[LudesLudesLudes]

71dsp:

I just wanted to ask you - how much power does a typical prelude motor lose to the drivetrain? I'm just trying to figure out approx. how much crank hp my motor is making. Thanks.

LLL

 

[DYI01]

i think its like 15-20% loss

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99 Pearlwhite Sportshift
15.45 @ 92.37

 

[jmcn]

The only real way to test this is to dyno the car at the wheels, then pull out the engine and dyno it from the flywheel. No one has ever done this.

The best we can do is to take Honda's 195/200 horsepower engine output as fact and figure that the average base model Prelude puts out 168hp or so. With that as an average horsepower at the wheels, that would be a 16% loss using 200hp at the flywheel. A Type-SH would be more of a loss, since it averages around 160hp to the wheels. That equates to a 22% drivetrain loss also using the 200-hp flywheel number.

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Prelude forum moderator
Prelude FAQ
AIM: jmcn97
'97 Prelude Type-SH

'96 Integra GS-R (R.I.P.)
jmcn.com

 

[Guest]

<font face="Verdana, Arial" size="2">Originally posted by LudesLudesLudes:
71dsp:

I just wanted to ask you - how much power does a typical prelude motor lose to the drivetrain? I'm just trying to figure out approx. how much crank hp my motor is making. Thanks.

LLL</font>

It's a bit more complicated than just a percentage loss. The loss will actually vary depending on RPM, but a percentage will work for ball park figures.

I would go with what jmcn said.

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Billy
North Texas Prelude Owners Group
www.ntpog.org

 

[99Prelude_LC]

got a tag on question, i see people do the dyno runs in 3rd, but isn't the 4th gear ratio closer to 1:1 so wouldn't that be the gear to do your dyno in?

 

[schwett]

there are a dyno plots comparing the base and SH, and there's no way it's an 8hp difference at the wheels. try 3 or 4 at a MAX. otherwise, i agree with you completely. 200 -> 165 = 17.5%, which is right about what i'd expect. some cars are as low as 10-15%, some are as high as 30%.

<font face="Verdana, Arial" size="2">Originally posted by jmcn:
The only real way to test this is to dyno the car at the wheels, then pull out the engine and dyno it from the flywheel. No one has ever done this.

The best we can do is to take Honda's 195/200 horsepower engine output as fact and figure that the average base model Prelude puts out 168hp or so. With that as an average horsepower at the wheels, that would be a 16% loss using 200hp at the flywheel. A Type-SH would be more of a loss, since it averages around 160hp to the wheels. That equates to a 22% drivetrain loss also using the 200-hp flywheel number.

</font>

 

[jmcn]

<font face="Verdana, Arial" size="2">Originally posted by schwett:
there are a dyno plots comparing the base and SH, and there's no way it's an 8hp difference at the wheels. try 3 or 4 at a MAX. otherwise, i agree with you completely. 200 -> 165 = 17.5%, which is right about what i'd expect. some cars are as low as 10-15%, some are as high as 30%.</font>

Yeah, because so few people dyno stock cars its hard to tell the average numbers for SH and base.

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Prelude forum moderator
Prelude FAQ
AIM: jmcn97
'97 Prelude Type-SH

'96 Integra GS-R (R.I.P.)
jmcn.com
Please buy my extra ZEX nitrous kit!!!

 

[LudesLudesLudes]

Is it safe to assume around a 17-20% loss then? I dynoed at 177hp and 150 lb/ft. That would be 207.1 - 212.4hp and 175.5 - 180 lb/ft to the crank, right?

thanks,
LLL

 

[schwett]

here's another stock dyno - this one is one of jackson racing's test cars before they put the blower on it. all stock :

if you dyno'd at 177 at the wheels, it would equal 216 at the crank with 18% loss. if the loss in peak torque was the same (it won't be since it occurs at a different RPM) you'd have 170 lb-ft at the crank. however, if the torque numbers on that stock dyno are accurate, then the drivetrain loss is only about 9% of the peak torque at 5200RPM. so i'd say you have 215hp at the crank and 165 lb-ft. whatever the crank numbers are, the wheel numbers are pretty damn good.