89TA383M5

I'm building a 434 and using my heads and TPI off my 383. Has this ever been done before? I have a fealing with a big cam it isnt going to rev over 5000rpms. How do you think it will do with the TPI? I want to hear your thoughts even if it may be that I'm dumb.

SweetS10v8

Heres my $.02....


I hope you LOVE torque, and low RPMs, because thats what your motor is going to be all about. I think the whole top end is too small for a 434, from the aftermarket TPI setup you have to the 200cc heads.

What size cam are you planning on putting in? Whats the one in your 383? The same cam from the 383 will act like a smaller cam if you swap it over to the 434.

Be careful on compression too, with flattops your going to be in the 11.7:1 range...

89TA383M5

Like 10:1 compression, and a big cam like 236/244 duration at .050 and .579/.602 gross lift with my 1.6 rockers. The cam in the 383 is way to small. Also my engine builder is going to port my heads and when he is has the short block done he was going to call Crower cams to get the right cam.

SweetS10v8

That cam is still small, but I am guessing thats because of the TPI. I havent gotten into any tuning, all my cams have been with carbs.

These were all solid roller motors I have had, in much smaller ci motors and all worked great(352 isnt in a car yet, but runs in the garage)

350 11:1 242@ .050 .580 lift
350 12.5:1 262@ .050 .667 lift
Detroked 400(352ci) 12.5:1 255@ .050 .613 lift

You have ci on your side, if you can get it tuned I would go bigger or you might get about the same performance out of your 434 as you did with your 383.....just thinking out loud...

86 IROC

iTrader: (3)

It will be a dump truck motor, lots & lots of TQ. If it's all you can afford for now, at least you'll have the shortblock in the car. Down the road you can do a H/C swap and look into a more appropriate efi manifold/tb etc.

89TA383M5

Can anyone with a TPI that has had a large cubic inche please reply. Will my intake even make any horse like 400hp up to 5 grand with a cam or will it die at 4000rpms and only have torque?

89TA383M5

Oh by the way I'm keeping my TPI and no way am I ditching it. My decision is either to keep the 383 with the heads ported and with the cam I stated before with a supercharger, or build a 434 with the ported heads and huge cam. No suprecharger for the 434.

TheMysticWizard

iTrader: (1)

If you're talking a stock TPI on this engine, you're gonna be majorly choking it. The stock TPI is designed around the 305, it is evident when you start swapping to after market parts on a 350. On a mild 350 the stock TPI is not much of a restriction, but as you add larger heads, exhaust, and a larger cam, the TPI starts being the restriction, and this is on a 350.

I would imagine on a 434, you would want to run a large cam, but you're probably gonna have to do major tuning with a larger cam, and the TPI system will still be a restriction. I would almost say stick to a smallish cam, and keep your power band real low. I don't think you'd be pulling much past 4500 RPMs on stock TPI on a 434. Torque will be unbelieveable tho.

SweetS10v8

383 + Supercharger > 434 tpi Hands down, no question.....

The TPI will kill the ability of the 434ci. And many people can make awesome power and times with a supercharged 383 TPI with aftermarket runners.

So you wouldnt put $600 into a stealthram to keep the 434, or a miniram($1200)????

SweetS10v8

Here is a visual for ya :lala:

Dr G

89TA383M5:- I think the bottom line is that you should do what makes you happiest, regardless of others opinions.

Have you ported out your TPIS Big Mouth Base and AS&M Large tube runners?

Which supercharger were are you thinking of if you stay 383ci? ATI D1SC? Out of interest why wouldn't you supercharge the 434?

Best of luck to you for whatever route you end up going down.

camarojoe

I am going to be honest here. Using ANY stock style tpi components is absolutely absurd on an engine of 434ci's. There are some corvettes that run Superrams on their 420ci motors that work out really well. Go with that intake or a Stealram at least. Get whatever heads you run to flow about 260cfm on the intake so you can make some power. I'd advise to go with some aftermarket aluminum heads no matter what, but that's my thinking. You need some serious flow to feed that kind of sbc even on a street motor. I figure if you can afford an aftermarket block you can afford and aftermarket intake and heads.

camarojoe

I am going to be honest here. Using ANY stock style tpi components is absolutely absurd on an engine of 434ci's. There are some corvettes that run Superrams on their 420ci motors that work out really well. Go with that intake or a Stealram at least. Get whatever heads you run to flow about 260cfm on the intake so you can make some power. I'd advise to go with some aftermarket aluminum heads no matter what, but that's my thinking. You need some serious flow to feed that kind of sbc even on a street motor. I figure if you can afford an aftermarket block you can afford and aftermarket intake and heads.

88TPI406GTA

I did have a TPI setup on the first version of my 406...it sucked.

I had the stock setup, except for an Edelbrock baseplate and stock 1970 400 heads (not bad) with a cam around 214@50 duration and lift abour .480

My referenced was that the identical engine was in a different car with a 650 Holley and a dual plane intake.

The TPI hit a wall around 4000 rpm...the torque was great, but a very narrow power band...like a diesel....

I would sell your TPI stuff and get a Stealth Ram....especially on a 434.

HTH,

89TA383M5

Keeping my TPI. So I'll probable keep the 383 and build that a little better and add a blower. I dont have enough money for a 434 supercharged. Oh also I only port matched the runners and big mouth base, I didnt do any real porting on them. Thanks for all your opinions guys! I'm probable getting an ATI P-1SC blower and a 3 core intercooler setup. That will be pretty cool I think.

88TPI406GTA

Two words: Wicked torque.



Gotta dig the blown 383...but the cost is going to be how to manage it...7749 ECM or aftermarket? Plus the accessories to make sure you don't detonate...

Why are you keeping the TPI again? Smog reasons?

383 rocket bird

Hey sweet S10 do you have a link to the original place that picture came from? Thanks -John

SweetS10v8

Does he have to switch ECUs? Or cant he just get a MSD BTM?




Ive had 4 people email me already here ya go....(right click it, and hit "save picture as")

Dr G

If he was to supercharge a 400+ci motor with a TPI LTR set-up would the forced induction 'overcome the restriction' and allow him to keep making power above 4000rpm?

Or would it still be a waste of time and best switched to Superram, HSR, MR or LT1?

SweetS10v8

It wouldnt overcome it. It still would be the restriction, now were just forcing air through a tight spot.

For the price of the HSR $600 totally installed, you cant go wrong! Now how do I convince my wife??

TheMysticWizard

iTrader: (1)

Tell her something broke, and you need to replace it, but why replace it with a stock crappy piece, when for a few bux more you can have a performance piece.

SweetS10v8

I drive it everyday, and goto college for high performance automotive. My friends and I talk about cars all the time, shes catching on to that one....

vampiroc

if you're planning on keeping TPI for either setup its going to severely limit your power production and an incredibly small power band. If you had a 305 you could work with TPI and find decent success, anything larger would be restricted extremely, figure a peak of 4500 with a 350, 4000 with an n/a 383, 3500 with a blown 383 and 3000 with a 434. Why bother with a big motor if you're not going to put the proper induction on it? We've already seen what a big torque motor choked off can do. they made a lot of them during the 70s and they were extremely slow and peaked out around 3000 rpm.