Updated KB Dyno #s: Help Needed

Hi folks,

I know some of you have been following my KB set up and thought I would post the latest news and see I could get any ideas from you that may help me in my quest for more HP.

To recap, my first time to the dyno, the car pulled 367 RWPH @ 5300 RPM, which I thought was pretty low for a KB set up (9psi IC). On top of that, allegedly, the A/F ratio was at 13.5...way too lean. However, my car didn't feel that way. No signs of hitching or detonation whatsoever.

Ken figured out that the 90 degree bend that I had in front of the MAF from my BBK CAI was throwing off the readings of the stock MAF. So, by Ken's suggestion, I got the KB CAI, Big Tube Kit, 90 mm MAF and their switch chip. He also figured out that the speed (shaft) limiter was kicking in at 5300 RPM on 4th gear.

I went back to the dyno last Saturday and have new dyno numbers which I have hesitated to post. Anyways, the car made 373 RWHP @ 5700 RPM and 391 RWTQ @ 4000 RPM. The new chip allowed me to go up to 5700 RPM, but again the speed limiter kicked in (well, that's what I think happened). The A/F, however, improved a lot...12.3. But the power is still way too low…from what I was expecting.

The car runs nice and feels extremely powerful. The thing is that the dyno runs are telling different RWHP numbers from those claimed by KB and from other KB owners. I was honestly expecting at least 410 RWHP on my car. Maybe the dyno is not working properly...I don't know. What do you guys think may be wrong? Could an exhaust leak be the root cause? Your thoughts are greatly appreciated.
 
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What size injectors? What size/type of fuel pump? I personally would be scared running an A/F ratio of 12.3 on a stock bottom end. I told Mike I wanted no more than 11.5 for my tune, which he did.

Maybe you're just not getting enough fuel...... :shrug:

Lawrence
 
I agree with Tom about checking the boost level through the pull. IMO, the AFR is still a little on the low side for a blown engine. Also, if you extrapolate out to 6,000 rpm you would be right at 410 rwhp. This is based on your dyno pulls ending at 5,400 and 5,700 rpm.
 
Firemanz said:
What size injectors? What size/type of fuel pump? I personally would be scared running an A/F ratio of 12.3 on a stock bottom end. I told Mike I wanted no more than 11.5 for my tune, which he did.

Maybe you're just not getting enough fuel...... :shrug:

Lawrence

The injectors are 36# and I'm using the KB Boost-A-Pump. I personally don't trust trust the A/F readings. The meter has never been calibrated. But just to be safe, I'm oredering the MAFtuner to twick the A/F a bit.
 
Michael Johnson said:
I agree with Tom about checking the boost level through the pull. IMO, the AFR is still a little on the low side for a blown engine. Also, if you extrapolate out to 6,000 rpm you would be right at 410 rwhp. This is based on your dyno pulls ending at 5,400 and 5,700 rpm.
There is no sign of belt sleepage as I'm seeing 9 psi of boost at WOT through the power band. I had the dyno technician to save the dyno data in a disk and I was able to perform a regression analysis of it. The statistical analysis showed that at 6100 RPM I should be seen somewhere between 400.8 RWHP and 418.4 RWHP, which is a moderately precise estimate when compared to KB claimed numbers. The statistical analysis was performed for a 95% confidence coefficient and used SAS for the analysis.