Hey Everyone...

I have done the search for this, just so you know in advance. Im planning on building my own 400 block for my 86 TA in the spring/summer. I'm most likely starting with a short block that I'll clean up...I could probably pick one up for around $500 dollars around here. My two questions are....what kind of power output can i expect from building this motor, and what would be the best tranny/rear end for it? Any advice in relation to this would also be great...and by the way, I plan on going with fuel-injection, not carburetor. Thanks.

 

Too many unknowns. You need to put together a combination that works well together, and with a specific goal in mind. How are you going to use this vehicle? Do you want a daily driver that will be respectable on the track, or do you want a track king that you can at least drive to the track? Is it a track-only car? How many RPMs are you willing to build it to take? What is your budget? How expensive of fuel are you willing to use full-time?

The induction/heads/cam/torque converter all have to be chosen to work together. You can have anything from a 265 HP torquey fuel-economy daily-driver to a screaming 600 HP barely-streetable killer. The faster you make it, the more it will cost you to operate it and keep it together.

 

This car will be more or less a daily driver. I would like it to be fuel-injected. Gas mileage is not my greatest concern, but I'd like to see at least 11-12mpg out of it. This will be a daily street car, but I'd like to go to the track and run 12's with it. I dont have much experience with the RPM ranges, but building a motor with something that makes decent power through the RPM band is i think a necessity. My budget is variable....I dont care if this takes a few months to put together...as long as its done right and makes me smile and imports frown, thats what matters to me So, in essance, I'm looking to get 425-500 hp out of this, naturally aspirated. No nitrous, no supercharging, or anything. F7Kid, thanks for the fast response...since I have little experience in this area, and just the basic understanding of it, I do need good advice and what to go about doing. I talked to a friend of mine that had a 425hp Iroc-Z....he told me to forget the 400 small block, to find a core 350 fuel injected motor at one of the junkyards, and turn it into a 383...or de-stroke the 400 to a 377 to make lots of torque...but somewhere else, the destroking came up and i was told that thats mainly for circle track racing. So as you can imagine, with all the choices, I kinda look like this ------> Thanks again for all your help.

 

Lose the TPI. It isn't going to happen with that on there. Put some other FI system onto it, such as a Stealth Ram.

Stay away from exotic stroking/destroking combinations, they just run up the tab without improving anything. If you can find a 400 block, build a 400. If you could make it go faster by de-stroking it, then people would be doing the same thing to 350s and making them into 327s instead of 383s; but as we all know, that's backwards. Just build a 400, get a set of good-flowing heads (NOT stock 400 heads, or your 305 heads), and some other FI, it is a piece of cake to get that to go fast. At that low of a power level, a stock 400 bottom end — crank and rods, but with high-quality rod bolts — would be entirely adaquate.

 

The big question, at least in my opinion, is whether or not you're talking 425HP to the flywheel or the the rear wheels?

IF it's to the rear wheels, forget driving it everyday, and you'll be looking for something to replace your broken tranny and rear, if you get any kind of traction.

I know RB and I disagree with the value of the TPI system, but that's life.

If you're GOAL is to run 12's at the track AND drive it DAILY, you won't NEED or want that much power ( that felt almost sacreligious to type ).

Since this is all opinions, either way, I'll chime in with mine, but you might be pleasantly surprised if you search the board for TPI And 400.....try clicking HERE


Using a 400 short block, rebuild the bottom end with good components. So we'll take the bottom end as basically stock. Now the big player here is the cylinder heads. If it were me I'd buy a set of Pro Action iron heads. The 180 cc intake runners would be my pref of a STREET engine. You can score a COMPLETE ready-to-run set for under $650.

Scenario #1

400, Pro Action heads, stock TPI system with the free mods, like cleaning up the plenum etc. You'll need some bigger injectors, and you'll need to get a custom chip.

With a cam made to make power in the 1500-5500 RPM range, this combo will make TONS of low end torque, and put down respectable HP numbers. Make sure you have a free flowing exhaust with headers and a good cat back.

The TPI, if working like it should, will ALWAYS make more LOW END, useable torque than a similar carb setup. Dyno after dyno test has proved this. And torque is what pushes the car, HP pulls it...simple analogy, but pretty damn accurate.

You're wallet will also thank you or not having to fill up every 10 minutes.

GO to Mike Davis' website. http://www.eecis.udel.edu/~davis/z28/

He did some pretty good things with the crappy TPI system. With an Edelbrock base and some aftermarket runners he broke into the 11's.........

Search user names for Mike Crews

He built a very streetable 383 w/ Vortec heads, Vortec TPI base, aftermarket runners, and he runs a 12.3 and he's convinced the cam he's using now is TOO small.


Don't let anyone convince you the TPI system can' support any power. YES, in it's STOCK Form it won't make as much power as a CORRECTLY set up carb, but take it from me, no matter what induction you use, if it's not tuned correctly, it won't make as much power as the engine is capable of.

