I'm building a 383 for my car which will get the LE3 treatment. The car is the one in my sig. It's got SLP mids, ramair and a Borla catback. The new motor will have the LE3 package on a 383 4 bolt block. I've got a set of flow matched 42lb injectors for it. I'm guessing it will make somewhere just shy of 500 hp at the flywheel. It will be tuned with a mail order tune to start off with and dyno tuned after all the bugs are worked out of it.

-will a 52mm TB be enough to support just under 500 FWHP? I have a good spare stock TB, can it be bored out to 52mm? Who could do this for me?

-can I use the stock FPR? I can have it tuned to run at the stock pressure, right?

-will the stock fuel pump be ok? I assume not, but figured i'd ask. If not, what pump should I buy to most easily upgrade the stock one? Maybe that is a mod I should do now, before the engine build gets too far along.

 

With that power, I'd imagine a 58mm throttle body would net you more hp, but I'm not 100% sure...

 

I first had a 52mm T/B on my 383 and I later switched to a 58mm, There was a definite difference in the quickness of the rev and peak power.

 

With 42# injectors, 58mm TB is what you want.

 

i would upgrade the fuel pump. a walbro 255 would do fine. they support over 600hp. and you should get a adjustable fuel presure regulator because it is a lot easier to tune the car after. its not easy to upgrade the pump. there is no access panel for it. you have to drop the tank.

 

42lb injectors will be plenty (just in case you were wondering). The stock FPR will be fine. I run an adjustable one to help assure me that the motor is getting enough fuel when using nitrous. The stock pump probably won't be ok. I've heard of some people running around 400 rwhp with the stock pump. Mine woudn't go over 360. I switched to a Walbro 255. You can purchase the Racetronix kit, and if you cut the hole instead of dropping the tank, it can be a pretty easy install. I'm running a 58mm on my 355. I figured it needed as much air as it could get and I would suggest the same for your stroker.

 

My engine dyno testing showed my 58mm TB was oversize at 500 flywheel HP, but if you back calculate the flow based on the 58mm meeting the engine's needs at 77% TPP, a 52mm would have been marginal at that level. I wouldn't hesitate to move up to a 58mm TB at that level.

You need at least 36# injectors. The 42's will provide a good comfort margin.

You need a fuel pump rated at least 205LPH @ 43.5psi. Anything larger provides a comfort margin.

Stock FPR will work fine.... NEVER "tune" with an AFPR, as I'm sure you know.

 

yes, sorry about that. i meant to set the desired fuel presure for your set up, and to adjust for future plans.(juice, charger, etc....)

 

for something in the middle there's a AS&M 54mm unit or on ebay there's a guy that sells a 54 or a 53.5mm unit. i have the 52 and am completely satisfied with the guy's work. clean, precise and works wonderfully. plus it looks stock...because it was stock. and it's only 200 plus shipping.

i am in no way affiliated with the guy i just like his work.

 

I had a 52mm t/b on my LE2 383 and it pulled vacuum above 5500rpm, as bad as 3". The problem went away when I switched to the monoblade, but I am sure that a 58mm would be sufficient.

 

Thanks for all the replies. It looks like I'll get a 58mm TB, keep the stock FPR and upgrade the pump.

 

Get the 58mm. Trust me on this.

 

I built a 383 all forged roller LT4 ..my first issue after the tune was the stock FPR .. couldnt keep up with the 42lb injectors .. second issue was stock tb .. when i upgraded to the 58 .. the diffrence in the car was night and day .. stock fuel pump was replaced way back because my stocker LT4 was rapin' the the fuel pump .. 255 walbro and youll be plenty fine

 

Could the stock FPR not handle the volume or what do you think the problem was?

 

I think that's what he meant. I have the Walbro 255 with stock fuel pressure 42# inj and it does just fine - so far.