I dyno'd my truck (04 HEMI)
#11
08-03-2004, 12:00 PM
RE: I dyno'd my truck (04 HEMI)
i think the only way to have anywhere near to a 0% loss would be if a crank was directly connected to each wheel. i know FWDs have less loss, but the tranny is always a cause of loss, especially in an auto. i bet the hemi under glass had a nice low hp loss.
#12
08-03-2004, 01:58 PM
RE: I dyno'd my truck (04 HEMI)
ok, from everything I know..... The average loss of power caused by a drivetrain is 15% in RWD and FWD vehicles. its almost 25% in 4WD vehicles and about 20% in AWD vehicles. 255 BHP (at the wheels) seems rather WRONG to me if If the engine is rated at 345 HP and you have a 4x2 (RWD) truck. I'd think 290HP would be a realistic number to see at the wheels.... but 255? If that is the case either the dyno wasn't configured quite right, or these HEMI's just aren't putting out. This troubles me a bit. BHP can also be estimated failry accurately if you have the 1/4 mile time and the weight of the vehicle. It would be interesting to see how that dyno numbers cross reference with a 1/4 mile HP estimate. Just a thought.
#13
08-03-2004, 02:03 PM
RE: I dyno'd my truck (04 HEMI)
I've done that before as well, using the quarter mile times and running them through the calculator to verify the HP. It is always close. For the estimates on chassis dyno loses, I've never seen anything claiming a lower lose than 20% for FWD or RWD. The operators of the local dyno tell me that it does vary from one dyno to the next what a vehicle will put out.
#15
08-04-2004, 04:29 AM
Professional
RE: I dyno'd my truck (04 HEMI)
ORIGINAL: mopartodd
Yeah, it's impossible, at least as far as I know. What I meant to say was that if the lightning is putting 360rwhp down then it's been modded and not putting out 360 hp at the crank.
Yeah, it's impossible, at least as far as I know. What I meant to say was that if the lightning is putting 360rwhp down then it's been modded and not putting out 360 hp at the crank.
#17
08-04-2004, 11:04 AM
RE: I dyno'd my truck (04 HEMI)
As far as drivetrain loss goes, I've always been told that it's around 15% for manuals and around 20% for autos.
I'm reasonably happy with the results my truck got considering the mileage it had on it at the time.
Airbrat's truck is right there as well when you consider the air temp. that they ran the truck in.
[sm=smiley20.gif]
#18
08-04-2004, 02:58 PM
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RE: I dyno'd my truck (04 HEMI)
ORIGINAL: hemiwolf
ok, from everything I know..... The average loss of power caused by a drivetrain is 15% in RWD and FWD vehicles. its almost 25% in 4WD vehicles and about 20% in AWD vehicles. 255 BHP (at the wheels) seems rather WRONG to me if If the engine is rated at 345 HP and you have a 4x2 (RWD) truck. I'd think 290HP would be a realistic number to see at the wheels.... but 255? If that is the case either the dyno wasn't configured quite right, or these HEMI's just aren't putting out. This troubles me a bit. BHP can also be estimated failry accurately if you have the 1/4 mile time and the weight of the vehicle. It would be interesting to see how that dyno numbers cross reference with a 1/4 mile HP estimate. Just a thought.
ok, from everything I know..... The average loss of power caused by a drivetrain is 15% in RWD and FWD vehicles. its almost 25% in 4WD vehicles and about 20% in AWD vehicles. 255 BHP (at the wheels) seems rather WRONG to me if If the engine is rated at 345 HP and you have a 4x2 (RWD) truck. I'd think 290HP would be a realistic number to see at the wheels.... but 255? If that is the case either the dyno wasn't configured quite right, or these HEMI's just aren't putting out. This troubles me a bit. BHP can also be estimated failry accurately if you have the 1/4 mile time and the weight of the vehicle. It would be interesting to see how that dyno numbers cross reference with a 1/4 mile HP estimate. Just a thought.
I read somewhere that the Subaru WRX has close to 30% loss!
I bet it would be less with 17"s... and even less with a manual tranny.
