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I would like to get some opinions and /or questions answered from the experienced Turbo guys on this forum.
I am thinking of installing a T76 Turbo on a stock 350 TPI with a T5 trans 3.45 rear axle.
The car will be 99% street driven and will run at 10-12 psi.
What RPM will the Turbo spool up on this stock motor ?
Will it be a dog off the line, lack power with a T5 behind it ?
Is this Turbo too big for a stock 350Tpi, by the time it spools up, will I be at or too close to red line on a TPI ?
I know the TPI is restricted and it will be replaced, but for now it and I are on a budget.
Thank you for your input !.
I dont have any experience with TPI stuff but know they dont like the RPM much. which "t76" are you thinking? If you are staying budget minded a ON3 76 will do the trick. the older 65mm turbine will work nicely on a tpi setup since you wont be reving too high but it may still cause backpressure issues up top. They make a 75 or 76mm turbine side now thats a direct replacement that will give you that upper flow. But it will be slightly more laggy. I would say a .96 76mm with a 65mm turbine will do the trick quite nice for a stock 350 tpi 5 speed car.
It will be fine on a 350. I have same turbine side on my 305 but the compressor is a 70. Its in the rear and it hits 10 psi pretty quick on a wot downshift. It was making boost by 2300 rpm stock auto stall, but since i gutted cat it stopped doing that. So i gotta make a straight cat delete pipe and wrap exhaust to get that spool back but it still is fun on the street
Its a .96 ar. If i want alot quicker action i can go .68 but it may start to choke the top end some. .81 would be perfect but there are no china based .81s that i know of. Turbonetics would be next cheapest option for a .81
I would like to get some opinions and /or questions answered from the experienced Turbo guys on this forum. I am thinking of installing a T76 Turbo on a stock 350 TPI with a T5 trans 3.45 rear axle. The car will be 99% street driven and will run at 10-12 psi. What RPM will the Turbo spool up on this stock motor ? Will it be a dog off the line, lack power with a T5 behind it ? Is this Turbo too big for a stock 350Tpi, by the time it spools up, will I be at or too close to red line on a TPI ? I know the TPI is restricted and it will be replaced, but for now it and I are on a budget. Thank you for your input !
The only drawback for the T5 is the weight of the vehicle in conjunction with the amount of power you're putting through it, which is why it is imperative that you ease it off of the line before getting into it. Once the vehicle has the momentum with moving, then it will be easier on the transmission, and you can be harder on it, so it will live quite awhile if you drive it this way. If you launch it hard, it will succumb right away...
The 3.45's are fine. You're able to control your RPM, so once you get a feel for what the engine likes, when boost kicks in and in which gear, you will be able to use that to your advantage for a much better driving experience.
Selecting a turbo, ideally it is best to pay for a dyno run (not a tune, just a run) to get an idea of what you are working with ahead of time, as this will better help you in selecting the turbo you need, not necessarily want. You're already aware that the runners are restrictive causing a restriction in RPM, but the turbo will increase that restriction, but at a price, so it becomes a balance of just enough turbo, but not so little to cause excessive heat, and not too large causing too much lag. Lag is the result of an engine not producing enough horsepower to spin the turbo, there is simply not enough exhaust pressure, as we're talking about a stock engine here. In the end you will more than likely do the opposite of what I am saying, meaning you will pick the turbo that you want, not the one the engine necessarily needs. Remember, any turbo will give you the boost pressure you need, it is just a resistance measure, it is the size though that will dictate too much hot air, or too much lag. There are remedies for both situtations (alky and anti-lag) but if you pick the right turbo ahead of time, you won't need to go that route...
You want a T76... but in my opinion it needs 60-1 turbo w.81 a/r.
Selecting a turbo, ideally it is best to pay for a dyno run (not a tune, just a run) to get an idea of what you are working with ahead of time, as this will better help you in selecting the turbo you need, not necessarily want. Yo
Not sure what you mean by this? Are you saying call shops looking for graphs of similar combos to get an idea of what the power curve looks like? Not as likely to find that information there but most likely find it on internet forums. Look for 5.0 ford guys and late model truck 4.8-5.3 guys as a guide. Not as many ppl do sbc stockers with snails
Maybe lt1 guys.
