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Discussion Starter #1
Posted from the Lancer register....It would seem that Gary from GT Art has been running again...750 BHP at the flywheel! :-0

My fave bit has to be:
The only real problem with the car is that it has so much power the chassis flexes quite a lot, and I see he has some pretty big cracks developing in the windscreen because of it.

I rest my case...the new way forward for rolling roads. I look forward to my return to calculate what I have with the new mods and an accurate figure.

NLW

Just a couple of technical notes for your interest.

All runs when we do power tests are done in `shootout' mode. This is a standard for these dyno systems which ensures the accuracy of the power figures. In real terms it means your power figures can be directly compared with someone elses - as long as both runs are done in this mode. It doesn't matter what day of the week, what the room temperature/humidity/pressure was, or who performed the power test - the figures are deadly accurate and reliable. So if you know of any high horsepower EVOs in the USA, or Asia with dyno sheets plotted on one of these dynos in shootout mode the figures are directly comparable.

The dyno only gives power at the wheels measurements. To determine the power at the flywheel we have been using a transmission loss of 24%. We think its fairly accurate, as we took the wheel horsepower figure + 24% trans. loss for the Norris Designs car and came up with a flywheel figure within 1bhp of what his engine made on an engine dyno - enough said.

For those of you who couldn't stay till the end - the run in the last Skyline GTR was good value!! 547bhp at the wheels, which is just over 750bhp at the flywheel. It took us some time to get the wheelbase on the dyno right so the car didn't bounce around too much, but once we had it sorted it was awesome. This car had run on the Tuning Japanese rolling road two weeks ago, and the best they could get was 506bhp at the wheels, because they had serious problems with wheelspin - that was with 4 big guys in the car + the driver. So it was nice to see what his true reading was.
The only real problem with the car is that it has so much power the chassis flexes quite a lot, and I see he has some pretty big cracks developing in the windscreen because of it.

I will have some torque figures for everyone at the start of the week, and I will probably add a page to our website to list all the figures for you. If anyone wants extra copies of their dyno sheets let me know - we keep all the runs on file on the dyno, so its no problem.

I've met some real posers in the Japanese performance world - but you're a good bunch of guys. If there's anything you need help with just give me a call.

Chris Davies
Motorsport Engineer - Technical Director
G-Force Motorsport
www.g-force-motorsport.co.uk:)
 

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Dyno Results

Nick,

Great to hear a good set of results for Gary.

However, how does 547bhp at the wheels equate to 750bhp at the flywheel? G-Force state a 24% transmission loss this would mean 719bhp at flywheel since 719 * 0.76 (ie 1 - 24%) = 547bhp.

This 719bhp would compare pretty accurately with the 715bhp on the TJ rollers, wouldn't it?

Guy

PS My car did 523bhp at wheels at TJ with no wheelspin and no backseat passengers.
 

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Can somebody please explain how transmission losses can be assumed to be an 'across the board' percentage. Surely the transmission loss for any particular car will be the same specific amount regardless of what total power it's making....? Why would Gary's car lose 24% of 700+ bhp when I'm only losing 24% of <500bhp?
 

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Discussion Starter #4
guys I have no idea!! I am a salesman...

PICK UP THE PHONE AND SPEAK TO CHRIS AT G FORCE 01296 434084
HE IS DA MAN. I suggest we all get up there for another test and new benchmarking.
Go on don't be afraid to hear sth new and exciting...
By all accounts their systems are new and very effective and the way forward. counter balance tempereatues diffs, changes in humidity, wheel spin and so on.

Pete I hope you are well and will send you pm.

Nick
 

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Well spotted Guy.
My instantaneous thought was 750~550~24%=Bollocks somewhere, so I never gave that anymore thought.

As for the within 1bhp of the engine dyno thing, that is proof of nothing either. It is only prooof of that particular car on that particular dyno with that particular bhp etc.....

For our comparisons TJ's is probably the most tried and trusted real world comparison.
It has probably run more skylines than any other in the UK so can justify this claim.
 

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Is 750bhp accurate?........

Just a note to clear up the 750bhp - transmission loss thing.

