what fuel pump for 18 psi in TBI?

[Daveo91Burb]

I'm still in parts gathering phase for my 383 vortec build. I have an enlarged 46 mm throttle body, but I'm pretty sure I will need to be running 18 psi or so with stock injectors (feel free to offer a different opinion). To get to 18 psi assuming I need a new fuel pump? What fits in the suburban tank? Can I get a TPI pump for like a Camaro or Corvette? And then I'll probably need a regulator as well? Thanks!

 

[skysurfer]

I don't think you're going to get the flow you need with stock sbc injectors. You would be better off with some 17084304 bbc injectors, preferably a pair that have been cleaned and flow matched.

A Walbro 190 fuel pump fits in the Suburban tank and will easily feed a 383. http://www.gmsquarebody.com/forum/showthread.php?t=745

Adjustable fuel regulator is a must. There are some that replace the unit on the tbi but I've read they are hard to adjust. An Aeromotive 13301 is rated up to 60 psi, can be mounted anywhere, and can be vacuum referenced if you're running over 18psi.

Read through this a couple of times, it will give you an idea of your fuel requirements providing you have a good estimate of your future engine's horsepower.http://www.dynamicefi.com/TBI_Fueling.php

 

[Daveo91Burb]

Thanks for the info, I have admittedly seen some of those posts but it's nice to have them in the same place!

I went through the math on dynamicefi.com. If I use the 17084304 injectors per your suggestion and assume 325 horsepower (what the TB I'm using is rated at) and 85% duty cycle I come up with 17-18 psi. However, if I find the bigger injectors, 81 lbs/hr, my psi requirement comes down to less than 15. I believe that's achievable with the stock pump by changing to a lighter spring in the TBI? Are there any pitfalls with this plan? I for sure want to do things right, but if I can do things right but a little less expensive I would love to go that way as this project has some financial constraints

 

[skysurfer]

Couldn't hurt to try switching springs, but as I understand it you need to go to a stiffer spring to raise the fuel pressure. There might be some trial and error with different spring rates to hit your target pressure. I still think some sort of adjustable regulator is easier in the long run. At the very least you'll need a gauge to see where you're at. The stock pump *should* be able to supply 15psi. I've read stock tbi setups have tested anywhere from 9-15 psi, but that's more of a reflection on the stock regulators than the pump itself. Give it a try, if the pump you have can't handle the work load then an upgrade is in order but it won't cost anything to find out.

 

[SkinnyG]

I modified a TBI fuel pressure regulator to use an allen-head cap screw to make the fuel pressure adjustable. It's not too hard. I think there is a tutorial online....

 

[skysurfer]

If you need anything, check with this guy. http://www.sprperformance.com.

He's a regular on ThirdGen and his ebay seller name is dctrumpet. http://www.ebay.com/sch/dctrumpet/m.html?_ipg=50&_sop=12&_rdc=1

I've done business with him and he's a great guy.

 

[Daveo91Burb]

Thanks for all the input, guys. I should have mentioned earlier that I've also been talking with David from Old School EFI who just happens to be in my hometown of Vancouver, WA (He's mentioned in this thread: http://www.gmsquarebody.com/forum/showthread.php?t=4560). He's also recommending the 17084304 454 injectors so that's what I'm going to start hunting for. However, he's also thinking he can make my proposed set up work without upping the fuel pressure from stock. If it works the way he's proposing, great, if not, then I can change out the pump and all that from there. I'll keep y'all posted, first I have to get the motor built though!