76 is alittle large compressor esp mated to 65 mm turbine. 60-66 mm would make better power per spool rpm and wheel size, in other words more effective wheel size for the application, but its easier to find cheap 70-76's. I think a 70 would be great on a stock l98. My 305 seems to like it and its rear mounted which is worse for spool
He's got a stock cammed L98, so he's looking at 4500 to 5k MAX shift.
He wants something that will be in boost as low as possible.
I was thinking like a T70 or something.
Do you think the T76 is going to spool quick enough, especially in a manual trans car ? I was guessing around 3,000 RPM for a stock L98.
He doesn't want it to be a stone leaving every stop light.
-- Joe
I would avoid the T76 turbo idea entirely if I were him, it's just a size that seems to get thrown around and people just gradually levitate towards it. I think with the smaller .81 a/r combined with the engine making roughly 220-230 horsepower naturally aspirated, he should see boost come in well under 3000-RPM in first gear. His cast assembly and stock valve springs are definitely more of a concern than that restrictive TPI. At his targeted boost pressure, he should be at 400 horsepower, the springs should hold with that amount of pressure, but he is right on the borderline of what a stock engine can handle, which is why he should toss the better intake concept out of the window until he has stronger springs, and a better cam to maximize the intake swap. He's limited to 400-450 horsepower with a stock bottom end, and even that much it pushing the issue. We normally see 3.8 GN's running 60-1 with a slightly smaller exhaust impeller seeing boost at about 2800-RPM with 3.42's out back, and those engine's make a lot less naturally aspirated...
Not sure what you mean by this? Are you saying call shops looking for graphs of similar combos to get an idea of what the power curve looks like?
No, what I am saying is having an engine dynoed to see what you are starting with is one of the first things a person should do to see what they, the individual, is working with. You cannot expect the exact same results copying another person's build from other websites, there are way too many variables. I don't feel comfortable telling him so and so did this, or I know this guy that did that. He has an engine with what appears to be a stock L98. A dyno will tell him a lot; if the heads were touched, if the cam was touched, etc, but if he has access to a datalogger, than that is just as good as it will give him hi fueling consumption, approximating horsepower. I honestly don't pick turbo's on engine size alone, again, way too many variables in my opinion. But to each their own I guess...
Oh ok that makes sense. Yeah from there you can easily get better data on sizing the compressor.
Your cheap china 76's are all capable of 500whp or so. Most that have the 65mm turbine are the limiting factor. Cant pass the flow. A similar 64mm comp and 65 turbine could likely make same power and spool quicker. My 6065 made same power as 7065's when i had them in my first combo
Just not sure who makes a reliable cheap 60-66mm anymore other than maybe gt45, and the borg s366 but both have a 71-73 ish mm turbine i believe. Likely would work well mounted up front with proper exhaust piping but it is a physically larger unit in the s366. Not sure on the gt45
Ptrim 65 mm turbines have been killer on 5.0 liter motors in the 400-550 whp range. Mild L98 shouldnt be too far behind that
I'm running this on a high compression 327 with TPI and have no complaints. I have an auto with low stall converter and it'll brake boost to 5 psi in 3-4 seconds at 2300ish rpm's. I am only running 9 lbs presently, but it spools to that in a hurry. It would seem that your lower compression and 20 additional ci would equate into similar performance.
I would avoid the T76 turbo idea entirely if I were him, it's just a size that seems to get thrown around and people just gradually levitate towards it. I think with the smaller .81 a/r combined with the engine making roughly 220-230 horsepower naturally aspirated, he should see boost come in well under 3000-RPM in first gear.
..
Street, can you explain this to me more. The Turbo has an .80 a/r . What if I did a cam change to help the 76mm along, will it help ?, what cam ?. Will I see boost well under 3000rpm ?.
