whats the max hp 50# injectors will support?

put down 550 last time out with belt slippage issues and 8 fading down to 7 psi. now the slippage is fixed and going back with 14-16 psi. expecting 620-650 rwhp and wondering if 50's will support it.

this whole fuel sytem is on the verge of being maxed out. walbro 340 and a boost-a-pump.

thanks....

Allen our local f-bud saw about 525rwhp with the MSD 50#/hr and it was well into the 80% duty cycle. I'm pretty sure that it will not efficiently do close to 600rwhp and for sure not over 620rwhp like you are hoping.

I got 611rwhp with 72#/hr, Walbro 340M and a Voltblaster. And I am seeing a little fuel pressure drop of a couple psi at the top end. This is suggesting to me that the stock fuel lines are getting to it's limit. You will see this effect even sooner if you are pushing with 50#/hr injectors at sky high fuel pressure.

I would definitely try with your current setup and increase your fuel pressure and see what you can get. But I would suggest getting the www.acceleronics.com converter and at least 72#/hr injectors probably bigger.

good luck

thanks for the info...this is an ls1 also if that makes a difference. i know they operate at higher fuel pressure if that makes a difference.

See sig, I am running 55#s with a DFI, but I had to really bump up the base pressure and then re-tune.

Wingnut

If you have enough pump to run up the FP, maybe 50#'ers could support ~600rwhp. Personally, I'd advise some bigger injectors and the Acceleronics low impedance injector driver.

Rich Krause

Rich is right. The only reason I still have the 55's is because I am running a DFI 6 and no converter. I am running an eliminator pump with #10 and #12 hookups braded all the way to the high-flow rails. My injectors are maxed and so is my pump pressure. However, on a high note - all that pressure sure smoothed out the idle quility of the high-z 55's.

If you can, do the converter and 72's. In the long run it will be worth it.

Wingnut

"I got 611rwhp with 72#/hr, Walbro 340M and a Voltblaster."

that pump puts out enough pressure to support that kind of power with out being close to maxed out? or is because you dont have to run high pressure with such big injectors? and the voltblaster is the kit that racetronix sells correct? i ask because i want to keep an intank pump, no sump or anything like that. please help.

well, you guys were right, it didnt make the power i thought it would.

going to go with impedence converter, 83's or 95's, and twin intank walbro setup...that should do it and get it over with for good!

Originally posted by mehoffz24
"I got 611rwhp with 72#/hr, Walbro 340M and a Voltblaster."

that pump puts out enough pressure to support that kind of power with out being close to maxed out? or is because you dont have to run high pressure with such big injectors? and the voltblaster is the kit that racetronix sells correct? i ask because i want to keep an intank pump, no sump or anything like that. please help.

Actually, I think the injectors are definitely not close to maxing out, but the fuel pump, the stock fuel lines, and stock fuel rails are getting close to maxing out. I'm not completely sure though. I'm quessing in that only because at the high end, I see my fuel pressure dropped from ~49psi to about ~45psi starting from about 36psi at idle. I think I can squeze some more in but probably not over 650rwhp. If you are shooting for over 600rwhp then the racetronix twin intank fuel pump maybe a good idea like Marshall93z is planning.
The voltblaster is different from what the racetronix kit comes with or the boost-a-pump. The voltblaster is an older unit that used to be very popular years ago with the GN and other high power cars. It increases voltage base on TPS to all electrical system in the car. This was added "to add a safety margin" and also because it is pretty cheap. The other ones are dedicated only to the fuel pumps therefore more specific and better.

Originally posted by marshall93z
well, you guys were right, it didnt make the power i thought it would.

going to go with impedence converter, 83's or 95's, and twin intank walbro setup...that should do it and get it over with for good!

Good luck. You will be very happy with the impedance converter and low Z injectors.

--Hugh

In my configuration from two seasons ago my car made 733rwhp with a 255lph in-tank, stock lines, rails, and regulator. The key was a Kenne Bell Boost-a-Pump and having enough injector. So, I would go about replacing the stock lines and rails until you are approaching this hp level.

Rich Krause

rich, what injector was you using?

I was using 8*50# "main" injectors and 3*90# injectors in a Carroll Superfueler. So, the total injector area was equivalent to using eight 83lb injectors. My current setup uses eight 90# injectors with the Acceleronics box and the SF is turned off.

Rich Krause

I just made my own dual 255 lph intank set-up. It was pretty easy to secure 2 pumps to the factory intank bracket, then Tee the fuel pumps into the single 3/8" hose.

The single hot wire isn't good enough for 1 pump, let alone 2, so I ran a power and ground for the 2nd pump out the top of the tank and up to a relay at the front of the car. I used a Wells (Autozone) oil pressure switch screwed directly into a vacuum port in the intake to trigger the pump with boost. The oil pressure switch turns "off" at 2 - 5 psi. Since the oil pressure switch is normally closed, I had to wire up 2 relays - 1 normally open to energize the circuit with the key on, the other normally closed to turn on the 2nd pump with boost.

I have my 83 lb/hr injectors wide open (safe until I get it on the WB O2) and the fuel pressure starts at 40 psi, then builds to 55 psi at the top of the gear, never falling off.


BTW, I'm selling a Superfueler with 3 - 55 lb/hr injectors and a 58 mm plate if anyone's interested.

Mike

Friend with MSD 50's, ati D1, and aeromotive fuel setup saw 560rwhp through an A4 and 4000ish stall (unlocked) at 5100 rpm, at which point the injectors were maxed out (~12:1 a/f ratio, 100%+ DC) - a/f ratio started leaning after that with no fp drop (still increasing 1:1 with boost) regardless of tuning changes. A swap to 72's cured this. The FP was at 60psi with the 50's also.

Also the 72's with lj's box were 10x easier to tune and idle nicer than the 50's :)


Chris

so all you guys are saying that if i make 550rwhp or so that the walbro 340 and 83# injectors will be over kill , and will be fine if i ever wanted to upgrade anything to run more boost. when you using the stock regulator how do you adjust the fuel pressure, throught the pcm? thanks for all the GREAT info

Originally posted by mehoffz24
so all you guys are saying that if i make 550rwhp or so that the walbro 340 and 83# injectors will be over kill , and will be fine if i ever wanted to upgrade anything to run more boost. when you using the stock regulator how do you adjust the fuel pressure, throught the pcm? thanks for all the GREAT info

The stock FP regulator is not adjustable and is not controlled by the PCM. But it is "vacuum referenced", so the FP vareis directly with manifold pressure. IOW, it is a "1:1 FMU" in a manner of speaking. I am using an adjustable FP regulator at this point, it can be a valuable tuning aid. But you may well not need one in which case just stick with the stocker.

Rich Krause

so for the amount of power i want to make the 340 and the 83 s will be just fine right? 550rwhp

83's will be fine. I just got done tuning mine on the WB O2 with 83's. I had the PE tables at +48% and A/F ratio was pegged rich. After backing off a bit on the PE, the A/F is now ~11.1/1 with the combo in my sig. at 13 psi boost.

The 340 will be marginal, perhaps not enough pump. A volt blaster / Boost a pump would make it work, though.

Mike