Thread: GOOD NEWS

well today i finally got my car dynoed after countless problems and delays. we ended up making 320awhp and a little under 276tq at 17.5psi on 91 pump. this was without any cam timing adjustments so we could have made a little more. afr was kept around 11.5. im going back in a couple weeks to tune on 100 octane and moooore boost, along with cam adjustments. i'll keep you guys posted.

hey not bad for a 600+ HP capable turbo!!!

:P

it's getting there, hold your horses. needs more tuning

i hope so, i put in some eagle rods and je pistons. it "should" hold up. haha anyways what kind of numbers have your guys seen out of a 62-1 or 60-1 on pump gas?? this seemed kinda on the low side to me and i was a bit dissapointed leaving the shop. i was hoping for at least above 350hp on pump. we only got 17-18 psi cuz i changed the WG spring to a softer one and it wouldn't make more. im gonna change it back to get it to make the 25-30 i want. also this was done on a dynapak dyno, i dont know how they compare to mustang dyno's.

Id say its fuel delivery :)

I know you had originally mentioned that you wanted to run lke 90 psi to get 550's to flow enough for that turbo.. But what kind of fuel pump are you running????



a standard walbro 255 cannot support 90 Psi at all.. A HP 255 can barely support that much pressure with enough fuel flow left over for 4x 600 some odd cc / min.. In fact.. At 73 PSI of fuel pressure a 255 pump can only supply a little over 3000 cc / min of fuel which divided by 4 is something like mid 700's.. But youd need to be flowing probably 20 some odd less percent fuel than that out your injectors to keep fuel even across the cylinders and keep some form of atomization up.. Im going out on a limb here but im gunna say without an exotic fuel pump setup your not going to be able to run enough pressure under load while your flowing fuel to support much more than mid 300 hp range..

http://www.roadraceengineering.com/f...pflowrates.htm

*Edit..

If you look at these graphs.. (THeyre in G/Hr but if you run the math its easy to see that the walbro pumps cannot handle that kinda fuel pressure..


@90 PSI @13.5 volts flows around 45 Gal/hr = 2833 cc/min / 4 = 708cc X4 = you could only run maybe 560cc/min per cylinder at that pressure.. The pump just cannot flow enough with that much pumping resistance...





= Just not going to happen

^^^^

Thats why people run freaking huge injectors :)

i have a supra TT fuel pump in it. it was in the car when i got it so i left it. i think i know what the problem might be. at the last second i changed the spring in the WG to a softer on and i noticed last night that it makes boost like a supercharger does. goes up with rpm where as with the other spring i made full boost at like 3600 and now it's not making full boost till much later. im gonna change the spring and run about 21psi and see what happens. i dont think it's a fuel problem, at 18psi the injectors were at just under 70% duty cycle. im gonna make a couple changes and put it back on the dyno and see what it does, im also going to adjust the cam gears and see what else we can squeeze out of her.