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Twin turbo 2.7 Cayman


trialsstar3

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Yeah 192BHP sound miserable doesn't it! 

Engine runs sweet, got compression numbers all about 225psig across all cylinders and I get great fuel consumption 41mpg... 

If there is something wrong I'm sure the angry snails 🐌 🐌 will find it 🤣

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Putting a random 20% on top of your peak number to guess your flywheel power is flawed.  It would be a lot better to use a dyno that can calculate flywheel power from WHP.  A decent dyno of that caliber, for example, can give you the same flywheel output but lower WHP when using heavier wheels.

 

Your transmission losses also increase as you work your way up the rev range; you won't experience the same loss at 2k as you would at 6k.  It's a linear curve, just like power output.

 

You have a WHP baseline and I would stick to that output, or get another baseline on a better dyno if you're genuinely interested in flywheel power.  I highly recommend Dyno Dynamics or TAT.  Entirely your choice, of course.

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26 minutes ago, Aaron said:

Putting a random 20% on top of your peak number to guess your flywheel power is flawed.  It would be a lot better to use a dyno that can calculate flywheel power from WHP.  A decent dyno of that caliber, for example, can give you the same flywheel output but lower WHP when using heavier wheels.

 

Your transmission losses also increase as you work your way up the rev range; you won't experience the same loss at 2k as you would at 6k.  It's a linear curve, just like power output.

 

You have a WHP baseline and I would stick to that output, or get another baseline on a better dyno if you're genuinely interested in flywheel power.  I highly recommend Dyno Dynamics or TAT.  Entirely your choice, of course.

It's my own Dyno. It doesn't have or need a 'drag feature' all that matters is WHP in the end, It's only for comparison. The Run down drag measurement is an option I could add but never needed it. I don't do Rolling Road 'Shootouts' 🤣

The 20% is an arbitrary approximate figure. I'm not in the game of comparing dynos to dynos. 

Here's graph from a Dyno that measures drag power consumption. 20220930_124821.jpg.8835d83e1e29e339b953df0232957bf8.jpg

This shows an approxmate loss of 14% 

Mine will be going on this dyno during tuning so will have some more data feedback further down the line for you all. 😊

 

 

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Just a little addition to the 'Better' dynos out there... Lets take the above graph again...

The Drag measurement on this shows a peak loss of 60BHP this is measured by allowing the rollers and drivetrain to slow at their own rate... So lets say the car was ran again but this time with 476 WHP but hang on the measured drag on the rundown is still only 60BHP why hasn't this changed.... Well why would it...

This (in my opinion) is why the 'better' dynos that measure drag aren't any better at all. 

So we add 60 to 476 = 536 flywheel power

60 as a percentage of 536 is 11% transmission loss... 

Now lets say the engine is upped to 1000BHP... But the rundown drag is STILL only showing a measurement of 60bhp

It still takes the rollers, wheels and gearbox the same time to slow down...

60 + 1000 = 1060

Transmission loss has now been dramatically reduced to 5.66% amazing!!!!

 

So lets say 60bhp is about the measured loss of of a Cayman drivetrain...

My 191WHP on my dyno (without drag measurement) plus 60bhp losses = 251bhp  calculated flywheel power

Oh look now my car is making more horsepower at the flywheel.... 🙃

I would have to add 31% transmission loss to my 191bhp to get to the 251bhp therefore I think the 20% loss I'm adding onto my dyno is fairly conservative. 

 

Moral of the story... It's pointless arguing about different rolling road flywheel figures.

The only way to accurately see how much power you're losing through drivetrain is an engine dyno then rolling road reads back to back. Or bolting the whole rig to a transmission dyno (measuring torque in and torque out) the difference is the efficiency of the setup..

You could get really cleaver and change your engine mounts for calibrated load cells then you'd have a way to measure torque produced at the engine, comparing that to the torque measured at the rolling road would make losses calculation very accurate. 

 

*Little addition* 🤣🤦‍♂️

 

 

 

 

 

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4 hours ago, Neil_jdmr said:

I actually redact my statement and think your 191whp/230fly is perfectly fine 🤣🤣🤣

It may have been the way I stated 20% transmission loss. I've added 20% of 192... So the actual 'loss' from flywheel power is 16.88% loss on my dyno. If we take 192 as the base and assume the transmission loss is 20% that puts the flywheel power at 240Bhp (240-20% is 192Bhp) also foud out that the 245'bhp' factory figure is actually 'PS' which equates to 241 English BHP.. so you see with all my bullshitterry I'm now only 1bhp down from standard. 🤣🤣

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On 30/09/2022 at 12:57, trialsstar3 said:

It's my own Dyno. It doesn't have or need a 'drag feature' all that matters is WHP in the end, It's only for comparison. The Run down drag measurement is an option I could add but never needed it. I don't do Rolling Road 'Shootouts' 🤣

The 20% is an arbitrary approximate figure. I'm not in the game of comparing dynos to dynos. 

Here's graph from a Dyno that measures drag power consumption. 20220930_124821.jpg.8835d83e1e29e339b953df0232957bf8.jpg

This shows an approxmate loss of 14% 

Mine will be going on this dyno during tuning so will have some more data feedback further down the line for you all. 😊

 

 

 

I'm going to go on a whim and say this is TAT?  The graph looks like TAT.

 

Anyway, enough about statistics... are the blowers on yet?  We are all eagerly waiting!

 

 

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I'm not sure what software that graph is from. I know its a Maha dyno so maybe theirs 🤷‍♂️

Ahh no blowers yet. I probably started this post a little early the parts are still in fabrication. Delivery is due for November I'm struggling with the wait 😬

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  • 1 month later...

That's going be a great winter project.  I'm jealous and really want another project but my previous one put me off after doing a 45kg gbox on my own,  on dodgy axle stands.

 

Good luck mate ill look for you on insta

 

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  • 1 month later...
On 21/01/2023 at 09:15, trialsstar3 said:

Thanks man, I've absolutely loved doing it and feel very lucky. I'm on my way to collect the car now from the tuners. 

🤩🤩🤩


ERRRRRRRMMMMMMM........... we damand updates! 

  • Haha 1
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