Hi All,

I took my car out to an event where they had a dyno set up to see what my car was putting out.
We ran into 2 big issues, one was the car didn't want to hold in 3rd, and the other was that they could put the gas pedal further than about 75-80% or the car would cut out, followed by some weird backfiring till the engine spun back down to stop.

The highest reading we got was about 260hp before it crapped out, which I'm pretty sure now was a fuelling issue but I wanted to see what I should expect from my build if anyone can give an educated estimate?

400 SBC block bored to +40
Hyperteutic pistons with -8cc relief
10.4:1 comp (estimate)
AFR 220cc heads ported and polished, 2.08in/1.60ex
XFI 280 HR cam
1.6 Roller rockers
36lb ford evo injectors running at 43.5psi
Holley Stealth RAM intake with Arizon Marine 58mm TB
LS1 PCM conversion with coil per cylinder setup

4L60E with stock TQ convertor
2.73 open rear end

I know the tranny, TC and rear end is weak and not ideal/right, and they're next on the upgrade list, but I just want to make sure the motor is where I want it to be before pouring more money in.

Any estimates?

 

 

Yeah sorry, fixed up, it was 2.08 and 1.6

That'd be 430 at the flywheel or rear?

 

To the wheels.
Bunch of guys have dyno'd that combo in a 383 and it usually nets around 400 to the wheels.I think VincentZ28 has that in a 383 with a Mini-ram and had mid 400 hp to the wheels. One day I'll get mine to a dyno but it's quite similar.

 

awesome, that's pretty much exactly where i want to be HP wise.

I've just ordered the 2000 firebird fuel tank with everything attached so i'll install that along with fresh AN8 lines re-routed to the other side of the chassis rail to avoid heating up from the headers from the tank to the engine bay, install a 2L surge tank, relocate the fuel filter to the front where I can reach it, and then plumb from that to the fuel rail and reg and hopefully that fixes my fueling issues.

Then build up the transmission to handle the HP.

My only problem is the diff now. I thought I had a 9bolt but its actually a 10-bolt.
9 bolt would be easier to upgrade being I'm in Australia, but not sure what to do about the diff now...

 

Read about joining a Ford 8.8 rear center section to the GM 10 bolt tubes. It's a somewhat common thing to do and if done yourself can be had for less than $300 for a rear end capable of handling 500 hp, so I've heard. If you have a shop get involved you'd probably be spending close to the same amount as a fab'd 9" housing here in the states. Look up the "Hiltsy mount" for a solution of mounting the torque arm to the ford 8.8. I'll be starting that project this winter.

 

As nice as it sounds to make a big inch SBC like a 383 or 400, it's really old school and the power potential gets expensive with more power expected.

On the other hand, an LS swap is easy to do. A 4.8 is small. A 5.3 or 6L can easily make 500 HP with a cam swap and some basic bolt on parts and still be very streetable.

Nothing wrong with an old school engine but the LS market has gotten huge.

 

Yeah, unfortunately in Australia they still hold their value a lot.

For a stock LS1 you're still looking at $2,000 for a tired 140,000km one with accessories.
Last time I checked even the rebuild kit was still about $800AUD
The you need the 4L60E to bolt up, which again you're looking at another $1500 for a reco'd one
Add to that a cam, custom headers for RHD TransAM and tuning, and the "cheap" option becomes more expensive.

Plus I already have the 400sbc built

 

Agree, you should have a pretty stout combo. 400 SBC can make a lot of power. The big diameter cylinder bore is magic.

 

Awesome

I've got a spare 10 bolt so i can cut that up to get the mounting tabs welded onto either newer Holden Commodore diff or a ford 8.8 so that will fix that problem, then I just need a magical torque convertor to fit a 4l60e 97 model with a snout that fits a 2 piece RMS flex plate in the 2500rpm range