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55 minutes ago, Cameron said:

Trust you do pick about the furthest away place you could , any excuse for a long drive.

 

Cameron

There's madness in my method (or something like that), I have an old pal in the neck of the woods, not seen each other in years, an excuse for a catch up.

Richard.

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Curious, you wouldn’t have the torque curve vs RPM would you?  I’ll assume rolling road and these curves (including) torque are the corrected to flywheel amounts, yes?  Trying to compare apples to apples as it were. In the states, we use hp & torque vs RPM for the graphs.  Sometimes just at the wheel if it’s a rolling road, sometimes corrected to flywheel if rolling road.

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2 hours ago, CK's TR6 said:

Curious, you wouldn’t have the torque curve vs RPM would you?  I’ll assume rolling road and these curves (including) torque are the corrected to flywheel amounts, yes?  Trying to compare apples to apples as it were. In the states, we use hp & torque vs RPM for the graphs.  Sometimes just at the wheel if it’s a rolling road, sometimes corrected to flywheel if rolling road.

As soon as I get the hard copy print outs I will scan and post them 

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Graham, I did a little linear regression analysis on RPM vs road speed estimates correlated with the corrected HP, flywheel hp, and torques values from the plots.  It is all pretty consistent. For those who care, HP = (torque x RPM)/5252    I would say this is true at the flywheel.  Correcting for drive train losses is ripe for argument.  It seems your dyno folks used a total of about 27% loss, some of that was environmental (hotter than standard day, pressure altitude etc) I'm sure.  Modern drive trains are a bit lower but then again, some of us have Toyota transmissions and nissan diffs and CV halfshafts. Your engine shows a good flat torque curve with best torque around 5035 RPM (estimate). That would be your VEmax point assuming that AFR's were good and ignition was optimized.  I would say that you could get a little more torque at this top end if you had a crank fired and mapped (16x16 table)  non dizzy system. Which means you would see HP gains as the RPM increased right up to your and your wallet's limit.  A Racetorations billet crank, block brace, cast sump, carrillo's, and light weight pistons, what? good to 7K maybe. If the torque stayed up around 180 lbft, that would be 240hp. It's just money, right?

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I think ‘transmission losses’ are measured byt the rolling road arent they?

the rr measures the effort required to turn the drivetrain at the end of the power run, ie on the way back down the rev range.

having said that Enginuity took 10 hp off the reading for my car, which i never understood?

steve

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6 hours ago, CK's TR6 said:

Graham, I did a little linear regression analysis on RPM vs road speed estimates correlated with the corrected HP, flywheel hp, and torques values from the plots.  It is all pretty consistent. For those who care, HP = (torque x RPM)/5252    I would say this is true at the flywheel.  Correcting for drive train losses is ripe for argument.  It seems your dyno folks used a total of about 27% loss, some of that was environmental (hotter than standard day, pressure altitude etc) I'm sure.  Modern drive trains are a bit lower but then again, some of us have Toyota transmissions and nissan diffs and CV halfshafts. Your engine shows a good flat torque curve with best torque around 5035 RPM (estimate). That would be your VEmax point assuming that AFR's were good and ignition was optimized.  I would say that you could get a little more torque at this top end if you had a crank fired and mapped (16x16 table)  non dizzy system. Which means you would see HP gains as the RPM increased right up to your and your wallet's limit.  A Racetorations billet crank, block brace, cast sump, carrillo's, and light weight pistons, what? good to 7K maybe. If the torque stayed up around 180 lbft, that would be 240hp. It's just money, right?

Yep I think you can safely say I've reached the limit of what I can afford................ but possibly not what is achievable. 

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2 hours ago, Steves_TR6 said:

I think ‘transmission losses’ are measured byt the rolling road arent they?

the rr measures the effort required to turn the drivetrain at the end of the power run, ie on the way back down the rev range.

having said that Enginuity took 10 hp off the reading for my car, which i never understood?

steve

Over inflated tyres allowance ?

Mick Richards

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1 hour ago, Motorsport Mickey said:

Over inflated tyres allowance ?

Mick Richards

I dont understand how tyre pressure would affect the readings Mick?

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A soft tire absorbs more energy, so the transmission losses increase and vice versa. So hard tires will result in higher measured power.

Regards,

Waldi

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Thanks, that makes some sense, but my tyres were at their normal pressure.

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I was picking up on the posting about the other TR6 having it’s tyres blown up so it didn’t sit on the rolling road frame.

As Waldi says it’s not unusual for an unscrupulous rolling road to blow tyres up to 40 lbs for better hp figures, so always scrutinise the dyno printout to check. So allowing a 10 hp downgrade when done would be generous, I’d expect less than 5 benefit.

Mick Richards

Edited by Motorsport Mickey
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  • 2 weeks later...

Earlier this week Revington TR rolling road tuned my car. They tell me their rolling road is only for tune up purposes etc, so I have no print out or hardfast figures. However they tell me the car pulled 114hp at the rear wheels (at what RPM I don't know) and with their educated experienced guestimate upwards of 170hp at the flywheel.

I have plenty of engine dyno testing through work, but know nothing of rolling road testing, so don't know if those guestimated figures are probable, what I do know is the car pulls like a train and is a pleasure to drive.

Richard.

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20 minutes ago, Richard71 said:

Earlier this week Revington TR rolling road tuned my car. They tell me their rolling road is only for tune up purposes etc, so I have no print out or hardfast figures. However they tell me the car pulled 114hp at the rear wheels (at what RPM I don't know) and with their educated experienced guestimate upwards of 170hp at the flywheel.

I have plenty of engine dyno testing through work, but know nothing of rolling road testing, so don't know if those guestimated figures are probable, what I do know is the car pulls like a train and is a pleasure to drive.

Richard.

Transmission losses are usually around 30hp - putting it in the 145hp ballpark which sounds reasonable for a 6.

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7 minutes ago, DRD said:

Transmission losses are usually around 30hp - putting it in the 145hp ballpark which sounds reasonable for a 6.

Maybe I mis-heard him and he actually said 140hp at the wheels, or maybe I'm dreaming with ambition? The engine has had some performance upgrades, either way I'm content with how it runs, 1200 miles since Saturday and it never missed a beat!

Richard.

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30hp loss in transmission is consistent with my car’s 143 at the wheels which showed 172 on the screen at Enginuity

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3 hours ago, Richard71 said:

Maybe I mis-heard him and he actually said 140hp at the wheels, or maybe I'm dreaming with ambition? The engine has had some performance upgrades, either way I'm content with how it runs, 1200 miles since Saturday and it never missed a beat!

Richard.

You will have, 140 at the wheels is good strong power and = about 170 flywheel if not a cad more.

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In the club sprint and Hillclimb champs we have power weight classes and use this calculation 

eg my class is 2a <130bhp/tonne

Where the power is at the Flywheel, which can be calculated from the power at the wheels plus 15% plus 10HP, and the weight is the weight of the car in its normal competition state excluding the driver. “

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5 hours ago, CK's TR6 said:

Yep a good article - the only figure that you can rely on is the wheel hp and then it depends on the rolling road and you can't assume that they will all agree.

You can only really compare cars on the same rolling road on the same day.

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