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Headed up to A.I. motorsport today to see what figures the GT-R has under its bonnet..
pretty pleased with the results...

standard car with hks y pipe. Thanks to jonny and phil for running her at short notice.
 

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So 504 BHP with 10% transmission loss? Not bad at all and if I remember correctly exactly the same as a std GTR dyno'd in EVO magazine?
 

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My car is the one in Evo magazine and my figures with just a Milltek Y-pipe were 407hp at the wheels which Surrey Rolling Road calculated as 512hp at the flywheel. Torque was 500lb.ft flywheel!

What type of rolling road did you use? SRR is a Dyno Dynamics, which typically reads a fair bit lower at the wheels than other types.

Just goes to show that one of the most pointless exercises known to man is to compare dyno graphs from different dynos!
 

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David,
If you're right that there is such a wide degree of variation then could I suggest that a more 'in-depth' explanation would be a useful article to print in your mag? How about some science and facts to back up your comments?

Of course you also need to factor fuel, tyres, etc etc, but I'd be interested to know more about the logistics and sense (or otherwise) of dyno testing.

I agree with you though that there shouldn't be 46bhp difference in such similar cars!
 

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Apart from tyres, temperature, type of dyno etc, if you want a reasonably accurate flywheel figure, you need to know the transmission losses.

I understand thath the GTR35 has much lower tranny losses than most cars (read it is only about 11-12%, so the 18-20% applied will give an inflated flywheel figure.

Cheers,
 

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Anyone who uses rolling roads regularly knows that the ONLY value is in doing direct "before and after" comparisons to show changes.
Anything else is a waste of time.

The only way to accurately measure a true power output is to use an engine dynamometer (and even then, I wonder how they accurately simulate 100mph airflow as the engine/intercoolers etc would experience in the car).
 

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Headed up to A.I. motorsport today to see what figures the GT-R has under its bonnet..
pretty pleased with the results...

standard car with hks y pipe. Thanks to jonny and phil for running her at short notice.
You coming to Crail again so i can SPANK you again:p
 

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Apart from tyres, temperature, type of dyno etc, if you want a reasonably accurate flywheel figure, you need to know the transmission losses.

I understand thath the GTR35 has much lower tranny losses than most cars (read it is only about 11-12%, so the 18-20% applied will give an inflated flywheel figure.

Cheers,
Nobody has ever actually verified the transmission loss.



Apart from that one garage who thinks that a run-down off-load is equal to the transmission loss. I can't even begin to figure where they dreamt up that logic from.
 

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Hi can anyone recommend a rolling road either in London or between London and Silverstone that i could get my car tested on.

Also, does putting it on a rolling road do anything to the warranttee?


(sorry if asking the obvious or something that was already covered but I couldn't find it)
Thanks
 

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Just got a pretty clear answer from Andy at Middlehurst on this.

Rolling road equals broken warrantee.
Very few rolling roads are capable of handling the GTR 4 wheel drive system (due to it be activated through G and wheel slip).
He knows of several cases of a transmission failure through using a rolling road.

Sounds like I will not be going anywhere near a rolling road in my baby!

I just have to live with the beleif that mine has 480+ bhp, maybe 500...
 

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yes i agree with Andy, unless the dyno load is correct you could see clutch overheat / 4wd errors.

And it does state on warranty document that you sign not to use on a dyno.

In U.S you can legally do it to check local emission state laws... or something to that manner :flame:
 

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I'm surprised Andy would propagate such scare stories.

There have been dozens if not hundreds of GT-Rs tested on rolling roads across the world. I have not heard of a single transmission failure occurring during such runs.

Of course you do have to turn VDC off to a dyno run and some people may be reluctant to do that. (Although a recent group action court case saw Nissan North America having to back down on VDC off = no warranty as per my thread on the subject.)
 
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