I hear you on the spring change and will budget that in.
Thanks
Last edited by cheesehomer; 09-28-2015 at 10:11 PM.
Street, can you explain this to me more. The Turbo has an .80 a/r . What if I did a cam change to help the 76mm along, will it help ?, what cam? Will I see boost well under 3000rpm ?.
I hear you on the spring change and will budget that in. Thanks
There is no need for a cam change, as remember, you're dealing with cast parts and are limited to 400-450 horsepower with conservative timing and cool air temps to avoid detonation. Yes, you will see boost come in before 3000-RPM with the turbo I recommended. The stock springs gave up the ghost in my application at about 450 horsepower, and RPM dropped. If your engine is making over 200 horsepower to the wheels stock, then 15-psi using any turbo is your stock short block's limit, so pick a turbo that will not lag or overheat to get you there. That is a solid eleven second car making that much power, and will waste most of what you come across on the street from a roll with no problem. A 60-1 turbo is not a gigantic turbo, but you don't need gigantic in your situation, you just need one to get you where you want to go, not exceeding your limit, and with what you already have. The idea is to balance what you already have with what you need to get you there without having to sacrifice anything. It's like member's wanting a gigantic camshaft then spending the rest of their build working around it to make it work, while sacrificing drive-ability with the ridiculous argument of; "streetable is in the eyes of the builder", which is just another way of saying I went too big, but won't admit it. Again, using who I learned from, and what they run, a bone stock Grand National will run 12's all day long with the teenie tiny stock turbo and larger injectors, and some have run in the 11's by pushing the issue. One teenie tiny step up to a TE44 turbo and they're running in the 10's shifting at the same RPM as you would even with the Tuned Port Injection, and it takes five hundred plus horsepower to get to that 1/4 mile number, a number which well exceeds your stock L98 short block's limitation. Knowing this fact, suddenly a 60-1 seems a little too big for your engine...
and it takes five hundred plus horsepower to get to that 1/4 mile number, a number which well exceeds your stock L98 short block's limitation. Knowing this fact, suddenly a 60-1 seems a little too big for your engine...
What part of the bottom end is going to give, or have you seen at 500hp? Rod, crank, block, or a combination of? Are you talking crank HP or RWHP?
There is no need for a cam change, as remember, you're dealing with cast parts and are limited to 400-450 horsepower with conservative timing and cool air temps to avoid detonation. Yes, you will see boost come in before 3000-RPM with the turbo I recommended. The stock springs gave up the ghost in my application at about 450 horsepower, and RPM dropped. If your engine is making over 200 horsepower to the wheels stock, then 15-psi using any turbo is your stock short block's limit, so pick a turbo that will not lag or overheat to get you there. That is a solid eleven second car making that much power, and will waste most of what you come across on the street from a roll with no problem. A 60-1 turbo is not a gigantic turbo, but you don't need gigantic in your situation, you just need one to get you where you want to go, not exceeding your limit, and with what you already have. The idea is to balance what you already have with what you need to get you there without having to sacrifice anything. It's like member's wanting a gigantic camshaft then spending the rest of their build working around it to make it work, while sacrificing drive-ability with the ridiculous argument of; "streetable is in the eyes of the builder", which is just another way of saying I went too big, but won't admit it. Again, using who I learned from, and what they run, a bone stock Grand National will run 12's all day long with the teenie tiny stock turbo and larger injectors, and some have run in the 11's by pushing the issue. One teenie tiny step up to a TE44 turbo and they're running in the 10's shifting at the same RPM as you would even with the Tuned Port Injection, and it takes five hundred plus horsepower to get to that 1/4 mile number, a number which well exceeds your stock L98 short block's limitation. Knowing this fact, suddenly a 60-1 seems a little too big for your engine...
My wife said she saw a "light Blub" over my head after I read this post.
Very true and it makes so much sense.!
Will that turbo be MAXed out ? or pushed to its limit's , but you are saying, so will my bottom end at 450hp.
