
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Car: 1988 Camaro
Engine: 355, 10.34:1, 249/252 @.050", IK200
Transmission: TH-400, 3500 stall 9.5" converter
Axle/Gears: Ford 9", detroit locker, 3.89 gears
Re: More HP on a budget
Your welcome.
The 305 to 350 swap is very easy.. If one fits, so does the other. It is pretty much pull off/out, bolt in/up type of swap.
As far as the block goes, needed mounting holes, etc. From 1957 to 2001 SBC gen 1 engines are all the same. If one fits the others will too.
The SBC did change some over the years and will cause some slight issues
86 and up has the 1 pc. rear seal and the takes a diff. flexplate/flywheel from the 55-85 engines. That can be worked around if needed though.
They have center bolt valve cover heads, and also the 86-95 has the 4 center intake bolt holes at a diff. angle than the older ones.. The 96-02 vortec heads don't even have the 4 center intake bolt holes.
You can swap heads back and forth on these engines. You can take say a 1969 350 and put your heads, and intake and TPI right over onto it.
I really recommend the 96-01 L31 truck vortec 350's cause they have roller cam, flat top pistons, PM rods, and great flowing heads, but keeping the TPI can get alittle pricey due to the vortec heads only having 8 intake bolts. So you would need a TPI intake base for vortec heads which is like $500
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
The 305 to 350 swap is very easy.. If one fits, so does the other. It is pretty much pull off/out, bolt in/up type of swap.
As far as the block goes, needed mounting holes, etc. From 1957 to 2001 SBC gen 1 engines are all the same. If one fits the others will too.
The SBC did change some over the years and will cause some slight issues
86 and up has the 1 pc. rear seal and the takes a diff. flexplate/flywheel from the 55-85 engines. That can be worked around if needed though.
They have center bolt valve cover heads, and also the 86-95 has the 4 center intake bolt holes at a diff. angle than the older ones.. The 96-02 vortec heads don't even have the 4 center intake bolt holes.
You can swap heads back and forth on these engines. You can take say a 1969 350 and put your heads, and intake and TPI right over onto it.
I really recommend the 96-01 L31 truck vortec 350's cause they have roller cam, flat top pistons, PM rods, and great flowing heads, but keeping the TPI can get alittle pricey due to the vortec heads only having 8 intake bolts. So you would need a TPI intake base for vortec heads which is like $500
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
08-20-2015, 09:47 AM
#27
Re: More HP on a budget
I really recommend the 96-01 L31 truck vortec 350's cause they have roller cam, flat top pistons, PM rods, and great flowing heads, but keeping the TPI can get alittle pricey due to the vortec heads only having 8 intake bolts. So you would need a TPI intake base for vortec heads which is like $500
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
Best bang per dollar. If you buy a new one through Summit, Jegs or the like you get a warranty too.
08-20-2015, 09:57 AM
#28
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Car: 92 RS
Engine: Sbc With h/c/i/e holly4150
Transmission: 700r
Re: More HP on a budget
Check out some of my post and maybe that will help you out.
305 with largest cam possible, Intake, holley carb, headers, full exhaust
https://www.thirdgen.org/forums/carb...carb-swap.html
4th gen posi rear swap
https://www.thirdgen.org/forums/tran...rear-swap.html
And after spending about 2500$ still slower than a lt1 4th gen
I know it gets said a lot but don't waste your money. Put a 350 in it (1st hand experience)
305 with largest cam possible, Intake, holley carb, headers, full exhaust
https://www.thirdgen.org/forums/carb...carb-swap.html
4th gen posi rear swap
https://www.thirdgen.org/forums/tran...rear-swap.html
And after spending about 2500$ still slower than a lt1 4th gen
I know it gets said a lot but don't waste your money. Put a 350 in it (1st hand experience)
08-20-2015, 06:02 PM
#29
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
Your welcome.
The 305 to 350 swap is very easy.. If one fits, so does the other. It is pretty much pull off/out, bolt in/up type of swap.
As far as the block goes, needed mounting holes, etc. From 1957 to 2001 SBC gen 1 engines are all the same. If one fits the others will too.
The SBC did change some over the years and will cause some slight issues
86 and up has the 1 pc. rear seal and the takes a diff. flexplate/flywheel from the 55-85 engines. That can be worked around if needed though.
They have center bolt valve cover heads, and also the 86-95 has the 4 center intake bolt holes at a diff. angle than the older ones.. The 96-02 vortec heads don't even have the 4 center intake bolt holes.
You can swap heads back and forth on these engines. You can take say a 1969 350 and put your heads, and intake and TPI right over onto it.
I really recommend the 96-01 L31 truck vortec 350's cause they have roller cam, flat top pistons, PM rods, and great flowing heads, but keeping the TPI can get alittle pricey due to the vortec heads only having 8 intake bolts. So you would need a TPI intake base for vortec heads which is like $500
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
The 305 to 350 swap is very easy.. If one fits, so does the other. It is pretty much pull off/out, bolt in/up type of swap.
As far as the block goes, needed mounting holes, etc. From 1957 to 2001 SBC gen 1 engines are all the same. If one fits the others will too.
The SBC did change some over the years and will cause some slight issues
86 and up has the 1 pc. rear seal and the takes a diff. flexplate/flywheel from the 55-85 engines. That can be worked around if needed though.
They have center bolt valve cover heads, and also the 86-95 has the 4 center intake bolt holes at a diff. angle than the older ones.. The 96-02 vortec heads don't even have the 4 center intake bolt holes.
You can swap heads back and forth on these engines. You can take say a 1969 350 and put your heads, and intake and TPI right over onto it.
I really recommend the 96-01 L31 truck vortec 350's cause they have roller cam, flat top pistons, PM rods, and great flowing heads, but keeping the TPI can get alittle pricey due to the vortec heads only having 8 intake bolts. So you would need a TPI intake base for vortec heads which is like $500
But again you can swap your heads and intake over onto the vortec engine. The vortec heads will make 30-40 HP more than your current heads though. So that $500 price tag don't sound so bad really.
If i want that rugged drag car sound im assuming i need a better cam. Can you recommend a good cam for the L31 vortec?
08-20-2015, 06:11 PM
#30
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
Good to know. Seems like everytime i check their 350s it says "only for 196x or older" or something. if you get a chance can you send me a link to one that would work ('01 L31 vortec)? I am skeptical about getting one from a junkyard... this sounds like a big project (for me) and i dont want to put in something questionable and have to do it over again or worse yet- never get it going and give up. Plus a warrenty sounds nice.
08-20-2015, 06:14 PM
#31
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
Check out some of my post and maybe that will help you out.
305 with largest cam possible, Intake, holley carb, headers, full exhaust
https://www.thirdgen.org/forums/carb...carb-swap.html
4th gen posi rear swap
https://www.thirdgen.org/forums/tran...rear-swap.html
And after spending about 2500$ still slower than a lt1 4th gen
I know it gets said a lot but don't waste your money. Put a 350 in it (1st hand experience)
305 with largest cam possible, Intake, holley carb, headers, full exhaust
https://www.thirdgen.org/forums/carb...carb-swap.html
4th gen posi rear swap
https://www.thirdgen.org/forums/tran...rear-swap.html
And after spending about 2500$ still slower than a lt1 4th gen
I know it gets said a lot but don't waste your money. Put a 350 in it (1st hand experience)
I think im a 350 convert
08-21-2015, 12:23 PM
#32
Re: More HP on a budget
Good to know. Seems like everytime i check their 350s it says "only for 196x or older" or something. if you get a chance can you send me a link to one that would work ('01 L31 vortec)? I am skeptical about getting one from a junkyard... this sounds like a big project (for me) and i dont want to put in something questionable and have to do it over again or worse yet- never get it going and give up. Plus a warrenty sounds nice.
08-22-2015, 12:41 PM
#33
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Car: 87 Iroc
Engine: modified 350
Transmission: high performance built 700R4
Axle/Gears: Strange S60 3:73
Re: More HP on a budget
Buy this motor put a bigger cam in it and you will have a smile from ear to ear.
