http://dynoperformance.com/sea...D=692
232 RWHP/ Looks pretty normal [actually slightly above normal] for a stock 145,000 mile 1992 at 93F sealevel *[California]..........but who am I to argue over a better 7-14 HP than average considering everything I've seen has been down 3-4% because of Atlanta's altitude.
*Especially at 93F........232/218= 6.4%
Plus most dyno runs were done on lower mileage engines some wear [less friction] and chain stretch may be showing up especially since things look a little wierd at 6300-6600 rpms.
1992 Q45 dyno run
very nice dyno numbers....but I have got to ask as I learned this one from you...
How do we know the dyno is calibrated correctly? I recall you saying that numbers and be about "+" or "-" 10%
Also I recall you said that the dyno operator has a lot of influence on how the dyno will read the numbers.
So how can we be certain that he is putting down this HP for "real" and it is not due to operator or dyno influence? I would like to know how to tell a good dyno from a bad dyno machine/operator.
How do we know the dyno is calibrated correctly? I recall you saying that numbers and be about "+" or "-" 10%
Also I recall you said that the dyno operator has a lot of influence on how the dyno will read the numbers.
So how can we be certain that he is putting down this HP for "real" and it is not due to operator or dyno influence? I would like to know how to tell a good dyno from a bad dyno machine/operator.
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Q45tech
- Moderator
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
298 x 0.78= 232.............. 232 + 66= 298.
SAE correction for 93F [93-60F=11/33.= 3% or 1.03 SAE correction factor. Yet they showed a 0.99 SAE correction factor.
All we can say is the numbers are probably close and the estimated Flywheel HP is probably somewhere between 287 and 309 HP.......
As I said 218 RWHP uncorrected is what I saw a few years ago on a newer engine. Correct that by 3% for altitude we get to 225 RWHP not a lot away from 232. Really 10 RWHP is an insignificant variation less than 5%.
Obviously engines will vary.
The fact that they published AF ratios and details lends weight to the conclusions.
The Dinan ecu promised 318 Hp and 337 lb/ft at flywheel that would translate to 16 higher or [337 x0.78= 263 lb/ft] vs 247 supposed stock.
Who knows we would need to test 10 Q on the same dyno to zero in on a more accurate determination.
Generally dyno operators read lower on the stock numbers to try to sell you their tuning expertise or some product......then the number magically get better.......these might be the best of 3 runs.
SAE correction for 93F [93-60F=11/33.= 3% or 1.03 SAE correction factor. Yet they showed a 0.99 SAE correction factor.
All we can say is the numbers are probably close and the estimated Flywheel HP is probably somewhere between 287 and 309 HP.......
As I said 218 RWHP uncorrected is what I saw a few years ago on a newer engine. Correct that by 3% for altitude we get to 225 RWHP not a lot away from 232. Really 10 RWHP is an insignificant variation less than 5%.
Obviously engines will vary.
The fact that they published AF ratios and details lends weight to the conclusions.
The Dinan ecu promised 318 Hp and 337 lb/ft at flywheel that would translate to 16 higher or [337 x0.78= 263 lb/ft] vs 247 supposed stock.
Who knows we would need to test 10 Q on the same dyno to zero in on a more accurate determination.
Generally dyno operators read lower on the stock numbers to try to sell you their tuning expertise or some product......then the number magically get better.......these might be the best of 3 runs.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Maybe those guys didn't take grade school math.
232/0.78= 297.436...............1.0 - 0.78=0.22 or 22% .78% of the power gets thu and 22% is used up heating the system betwen the flywheel and road [or chassis dyno drum].Well actually some is heating the drum/road.
I prefer 0.787 since I believe the losses are more like 21.3% than 22%.
The flywheel numbers are worthless they mean nothing all that counts in acceleration are rear wheel numbers.
232/0.78= 297.436...............1.0 - 0.78=0.22 or 22% .78% of the power gets thu and 22% is used up heating the system betwen the flywheel and road [or chassis dyno drum].Well actually some is heating the drum/road.
I prefer 0.787 since I believe the losses are more like 21.3% than 22%.
The flywheel numbers are worthless they mean nothing all that counts in acceleration are rear wheel numbers.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
As to the percentage of loss 15 or 17 or 18 or 20 or 22% that is where the error is. Assumming that a single car is representive of 10,000..........statistical sample theory says you must check at least 20 of the same year to be assured of a 9.5% error........we really need to sample 70 Q of the same year to get down to a 5% accuracy.
Most maufacturers don't really know the true flywheel power of all the engines, they know the allowable tolerances of assembly and calculate the variances possible and sample a few and persuade themselves that they are all within 5%.
The SAE uses 15% for manuals and 20% for automatic but the percentages are only valid at the peak torque rpm.As rpm exceed 4,000 rpms the frictional losses increase how much is anybody's guess.
Most maufacturers don't really know the true flywheel power of all the engines, they know the allowable tolerances of assembly and calculate the variances possible and sample a few and persuade themselves that they are all within 5%.
The SAE uses 15% for manuals and 20% for automatic but the percentages are only valid at the peak torque rpm.As rpm exceed 4,000 rpms the frictional losses increase how much is anybody's guess.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
I guess if anything the torque numbers should be decreased by 2% up to 4,800 rpm, 1% up to 5,500, and remain unchanged at higher rpm to better conform with SAE methodology.
Since the REAR tire and drum interface can be more than a third of the frictional loss......important to submit tire type, temperature and inflaton measurements just before and just after test.
Since the REAR tire and drum interface can be more than a third of the frictional loss......important to submit tire type, temperature and inflaton measurements just before and just after test.