Finally got 750 miles on the new engine so I started to turn up the boost. I made it up to 11 psi and the DW600's are totally maxed out. I am just touching 99% duty cycle at redline. This is with 51 psi base fuel pressure, a Walbro 255 and drillout out fuel rail restrictors. I've got a set of ID1000's on the way, I am hoping the Walbro will be able to keep up at 14 psi of boost.

Even with just 11 psi and very conservative timing, it makes awesome power. 2nd gear is massive wheelspin and 3rd gear makes the back end wander. If I hit a bump or a crack in the road at full boost in 3rd, it starts to spin. I've got a 3.90 FD and the stock viscous diff currently, but I have a Quaife in a box in the garage that I am going to install this winter, along with the stock FD. Also I am on 275 Falken FK452's, some sticker tires are definitely going to be needed sooner than later.

 

what are you considering "conservative timing"?

 

Single digits and climbing into the low teens toward redline at 175 kpa (~11 psi).

I have been monitoring the knock sensor signal and I dont see anything that obviously looks like knock. In fact I get much higher spikes on decel and in between shifts (shift knock?) than I ever see under boost.

What do you consider conservative timing on 93 octane and 11 psi with relatively large turbos?

 

It's not really shift knock isn't just engine noises that the sensor picks up. That's why it's good to tune the knock thresholds (if you have a proefi or haltech).

As for the injectors, if you have stock rails and stock supply lines then those are your restrictions. walbro 255 should get you over 500hp and will flow more fuel than 600cc injectors so if you are out of injector then it's due to the high resistance of stock rails. Do you have return system? I guess if you do'nt have a rising rate regulator then that will reduce the amount of power you can make. You definitely don't need 1000cc injectors for a single walbro.

 

I just finished a BP single turbo tune...made 610 at 18lbs. Fuel system was 850cc DW's, stock rails, aeromotive 340lph pump and basic fuel return kit and IDC was 70%. Base fuel pressure was 50lbs static. Made a few pulls that were pretty rich when starting to dial in, i think that set up is good to 650ish before we find out if the rails or pump is going to limit us...

 

Also we started tuning the car with a stock fuel system configuration(returnless) and at 550whp fuel pressure was dropping about 8 lbs in higher RPM's and IDC was about 15% higher to maintain the AFR's....

 

So that is with the stock supply line from the tank?

 

Stock feed lines and rails, no modifications