I guess you live and learn. Thanks for the help. 
fuel pressure ?'s
Thread Starter
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
fuel pressure ?'s My last trip to the dyno i ran out of fuel a 5,200 RPM, (20psi) with #60 injectors and a single 255 in tank, stock fuel rails. I'm seeing #10 of boost after 5,000rpm.
I installed a kenne bell boost a pump last week. I have a fuel gauge that i plumed from the fuel rail to the back of the hood so I can see it while driving,this is not a electric gauge. When going WOT the fuel pressure holds at 55 to 60 psi untill I cross the 5,500rpm range then it drops to 40/45 psi and holds to 6,700rpm. So my ? is do i need to maintain 60 psi of fuel pressure at all times? Do i need two pumps? I'm hoping to get back to the dyno in the next month to finaly have it tuned again and I dont want to spend $500 to find out I need more fuel again. Any sudgestions would be great.
I installed a kenne bell boost a pump last week. I have a fuel gauge that i plumed from the fuel rail to the back of the hood so I can see it while driving,this is not a electric gauge. When going WOT the fuel pressure holds at 55 to 60 psi untill I cross the 5,500rpm range then it drops to 40/45 psi and holds to 6,700rpm. So my ? is do i need to maintain 60 psi of fuel pressure at all times? Do i need two pumps? I'm hoping to get back to the dyno in the next month to finaly have it tuned again and I dont want to spend $500 to find out I need more fuel again. Any sudgestions would be great.
Last edited by conan; Aug 23, 2008 at 08:12 AM.
I would put another pump in. If pressure is dropping like that then your streachin that pump. There is a sticky in the fuel or here on how to diy twin pumps way less than a sponser one and its used on a 800 hp car.
Thread Starter
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
Thanks for the info. I found the sticky in the fuel section on the dual pumps.
Thread Starter
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
Thread Starter
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
We stoped tuning @ 5,100 rpm and it made 543rwhp 502wrtq. Fuel pressure went to 20psi around that rpm. Now with the kenne bell boost a pump turned up all the way fuel pressure holds 55 psi untill 5,500 rpm then drops to 45 psi and holds there all the way to 6,800 rpm's.
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I would save yourself the problems later and just do the dual pumps now. What you have now is like a bandaid. It could be tuned around being that it doesn't drop below 45 they could tune around the problem but you are better off doing it right the first time. Your set up is similar to mine. forged 347, ported stock heads, 224/232 .581/.595 114lsa, 1 7/8 kooks, mufflex, 60# injectors and I have dual intanks. Seeing 12psi I made 605rwhp, 522rwtq
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Verdad Gallardo Thread Starter
Joined: May 2004
Posts: 6,492
Likes: 6
From: Back in the Burg
Thanks for the info. I want to have everything right this trip to the dyno. I have to go from park city UT to las vegas to have it tuned this time and its about a 6 hour drive not to mention $4.40/gal for diesel to tow it down there. Any imput on keeping the kenne bell boost a pump in with the 2 fuel pumps or just the pumps.
I would run just the 2 pumps. Also do you have a adjustable FPR I have a boost referenced one and I am running around 60psi @idle and damn near 70psi @6800rpm. I also did 8AN feed lines and used my stock feed line as a return line.