I just bought a complete 400 sbc off of ebay. im picking it up in two weeks and will then begin the slow teardown and rebuild. Im looking for some tips, or ideas as to how i will be able to get 475-550 hp out of this motor. It is a 2 bolt block, casting 509, Stock 400 heads, and what i believe to be a stock 400 intake.

Some ideas i have been tossing around are that of using a tunnel ram intake with two 750hp holley carbs, with a stock crank and stock rods, but with forged pistons. I know ill run into hood clearance issues, ive always fancied an aero scoop anyways.
But im looking for budget oriented tips and suggestions as to what i could do to this motor to make that kind of power and be able to be driven daily, taken to the strip and beat on, and then driven to the movies afterwards to appease my lady while keeping some sort of decent mileage.

Another question, The motor in my car now is a seized tbi 305. Would i be able to use the tbi setup on my 305 on the 400, obviously to make the power id need to switch out he injectors and reprogram the ecm, but would it be possible? Or would it be a waste of time?

Thanks in advance fellas. Oh, and Steve, I probably will get the block studded, ive read that reccomendation youve given in a few other 400 sbc posts, but does studding the block really help...
Ill supply pics of the buildup and what not as it goes on, but im looking for suggestions now...

 

Forget your TBI at even half that power level. You're not going to get 500 HP out of a 170 HP induction and fuel delivery system. Get real.

HP comes from flow. HP is the time rate of doing work. Work (energy) is produced by burning fuel molecules. Fuel requires air to burn. The time rate of work is therefore the same thing as the time rate of burning fuel, which requires a given time rate of air molecules..... measured in cubic feet per minute. Flow. In its simplest form, HP is directly proportional to flow.

The first thing you need to do is throw away the stock 400 heads. They are garbage. That motor in stock form produced about 180 HP; the primary reasons were the heads and cam. Fins a set of really good-slowing heads without spending megabcuks. The Vortec heads might make a good choice. Stay away from 305 heads, any smog heads from the 70s, etc. etc.; and try to keep your compression ratio to 10:1 or slightly below. That means get your heads first, then pick pistons with a dish to produce a workable CR. DON'T try to do it the other way around, you'll be asking for trouble.

A good place to begin is to figure out what the emissions requirements are where you live. If it's where I think it is (West Chester?), you have to pas a IM240 dyno test. That sort of limits how wild you can go on the cam.

I have 4 cars, and I live in Loveland and work in Mason, so even though I just moved here from Southern California, I'm fairly familiar with the emissions procedures....

 

"Driven daily" and "dual 750 HP carbs with a tunnel ram" are two mutually exclusive things...

If i were you...I would focus on a single carb, dual plane intake setup to about 450 HP..after that...look at more serious options.

Don't go for an intake like the tunnel ram because it looks cool...especially if you hope to drive the car on a regular basis.

 

i think you can easily get the power you want from your 400.

my current car has a tbi and i like it, but the previous poster is right, tbi just can't be made to support that sort of power.

look at this month's super chevy. they got 530 hp and 500 lbs ft torque from a stock gmpp 383 short block with an off the shelf gm cam and ported fast burn heads. they used the accell dfi gen 7 fuel injection, which has to be responsible for a lot of that power, but it's incredibly expensive. i do believe that basic setup could have made close to 500 hp with a well tuned carb setup.

if you go with something like that one, watch the cam they chose. it made 400 ft lbs torque at 2,000 rpm. looks great on a dyno or with slicks, but on the street it means wheelspin, wheelspin, wheelspin.

my old 400 setup made over 450 hp on regular gas with old-tech heads and cam:

stock 400 shortblock with stock dish pistons.
350/300 (double-hump) heads milled 0.40
engle 5.10 lift, 3.10 (advertised) duration, 110 degree center cam
weiand single-plane intake
850 holley double pumper
hooker 1 3/4 long tube headers
gm hei ignition

that setup ran 12.40s-12.30s on horsepower, 11.70s-11.60s on nitrous in a 70 chevelle with a turbo 350, 3.31 gears on street tires and through the mufflers.

the 2003 version of that engine would have upgraded vortec heads or afr 190s (maybe fast burns?), a dual-pattern cam, and a smaller carb. i believe there was more in that setup, but i didn't know how to tune it.

people will look at that and say too much cam, use a dual plane intake, 1 5/8" headers, more gear, etc., but the long-duration cam, single-plane intake and big tube headers cut just enough torque off the bottom end to let the car launch like a rocket and the short gears limited wheelspin, too. i put 3.73s in it and slowed down. one of the beauties of building a torque monster is that it'll pull a short gear.

i'd LOVE to put a 400 like that in my firebird, but the tbi won't support it and i don't think the chassis will support all that torque on real street tires, either.

i'm going to look into the dfi. the kit is 3,700.00, but a complete tpi capable of supporting that engine from arizona sport and marine or t.p.i.s. is that much, too.

simple as carbs are, i believe efi is the future.

whatever you do, put your money in the heads and induction. john lingenfelter once said great heads and a mild cam will always make more power than a great cam and average heads.

 

P.S. on a street engine, there's no need to go with studs or splayed cap 4 bolt mains. as a matter of fact, stock 2 bolt is actually stronger that stock 4 bolt.

 

Thanks for the info guys, but heres another idea ive come across...

What if i built a 383 destroker. Id bore the block 3 over. I believe I could get a completely forged 350 bottom end into this block, sacrifice some of the low end torque like sean has stated, and then Id have a two faced motor. Itd be perfect for street driving at low rpm, but when i would need the power, id just need to get into my powerband of 3-8 grand.

I know I know, theres no replacement for displacement, but I think a motor with dual personality would be more fun for me.

is there a differece in power between a 383 stroker, and a 383 destroker?

Or should i just build the 400 normally

 

Thats for damned sure. :nono:

 

406!!! 406!! and do F.I. :lala: :lala: :lala: