MRC Tuning vs. pippyrips' B7 RS4
04-01-2009, 06:14 PM
#12
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Does it have an oil drain back into the block?
04-01-2009, 10:29 PM
#15
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What is this "issue" with the Milltek?
04-01-2009, 10:42 PM
#16
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I just asked over there what drivetrain loss they added in. But you say "measured" loss... not possible for most folks, but that's what I want to see. The Euro guys are really mad about exaggerated hp for this engine. What is the accepted drivetrain loss for this car?
04-02-2009, 06:39 AM
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Drivetrain losses on the RS4 are sizable, as they are generally on AWD cars. For example, if you assume the US SAE claimed number by Audi of 414 crank hp is correct (which translates to the European 420 hp), most RS4s that have been dynoed stock are in the very low 300s wheel hp. I've dynoed mine and got 325whp which is with the Milltek cat-back, which is known to add a good 20 or so hp. If you assume it added nothing, than the drive train loss of 325whp/414chp yields about 21.5%. If you adjust for the exhaust, it is likely 24-25% easily. Either that, or the 414 SAE manufacturer-claimed figure in inflated.
To contrast this with a RWD car, my 394 crank SAE HP rated E39 M5 in fully stock form yielded a shade over 330hp (331 IIRC) at the wheels (coincidentally both the M5 and the RS4 have been dynoned at the same machine). This translates to about 16% drivetrain loss. Headers alone added 30whp which was def noticeable, but that was probably due to the fact that the stock headers were very restraining and inefficient. The RS4 exhaust components seem to be better optimized, but you can obviously do a little bit better with downpipes and a catback.
I will be dynoing the 135i soon (same machine), from what I have seen the numbers of SAE 300 crank HP/300lbs tq as advertized by BMW are grossly understated. My dyno shop showed me at least a dozen runs on different 335i that in fully stock form produce 270+ whp and 290wtq. I can tell you that the drivetrain loss on those is certainly more than 10%, so that tells you that the claimed numbers are very conservative. I've heard the same about the GT-R. I mean if the naturally aspirated 3.0 BMW engine produces SAE 255hp, you would think adding 2 turbos (granted small) would yield way better than 300...
04-02-2009, 07:08 AM
#18
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O2 sensor in Milltek downpipes is placed too far away from exhaust ports
Audi/VW ECU design for FSI wants the sensor to be as close as possible, so that the ECU can differentiate mixture control for each cylinder. If you compare stock and Milltek O2 placement, the difference is obvious, and should have an impact at high RPMs.
Audi/VW ECU design for FSI wants the sensor to be as close as possible, so that the ECU can differentiate mixture control for each cylinder. If you compare stock and Milltek O2 placement, the difference is obvious, and should have an impact at high RPMs.
04-02-2009, 07:48 AM
#19
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Obviously not working as efficiently as they had hoped...
Not sure if an aftermarket setup would assist if it was still plumbed into the intake side of the engine. Venting to atmosphere would do the trick... but only if the car wasn't used on public roadways of course...