We have been speaking to Gary about the problems associated with running his car on a RR for a few weeks now. Thankfully he could make it on Saturday so we were happy to run his GTR.

You guys had a RR day a couple of weeks ago - where Gary posted 506bhp at the wheels and 714bhp at the flywheel. Impressive figures no doubt. We had been told that there were problems with wheelspin on his car and therefore he was sceptical as to whether the wheel bhp figure was accurate - as he didn't think that RR could hold the power his car produced.

We ran the car here - no wheelspin, no problems - and got 547.7bhp at the wheels. Without getting into an argument over drivetrain losses we simply added the extra wheel bhp to the 714bhp flywheel figure (which means we did not take into account the extra losses with the extra bhp) and said it is at least 750bhp.

The only real way to determine flywheel power is on an engine dyno, and the only real way to determine drivetrain loss is by running the same engine - in car - on a RR and subtract the wheel bhp from the engine dyno's flywheel bhp. We do not claim any accuracy in determining flywheel bhp figures from a RR - but we do guarantee the accuracy of our wheel bhp figures.

This is a revolutionary RR for this part of the world. More details about RRs and drivetrain loss/flywheel bhp can be found at www.g-force-motorsport.co.uk - follow the links for the RR and you can see for yourself.

We have found that 24% is a good ESTIMATE for the Lancers. However bhp at the wheels is the ONLY truly accurate measurement of power on a RR.
 

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Chris,

I've been told your set up is extremely impressive, some very happy customers!

In the interest of accuracy, would it not be more accurate, when trying to calculate flywheel bhp, to establish/calculate a set level of transmission loss for each particular car, e.g. say 130 bhp for an R33 GT-R running in fourth gear, and then add this to the 'at the wheel power' measurement?

Am I correct in thinking that there should be no correllation between the transmission losses and flywheel power.

How do Maha dynos calculate transmssion losses on run down or is this just a preset calculation?

Peter.
 

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urghh!

Just followed the hyperlink and there are bloody Porches all over :D
 

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Rollers

Chris (from G-Force),

Thanks for your response.

I know we should only be talking about wheel bhp, but everyone unscientifically likes engine bhp (as I think I said to you in a long email about 6months ago).

Are you saying that the 547 at wheels is uncorrected and that the corrected number (for temperature) was higher and you added the transmission losses from TJ to that number? If so, I see your logic, but this would work only if they were run in the same gear, what gear was used at G-Force?

Peter,

Transmission losses vary with gear used, gearbox design, oil temperature, but are not a constant figure and increase with engine power. For example if a GTR had 140bhp of transmission losses, that surely doesn't mean that if it only had a 140bhp engine (say remove 3 spark plugs), that it would be unable to turn the wheels.

Guy
 

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Re: Rollers

Guy said:
Peter,

Transmission losses vary with gear used, gearbox design, oil temperature, but are not a constant figure and increase with engine power. For example if a GTR had 140bhp of transmission losses, that surely doesn't mean that if it only had a 140bhp engine (say remove 3 spark plugs), that it would be unable to turn the wheels.

Guy
Guy,

I do realise that transmission losses will vary depending those factors which you have stated above but you seem to have missed my point, I cannot understand why cars with stock transmissions will not have their forward motion impeded by **roughly** the same amount regardless of the amount of power their engines are producing.

I cannot see why a car with 500 bhp will suffer twice the transmission losses than a car with 250 bhp just because it produces twice the power..... This will be the case if you simply apply a percentage.

Peter.
 

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Rollers

Why all this then?

From what we saw and what we run and what was explained by the guys at GF, thier rollers are very very impressive and very accurate. I personally put Chris's offer to the test by placing my finger on the load sensor to gauge just how accurate the machine was and wow.

I have been talking to Chris this afternoon about a rolling road day and will post a poll for a suitable date in the events section of the forum. They cannot accomodate a day until August so we can all find out on the day just how accurate their dyno is.

One thing has to be said for these guys, they have nothing to gain by producing figures for different cars with differing accuracies, they are Porsche specialists and we are very priviledged to be asked to run our cars on thier very expensive equipment. Regardless of other dynos and whats been proven in the past, the accuracy of power at the wheels is unquestionable from what we have seen on Saturday and we should take advantage of thier kind offer to host a dyno day.