Originally Posted by project89
id put a 66 or 70 on it 76 will work but may spool a lil bit slow
or a gt45 with a quick spool valve
I know you have had experience with that size of turbo, but it was in a twin format. Can I ask your reasoning in suggesting a 66 or 70 ?.
I want to thank everyone for their two cents, I very much appreciate it.!
Big learning curve for me on this build.
George
What part of the bottom end is going to give, or have you seen at 500hp? Rod, crank, block, or a combination of? Are you talking crank HP or RWHP?
The rod hardware.
The pistons.
Back when I was young and poor and had to use stock parts, those were the things that would break for me.
Now I just break stuff by being stupid.
Though RPM probably won't cause a rod issue, almost all of us have had detonation either from a very cold night at the track of a burp somewhere else. Cast pistons turn into dust
I know you have had experience with that size of turbo, but it was in a twin format. Can I ask your reasoning in suggesting a 66 or 70 ?.
I want to thank everyone for their two cents, I very much appreciate it.!
Big learning curve for me on this build.
George
i ran twin 57's with t3 turbines , the cold side wheels were capable of more power then the turbine wheels could flow, if the turbines could have kept up they would have been good for 900 ish hp
a single old school garett t66 will do around 650hp at max efficiancy and peak at 750-800ish with efficiancy dropping fast ,
the new school compressor wheels are much more efficiant and move more air for a stock tpi u really dont need a much larger wheel
the nice thing about sometimes going larger is that u useually make more power at lower boost numbers cause the turbo flows more
ill take fasteddis and my v6 car for example both of us ran the 57mm units on our 3.1's at 16+ psi the cars would run high 12's
we both later swaped to 61mm turbos him a gt3582 and me an old school t61 , cars then went low 12;s at about half the boost presure as before
Back when I was young and poor and had to use stock parts, those were the things that would break for me.
Now I just break stuff by being stupid.
Though RPM probably won't cause a rod issue, almost all of us have had detonation either from a very cold night at the track of a burp somewhere else. Cast pistons turn into dust
-- Joe
Thanks. I'm constantly wondering how far my 45+ year old 2 bolt block and crank can go and how much it will take. I've got aftermarket rods and pistons (forged) so hopefully.......time will tell.
Thanks. I'm constantly wondering how far my 45+ year old 2 bolt block and crank can go and how much it will take. I've got aftermarket rods and pistons (forged) so hopefully.......time will tell.
OP - I don't want to hijack your thread:/
search on the turboforums.com for the grenade thread
marty is also a member here bone stock 2 bolt block into the 8's with tpi , the motor is still alive to this day now turned down a lil bit in another car
this is an example of a well tuned and thought out engine/turbo combo and how much the tune matters in making one of theese things live
My Turbonetics 62-1 1.0 a/r exhaust housing worked well for my setup. It got me into the 10's, and spooled super quick. My car is automatic with a stall tho. My current Turbonetics HP76mm spools slightly slower, but pulls a lot harder up top. I think for a stock L98 a 60-1 or 62-1 would be ideal.
Either the T70 or T76 will be fine. Since it has the T5 I would go with the T70.
If you look at the comp maps, both wheels will be in the "happy" zone for a stock 350 TPI.
I have one stock 305ci with a T70 comp, 1.28 A/R T6 (not T4) turbine. It spools at about 2300 RPM and will make about 4-5 PSI of boost on the foot brake.
Would a smaller wheel work? Yes it would. But the china T70 or T76 are cheap and widely available.
Lots of the china turbos have mismatched compressor/turbine setups. Look at the outlet pipes on the T70 and T76 turbos. 3" outlet is way too small. Doesn't even meet the rule of thumb for out pipe size vs turbine wheel size.
Either the T70 or T76 will be fine. Since it has the T5 I would go with the T70.
If you look at the comp maps, both wheels will be in the "happy" zone for a stock 350 TPI.
