Your a right. No way... But that is what the dyno sheet said.. The engine only number was in the 330 range.

No mistake here.. I was there!

 

I'm sure glad to see this.....So it ain't just me that feels this sort of nonsense goes on.

 

Look what this post turned into. I just wanted to know what the difference is between STD and SAE on a dyno was. I may be sorry for this one, but is there a formula to convert one to the other?

Thanks,

Clayton from Las Vegas

 

If anybody can tell us what the different smoothing factors are it would be very helpful. All I know is that there are 1-5 smoothing factors that I have no idea what they mean.

 

Multiply your STD readings by .965 ....it will be very close.

 

To get SAE J1349, you apply the following formula to the uncorrected horsepower:


where:
cf is the final correction factor multiplier
Pd is the pressure of dry air in hPa
(990 hPA = 99 kPa)
Tc is the air's temperature in degrees Celsius

The smoothing factor does just what it sounds like it should do... it's smooths out peaks and valleys with more smoothing or less smoothing.

 

Math must have been your major!! So smoothing does not affect final HP/TQ numbers but rather just smoothes out peaks and valleys?

 

Uh, no. I just know how to use Google pretty well The smoothing factor is just that, smoothing the peaks and valleys. I suppose it could affect the peak numbers if there was a big peak and the smoothing dropped it a bit, so I'm guessing that if anything, it would cause your peak numbers to be less than actual.

 

Pretty good..... (the Google statement).

And smoothing just averages the numbers so to speak, removing abrupt peaks and dips to form a "smoother" curve to compare to a former run and draw conclusions from. And I have seen some claimed numbers with low smoothing numbers (more peaks) which really looked like more of a spike in the curve....but 500 sounds and looks alot better than 495.

A dyno is a tuning tool and can be used for comparisons but unless your comparing figures from the exact same dyno (at the same facility) there will always be some sources of error even comparing corrected results. One shops weather station may be placed in a more optimal spot than another shop....the dyno itself could read a small pertange different than another identical model, etc. etc. There are many small variables and a stacking of tolerances that make the dyno game a bit dicey at times. Thats why I always look for the performance to back the numbers....more specifically the MPH, but now you must also consider track conditions and more importantly density altitude as well if your want to try an analyze how much power a vehicle is producing.

Regarding the DynoJet's reading higher, while I agree they do if everyone quoted DynoJet numbers it really doesn't matter....in my opinion there are more DynoJets out there so they do represent the standard. Seems most Mustang dyno's read low but others claim they can be altered to read closer to a DynoJet. The best thing you could probably do for yourself is speak to the shop owner when you test and have him inform or show you what a typical power and torque number might be for a similar combination. Every dyno owner knows a good number from an average (or below average) number on his equipment...that would be a better piece of info if you knew nothing about the dyno you were testing on (versus trying to compare your data to what you see routinely on the Internet). Also, it's always best to baseline on a particular dyno before you mod the car so you can better eveluate the real gains you have made....whether that dyno is generous or stingy with a number doent matter if you baseline your vehicle first. The net gains from the money and time invested is what you are ultimately trying to quantify.

Happy Holidays,

Tony M

 

To concur with Fastbasser's comment on a car dyno'ing 410 and turning 11.1 at the track, if you do the math it doesn't make it.

HP= LBS /(ET/5.825)3 "TO THE 3RD POWER"
or
HP = LBS X (MPH/234)3

So, if a loaded C5 coupe with driver weighs on the high side at 3500lbs and turned the quarter at 11.1 at 123mph, you get:

3500 x (123/234)3 = 508 hp. Now even if we assume a driveline loss of avg. 15% we are still in the 430's rwhp. Car probably actually weighed less but these are grenade level numbers for a friendly discussion.

I've seen the same car dyno very different numbers on different dynojets and even more when run on a Mustang Dyno. As stated, stick to one dyno and baseline on it first. Assuming there is no "manipulation" going on, any gains or losses from mods or tuning should be realized.

I think a dyno has it's use, expecially in R&D, but I prefer a good street tune and take it to the track.