Roll On Performance

W

William Quantrel

We know the 40 can easily reach 200 mph even with 400hp.

We also know it is light at 2400 lbs with has an impressive power to weight ration seeing as most are intent on putting in 450-550 hp.

I was wondering what the roll on performance is from 60 mph up to 150 mph and beyond compared to cars with similar power but with 1000+ lbs more weight?

What does the 1000-1500 lbs weight difference equate to in a roll on?

Have any of you had a highway pull with a Gallardo, R8 V10, SL63-65, or 911 Turbo?
 
D

Bob Lemke aka deckofficer

Do you mean a top gear (OD) roll on, and at what rpm? I'm 600 lbs lighter than a GT40, but as tall as I'm geared, a roll on in 5th at 60 mph is rather pedestrian because the engine is only at about 1550 rpm. Now a top gear roll on at 120 is a different matter because in top gear I would be at 2800 rpm and my torque there is 516 lb/ft and this is propelling a car that weighs 1790 lbs.

DSC01409.jpg
 
W

William Quantrel

Not a top gear roll. A performance roll at optimum rpm.

60 mph is not likely to have wheel spin. M6board.com do these roll ons and pit all kinds of cars against each other. I wonder how the GT40 would stack up?

516 ft-lbs and 1800 lbs? Wow.
 
R

roaldin

My car - standing start 700 metres was between 20 and 40 kph faster than the modern supercars, including Murcilargo, Gallardo, Carrera GT, F430, R8 V10 etc.
Those cars have traction control, some have launch control, some have AWD. I have no nannies. I suspect that given that result a reasonably powerful GT40 could walk away in a roll on race.
For the above event my car was nowhere near potential having been put together in a bit of a rush and with only basic tune. Sorted properly the gap should be bigger.

Have never had the opportunity to try a direct comparison as specified above. Unlikely to happen either unfortunately, my reckless road days are long past.

Hope this is relevant enough.

Tim.
 
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W

William Quantrel

Hi Tim,

What are your engine specs?

When you launch from a standstill, what rpm do you launch at?

Do you experience a lot of wheel spin or does it just hook up?
 
R

roaldin

Wheel spins like a bas...d. 1st and 2nd difficult to moderate, 3rd ok if I feed in the throttle.

It's a 364. I don't have dyno' figures for it ATM - The tune didn't get that far (the dyno' broke, which I've mentioned elsewhere. I'm quite proud about it ;) ).
Hopefully it'll be run properly in the near future.

Rear camber was left where I have it for circuit - about 3 degrees - so straight line traction isn't as good as it could be.

Hopefully this link will work - www.youtube.com/watch?v=ZyRJAbPIquk .


Tim.
 
Howard Jones

Howard Jones

Supporter
Roll on performance is what these cars are all about. Kinda like comming off a 3rd gear corner at 3Krpms. My car will pull real hard all the way to the red line in 3rd and 4th and after making the change into 5th pull really hard until I can't stand in anymore at about165ish.

I have the LIDAR "receipt" to prove it at 131................... Not many cars out there that will continue to accerate after 150mph. If you hit it hard at 80mph you can even give a fast bike a suprise now and then. They never get out run by cars and are not ready for a full pull most of the time.

I even took out an Enzo once because the guy didn't commit after he honked at GT40 in a red ferrie 3 times and nodded his head. Before he could get the electric paddle thing going I was at full song and changing gears baby. Roll on Betty roll on!

Oh and I don't do that anymore. You shouldn't either I supose.
 
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roaldin

The speed reading was taken before the finish. My data tells me that top speed was 268 kph.
You can see the tacho reading 6000 in fifth (6 speed Audi).
The car with the radar can be seen just after the start of the Armco. It was taking speed facing toward the finish but it was not accurate.
I have now seen data from other vehicles that also disagreed with the radar.

Next year I will have the speedo working I hope but I will also have gps speed recorders visible in camera.
Hopefully the official recording will be done more accurately next year. It was their first attempt. Even the radar operator said that his gun was not accurate above 200 kph.
To be fair I don't think they were expecting drivers to take it seriously, as you can see the road isn't exactly an air strip. I have suggested that they need something a bit better - High speed camera ala Mythbusters would be cool. :)


Tim.
 
