Blk_A4

<center><img src="http://pictureposter.audiworld.com/62296/neuspeed-exhaust-dyno.1.jpg"></center><p>Can anyone tell me why this dyno shows very low HP and TQ with P-chip and exhaust. I mean isn't it should be at around 170WHP and 180WTQ for P-chip with exhaust. Am I missing something here or CVT has different way of calculating the tranny loss compare to the 5-speed.

I believe that it's way too low for the mod. Correct me if I'm wrong but something has to be wrong here.

Your help is appreciated.

Skene @ PES Tuning

Unless you were using an engine dyno.

Plus you must factor in drivetrain loss at the wheels. This is affected by all parts rotating from the flywheel through transmission down to the wheel hubs.

This would equate to the loss of Hp and Tq.

Hope this helps.

Blk_A4

Don't you think this dyno show too much of drivetrain loss. Let me give you an example, I have 2002 Civic SI which is rated at 160@crank, I dynoed it after the few mod it measured 152@wheel not @crank.

Now A4 CVT rated 170HP and 160TQ from stock and assuming that their is 15% tranny loss, wheel HP and TQ should be at around 144 and 136.

This modified A4 shows less HP than stock wheel HP and you only gained 27 in TQ. Unless P-chip and exhaust only gives you few Hp and 27TQ which is hard to believe from butt dyno.

Help me here I'm wrong.

joe@vwvortex

and the type of dyno. Dyno's are really only good at measuring the delta - or the difference between stock and modified. You need to get a baseline dyno stock - and then add modifications and TRY to keep all other factors constant.

Most FWD VW's with the 180hp engine are dynoing at 163 whp......

Blk_A4

this is very hard for me to believe that CVT drivetrain loss is that bad. Just think about it. If there is 20% (I think 15% more typical in most cases) drivetrain loss for 200HP and 200TQ A4 CVT. You should see 160WHP on Dyno chart not 135WHP. I believe that TQ is close to their claimed number but I think it's still low.

joe@vwvortex

as it appears that you had your car dyno'd there. What gear did they run the dyno in? To get relatively accurate results you need to run in the gear that is closest to 1:1 - sometimes 3rd other times 4th. If I remember correctly CVT doesn't have predetermined gear ratios so this may present a problem. Also - some load based dyno's - such as Mustang dyno's give much lower numbers than others such as Dynojets. APR's DynaPak gives yet different numbers because the readings are taken from the wheel hub not from the tire. The amount of drivetrain loss is a guess unless you have a dyno of your engine stock and also if you have the same dyno doing similar dyno's of the same stock engines to get a baseline. Who knows. You're car may not be running right stock. Bad MAF or 02 sensor, you don't know unless you have a baseline set to compare it to.

CrazyBobby@ModSport

but my runs at the track tell me thats not true...the best thing to do is get a baseline dyno, then dyno after mod, and you can tell the difference... i wouldnt rely on it for accurate numbers though... i ran the quarter mile at 15.2 with slipping clutch and 87 trap speed... if you use a different calculator it puts me at about 190-200 hp according to some charts... who knows though :-)dont get discouraged from the dyno chart...