There are PLENTY of people running LOW 13's, WELL into the 12's on 350 based TPI motors, so you won't have a problem with the 400 doing this and still being a very mild motor.

The question may come down to HP vs. $$$ spent. The stealthram is very attractive for the price, and when you consider the price of it to start with, it's not bad at all, but I'm tight, so that's me.

If you want to build the engine first, get it running, then start modding the induction, I don't see you having any problem building a healthy 400, using the stock TPI setup and as long as you work on the tune with the correct chip, you shouldn't have any trouble with 12 second ET's, your main concern will be getting traction regardless.

EFI is here to STAY. An identical motor will almost always make more torque and have a more consistent power curve with EFI vs. carb. But the big factor is STAYING In tune regardless of weather, temp etc.

I messed with, and still do, carbs for more than a few years, and I still think they have their place. But whenver someone wants to drive a car everyday, and still go fast at the track, EFI is the best compromise between the two.


Search this board and joing the 3rd gen mailing list and good luck.



Later

 

I know this is off the subject, but what do you guys think you could get out of a 350 TPI setup? Say with some port work and a couple other small mods?

 

Maybe 350hp.

 

The highest actual measured RW HP I've ever seen out of a N/A TPI 350 was 317 HP. And it wasn't with a few cheap mods.

TPI basically has a "brick wall" of HP at around 325. It simply doesn't support flow above that, in fact it is deliberately designed in such a way as to defeat higher RPM operation than around 4600. While you'll hear people talk all day long about "I shift my TPI at 6000 RPM", in fact either their tach is off (when those fail in these cars they almost always read high) or their car would go faster if they shifted at 5000 RPM instead. TPI is what it is, and does very well at what it's designed to do, which is to produce a monster torque peak at around 3600 RPM, by the use of the sound waves generated within the engine's intake system, and using them to reinforce cylinder fill; but the physical reality of it is, it doesn't support high RPM operation, and therefore high HP. The design sacrifices all hope of effectiveness above about 4500 RPM, based on the speed of sound and the runner lengths, in favor of that 3600 RPM peak. Even raw flow isn't the issue so much as the sound (pressure) wave effects.

350 flywheel HP is usually just about enough to break into the 12s with a well-tuned chassis and the right torque converter.

You need to make a decision: either keep the TPI, and all of its positives and negatives, and accept the fact that no matter how many cubes you put under it, you're going to reach an absolute limit on how much power you're ever going to get out of it; or put some other induction system on it, which might include a carb or one of the alternative FI systems that do support high RPM operation. Option A limits you to around 325 crank HP, period. Option B might cost more initially but will be far cheaper in the long run if you want more than 350 HP. You have to make that choice.

That said, have you ever actually driven a car with a motor that actually produces 350 HP as installed in the chassis (not on a dyno stand)? It's a pretty peppy power level. If you're accustomed to TPI at 230 HP or whatever, it's a major boost.

 

That's a GREAT point.

IF, and this is a big IF, you think that later down the road, mid to high 12's WON'T be fast enough, it will be cheaper in the long run to go ahead and go with something like the Stealth Ram now.

I've owned several 12 second cars and a 11 second car, all were DRIVERS, and most people don't realize when they read messages or emails, how fast it is for a DRIVER.

Anyway, at least in my experience, anything faster than the 12 flat, high 11 second bubble, you REALLY get to the point when you start sacrificing things for those times. Other parts in the car / chassis will show their age and fail.

That's why I'm still VERY curious to see how all these low 12 and 11 second LS1 4th gen's hold up after some miles. As it is now, most all of these guys that build really quick one's, tend to retire these cars from driver duties and buy a "beater". I like driving my IROC, that's why I bought it. So if I ever have to choose driver reliability over speed, it's no contest.

And alot of things will come down to the fact that REALLY fast cars that weren't built with an eye on keeping 'em reliable get sold, or retired to weekend duty.

Like I told a guy last week......who told me how his LS1 car ran 11's....I then asked where it was and why he wasn't driving it? It got quiet.

The final decision is up to the person building / driving the car, and to me, these cars are meant to be DRIVEN, and not just 1320ft at a time.


Later

Chris

85 IROC
Function over form

 

Ctandc...

You have been very helpful in helping me decide what to do..thank you for sharing your knowledge and advice with me. I guess I wasnt clear on what kind of induction i was gonig to use, but my intake choice would have been Accel's Superram with the 1000 cfm throttle body. Anyways, I have alot to consider,and I will certainly have to think deeply about this some more. I have some time before i start building, so I can take taht time to research and gather prices for everything, depending on what application i go with. The 425 hp figure i want was for the motor, yes. I just want to run 12's. I'd be happy with that. I really have to think hard and decide what to do....but again, I sincerely appreciate everyone's help and advice. Thanks again.

 

Why not build up a big block? It's not too difficult of a swap from what i've heard and read here and it is VERY easy to make around 500hp and enough torque to rip almost anything else a new one with something like a 427 or a 454, and there are some pretty nice EFI systems out there for big blocks too.

Plus, you would also be ableto brag about having a big block Camaro