92GTA

I have an idea for an engine that I've been tossing around and I want to get your guys input on it. I have allot of reasons for going with such a set up as shown below including stuff like: Uniqueness, can use existing headers and exhaust (I think?), keep the appearance of my engine compartment almost stock aside from LT4 intake, can keep all of the accessories mounted in the factory position like A/C and alternator, I already have the 400 block and need an intake to clear my STB, plus some others.

Here are the basics:

1) 400ci SBC, see outline page for details.
2) LT4 Heads Ported & Polished, Modified Cooling Passages set up for the 400
3) Ported LT4 Intake

For more details you can see my rough outline here: http://www.TransAmGTA.com/400ci_LT4.html

Please let me know your guys opinions on parts and stuff. I know the LT4 "Hot" cam is WAY to small for this engine but I was thinking about trying to stay CA legal, hell once it passes I have 2 years until the next test so I can swap in a better cam if I want for inbetween the tests. I just figure it would be a cool project for my 92 GTA for when I get back on my feet and if I still have the car.

I've already considered the LS1, 383's, 396's and stuff and by far I like this the best. Just a personal preference I guess. I just need your guys help to make sure I have all of the correct parts I'm going to need...

Thanks!

Mike94ZLT1

Wont work. You can't put LTx heads on a Gen 1 SBC.

92GTA

Actually you can. I've seen it before where guys have modified the cooling passages on LT1 heads to fit a 350 block (yes a Gen 1 SBC), so why not the LT4...

93midnightta

i've never believed that the 400sbc is a good platform to build on...they blow apart to easily. if you plan on boring it over don't go that way...it makes the 400s walls paper thin.

92GTA

I don't plan on boring it over, that's why I said 400ci instead of 406 or something. Atleast I have the 2 bolt high nickel block to start with so with splayed main caps it should be just as strong as any other SBC, if that's saying anything

I've already had the block gone through by a machine shop and it only had 40K miles. It doesn't need to be bored or anything, I plan on always keeping the stock bore as long as I can, .030 over at the MOST. After that, I would sell the block.

Thanks for your input.

Mindgame

Not true.
Explain to me why you feel that way and I can probably convince you otherwise. Most people have misconceptions about the 400.

In reality, most 400's will go .060 over without too much fuss and they can be built plenty strong. Lots of guys have put 1000+ hp through an OEM 400 block.

-Mindgame

93midnightta

my friend had a 400sbc bored .60 over and was making good power. only problem was that the piston blew through the wall and killed the block. when he pulled the heads there was a nice big hole in the wall and we were both quite shocked.

92GTA

I would never recommend going more than .040 over on a 400 SBC and as long as you really going through the cooling passages and have a good radiator and fan system, you will be good.

Mindgame

Tough to push an aluminum piston through a steel block but yeah, I've windowed a few blocks with connecting rods that let go, broken cranks, stuff like that.
Breakage is just something that happens, but you'll see the same thing happen to any block..... Bow-tie, Rodeck, Donovan. That's no indication that the engine itself is "bad" though.

-Mindgame

Mindgame

.040, .050, .060... doesn't matter. As long as there is ample thickness on the thrust side of the bore, you can do it. That's what they make a sonic check for... so you don't have to guess.

-Mindgame

Injuneer

A pair of new LT4 heads, and intake, and extensive porting of the heads and the intake, then weld and drill the LT4's to fit the Gen 1 SBC, and you will have spent maybe $3,500.... about 1.5X - 2X what you could get a good set of Gen 1 aftermarket SBC heads for...... why?

92GTA

I want to stay FI but the TPI system is too limited and I don't want to go LS1. Can I get a better set of aftermarket heads for less that will work with either a Miniram or LT1/LT4 intake? Also I want the more modern computer and FI system...

Mindgame

I agree with the "why".

With the 400, you get the big bore and with that you get the opportunity of running larger valves (better deshroud) with better cylinder heads. The sky is the limit there.... why go the other direction?

Yes you can get a Miniram for 1st gen blocks. You can also run any aftermarket FI system you want.... accel, FAST, you name it.

-Mindgame

got_hp?

what i dont understand, is you have a $10k budget, but your goal is 450rwhp?


umm......if you only want 450rwhp, why bother with all this custom work? buy a fully assembled 383 from one of the vendors for half the price, and just as much power.

Dr.Mudge

Unfortunately, a 383/396 L98/LT1 will not pass smog making 450 RWHP, maybe a 400 block can, without a cam swap its going to take some creativity and I dont think LT4 heads can do it without some money.

Camswap should be a consideration, weenie cam for smog and a HP cam for post smog. For the SBC though you can get some pretty nice heads, sticking to LT1/4 stuff seems kind of crippling and troublesome.