I have one stock 305ci with a T70 comp, 1.28 A/R T6 (not T4) turbine. It spools at about 2300 RPM and will make about 4-5 PSI of boost on the foot brake.
Would a smaller wheel work? Yes it would. But the china T70 or T76 are cheap and widely available.
Lots of the china turbos have mismatched compressor/turbine setups. Look at the outlet pipes on the T70 and T76 turbos. 3" outlet is way too small. Doesn't even meet the rule of thumb for out pipe size vs turbine wheel size.
The outlet's on the chinese T70 and T76 are 2.5". I always thought they were kinda small too.
Would a smaller wheel work? Yes it would. But the china T70 or T76 are cheap and widely available.
That was my reasoning. On3 and similar are available everywhere for cheap. 280 shipped nib from a classified ad
Comp outlet is 2.50". Turbine down is 3.0". It may be small but can make 500-550 whp thru it. Idk what backpressure is but a couple local cars including mine have made between 800-1100 whp on the 64mm ptrim 3" downs. So 400-550 each. But thats on 6-7liter v8 twins. A 5.0 single could max that turbine out sooner.
Was hoping to see that with my rear 305 but i gotta do some work to the motor i think before i will see it. Ignition may be too weak, plug gap too wide and also cam may not be a L98 cam but may be a peanut. I havent checked lift yet
I found this in my local area and was wondering if I could get some advice if this will work well on a stock 305 or 350. The guy who owns it says he bought it with the car, but was never installed and doesn't know anything about it. I asked him to send me all the numbers that he can see on the housing of the turbo.
Turbocharger
A/R.60 T3/T4-1
serial no#KD0903068
Hot side
2 1/4 AM56CYS102
AR.63 M58 M3
I agree with Orr89 and Anesthes on using the cheap and reliable On3 or ebay equivalent 70mm or a 76mm...they sound like its a bit too big on paper but the the outlets are smaller.It would still spool quick being front mounted and you use 2.25/2.5 hotside piping.Boost will spool around 2500rpm..nothing crazy as i mentioned in our Pm's by a pound or 2.hey are cheap turbos that are easy to get and are extremely similiar parts to a turbonetics side by side.Mine has taking a serious beating and Im overevving my ls turbo shouldnt be running it over 6000rpm from backpressure and it spools and quick on the street and I have a 3.27 gear.
With the t5..your in the same boat as me..dont launch hard.You wont need to.Just come off the line nice and easy and then drop the hammer of Thor and it will rocket past most.My main concern is that all of us are guilty of the number one thing.We never are happy with what we got and eventually want more as we get comfortable with new power.If he is going to build a turbo setup..he is better to build it with upgrades to motor in mind.How long do you think a stock turbo tpi will quench your thirst before its turns into a turbo cam/headwork..and the worst one..I want more boost.Boost is addictive and things will happen as you learn to play with it.
Can someone HELP ! me understand how the same stock 350tpi engine will react and spool differently between the two sizes, 70m and 76m Turbo. I would think that such a vast difference in a compressor wheel on the same engine would make a HUGH impact in the end with spooling, lag, max rpm and end HP numbers OR am I just over reacting where the difference will be very minimal ???
I have read so many different builds and it's become so confusing to me.
I respect everyone's build's and appreciate all opinions.
Thanks George
Honestly between the 70 and 76 lag will probably be marginal and price is virtually the same.The 70mm would be more ideal for stock 305/350tpi..dont over think it.There are many other factors that affect the overall performance to worry about.You wont be sorry either way you go. Commit to one of then and start building.Id be more concerned about tires..clutch..rearend because once you have boost..all your going to do for the first while getting used to the car and ironing out the bugs is hitting boost every chance you get and lag wont be on your mind.You will make goobs of torque..out of boost the car should drive like stock which is still fun for a tpi and a t5.Im still suggesting you get a boost controller to start with which will fine tune things and wideband o2. there are many ideas here..there is no exact right or wrong which is why its hard to choose one.Every setup is different..some like the bigger is better or others like to be precise and build things to spec out perfectly for max performance and reliability..and then man of us just build with what we get our hands on..have some fun and learn and grow.
