Dyno questions and new pictures of the Coupe

[Renee M Coupe]

Hello all! Thought I would share some pictures with you. I bought a universal mount that acts like a tripod mounted on the car. I mounted my digital camera outside the car, just above the mirror. This is my initial attempt using it, I should get better results when I am the passenger.

I have a question on dyno results with Dynojet. A few weeks ago we had a dyno day at a local turner. My car is bone stock, the results they gave me after the dyno: 211 hp, 210 torque. Their printer was not working and I did not obtain a print out that day. The next week, the chart arrives in the mail with different results: 203 hp, 203 torque. (The shop told me they made a mistake when the printed the charts and they will resolve and send a corrected copy). Everyone else that I have been in contact with from that day has had the same issue, the results they were given that day are higher than the print outs. (Most people also thought the initial HP numbers were higher than expected).

I know the results are based upon temperature and altitude entered before the run. This is not an exact science, but how much variance is acceptable? Could they have inflated the results by using a higher temperature during the run? Has anyone else put their stock S52 on the dyno (late '98 build)? I want a reliable base line number, not an inflated ego boost number. Any thoughts?

Does this engine put out 240 HP or 250 HP? I was told it is rated at 240, but is actually 250.

Thanks!

Renee
'99 M Coupe
'90 Jetta GLI

[Renee M Coupe]

Clear corners in:

[Renee M Coupe]

3 coupes from the dyno day. M Coupe Mike in the middle.

[Renee M Coupe]

Rear

[gbrown.dsl]

The consensus seems to be the S52 is a bit stronger than advertised.

[NoSoup4U]

Renee-

It depends on so many factors that it's really hard to tell, numbers can be very misleading and deceiving. Do you know what type of dynojet it was, a 248c, a superflow windyn, etc. These play parts as well...was it an inertial dyno or load dyno .. was it a dynapak or dynojet?

Notwithstanding that, what was the temperature when you dynoed?

I am guessing; but, I am wondering if they gave you ACTUAL uncorrected rwhp that day. Maybe, temperatures were really favorable with low humidity, etc...etc.

The dyno sheet that you saw (or print-out) they gave you, can you see the correction factor ... e.g, STD or SAE (most common). Most places will give out SAE numbers ... but, STD numbers will actually be HIGHER than SAE numbers.

So, you might have seen STD numbers that day as well, SAE vs. STD might explain this deviance.

I forget what drivetrain losses are on the mcoupes, around 13% IIRC ... maybe higher?

[Renee M Coupe]

Thanks for your input.

It was 74 degrees and the print out is not SAE corrected. I know it is a Dyno Jet, but I don't have any further details on it. I do know that they need to upgrade their software. They are currently using a DOS based version.

[NoSoup4U]

here you go...These are the correction factors and a brief synopsis that I posted before ... hope this helps:

SAE (Society of Automotive Engineers), USA. Power is corrected to reference conditions of 29.23 InHg (99 kPa) of dry air and 77 F (25°C). This SAE standard requires a correction for friction torque. Friction torque can be determined by measurements on special motoring dynamometers (which is only practical in research environments) or can be estimated. When estimates must be used, the SAE standard uses a default Mechanical Efficiency (ME) value of 85%. This is approximately correct at peak torque but not at other engine operating speeds. Some dynamometer systems use the SAE correction factor for atmospheric conditions but do not take mechanical efficiency into consideration at all (i.e. they assume a ME of 100%).


* STD or STP. Another power correction standard determined by the SAE. This standard has been stable for a long time and is widely used in the performance industry. Power is corrected to reference conditions of 29.92 InHg (103.3 kPa) of dry air and 60 F (15.5°C). Because the reference conditions include higher pressure and cooler air than the SAE standard, these corrected power numbers will always be about 4 % higher than the SAE power numbers. Friction torque is handled in the same way as in the SAE standard.


* ECE (European Community), Europe. The ECE standard is based on the European Directives. Power is corrected to reference conditions of 99 kPa (29.23 InHg) of dry air and 25°C (77 F). Friction torque is not taken into consideration at all.


* DIN (Deutsche Industrie Norm), Germany .The DIN standard is determined by the German automotive industry. Power is corrected to reference conditions of 101.3 kPa (29.33 InHg) of dry air and 20°C (68 F). With the advent of European legislation and standards, national standards such as the DIN (formerly widely used) are now less significant.

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John in Houston also posted some good information regarding the weather stations that I did not know about ::

Actual Horsepower is the 'actual' power that your car made on the dyno, that day, in those conditions. No extra calculations were required to come up with that number. Your car turned the drum and made 'X' horsepower (based on the amount of power it takes to turn the drum which is a known variable).

SAE or Corrected Horsepower is the 'corrected' power figures for that day. The dynos (at least the newer ones) have a weather station connected to them. They measure relative humidty, ambient temperature, etc and apply a correction figure, based on these readings, to your actual HP number. This number can then be compared to any other SAE HP number anywhere, anyplace, anytime. (forgot: There is also a spot for elevation in the software setup... so it corrects for Ft above sea level also).

Now, don't think for a minute that the SAE correction factor is foolproof. Many dyno operators have found that if they move the weatherstation to more favorable locations, then they get higher SAE numbers. Also, some of the older dynos don't have a weather station and thus rely on the $4.50/hr operator to key in the conditions from a hand-held weather station, or not at all.... thus opening the door for user error and corrupted data.

All in all, you really want corrected numbers... and you really want to stay at the same dyno facility as you are going through your testing. Different dynos can read higher / lower than another dyno.

Also, as to why you got Actual HP numbers instead of SAE.... alot of operators will print out the higher numbers so that the customer is happy. Then again, some of them are just dumbasses and don't know the difference.

**************************************

If you really want to get technical -- here's some articles on dynojets, conversion factors, etc... probably more information than you want to know

http://wahiduddin.net/calc/cf.htm

http://www.vishnutuning.com/dynos_dont_lie.htm

http://www.idavette.net/hib/dynojet/

[1BMW2VWs]

Hey, Renee,
Did you debadge your rear end?
I was going to suggest since the motif on your car is black and smokey, you might wanna pick up some of that spray tint and try smoking those bumper lights a touch. I think they'd look good and match the wheels.

[SilverStreak]

Nice pics!

Keep in mind, no 2 engines are identical, some are stronger than others for no apparent reason. My car when it was stock put down 198 rwhp on a Mustang dyno, and it's only rated at 225 bhp...

[Renee M Coupe]

I did remove the rear badge. I have personalized M plates and thought it was a bit gratuitous.

Thanks for the suggestion on the tail lights. I am going to hold off for now since I am having issues with the finished of the wheels.

[1BMW2VWs]

Well, I wasn't quite thinking about the tail lights, I meant the front bumper clears you have now...

[Renee M Coupe]

Yes, that would look really good! And it would probably still work if I went back with the stock finish wheels. (I don't know where I got tail lights).

Do you have pictures of your car out here yet?? Any mods?

[tripleM]

Nice pixs Renee! I still say that the stock Mcoupe wheels are the best looking IMHO

Re: your Dyno result..it is odd that they would send your dyno back w/ that much of a correction considering that from all I've read...most Coupe dyno @ a much higher data pt. w/ a correction factor of 15-17.5 on the Dyno Jet & 12-13% on a Mustang Dyno.

Anyhow it's an inexact science...& your Coupe isn't on steroids :P

-

[IwantMCoupe]

dont smoke your tails with the spray tint, it ends up looking all dull and gross after awhile.

[Greg]

Looks like your rims could use a good washin':12: