Faster At Le Mans: Race Car or Street Car?

May 25, 2006
7,300
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Ft. Lauderdale
This question has been bouncing around my head for some time,, We are now seeing the capabilities of the street car . I've come to my conclusion. You may think the answer to this is easy . I think most would immediately choose the race car but let me go thru some things to consider.

First we need to establish the basics.. The race car set up would be exactly as it was when it ran last year. BOP'ed to about 450 - 480 HP . The street car would be a Competition coup. or heck maybe even a base model with the Ti exhaust and CF wheels. To level the playing field I would like to have them on Identical tires but the race car runs on 18" wheels so that's not going to work with the CC brake so we are going to put the Street GT on Hoosiers. 1/2 tank of fuel for both cars.

Known elements to consider:
Le Mans is a very large track with a lot of fast straight sections and long high speed sweeping turns.
- The race car at 450-480 HP runs about 180 MPH at top speed. It's going to have more lateral grip for sure.
- The street Car has 647 HP and a higher top speed. I'm not sure what the top speed is in Track mode because the deployed wing is going to add some drag. I'm sure it's going to be well below the 216 MPH but I would hope it would be at approx. 200 MPH The Comp Coup's weight will be close to but slightly heavier than the race can but not by much

So in the hands of one of the Team drivers what car will have the faster lap time ?? A demo at the 2017 Le Mans event would be a great PR stunt !! Raj, can you set this up !! Curious Cats want to know !! ...:lol
 

stuntman

GT Owner
Jan 15, 2015
211
0
Racecar. Hoosiers aren't close to the best tires on the planet (Confidential Michelin). Racecar has more downforce, is lower, and gear ratios specific to LeMans.
 
May 25, 2006
7,300
1
Ft. Lauderdale
It's only for a lap or Two.. It's not an extended race. When Hoosiers get hot they are super sticky and they are light which will help the acceleration. The stock tires may be suitable for the run off , they are super sticky as well.. The tire selection is only there as a realistic option of what might be available.

The 7 speed DCT has short tight ratios so there won't be an advantage for the race car there..

The debate is this... Are there enough high speed areas that allow the street car to use its power and lower drag advantage / speed advantage to overcome the lateral grip advantage of the race car ?
Having been in a car going around the Le Mans Track I can tell you it's a fast circuit with less tight low speed areas,, after being there I understand why the drivers love it !!
 

Vince H

GT Owner
Jul 23, 2012
2,196
5
Southern California
Racecar, otherwise they would do just that. The wing and ground package makes late braking and quicker exiting all the advantage over the straight line speed . . . . . I think . . . . . maybe . . . . . . only FPR/CGR knows for sure. Haha!


Vince H
 

Ed Sims

GT Owner
Apr 7, 2006
6,691
3
NorCal
There is less active aero on the race car due to rules but I would think the race car suspension is better suited for the harsh endurance race world & that would make a big difference. So even with a two lap sprint I feel the race car would be faster.

Ed
 

KennethClay

GT Owner
Oct 15, 2012
490
0
New York
Really depends on the tightness of the track. Extra power and active aero would help the street car. If it were even close, it would be an absolutely terrific PR move to schedule the "duel"!
 

Indy GT

Yea, I got one...too
Jan 14, 2006
2,367
1
Greenwood, IN
Racecar. Hoosiers aren't close to the best tires on the planet (Confidential Michelin). Racecar has more downforce, is lower, and gear ratios specific to LeMans.
Stormy,

As you rightly point out this takes some thought. I am going to be a contrarian.

LeMans is a fast course. That means horsepower and good aerodynamics. I believe that was the winning strategy last year. We may have been BOPed down in power but the Ford aero masters did their job in spades and gave the car a very low drag coefficient. Form and Function in concert.

I would tend to downplay the tire differences. Hoosiers, Sport Cup2s, Michelin race tires...eh their all very good.

OK, stuntman says racecar has 1) more downforce. well nothing is free so to get downforce you also get aero drag which eats up horsepower. As LeMans is a fast track favoring high speed over turns, I want less downforce and less attendant aero drag to enable higher straight line speed and lower lap time. 2) racecar is lower. Well maybe but certainly not by much. With the production car in Vmax mode it is pretty darn low to the ground. I think equal benefit to both. 3) racecar has favorable gear ratios. Well "favorable" is relative. Unfavorable gear ratios (whatever that is) can be overcome by higher engine torque and horsepower. Afterall the transmission is nothing but a torque multiplier, so if you have more torque/power in the street car (No damn BOP crap) then you do not need the same gear ratios as the lower horsepower racecar.

I think you put both the racecar and a competition version of the street car in Billy Johnson's command, he is fastest in the street car!:biggrin

Raj, can you make that happen?
 
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stuntman

GT Owner
Jan 15, 2015
211
0
Hoosiers are nothing compared to the Michelin Slicks that are on the Ford GT racecars, whose tires have the best technology of any tire Manufacturer in the world.

Downforce improves braking as well as cornering. LeMans has A LOT of low speed corners and chicanes, and heavy braking zones. Downforce does come at the expense of drag but there's far more time to be had in braking and corners than there are in the straights. There's a reason the P1s set the LeMans lap record with the mulsanne chicanes over the previous time before the chicanes were put in. Acceleration from the hybrids and downforce.

The GT40s had higher top speeds than modern P1 cars, and generally, racecars these days are far faster with far less power than cars from 5-10 years ago. How? More downforce.

Plus the racecar is lighter.
 

cobra498

GT Owner
Jul 14, 2010
293
0
It is all about time in the corners, the Race car will undoubtedly pull higher G loads in braking and cornering so it wins hands down.
 

ENZO BTR

GT Owner
Sep 11, 2005
904
0
Southern California
So glad I wasn't the only person crazy enough to wonder about this.

Lighter weight of race car is more than offset by increased power of street car on acceleration, so that advantage evaporates. Now you're down to grip and brakes. Racecar has advantage in both, but I don't know how big the advantage is. Lap times would tell us, but I think it would be closer than many of you think...

More fascinating would be to get the same situation with Ferrari, Porsche, Chevrolet and Aston Martin -- race their street versions versus the race cars.

Now THAT would be very telling... :biggrin
 

Ed Sims

GT Owner
Apr 7, 2006
6,691
3
NorCal
I think a better question would be which production car: MacLaren, Ferrari, Lambo, Porsche, AM or Ford would be faster at LM?

Ed
 
May 25, 2006
7,300
1
Ft. Lauderdale
Hoosiers are nothing compared to the Michelin Slicks that are on the Ford GT racecars, whose tires have the best technology of any tire Manufacturer in the world.

Downforce improves braking as well as cornering. LeMans has A LOT of low speed corners and chicanes, and heavy braking zones. Downforce does come at the expense of drag but there's far more time to be had in braking and corners than there are in the straights. There's a reason the P1s set the LeMans lap record with the mulsanne chicanes over the previous time before the chicanes were put in. Acceleration from the hybrids and downforce.

The GT40s had higher top speeds than modern P1 cars, and generally, racecars these days are far faster with far less power than cars from 5-10 years ago. How? More downforce.

Plus the racecar is lighter.
The race car is lighter but not by much,,,
A question for you. Have you ever run Hoosiers on a racetrack? Have you ever run Hoosiers on the Ford GT?

Let me tell you a little story. There is only one rear tire produced to the exact same size as the stock Goodyear's. That's a Hoosier rear tire. Is this a coincidence.. no. Hoosier worked with Ford in developing and evaluating tires for the GT.
Ford tested and evaluated using Hoosier tires for the OEM Road Car Tire on the 05 /06 GT.
It turns out that they worked too well... How is that you may ask. One of the biggest factors IN braking performance is the adhesion of the tire.
In test sessions at PBIR The Hoosiers had so much grip that would overheat the brakes very quickly by allowing the strong brakes provide more stopping force generating more heat than they would with a less sticky Tire.
This was one factor for Ford deciding not to use Hoosiers as the OEM tire. If the Hoosiers were good enough for Ford Engineers to evaluate as an OEM tire and they're good enough for my car for racing and track days.. The above Info came directly from Hoosiers engineering / tech division.

This leads into the next section of analysis of Road car vs race car. As Explained the amount of tire grip is a major factor in how much brake force is available.
How many of you have experience with carbon ceramic brakes on the racetrack ? . I can tell you that have no equal. There's a reason why Formula 1 and in the Top tier racing use them. The amount of brake Force they can develop his unmatched. You also have the benefit of lower rotational Mass which can help your acceleration and your braking due to the lower flywheel effect.
. so how does this relate to our Comparo between the race car in the street car and I'm not sure what the combined weight of the race car , tire rim and brake rotor is but I'm going to go on a limb and say the street car with the carbon fiber wheels and the carbon-ceramic brakes and the stock width tire as an overall package is definitely lighter than the race car.
Combine the phenomenal stopping power of the carbon ceramic brakes and the active Aero air brake with the proper Tire in the front the road car will match or out brake the race car from higher speeds ... For the record the GT LM class is not allowed to use carbon Ceramic brakes.


I'm just sayin'' at LeMans it might be closer than you think !! Raj , Billy where are you ?? ..:lol
 
May 25, 2006
7,300
1
Ft. Lauderdale
So glad I wasn't the only person crazy enough to wonder about this.

Lighter weight of race car is more than offset by increased power of street car on acceleration, so that advantage evaporates. Now you're down to grip and brakes. Racecar has advantage in both, but I don't know how big the advantage is. Lap times would tell us, but I think it would be closer than many of you think...

More fascinating would be to get the same situation with Ferrari, Porsche, Chevrolet and Aston Martin -- race their street versions versus the race cars.

Now THAT would be very telling... :biggrin
:huge:
 

stuntman

GT Owner
Jan 15, 2015
211
0
The race car is lighter but not by much,,,
A question for you. Have you ever run Hoosiers on a racetrack? Have you ever run Hoosiers on the Ford GT?

Let me tell you a little story. There is only one rear tire produced to the exact same size as the stock Goodyear's. That's a Hoosier rear tire. Is this a coincidence.. no. Hoosier worked with Ford in developing and evaluating tires for the GT.
Ford tested and evaluated using Hoosier tires for the OEM Road Car Tire on the 05 /06 GT.
It turns out that they worked too well... How is that you may ask. One of the biggest factors IN braking performance is the adhesion of the tire.
In test sessions at PBIR The Hoosiers had so much grip that would overheat the brakes very quickly by allowing the strong brakes provide more stopping force generating more heat than they would with a less sticky Tire.
This was one factor for Ford deciding not to use Hoosiers as the OEM tire. If the Hoosiers were good enough for Ford Engineers to evaluate as an OEM tire and they're good enough for my car for racing and track days.. The above Info came directly from Hoosiers engineering / tech division.

This leads into the next section of analysis of Road car vs race car. As Explained the amount of tire grip is a major factor in how much brake force is available.
How many of you have experience with carbon ceramic brakes on the racetrack ? . I can tell you that have no equal. There's a reason why Formula 1 and in the Top tier racing use them. The amount of brake Force they can develop his unmatched. You also have the benefit of lower rotational Mass which can help your acceleration and your braking due to the lower flywheel effect.
. so how does this relate to our Comparo between the race car in the street car and I'm not sure what the combined weight of the race car , tire rim and brake rotor is but I'm going to go on a limb and say the street car with the carbon fiber wheels and the carbon-ceramic brakes and the stock width tire as an overall package is definitely lighter than the race car.
Combine the phenomenal stopping power of the carbon ceramic brakes and the active Aero air brake with the proper Tire in the front the road car will match or out brake the race car from higher speeds ... For the record the GT LM class is not allowed to use carbon Ceramic brakes.


I'm just sayin'' at LeMans it might be closer than you think !! Raj , Billy where are you ?? ..:lol
Apparently Ford claims the MPSC2 for the GT350R are roughly as sticky as Hoosier R6 DOT-R racing tire. So the new R7 is what? A second faster than the R6? So you're telling me the greatest tire manufacture in the world that has won countless Formula 1 championships and LeMans races (overall) can't make a race tire that's more than 2 seconds faster than their treaded road tire? :confused

One of the biggest factors IN braking performance is the adhesion of the tire.
True, and downforce improves that adhesion of the tire, and the racecar has more of it.

Brake torque is a function of the mu/friction of the pad, diameter of the rotor, piston area and applied pressure. An iron rotor and corresponding caliper & rotor size and pressure can make as much torque as a carbon rotor. The main advantage of carbon rotors is the reduced weight. After all, the GT350R does not fade it's massive iron rotors since it can lock up tires easily from high speeds over and over again, and the FPRS in Utah uses stock pads on their 350 school cars. -so the higher cost wasn't worth equipping the 350R with carbon rotors over the iron. And carbon rotors need to be sized larger than an equivalent iron rotor.

The 05/06 GT had undersized brakes for it's performance. Look at modern supercars, which aren't a whole lot faster than the 05 GT, the biggest difference is the size of the brakes.
 

Indy GT

Yea, I got one...too
Jan 14, 2006
2,367
1
Greenwood, IN
Stuntman, take it easy on my buddy Stormy. (And Stormy seeeeeemed to be supporting my supposition that the street version might be faster).

I would have to agree with you after extended conversations with John Church, the Michelin's have got to be the best tire for communicating the acceleration/decereration wishes of the driver. But is that enough for a 1 lap sprint at LM with all the other identified differences between the two cars. Racetrack weight is a very important factor (ask the BOP sanctions guys) and rotational inertia, available engine torque and active aerodynamics all play important roles in determining the ultimate lap time. We'll assume racecar driver skill is constant between the two vehicles :).

Too many significant variables to guess. We need to get Ford to consider this a marketing opportunity.