Can someone HELP ! me understand how the same stock 350tpi engine will react and spool differently between the two sizes, 70m and 76m Turbo. I would think that such a vast difference in a compressor wheel on the same engine would make a HUGH impact in the end with spooling, lag, max rpm and end HP numbers OR am I just over reacting where the difference will be very minimal ???
1st - the difference between 70 vs 76mm turbo is not 'VAST';
2nd - max rpm is going to be limited by the runners unless you pick an exhaust side that chokes off the exhaust flow from the header to the turbo. Most everyone has mentioned that the 70mm is NOT small enough to cause this. So, back to the runners - max rpm 50-5200
3rd - I can't offer any facts about spooling, lag or end HP numbers - only guesses (that you don't need)
I'm running the 76mm On3 with .96a/r exhaust side on a 327 with an auto. Be advised it's not too big. On launch with a 2400 stall I'm making 14psi at 3500. On the dyno it takes less than 1000 rpm's and 1.5 seconds to go from 99kpa (zero boost) to 14 psi. I do realize that your 5 speed is going hamper the boost build rate as compared to my motorat launch, but you have the advantage of more cubes to increase the amount of exhaust flow. Also keep in mind that my long block is not stock compression, head flow or cam (I think the cam is actaally hurting it though.)
UPDATE:
My luck, the Canadian dollar has taken a SH*T fall right when I decided to take on a turbo build, parts are very much cheaper in the USA.
So I have been eye balling all the local classifieds daily looking for parts to complete my build. I was able to purchase a lightly used Dynamic EBL for less than half of new. I have decided to go with a 70mm and use my current stock 305 in the car, learn, tune and probably blow up before building a turbo friendly 350.
I found a Hybrid t3/4 turbo 70mm chi-knee knock off on a local site and the owner doesn't know much about as he got it with a bunch of other stuff that he purchased.
I would like to ask your opinion about this turbo ..too small ??
-The housing on the cold side has A/R 70 M24 ,
a/r 70 I assume is the cold side wheel, what is the M24 ?
Would anyone know what the a/r for the hot side be ?
How could I find this out ..? no other numbers or markings on the housing.
Thanks George
those blue tag units were the first design/copy something with them isnt right , the ones that were water cooled were the worst , they would always burn up the bearings in them ,
those blue tag units were the first design/copy something with them isnt right , the ones that were water cooled were the worst , they would always burn up the bearings in them ,
I didn't buy it, Just noticed it in a local classified.
Thanks for the info '89, I'm going to stay far away from that one.
I also noticed a member has a set of 55lbs injectors on sale here. Would that be a good set to start with on the stock 305 and can I use them if I go to a stock 350 later ??
Anything for the 305 will carry over to the 350..i wouldnt factor in the 305 as part of the build since all of this will be going onto the 350 later.Tuning is what will keep everything happy.Any of those 3 turbos will work fine..the differences are are so close.Id pick the 70mm on3 for the stock 350 and call it a day..you will plenty other things to worry about once you have a turbo in your hands that will nickle and dime you to death..choosing the big parts and working around them is easy right now lol.
Anything for the 305 will carry over to the 350..i wouldnt factor in the 305 as part of the build since all of this will be going onto the 350 later.Tuning is what will keep everything happy.Any of those 3 turbos will work fine..the differences are are so close.Id pick the 70mm on3 for the stock 350 and call it a day..you will plenty other things to worry about once you have a turbo in your hands that will nickle and dime you to death..choosing the big parts and working around them is easy right now lol.
He has a complete kit custom for his thirdgen. He just needs the turbo itself, and to fabricate the downpipe.
From all the pm's and on this thread with Cheesehomer was there any mention of having any parts at all yet for the turbo build.If he had a full kit and just needed a turbo I doubt this thread would be this long to pick something..anything to get the car up and running with some boost on a budget turbo.
09-27-2015, 07:33 PM
