Sachin Misra

Got the car dyno tested this weekend on a AWD dyno, even though my fuel/timing maps are not 100%. This is evidenced by the torque curves which shows 2 massive drops. At least now I know where to adjust them.

Peak HP to wheels was 308, torque was 285. I'm assuming a 20-25% drivetrain loss which brings its to 370-385 hp. I was hoping for 400HP. Hmmm, smaller pulley??

MPB993

Sachin,

the numbers look good. With a 2.6" pulley I make 318 rwhp on the M90 and use alcohol injection to cool the intake and kill detonation. I have a tip which I think is a little less efficient than a manual. What size pulley are you running.

Cheers, Mark.

JasonAndreas

Did you measure the air-fuel ratio while on the dyno?

Sachin Misra

Appears to be a 3" pulley. It produces 6-1/2psi at the SC, 6 through the IC.

Sachin Misra

No we did not run a O2 sensor test, too many other cars were scheduled for that day. I hope to run a more comprehensive dyno test after I tweak the fuel/timing maps.

TheOtherEric

What a coincedence- I put my car on GRD's dyno Saturday morning! Oddly, I measured lower than expected, but a consultant there who has loads of experience with Porsches said that my higher drivetrain losses on a C4 was normal. If you disconnect the drive shaft for the front, you'll be closer to 15% that one might expect.

Then I started thinking about this....and he agreed with me that it's probably not good on your viscous coupling to do AWD dyno pulls. [EDIT: deleted my own misinformation]

To make a long story short, I'm guessing you have 410 hp at the flywheel.

Sachin Misra

Eric86Red911,

Too bad I didn't get to GRD earlier. Do you mind posting your chart?

385hp or 410hp, its still a blast to drive.

cecil

I haven't put mine on a rack put when someone ask I figure around 380, 385. I hooked up a boost gauge and the highest it got was 6.1. This was at hard acceleration from low rpms in second. I think it makes the car just right for a street car. Mine is a C2

Sachin Misra

Thx Eric.

Lagavulin

Sachin, it's too bad you didn't use an O2 sensor for your pulls as it would have given lots of good, relevant info.

Are you running a wide-band O2 sensor? If not, I suggest getting the one from LM-1 Motorsports:

http://www.innovatemotorsports.com/

It is money well spent, and a 'must have' for a forced induction car.

How are you tuning your fuel maps? What tools are you using?

I would not recommend turning up the boost on a 11.3:1 static compression ratio engine, and especially so if you're not sure of the fueling.

By the way, did you find that your earlier loss of boost at high RPM a couple of weeks ago attributed to a loose belt?

Sachin Misra

Lagavulin,

Yeah, its too bad we couldn't. Not enough time. I'll look into the wideband O2 sensors. I'm using the Split Second software that is written for the split second box that came with the kit.

I talked to several forced induction experts while I was at the dyno run, and what they surmised was that the blower is at the peak of its efficiency and the intercooler is cooling the air to the point where the blower can't keep up or the boost guage is not indicating true boost levels?

They said they have seen this in the past, where the blower is running at at full boost wo an intercooler. As sson as an intercooler is added, the bosst guage drops off at higher RPMs. I tend to agree as I don't "feel" a loos of boost.

MPB993

Lagavulin,

I agree with you that turning the boost up is not the way forwards on 11.3 static compression, mines down at 9.5 static but I was amazed at how much difference alcohol/water injection made to the kit without an intercooler. Lots of discussion on the subject over on the turbobuick webpage. I've used a A-W chargecooler and taken it off in preference to the alcohol/water due to weight and space limitations under the stock tail. Now at 30,000 miles on this setup and still going strong. I believe that the M90's linear flow / rpm value against the engines improving efficiency is why you see a drop in pressure as revs rise. The M90 has linear intake air flow up to at least 14k rpm. I see the same without the intercooler but as Sachin says it doesn't effect the torque curve much so I dont think the belt is slipping.

Mark.

Sachin Misra

Mark,

How much boost are you running with the lowered compression?

MPB993

Sachin,

I see about 9lb with the alcohol flowing but think it would probably be a little more without it. The alcohol/water reduces the tempurature and hence the pressure in a similar way to an intercooler.

Cheers, Mark.

Sachin Misra

Thx Mark.

BTW, Have you talked to Ross or Tito lately. If you see them please say Hi.