81WideMariah

iTrader: (8)

Need some opinions guys.... I've decided to go ahead and turbo the 12a in my 81. It will be a blow-through set-up using a 45 DCOE prepped by the Cheese Meister himself. Planning to run between 10-15 psi boost on a large streetport using a RayJay T40B, tubular manifold with 2" runners and 38mm external wastegate, and intercooled of course, with the likely possibility of water/meth injection at a later time. Dizzy will be locked at 10 degrees BTDC with 10 degree split, and an MSD 6a firing a 2GCDFIS. I'm also running a Mallory 4309 1:1 RRFPR base pressure should be around 2.5 to 3 psi.

Now that we've covered the basics, here's what I need help on. I've seen lots of guys running walboro 255 external pumps, but honestly they really seem like overkill. I've found cheaper pumps that flow slightly less but should be enough to handle what I'm trying to do. Check out this link...

http://2.3liter.com/Calc1.htm#FPHP

Using a BSFC of .6 and trying to make 300hp I should only require 29 gph or 110 lph. This MSD pump is capable of delivering that and then some.

http://www.summitracing.com/parts/MSD-2225/

I'm thinking this will be enough pump... am I wrong?

Next, I've seen lots of guys have dropped the tank and built surge tanks or baffles or even sumped the tank, which is fine and all, but I'm trying not to break the bank on the fuel system alone. So my question is can I use a FI fuel filter before the pump to act a s a mini-surge tank? I'm not one of those guys that runs his tank to empty all the time either, so I don;t think I'll have too much of an issue with pick-up in the tank.

Lastly, I see lots of guys are swapping out the stock feed line for a larger 3/8 or even 1/2 in line and using the original supply line as a return. I'm having a hard time believing this is necessary. Any thoughts? Anybody running 10-15 PSI on stock fuel lines?

As always pics are welcome and appreciated.... thanks in advance.

81WideMariah

iTrader: (8)

30 views and no thoughts?

PercentSevenC

I'm using that exact pump. It's plenty.

I'm using a stock 12A tank with a stock 5/16" send line, and a 5/16" return line to the stock 1/4" return on the tank. I haven't run into any issues with fuel starvation despite my ridiculously rich WOT AFRs (I have no intercooler), and my fuel pressure is rock solid at idle (which is where you would expect to run into problems with the return line). Granted, I'm not making that much power yet, probably closer to 200 WHP.

Edit: Still, look at how small the fuel inlet to the carb is. Much smaller than 5/16". That would be your bottleneck, not the lines.

81WideMariah

iTrader: (8)

I figured that pump would be enough.... how did you do the return line? hard line or braided?

PercentSevenC

I used the stock hard return line from a GSL-SE, which is 5/16". From that line to the tank I used a piece of regular 1/4" hose with one end stretched to fit the 5/16" hard line.

theNeanderthol

iTrader: (1)

Summit stamped their name on that pump and they sell it at for a bit cheaper. it looks identical, as well as the specs. So I think it's actually the same pump. So that could save you a few bucks.

Sorry I have no real world experience with the stuff you are asking. But every time I do the math and the research, I come up withe the same answer as you; that yes the smaller pump and the stock lines would be sufficient for a blow though like yours. But again, I've never done it.

Siraniko

iTrader: (13)

just run a MSD FI pump

rx71king

iTrader: (6)

can the mallory 4309 handle fi pump?

81WideMariah

iTrader: (8)

I've never heard anything to the contrary, so it should.... the 4309 is a bypass regulator so rather than trying to restrict flow to achieve desired pressure it returns excess fuel/pressure back to the tank, that's why having a properly sized return is important.

81WideMariah

iTrader: (8)

Thanks Wacky.... just ordered one yesterday.

rx71king

iTrader: (6)

i should no that . i have one on my car. i have mallory 140 pump ran up to 15 pounds of boost no problem