--------------------------------------------------------------------------------

Hi,

I have a 1992 (LT1) with 100,000 miles all stock except for Borla muffers dyno'd at 273hp and 305tq. This was on a Dynojet (STD). SAE was at 266hp and 297tq.

Whats the difference between STD and SAE?

Thanks,

Steven

 

SAE is good.

STD means you should have been more careful.

 

Okay, a serious response this time, lest CFI-EFI makes a cold/nasty post (I like warm/fuzzies).

taken from a yahoo search (second listing):
Correction standards which is Calculated for HP and Torque. CORRECTED means what is Actually measured on that day is then passed thru some formulas to CORRECT the readings to match a single Standardized Air Temperature, Barometric Pressure, Humidity, Altitude and Dyno Friction. The purpose being that on one day the Temperature is for example 70 degrees. The next day it is 85 degrees. At 85 degrees the car will make less RWHP than on the day when it was 70 degrees because is was hotter out. The theory here is that, as we put new performance parts on our car, we need a Consistent way to measure any gain (or loss) without confusing the issue with Environmental factors such as temperature and humidity that have a DEFINITE affect on RWHP, so we get more accurate readings for the Net RWHP gain made by a Pulley change or Headers, etc..

The most common correction factor is SAE (explained below). STD and STP (almost identical to each other STD/STP) is very commonly used in the performance industry also. Whatever you pick as a correction factor, you will want to stick with it as you continually Dyno your car over time. That’s because you want to be able to tell over time, a consistent way to measure performance gains made by upgrades you made to your car and this is the only way to do it.
STD and STP generally come out with about 4 % higher numbers than SAE since the temperature in the standard is lower in STD than in SAE. It still makes no difference what you use as long as you are consistent. If you use SAE then always use SAE. If you use STD then always stick to STD.
-------------
SAE -- The SAE standard applied is a modified version of the SAE J1349 standard of June 1990. 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%).

· STP -- The STP (also called STD) standard is 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.

 

in other words, the difference is 8 hp.

I agree that the key is using the same test method each time.

I have a dyno for battery powered RC cars, and even tho there is no standard, having the same box, and using it each time, is the way to tell the two apart. It simply gives a baseline...

 

Thanks for the explanation!!!

Steven

 

I like it warm and they make razors to fix the fuzzies.

 

about 7 HP and 8 ft-lb

 

No Kidding.

 

WHOA! It's a family show - let's keep it clean!