I dont like how my cars power has been thrown to question as if Garys figures are bullshit then so are mine which isnt a nice statement to make really but I know how things on here can be taken literally and I am sure nothing is meant in a harmful manner so I regard the comments in the same fashion but what we all need to do is get up there and have a go and see what happens. This is supposed to be the best dyno over here so lets put it to the test. The figures produced on this dyno were very consistent with what was expected by all the cars run with a couple of surprises and dissapointments for some as per the usual dyno day scenario, its not as if suddenly all cars ran had 50hp more than they were expecting.

If anything the new dyno is a breath of fresh air and we should all be delighted that we can be allowed to use it for our own cars.

We had a great day on Saturday, thanks for making us feel welcome Chris and Isaac, very impressed with your setup and hope to see you again soon, I am sure Rob and Gary feel the same.

Andy Barnes
 

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Rollers

Dirk,

Stop taking offence mate! No-one has questioned Gary's power.

The 547bhp he achieved at the wheels is an accurate fact, for those rollers, in the gear he used (3rd?).

The only question was how this equated to 750bhp at the flywheel..........

The G-Force roller set-up sounds very good and I would be delighted to attend a GTR Dyno Day there (as I would anywhere). so put me on the list.

Guy
 

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Dirky.
Perhaps you are right and we could do with a change of venue.
Some people will want a new dyno figure on the same dyno after doing some mods so may not be up for this, but it is always a good day out.
Get it organised:D
 

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Andy Barnes (not getting all serious are we)

As for a breath of fresh air its always nice to go somewhere new and it sounds like a good idea.

Come on Dirk, Guy ain't after slating anyone he just needs to have the facts right in his mind before he pays his money trying somewhere new. He's spent /is spending a lot of money on his car and just wants to make sure that what he may do in the future is a true reflection having used TJ for so long.

I don't really get involved in these posts as its a bit over me head sometimes so perhaps you should do the same and chill baby :) .

glen
 

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OK Then

Guy,

I am not taking offence, dont do taking offence, just dont like unfair critisism of my car thats all, I dont doubt your's or anyone elses power and would never suggest that a figure someone quoted me was untrue or mis-calculated.( see GTR32 )

I am certainly not trying to fight Garys battles for him either, he's a big boy now but if you doubt one you doubt both as we were the only skylines to run and it cuts deep.

The fact of the matter about all this nonsense is that I am sure you, like everyone else out there including me would like to know if you had some extra horsepower in your car that a previous rolling road couldnt measure or pickup? It is undoubted that the majority of cars have been measured elsewhere in the past but I have never had the ins and outs explained to me in such detail that I really didnt understand what the fick they were talking about after the first 3 sentences that would make me realise what this dyno stuff is all about and why figures can increase of decrease within a 10 minute period. Both my runs at GF were identical, 403.5hp at the wheels both times and with a small interval in between as previously tested which seals the deal for me.

After spending so much money on these money pits I wonna know exactly what power I have and was it what I expected/was promised?

And a little advert for Gary after Saturday's performance- It does and runs EXACTLY as he promised and I requested, in fact its better, 403.5 at the wheels running 1.3 bar of boost is more than I expected (considering a week prior I run 414 at the FLY @ 1bar at TJ ) and I cant wait for my new EVC so I can sort out 1.6bar and get the real HURRICANE, shame it would only set 1.3 on Saturday and we had no time to mess around with it.

ROBBED I WAS, OUTRAGIOUS< THE SKYLINE CURSE STRIKES AGAIN!

UNTIL NEXT TIME...........

:smokin:
 

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Gren San

Just seen your post after my essay..

I put Andy Barnes as Chris @ GF dont know me as Dirk Diggler and I wanted to say thanks as he was posting on the subject -So Ner:p

As for Guy spending his money, £ 35 wont break anyones bank to find out what a breath of fresh air feels like, anyway, who are you his mum?:D

Chill - I am ICE MAN, so laid back I may just fall asleep!

Winkle

:smokin:
 
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