![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
It would be a lot easier if everyone just quoted rwhp.
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
The only real way to know is to benchtest the engine on a dyno out of the car and then do a rolling road test with it in the car.
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
What have people heard
![](./images/smilies/spacer.gif)
![](./images/smilies/spacer.gif)
Thank for any replies, Tom
Moderators: IMOC Moderators, IMOC Committee Members
Lauren wrote:my engine produced 182bhp@flywheel
126bhp@ the engine.
Everbody else there ie Toni, Mark had the same losses.
RWHP is meaningless.Flywheel is the sensible way.
Obviously a dyno is the only way to see actual power, but it doesn't reflect the environment in which the engine lives.
A couple of reasons why RWHP is crap is because rollers do not reflect a road surface ie there is lots more resistance due to the two rollers.Tyre pressure and type also makes a significant difference.
Worse still if your car is strapped to the rollers then his heightens rolling resistance, so by measuring coast down the drag of the drivetrain can be measured and thus flywheel figure worked out.
Tis the only way that makes sense.
So if you think about it the amount of power my car would put down on the road would be more than that measured as RWHP on the rollers.
allan welsh wrote:Lauren wrote:my engine produced 182bhp@flywheel
126bhp@ the engine.
Everbody else there ie Toni, Mark had the same losses.
RWHP is meaningless.Flywheel is the sensible way.
Obviously a dyno is the only way to see actual power, but it doesn't reflect the environment in which the engine lives.
A couple of reasons why RWHP is crap is because rollers do not reflect a road surface ie there is lots more resistance due to the two rollers.Tyre pressure and type also makes a significant difference.
Worse still if your car is strapped to the rollers then his heightens rolling resistance, so by measuring coast down the drag of the drivetrain can be measured and thus flywheel figure worked out.
Tis the only way that makes sense.
So if you think about it the amount of power my car would put down on the road would be more than that measured as RWHP on the rollers.
um rolling roads measure roller torque which is then converted to power at the wheels, then the operator makes up a tranny loss and charges you accordingly.
My old mk1 did 80BHP at the wheels with the cam timing out 1 tooth on both cams, then it did 100BHP at the wheels with the cam timing corrected, then it did 110BHP with a mongoose exhaust on it.
It had 100K miles on the clock too
Tranny losses areinaccurate
since they are measured by using the rollers to turn over the gearbox with the clutch in
Whereas in real life its the engine that accelerates the gearbox and since gearwheels have different profiles on each side of the gearwheel you are going to get different losses depending how you drive the box
USe the same dyno everytime and get roadwheel figures everytime.That way you can compare back to back
Lauren, if that gearbox of yours lost 60BHP I'd of binned it and got a new one
allan welsh wrote:Lauren wrote:my engine produced 182bhp@flywheel
126bhp@ the engine.
Everbody else there ie Toni, Mark had the same losses.
RWHP is meaningless.Flywheel is the sensible way.
Obviously a dyno is the only way to see actual power, but it doesn't reflect the environment in which the engine lives.
A couple of reasons why RWHP is crap is because rollers do not reflect a road surface ie there is lots more resistance due to the two rollers.Tyre pressure and type also makes a significant difference.
Worse still if your car is strapped to the rollers then his heightens rolling resistance, so by measuring coast down the drag of the drivetrain can be measured and thus flywheel figure worked out.
Tis the only way that makes sense.
So if you think about it the amount of power my car would put down on the road would be more than that measured as RWHP on the rollers.
um rolling roads measure roller torque which is then converted to power at the wheels, then the operator makes up a tranny loss and charges you accordingly.
My old mk1 did 80BHP at the wheels with the cam timing out 1 tooth on both cams, then it did 100BHP at the wheels with the cam timing corrected, then it did 110BHP with a mongoose exhaust on it.
It had 100K miles on the clock too
Tranny losses areinaccurate
since they are measured by using the rollers to turn over the gearbox with the clutch in
Whereas in real life its the engine that accelerates the gearbox and since gearwheels have different profiles on each side of the gearwheel you are going to get different losses depending how you drive the box
USe the same dyno everytime and get roadwheel figures everytime.That way you can compare back to back
Lauren, if that gearbox of yours lost 60BHP I'd of binned it and got a new one
Lauren wrote:Everybody elses gearbox showed the same losses as mine.![]()
feral4mr2 wrote:Lauren wrote:Everybody elses gearbox showed the same losses as mine.![]()
how did everyone get a difference between flywheel output and rear/rolling output?all pull your engines or am i missing something here??
(You should be in bed, by the way)
Lauren wrote:Well Toni, Mark and I all had our cars on the rollers on the same day and we all got flywheel and at the the wheel figures.they all showed the same difference.
![]()
feral4mr2 wrote:Lauren wrote:Well Toni, Mark and I all had our cars on the rollers on the same day and we all got flywheel and at the the wheel figures.they all showed the same difference.
![]()
ok, but how did they give you flywheel figures?
Icsunonove wrote:John, I have some good news for you![]()
According to my basic calculations and our British bull$h1t fudge factor:
I estimate your engine is producing about 270bhp at the flywheel![]()
!
Can you ship it to me from Queensland to Derby when you finally kill it?
I will rebuild it and fit it in my car!
Tom