TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I just traded my toyota camry for a corvette with a cracked block(i was told it was just a bad head gasket), and it cant really be repaired. I cant afford a new or even remaned short block right now... but i have a 400 motor out of a stock car in my garage, with no carb. Can i take the tpi off my 350 and put it on my 400? i know the details are necessary for a good answer, but i only have a few. The guy i bought it from said it has Dart II heads( maybe iron eagle or WP, he swears theyre dart 2s). I think he said 64cc chambers, with 2.05 and 1.60 for valves. What i know about the cam is not so specific, He just said that it was really big. i also know it has domed pistons.
He seems to think it will not work, but i think he may have an alterior motive, He is still calling the engine "his". He said the crank wasnt right for my auto transmission and it would have no compression, and once i got it in i wouldnt drive it out of the garage. my dad thinks the crank is externally balanced, but idk what that would even mean.
Can anyone help me please? If more details are needed i will try to get them from him, just let me know. I dont want to race, i just need to drive!!
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Last edited by cwf3261; 10-22-2009 at 03:56 PM.
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I think your going to really have to know about that cam. If not it would be better to put one in you do know about. Unless you have the experience tuning chips, I would think about that before you get in to it.
I just talked to him about the cam. He again told me it was wayy too big. he said it had somewhere between 500-550 lift, and 280 duration. he said it had "no comp or anything like that". had Said it was a racing cam. Is he correct tellin me it wont work?
400s are externally balanced engines. If you look at the harmonic balancer, you'll see that it's got a big section missing on one side of it. Also, there is a counterweight on the flexplate. However, it should bolt to the trans fine, I had a 400 in my old 83, bolted up to a 700R4 with no problems.
I would think TPI could be made to work well on a 400. TPI doesn't do well at high rpm, and neither do 400's. Therefore, it seems to me like you would want to build a setup that would make good power below 4500-5000RPM, and set up for lots of low-end torque.
__________________ North Texas Third Gen Association 1988 GTA 5.0/M5/3.45 LSD, T-Tops, Digital Dash, Leather - Current Ride 1983 Firebird S/E - Stripped 1995 Chevy 1500 5.7 Ext. Cab - Daily Driver
Thanks for the quick reply.
I kind of figured i would be stuck with an all-torque machine. But if i were to do that would it be somewhat limiting the potential of the 400 block? Even if it was, it would still have more power than the same setup on a 350 right?
If it is true that the cam is not right and i would have no vacuum, could i take the stock vette cam out of my cracked 350 block and stick it in the 400 with good results, or should just get a new cam more tailored to my situation? If so can anyone recommend one?
I had a 400 in my tpi iroc for a few years and it ran great. Sure it ran outta air @ 4500 rpm and the nose of the car would fall.
So I just shifted at 4500. It ran high 8's in the 1/8 mile with an L-82 (old corvette) cam. It idled better with the stock 305 chip in it; but, It was a good bit faster with hypertech chip in it. Make sure that you use a 400 flex-plate.
I used 350 tpi injectors (24lb) and an adjustable fuel pressure regulator set @ 50psi. I then changed the injectors to 28lb SVO's; but, I never could tell the difference. It ran the same. It didnt really have any high-rpm power, but that thing was FUN. So much torque. I now have a rebuilt 350 in there and there was a good bit more low-rpm torque with the 400. I really liked it. The tpi is kinda like a 'restricter-plate' on a 350, much less a 400. But with factory rear-gears you will really like it.
good luck
No, it's the other way around. 400s have a long stroke, and long stroke engines aren't high revvers. a 383 is just a 350 with a 400 crank.
I knew 383s are longer strokes than 350s, and a 383 is a 400 crank.....