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MHNCO

Mike

Lifetime Supporter
It would be interesting to see how a 40 would do in the standing mile events. Stock Ford GTs I believe can hit about 185-190. It doesn't take much mods to put them over 200. The 40s with their lighter weight should approach 200 one would think.
 
W

William Quantrel

Tim,

I was going to ask what gearbox you have. It doesn't look like you need to use 1st. I am thinking launching in 2nd would give you more traction.

Was wondering if you had a ZF and if a taller 1st gear would get you off the line better - 2nd gear with the Audi box.
 
R

roaldin

Times weren't the goal, just speed. A bit of wheel spin doesn't take up any road distance, just time, so I thought I'd give the clutch an easier time.

The engine was only just finished in time and the car was still going together on the trailer the day before the event.
I had no dyno' sheet to work out optimum shift points etc, just drove it different ways to see what happened.

Inlet manifold wasn't matched with the heads - pretty bad match really, engine was guess tuned above about 5500 as the dyno' broke two days before the event, even had fuel problems... It was a hell of a rush job to get there, as you can see by lack of speedo...
There's another run on YouTube that shows me driving it differently.

Almost forgot to mention, the cam that was delivered was not the correct
one...

I have a plan to change the ratios for something much better, but it'll have to wait for now, I have other priorities ATM.

Tim.
 
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roaldin

Btw, when I said I was 20 to 40 kph higher than the others I was using the official speeds as they were recorded on the last day of the event, not my data for me versus official times for the others.
Actual speeds would have been higher for everybody.


Tim.
 
C

Cliff Beer

William Quantrel said:
We know the 40 can easily reach 200 mph even with 400hp.
Click to expand...

"We" do know this? Who's "we" in that sentence if you don't mind me asking?

"I" know what it takes to get to 200mph in a road car. As in first hand experience...me personally. Have "you" taken a road car to 200mph so you "know" it? Better yet, any first hand top speed experience with a GT40?

The vast majority of car folks dramatically underestimate what it takes to get a road car to 200mph. It's easy getting to 150 or 160, even 170 with some finesse. 200 is a whole different ball game however.
 
R

roaldin

Fact is, GT40 shaped cars with 400 bhp managed it at some place called LeMans, in Europe somewhere I think, about 40 years ago. I'm pretty sure that's right... ;)

I know whatever project you were working on was difficult Cliff, on the other hand there are a number of people that have managed it without too much difficulty in cars far less slippery than a 40. Modified GT-Rs manage it quite often. There is plenty of evidence about for this. (I think I've posted links on every other thread I've seen here that goes this way.)

Wouldn't like to try it in one of those Italian or German jobbies though, shudder, scary thought... Well the Italian ones anyway...;)

Anyway, these threads always get dragged in this direction.
Yeah it's possible, it's been done. How many replicas could do it? Who knows, but I bet some of them can and I'd suggest some may have done it. Not
everyone is willing to say "yeah I did 200MPH on a public road" on a public forum. Finding a racetrack to do it on is not as easy in some places as it is in others.
GPS devices give a good enough reading, much better than a conventional speedo.

To be fair to William, I think the 200MPH comment was incidental to his question.

Tim.
 
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W

William Quantrel

Cliffbeer2 said:
"We" do know this? Who's "we" in that sentence if you don't mind me asking?

"I" know what it takes to get to 200mph in a road car. As in first hand experience...me personally. Have "you" taken a road car to 200mph so you "know" it? Better yet, any first hand top speed experience with a GT40?

The vast majority of car folks dramatically underestimate what it takes to get a road car to 200mph. It's easy getting to 150 or 160, even 170 with some finesse. 200 is a whole different ball game however.
Click to expand...

Odd question to ask Cliff. Are you not aware that in the late 60's Ford raced at a place called Le Mans and their cars, the GT40, reached 200+ mph down the main straight?

"We" means "the collective of all those who are aware of this fact" over the last 40+ years. "We" is used in this context. As for answering the rest of your questions, I haven't a clue where to begin. I am not sure why you are implying I am some type of arrogant or elite member of the 200 mph club or acting as a poser.

Almost as if you are attacking me for asking a simple question. Have I offended you in some way?

Where on God's green Earth do you get that I have gone 200 mph in a GT40 or otherwise? On what grounds do you ask if I have first hand experience? What's your angle here? What's your beef?

Did I hit a nerve here? I am at a loss.
 
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