carace

and being on the dyno. I had my stage III Passat dyno'd today and I am once again confused with the results. I was given two charts, one chart labeled "actual measured horsepower" and the other altitude correct horsepower.

Clark@turbo5.com

I know from my days as a Dyno operator that Actual measured HP is exactly that.. Its the HP that the Dyno measured at the wheels of the car regardless of the temp and altitude.

The second chart is the corrected Hp level. Might be SAE who knows. They take several things into account and correct the figure. This way if you are in 6000ft you will get the same reading at 500ft as where measured will have a HUGE difference. Altitude, temp, and humidity are a few of the factors that can effect Hp output.

I would pay attention to the corrected if I was you. Those numbers will jive with other runs made on other dynos of the same type.

If you go back to that dyno in the summer the corrected Hp should be close while the measured will most certainly be lower.

Hope this helps.

Clark<ul><li><a href="http://www.turbo5.com">http://www.turbo5.com</a</li></ul>

Afrosquad

You mind posting the dyno run results?

carace

Runs were made in third gear. Boost topped out at an indicated 23psi. Sunoco 100 was the fuel used. First run intake temp. topped at 126 and second run went to 173. There are other things on the engine. This is not a basic stage III!
Absolute barometric pressure 24.82in.Hg.
Vapor pressure 0.14in.Hg.(what is this?)
Intake temp. 57.6F
Gear ratio 53.98RPM/MPH
Correction factor 1.19

http://albums.photopoint.com/j/View?u=1072990&a=7923852&p=35044681
http://albums.photopoint.com/j/View?u=1072990&a=7923852&p=35044674

carace

Correction;runs made in fourth gear

Clark@turbo5.com

Here is a link that explains Vapor pres better than I can.

I take it that the Higher reading graph is the corrected Hp and the lower is the wheel hp. Was this the 248c dyno?


Thanks

Clark<ul><li><a href="http://edie.cprost.sfu.ca/~rhlogan/vp.html">http://edie.cprost.sfu.ca/~rhlogan/vp.html</a</li></ul>

carace

He also gave me a printed chart of hp at a given rpm in 250 rpm increments. I see that I will probably start shifing the car at 6500 at the track instead of going all the way to 7400. I was suprised how the cams(Schrick) did not start to fall off badly until past 7000rpm.

Clark@turbo5.com

But it bounced back.. Email me.


Clark

RS

Actual hp is what the dyno recorded at the wheels.
I am not sure what the higher numbers are. I would contact the Dyno shop to see how the corrected numbers were derived.

The most interesting point is how the numbers dropped off on the second run at higher RPM. Is it because of the elevated charge temps? Do you have a FMIC?

I think this is the first actual stage III dyno numbers I have seen on the forum. Pretty impressive results.

carace

He did explain that the corrected numbers take into consideration my altitude(over 5000 ft) which at the time I did the dyno was actual times 1.19. Basically an engine was losing 19% power at this altitude. I believe turbos help make up some of the diffence but not all. I would like to dyno the car at close to sea level. That would be the only way to tell. My guess is that the 310 hp would be very close to crank hp after I have thought about it a little. 310 is just too high to be wheel hp. A little math shows me that at 310 crank hp x .85(15%drivetrain loss seem acceptable to me for a manual front drive)=263.5. Very close to my actual hp that was measured. Probably gain some power while in motion due to air over the intercooler. I do have a front mount. I will try to post my data logging I did on these runs. I would like to hear anyone elses idea on the validity of corrected numbers for turbo cars.