But I thought it was the rod to stoke RATIO, that makes a 400 a good RPM engine. Whereas the 383 rod to stroke RATIO was more on favor of low RPM & torque.
all a 383 is is a 350 (4.00) bore with a 400 (3.75) crank simply the bore on a 400 is 4.125 and thats where the extra cubes come from... i would think that you would want a cam with not as high a lift to tame the idle down a little bit but with a nice duration to allow that thing to breathe although the valve size helps alot from what i have learned on here about the flowing of the tpi it doesnt lol... sort of like putting a 500 cfm carb on that 400 it will fall over like the tpi does at high rpm... something that you want to be careful of is that if that motor is what you say do not run cheap fuel in it as the compression ratio should be near 12.5:1 and you will have issues with detonation and will kill it before you get to enjoy it!!!
I knew 383s are longer strokes than 350s, and a 383 is a 400 crank.....
But I thought it was the rod to stoke RATIO, that makes a 400 a good RPM engine. Whereas the 383 rod to stroke RATIO was more on favor of low RPM & torque.
The rod to stroke ratio is part of it, a shorter rod with a long stroke will increase piston side-loading, but the long stroke is also part of it. Simply put, longer stroke means more piston movement at a given RPM, more friction, etc.
__________________ North Texas Third Gen Association 1988 GTA 5.0/M5/3.45 LSD, T-Tops, Digital Dash, Leather - Current Ride 1983 Firebird S/E - Stripped 1995 Chevy 1500 5.7 Ext. Cab - Daily Driver
I would think that he's telling you the truth, the cam in that 400 is probably all wrong for a TPI setup. Most stock car motors i'm familiar with are running much higher rpm's than what our cars are designed for. Can you make it work? Sure, are you going to do it cheaply? Probably not, also you didn't mention what year corvette, I'm assuming they're like our camaros and switched rear main seal designs, as well as centerbokt heads, I'm not sure but didn't the vettes get those changes typically a year or so before our camaros?
My point is when you reresd his initial post he's looking for the cheapest way to get back on the road, and I'm pretty sure the 400 swap will end up costing him big $$$ to get it drivable...
The rod to stroke ratio is part of it, a shorter rod with a long stroke will increase piston side-loading, but the long stroke is also part of it. Simply put, longer stroke means more piston movement at a given RPM, more friction, etc.
I understand all that, but it addresses none of what I have always understood. That a 400 is a high RPM engine, whereas we already know, the TPI is not. So not a good marriage.
I understand all that, but it addresses none of what I have always understood. That a 400 is a high RPM engine, whereas we already know, the TPI is not. So not a good marriage.
In other words.....It wouldn't work very well.
400's are not high rpm engines. Think of it as a factory stroker engine, a 383 with a larger bore.
__________________ North Texas Third Gen Association 1988 GTA 5.0/M5/3.45 LSD, T-Tops, Digital Dash, Leather - Current Ride 1983 Firebird S/E - Stripped 1995 Chevy 1500 5.7 Ext. Cab - Daily Driver
Except for the fact that he said the 400 in question used to be a motor in a race car... A lot more info on his vette and the 400 motor is needed. Can it be done, yes... Will it be cheap? NO!!! It's not going to just bolt in and fire up for a cruise down the street, most likely not... I think you've missed what he's looking for, a cheap quick fix...
i have to disagree with almost 'all' of you.
High rpm motor, low rpm motor?
What does that mean? If you have a big enough cam, heads, carb; ANY of theses motors will happily rev to 7000 rpm or more.
If you put a 400 in a tpi car, it will work great, with tons of torque,,,almost big-block torque; but it wont make over 300 hp or so, just like a 350 or a 383.
If you put a big cam in it, it aint gonna work. A tpi will only make aprox 300 hp no matter what you do to it. It wont rev over 4500 rpm, because it will run outta breath. You can only suck "so" much air through a straw. It doesnt take much to make a 350 run outta air with a tpi. If this guy has a big cam and big heads with a tpi, it will only be a waste of time,,he is still gonna be limited by the tpi. Now; a corvette cam (what does that mean) might run great.
I am running a L82 (corvette) cam in my car, and I ran the same cam in my car when I had a 400 tpi. It was a fantastic cam for my car.
