Rolling road results
Discussion
I went to a south coast forum organised rolling road day today and thought I'd share the results.
I had 3 reports this RR is very accurate or at least matches very closely with other RRs so I will ignore all comments relating to the validity of these results
186.7BHP @ 6083rpm (120HP @ 5000rpm at the wheels)
193.7lbft @ 3171rpm
Graph below;
green - wheel HP
red - flywheel HP
blue - torque
I had 3 reports this RR is very accurate or at least matches very closely with other RRs so I will ignore all comments relating to the validity of these results
186.7BHP @ 6083rpm (120HP @ 5000rpm at the wheels)
193.7lbft @ 3171rpm
Graph below;
green - wheel HP
red - flywheel HP
blue - torque
I bet it was a tad noisy too 
steve j said:
Hmm, I was behind you at Cosford and it sounds great 
Mine is running rather well now and I fancy it sounds better 
Steve, I still haven't heard yours so I'll hold my judgement on that one Mine is running rather well now and I fancy it sounds better Can't wait to hear them together though!
tozerman said:
That looks a very healthy engine you've got there, good stuff, although 66bhp is a big transmission loss isn't it ?
cheers.....Tony..
I am very pleased with the engine but the transmission losses worried me a bit too. It's better than one of the M3s though which had 202HP at the wheels and 320 at the flywheel. Thats a hell of a loss!cheers.....Tony..
I wonder if a diff and gearbox oil change plus having a look at the prop shaft would help that at all. I'm not sure there is much you can do about drive train losses though.
I did notice thought that the speed reached at the rev limiter was 135mph and thats in 4th. I was under the impression the car had a top speed of 130-140mph but this implies it would be a lot higher... Not that I'd want to go that fast in an S!
makes me chuckle every time.
I SAID, NOW YOU KNOW WHY EVERYONE...... orange_dodo said:
I wonder if a diff and gearbox oil change plus having a look at the prop shaft would help that at all. I'm not sure there is much you can do about drive train losses though.
I did notice thought that the speed reached at the rev limiter was 135mph and thats in 4th. I was under the impression the car had a top speed of 130-140mph but this implies it would be a lot higher... Not that I'd want to go that fast in an S!
On my S2, maximum speed was in 4th gear and it didn't have enough power to red line in fifth. I think 135 is a realistic top speed for a healthy car.I did notice thought that the speed reached at the rev limiter was 135mph and thats in 4th. I was under the impression the car had a top speed of 130-140mph but this implies it would be a lot higher... Not that I'd want to go that fast in an S!
I'm not sure what to make of the rolling road printout. The red and green lines appear to show power at the road and at the flywheel, but the curves are completely different shapes and I don't believe they're showing power 'before' and 'after' transmission losses.
The implied 66 bhp transmission losses seem unrealistically high to me. Typically, losses would be around 30 bhp. A transmission can't have much higher losses than that without suffering severe damage, so assuming it didn't blow up a few minutes later I think you can be pretty sure the actual transmission losses are roughly typical and that will be around 30 bhp.
I found this article on Google. Makes very interesting reading but no idea if it is acknowledged as correct. Note copywrites:
http://www.pumaracing.co.uk/POWER3.htm
Andy
http://www.pumaracing.co.uk/POWER3.htm
Andy
Putting on my engineers hat for a minute I know that wheel HP is probably fairly accurate as it is the actual power being put out onto the dyno rollers but the transmission losses are just an educated guess.
If you take the difference in power at 6000rpm there is about an 80hp drop in the drive train. Thats 60kW which is going to be 90% heat. If that was the case then the gear box and diff would be a puddle of metal after a spirited drive.
The 120 wheel HP is the important one so thats what I would look to improve.
Putting my TVR owners hat back on.... 186 BHP WOOHOO
If you take the difference in power at 6000rpm there is about an 80hp drop in the drive train. Thats 60kW which is going to be 90% heat. If that was the case then the gear box and diff would be a puddle of metal after a spirited drive.
The 120 wheel HP is the important one so thats what I would look to improve.
Putting my TVR owners hat back on.... 186 BHP WOOHOO
S2Andy said:
I found this article on Google. Makes very interesting reading but no idea if it is acknowledged as correct. Note copywrites:
http://www.pumaracing.co.uk/POWER3.htm
Andy
David Baker knows what he is talking about, and you can take that article as gospel.http://www.pumaracing.co.uk/POWER3.htm
Andy
Hi Tom
I was at this event as well, in the green Chim 500.
I was also alarmed at the transmition power loss. Having said that when they strapped my car down on the rollers (R888's at 24 lb)the tyres were squashed. So thought that this would have a detramental effect on the 'loss' of power between the wheels and fly on the run down.
Last Saturday 287 bhp 340 ft/lb
Last December 304 bhp 330 ft/lb
The December result ar Surrey Rolling Road.
So some how I have gained torque and lost BHP.
Good to know the TVR's are still flying the flag, mine was 2nd loudest
Barrie
I was at this event as well, in the green Chim 500.
I was also alarmed at the transmition power loss. Having said that when they strapped my car down on the rollers (R888's at 24 lb)the tyres were squashed. So thought that this would have a detramental effect on the 'loss' of power between the wheels and fly on the run down.
Last Saturday 287 bhp 340 ft/lb
Last December 304 bhp 330 ft/lb
The December result ar Surrey Rolling Road.
So some how I have gained torque and lost BHP.
Good to know the TVR's are still flying the flag, mine was 2nd loudest
Barrie
Edited by biper on Thursday 19th May 11:16
Hi Barrie,
I remember you talking about your tyres deforming. I can imagine that would affect the results but I would have thought it would make the Fly Hp higher. I have Toyo 600 F5 on the rear at 27psi and they strapped mine down on the centre out rigger support so mine didn't deform at all. The coast down is a complete guess though so as magpies said it is only the wheel power you can really trust.
How did your wheel HP compare between Surrey and Regal?
They were the only 2 cars louder than the dyno!!
I remember you talking about your tyres deforming. I can imagine that would affect the results but I would have thought it would make the Fly Hp higher. I have Toyo 600 F5 on the rear at 27psi and they strapped mine down on the centre out rigger support so mine didn't deform at all. The coast down is a complete guess though so as magpies said it is only the wheel power you can really trust.
How did your wheel HP compare between Surrey and Regal?
biper said:
mine was 2nd loudest
They were the only 2 cars louder than the dyno!!
GreenV8S said:
S2Andy said:
I found this article on Google. Makes very interesting reading but no idea if it is acknowledged as correct. Note copywrites:
http://www.pumaracing.co.uk/POWER3.htm
Andy
David Baker knows what he is talking about, and you can take that article as gospel.http://www.pumaracing.co.uk/POWER3.htm
Andy
The R/R computed that up to 229bhp @ flywheel, which though perhaps less than I was hoping for compared to the daft TVR figures, seems about right according to the above article.
It's how the car performs on the road (or track) that matters, and whether or not improvements have been made by tuning on the R/R session.
I think my car's almost 8 bhp @ wheels improvement, plus fuelling put right made the session well worthwhile.
Here's the sheet:
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