I have noticed many people on here with similar mods to mine having much higher karman readings than me. I average between 1690-1710 with my highest being 1734. Other people are seeing mid to high 1800's with similar setups to mine. What gives?

 

I feel the same. I don't see above 1800 either. I suspect three things: (1) our boost gauges read low; (2) our intakes are really causing issues; or (3) everyone else has a big boost leak

 

I would assume it's one of two things:

1) Your Injen intake messes up the readings, or
2) You are running lower boost.

In daily driving with a cat-back and no cams, I see 1820-1830hz at the top of 3rd gear on 21psi. At the track, when I turn the boost up some on a mix of 104/93oct, I max at 1860hz.

You should probably be seeing 1950 or so...

 

What are you using for a boost gauge?

I have a Defi D but I have no idea whether it's right. In my car, I see 20 on the Defi gauge, 18.7 or so on the Blitz ebc, and 17.2 or so on the AEM map sensor (which people generally say reads low). I also have a fairly pricey tire pressure gauge and when I inflate a tire to 21 on that gauge, my boost guage reads the tire at 20. When the tire gauge reads 30 however, the Defi boost gauge reads 31. I give up...

 

lol i feel the same bro. I am using a regular $60 autometer gauge. About 6 months ago I was on a dyno and my gauge matched what the dyno read for boost, so I thing the gauge is pretty much on. I have tuned my car where I am running 11.3:1 afr at 4500 rpm and 11.6:1 at 7000 rpm. I have played with the settings a little by riching it up and leaning it out, but haven't posted any significant changes in my karman readings.

 

Yeah, tuning the AFR won't change your Karman readings, since that is the airflow mass being read by the MAF, but changes in boost and downrage airflow (free exhaust, etc) will affect it.

BTW, do you have any timeslips to use as a tool for comparison with your karman readings?

 

No timeslips to compare to, nor do I have an awd dyno in the area to compare to either.

 

Go hit the track then. Your mph will be an indication of the power you're making (or not making). You should expect 112-114 on 93oct.

Oh, that is unless you still have the stock cat. I couldn't tell for sure from your mod list...

 

This is a little off-topic, but I think you want to be richer around peak torque and then leaner up top. It looks like you have the reverse.

 

yea that was a typo. i meant 11.3:1 at 4500 rpm and 11.6:1 at 7000 rpm. thanx i corrected it.

 

no i don't have a cat. i'll correct that in my signature. thanx

 

I would heavily suggest the intakes are causing your MAFs to read low ... this could potentially result in lean spots (because it is reading less air than what is actually going in) that could damage you engine if you are already leaning out the factory AFR ... I recommend swapping back to your stock airbox before something bad happens ... Intakes have been know to do this on the EVOs

EVO8LTW: you want it to be leaner at lower RPMs (peak torque) and richer as the RPMs rise for safety ...

 

Nah...we both have widebands so no issue with lean spots. As far as the intake, I swapped in my stock MAF pipe (with cone filter) yesterday and it didn't make much difference in peak Karman numbers.

BTW, I disagree on leaner at low RPMs and richer up top. Peak torque = max cylinder pressure and greatest chance of detonation, so that's where you want to fatten everything up. Up high cylinder pressures are lower and boost is tapering.

 

ok i hooked up a friends boost gauge last night "stewart warner" and it reads the same as my current boost gauge. i have no clue what the issue is.

 

I get about the same reading. Usually around 1700-1750. I think I've hit almost 1800 a couple times on race gas.