The specs are,,,if i remember right,, 222 degrees @.050 and approx .45 lift with an LSA of 114.
The computer like it,,makes great torque, plenty of vacuum and it will happily rev as high as my tpi can stand it. The same cam in a 400 would be even a little milder,,tons of torque....really great street engine. Just dont waste your time on a 4.10 rear or big heads or anything like that.
Someone plug in the numbers in a desktop dyno program.
Over 400 ft/lbs of torque from 2200 all the way up to 4500 rpm.
maybe 275 hp.
Combine that with a 3.23 or 3.42 and you gotta fun car. My 350 with the exact same setup makes the same hp, but approx 50 ft/lbs less torque than my old 400. But; now I get a few hundred more rpm outta the engine with the 350 before the nose falls, but it still runs outta air (tpi limited)
i have to disagree with almost 'all' of you.
High rpm motor, low rpm motor?
What does that mean? If you have a big enough cam, heads, carb; ANY of theses motors will happily rev to 7000 rpm or more.
If you put a 400 in a tpi car, it will work great, with tons of torque,,,almost big-block torque; but it wont make over 300 hp or so, just like a 350 or a 383.
If you put a big cam in it, it aint gonna work. A tpi will only make aprox 300 hp no matter what you do to it. It wont rev over 4500 rpm, because it will run outta breath. You can only suck "so" much air through a straw. It doesnt take much to make a 350 run outta air with a tpi. If this guy has a big cam and big heads with a tpi, it will only be a waste of time,,he is still gonna be limited by the tpi. Now; a corvette cam (what does that mean) might run great.
I am running a L82 (corvette) cam in my car, and I ran the same cam in my car when I had a 400 tpi. It was a fantastic cam for my car.
The specs are,,,if i remember right,, 222 degrees @.050 and approx .45 lift with an LSA of 114.
The computer like it,,makes great torque, plenty of vacuum and it will happily rev as high as my tpi can stand it. The same cam in a 400 would be even a little milder,,tons of torque....really great street engine. Just dont waste your time on a 4.10 rear or big heads or anything like that.
Someone plug in the numbers in a desktop dyno program.
Over 400 ft/lbs of torque from 2200 all the way up to 4500 rpm.
maybe 275 hp.
Combine that with a 3.23 or 3.42 and you gotta fun car. My 350 with the exact same setup makes the same hp, but approx 50 ft/lbs less torque than my old 400. But; now I get a few hundred more rpm outta the engine with the 350 before the nose falls, but it still runs outta air (tpi limited)
So your saying that it would do better with a carb? I found someone who has a "like new" edelbroch single pump 650 carb for $50. Would i get any more power out of the motor if i ditched the TPI system all together for the 650? idk how they really compare, im a *bit* concerned about gas mileage.
Also He told me that the compresson was somewhere around 12:1. With that i would have vacuum problems with the automatic transimission right? Is there any type of vacuum pump that will fit in an 85 corvette?
Oh and guess what, I took off those 461 heads...and there all nice and filled with concrete! I think its just the steam holes. What can i do about that?! would i be better off with the stock 85 vette 350 heads?
Sorry for all the questions but i really appreciate the help guys, this is my first build.
Ok, it's fun to dream and speculate, but if you don't have the money for a short block, how do you plan on pulling this off? At best you have a "free" 400 small block that hopefully ran when pulled from a race car. How longs it been sitting? If it's been sitting long, it will probably need freshened up. If it was ever raced it's probably been run pretty hard, also not in your favor. Now your talking about taking a fairly high tech 1985 corvette and putting an antique of a motor and carb setup on it??? Why? I promise you it's no easier and won't save you money in the long haul. This car is going to cost you $$$. Do you really want to end up with an 85 corvette with a used up motor and a $50 carb?!?! Think about that for a minute... Odds are unfortunately not good that it will run right and be dependable. You want to make that corvette run great and be dependable? Find a stock motor to rebuild, or buy a replacement motor from a reputable supplier. Odds are that your 85 corvette in stock form would put a big grin on your face the first time you drove it in comparison to your old camry! Just my $.02, it's your car, but I've been down this road before and what seems to be the cheapest and quickest fix usually never works out that way.