08-24-2015, 07:47 PM
#34
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
If I already have a rear diff with POSI and 28 splines (but low gears - 2.73), is it still recommended to replace the entire assembly with something from the junk yard? I'd like to get 3.73 gears and keep the POSI/28 spline. Also my existing rear diff has drum brakes so I tend to think finding a 28 spline/POSI/3.73/drum setup is going to be a toughy to find at the junk yard. I got a rough estimate earlier in this thread for rebuilding the rear diff... is that ONLY for upping the gears though??
08-24-2015, 08:06 PM
#35
Re: More HP on a budget
You have got the 10bolt rear from '90-'92 with 28 spline axles - which is just as strong as a 4th gen rear. The 4th gen rear is just little wider than a 3rd gen rear.
Still If you can find a posi disc brake rear with 3.23 or 3.42 gears from another '90-'92 f-body or a 4th gen rear you will be better off with the larger rotors and pbr style calipers.
3.73 gears are a little steep for a TPI car but it will have a lot of punch down low and in the mid range. With that gear set and the 3.06 1st gear in the 700r4 traction will become a problem to contend with on the street.
Still If you can find a posi disc brake rear with 3.23 or 3.42 gears from another '90-'92 f-body or a 4th gen rear you will be better off with the larger rotors and pbr style calipers.
3.73 gears are a little steep for a TPI car but it will have a lot of punch down low and in the mid range. With that gear set and the 3.06 1st gear in the 700r4 traction will become a problem to contend with on the street.
08-25-2015, 10:29 AM
#36
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
Yaj15 - would 3.42 be better than 3.73 for launching off the line, due to better traction? I want to be able to launch well from the line and im not too interested in top speed. I figure 100mph is the fastest i'd ever go.
08-25-2015, 11:05 AM
#37
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Car: 92 RS
Engine: Sbc With h/c/i/e holly4150
Transmission: 700r
Re: More HP on a budget
3.73 would give you a better launch and with a good set of tires you will be ok. my 4th gen with 275/40 nitto 555r will only spin if I dump the clutch and it makes 423hp at the wheels
08-25-2015, 12:12 PM
#38
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Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: More HP on a budget
You put 3.73s in there and you will hit the speed limiter faster than you will hit the 1/4 mile unless you get it deleted in the chip or change your vss out to correct your MPH gauge. 3.42s will be plenty. Actually just better all around for low RPM powerband cars like 3rd gens. Ive got 3.73s and im fixing to go down to 3.23s. 3.73s do make it launch good but its a lil too much in my opinion unless you have a bigger cam and an engine that can breathe past 4500 rpm. If spinning gives you a problem those Nitto drag radials are great and you can get em in 245-50-16s.
08-25-2015, 12:30 PM
#39
Re: More HP on a budget
Yes like the other members have said. 3.42's are really all you need to go to with these lower rpm style motors. If you were putting in a motor that had a higher operating power band (LS motor or small block with a mini ram intake) then 3.73's would make more sense then.
08-25-2015, 07:14 PM
#40
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Car: 1990 GTA (T-Top)
Engine: 305 TPI (LB9) / 115k miles
Transmission: 4L60 (MD8 non-E)
Axle/Gears: 2.73 (GU2) 28 spline POSI (G80)
Re: More HP on a budget
cool. I'll plan to either go with 3.42 or 3.73. I'm thinking if I go through the trouble of swapping to a 350 I may as well put in the LT4 hotcam and the 1.6 rockers for the extra lift. I heard this is possible in a different thread and will still fit under the valve covers.
Can anyone recommend good headers/catback and fuel injectors to use with this setup?
Regarding the chip, what all is configurable? I imagine the fuel injector settings would be one, spark plug timing another, and sounds like speed limiter is yet another, but what else are no-brainer items to modify when I get a chip burned?
Can anyone recommend good headers/catback and fuel injectors to use with this setup?
Regarding the chip, what all is configurable? I imagine the fuel injector settings would be one, spark plug timing another, and sounds like speed limiter is yet another, but what else are no-brainer items to modify when I get a chip burned?
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