Ok, it's fun to dream and speculate, but if you don't have the money for a short block, how do you plan on pulling this off? At best you have a "free" 400 small block that hopefully ran when pulled from a race car. How longs it been sitting? If it's been sitting long, it will probably need freshened up. If it was ever raced it's probably been run pretty hard, also not in your favor. Now your talking about taking a fairly high tech 1985 corvette and putting an antique of a motor and carb setup on it??? Why? I promise you it's no easier and won't save you money in the long haul. This car is going to cost you $$$. Do you really want to end up with an 85 corvette with a used up motor and a $50 carb?!?! Think about that for a minute... Odds are unfortunately not good that it will run right and be dependable. You want to make that corvette run great and be dependable? Find a stock motor to rebuild, or buy a replacement motor from a reputable supplier. Odds are that your 85 corvette in stock form would put a big grin on your face the first time you drove it in comparison to your old camry! Just my $.02, it's your car, but I've been down this road before and what seems to be the cheapest and quickest fix usually never works out that way.
well the carb is brand new, and comes with an intake, its from a buddy of mine.But from what all you guys are telling me i guess ill just forget the whole idea until i can afford a new 350 short block. Which wont be for a long time. ill have to take the 400 and put it in my 84 trans am, it has a stick. I found out today that that 400 motor has a circle track comp cam, and too much of a stroke and i guess i would end up burning up my automatic trans on the vette. i just need a car that will run... i really wanted to get the corvette runnin first but i guess that 400 is goin in the trans am. Man, i wish i could make this work but, i guess not.
Still, does anybody know why somebody would put concrete/ epoxy in the steam holes?
should i try and get it out of there?
Using a TPI on a 400 isnt the best idea, mostly because the TPI does not flow much air and the 400 irregardless of what RPM you plan to run is going to want a lot more air than a 350 will and on a 350 the TPI is marginal. Its going to make a lot of torque and low in the RPM range, but its going to die at upper RPM. You could always switch the cam to something appropriate, not that hard to do. I'd be more concerned with compression, even with a carb, to be able to run it on pump gas. "Domed" piston is really vague, and so is "stock car" engine. Everyone has a stock car engine, from a Vette, with a 3/4 race cam, that makes tons of power. Honestly without knowing exactly what is in there, all the talk is meaningless. If you cant find out exactly what it is, might be best to pass and buy something you know the specs of.
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i ran stock tpi when i first put the 406 in my 85. this was before i even paid off the car-like 1988. nobody was into 400's back then. i ran maf and the hypertech chip for a 305. i cranked up the fuel pressure. it was a giant bottom end holeshot machine. breathing above 4k rpm sucked and killed power. it was really fun on the street. it ran a mild flat tappet crane cam and i liked it. you need to get an idea of your compression ratio with the 400 and put a smaller cam in it. be mindful of the balance and have any reputable balance shop set you up with a balance matched flexplate/flywheel to the 400 imbalance. get the correct balancer. i have a stock one if you need it. pm me. you can run a 400 with the stock tpi while you hunt for your ideal induction system. 400 sbc were NOT ever rpm motors. ever. short 5.56 rods would load the he!! out of the cylinder sidewalls. even with 5.7 rods they are fairly in the realm of "torque producer" type of motor. i think 400's were truck and station wagon movers. caprice and the like. i put a superram and fixed its breathing issues.
__________________ 1985 IROC Original Owner.Original silver paint, Roller 406c.i., 4 bolt, Superram, accel DFI 6. serpentine setup, Factory GM 1LE brake set-up, richmond 5 speed, 1 3/4 slp, jet hot, gale banks 2OTL power pack (vintage), eibach, grey leather flo-fits, A/C delete, 29k original miles and never been driven in the rain. all original parts are on the shelf. original window sticker and build sheets. 1996 Z28 M6 LT4 kit, hotcam, obd1, C5 brakes. And then theres the road runner.
Would i get any more power out of the motor if i ditched the TPI system all together for the 650? compresson was somewhere around 12:1. With that i would have vacuum problems with the automatic transimission right?
Budget "get it running" fix , put a carb on it .Will rev higher with carb v TPI
Compression is not a problem with good gas .Vac is dependent apon the camshaft.
T700 tans has cable control so vac not a problem but may be for brakes.
Keep in mind, a 400 block is about 17% larger. All other things being equal (which they are not) you would need 17% more fuel to proerly burn air. It's not qute that simplistic though. Even with SLP ported runners for more air, it won't be a high end revver. It will put your butt in the seat on launching though.
__________________ "Shammoo" 1993 Caprice wagon, ex "Kicker Audio" demo car. Shaved roof rack, trim and badging delete, Filled gate, license plate moved to rear rollpan, Fiberglass EURO chin, Impala grill, clear front corner lamps, dropped suspension, Bell shocks. BFG phatties on Tomahawk rims.
TBI to TPI swap in progress. 406 ci, AFR 195 heads, Comp cams XFI 230/236@0.050, SLP siamesed runners, 1.6 roller rockers, shorty headers dumping into Doug Thorley sidepipes. 730ECM with prominator, Coming soon .. Nordskog digital.
hey all things aside on a tpi if i was to get the port work done that can be or buy an aftermarket setup what is the reality of rpm i can get to?... i too have a "race motor" that i could throw in though its only a 358 as it sits makes its peak hp at just about 6500rpm +or- and so a cam change is for sure but what would i expect out of a ported tpi its not that i want to rev i dont care reving hurts motors i know thats why i spend thousands to allow them to rev but its what can i get outta one so i know what cam to buy this motor is a vortec headed flat top piston 3.48 stroke 5.7 rods 1.94/1.50 valves (ran real short track on off gas fast) heres the cam in it now great outta the hole but comes on halfway through the tpi range lol http://compcams.com/Cam_Specs/CamDet...?csid=138&sb=0
Nope. A 377 is a 350 with a 400 crank. 383 comes from a .030 over bore 350, with the 400 crank.
350 crank in a 4000 is a 372, which is a high revver.
You're talking about virgin bores. Both combo's are popular and are known for the .030 overbore ci results whether it went .030, .040, or .060 over. It's not technically correct, as you point out.
You're talking about virgin bores. Both combo's are popular and are known for the .030 overbore ci results whether it went .030, .040, or .060 over. It's not technically correct, as you point out.
Yes, but .030 over on a 400? The walls aren't exactly thick to begin with. I wouldn't go any further then 30-over. That makes for a no-rebuilder engine.
350 crank in a .030 over 400, is a 377 and still a high revver. No that would REALLY suck under a TPI manifold. Low rp, intake on top of a high rpm block?
Yes, but .030 over on a 400? The walls aren't exactly thick to begin with. I wouldn't go any further then 30-over. That makes for a no-rebuilder engine.
350 crank in a .030 over 400, is a 377 and still a high revver. No that would REALLY suck under a TPI manifold. Low rp, intake on top of a high rpm block?
I agree 100% there. But it'd be just as crazy to put a TPI on a 400 with an unknown cam.
With a mild compression ratio and a conservative cam (Comp 252H looks good) it could be a fun driver.
1985 IROC Original Owner.Original silver paint, Roller 406c.i., 4 bolt, Superram, accel DFI 6. serpentine setup, Factory GM 1LE brake set-up, richmond 5 speed, 1 3/4 slp, jet hot, gale banks 2OTL power pack (vintage), eibach, grey leather flo-fits, A/C delete, 29k original miles and never been driven in the rain. all original parts are on the shelf. original window sticker and build sheets. 1996 Z28 M6 LT4 kit, hotcam, obd1, C5 brakes. And then theres the road runner. 
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