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      09-21-2021, 08:30 PM   #1
Pistolerom5
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First track event with my G80 M3 Comp

Got a chance to run my m3 at the local track this past weekend. Oh wow, I am impressed that such a big heavy car can do so much so well. Acceleration is strong, pulls hard out of corners. Brakes are firm and fade free. Trail braking is a breeze. Turn in is immediate and transitions are super quick with barely any scrubbing. The car corners so well for a 3800 lbs heavy weight. The carbon seats were amazing, held me in place. Engine and Exhaust sounds good, even though I think most of it is fake noise from the speakers.

The not so good, tire wear is pretty significant. Fuel consumption is scary, have to fill up after 2 sessions. Tank was full, did about 24 laps and computer said 20 miles remaining. I used 5 tanks of gas to commute to track and did about 60 laps. That’s like 2 mpg. Could also use a louder exhaust. Also, the front proximity sensors kept going off every time I braked with a car in front and one time it slammed on the brakes on its own. Super annoying.

Here is a video.



Question to those that track.
1.What tire pressures are you running, I was at 28psi cold, and after a session, tires are at 38psi and about 190 degF.

2.Worth going to stainless steel brake line? Pedal pressure is good with no fade. Also worth going to a more track focused pad?

3.Running stock wheel set up, was thinking about going to a square set up to facilitate rotation, would a square set up work? That is, I’d buy 2 rear wheels for the front.

4.anyway to turn off the brake proximity warning and intervention? It’s super annoying for it to chime every time I go into a corner with a car in front of me. And one time, it auto braked as it must have sensed too high a closing speed.

Thanks in advance for your advice.
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      09-21-2021, 09:29 PM   #2
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4. You have to turn off the safety stuff with the little button on the dash. (see pic)

You hold it for a few seconds to turn everything off.
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      09-22-2021, 01:15 PM   #3
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1. I use front 38psi, and rear 36psi HOT. Measured immediatly after every session, and adjusted as needed. 2 lower on the rear for a bit more grip on acceleration out of the turns.

2. Absolutely, and throw in some good quality high temp brake fluid too.

3. Individual choice with minimal noticable performance difference on a track unless you happen to have the skill level of a pro driver. In which case, what the Hell are you doing at an HPDE event?

4. Already covered.
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      09-22-2021, 08:28 PM   #4
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I get 4 mpg while tracking. Started with a full tank and did just about 60 miles in one hour long session and had 20 mile range left.

In have thought about tires too, I did one day on my mps4s and ran 26 cold 38 hot. No issues with traction. Check your shoulders to see if they are wearing to the end of the shoulder treads, over too high, under too low..

I git a set of 963m wheels with cup2s and they are stickier. I mainly went that route to preserve my 4s set for daily driving.

I might experiment with different tires over time.

Next time I mount my track tires ill throw the rears up front and see whats what and of its even possible to run that size up front. They are .4% larger circumference and diameter than front
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      09-28-2021, 08:11 AM   #5
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Most of your questions depend on level of experience and how close to the limit you are driving. Keep it stock till you feel you are approaching that limit. Then make incremental changes. As for TP, haven't tracked a g80 yet but based on experience of cars with similar power/weight, 38-40 hot is about where you want the tires (assuming Michelin Pilot Sport 4s).
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      09-28-2021, 09:15 AM   #6
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Quote:
Originally Posted by BMWRacer523 View Post
Most of your questions depend on level of experience and how close to the limit you are driving. Keep it stock till you feel you are approaching that limit. Then make incremental changes. As for TP, haven't tracked a g80 yet but based on experience of cars with similar power/weight, 38-40 hot is about where you want the tires (assuming Michelin Pilot Sport 4s).
39-40 hot is WAY too hot. The car will feel greasy at this pressure.

I ran on my MPS4S before my track tires came, and got excellent wear at 34 hot. Would start at 29 cold and get the tires to 160 degrees and see what your pressure does.

BTW - The in car pressures and temps are not that accurate, especially the temps, they read about 25 degrees cooler than actual, since they are measuring air temp inside the tire, and not the tire temp itself. I know this because I run the cup2 connects which has the sensor actually against the physical tire and it reads hotter.
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      09-28-2021, 02:38 PM   #7
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Quote:
Originally Posted by beachBmmr View Post
39-40 hot is WAY too hot. The car will feel greasy at this pressure.

I ran on my MPS4S before my track tires came, and got excellent wear at 34 hot. Would start at 29 cold and get the tires to 160 degrees and see what your pressure does.

BTW - The in car pressures and temps are not that accurate, especially the temps, they read about 25 degrees cooler than actual, since they are measuring air temp inside the tire, and not the tire temp itself. I know this because I run the cup2 connects which has the sensor actually against the physical tire and it reads hotter.
We have crew measure with pyrometer and external pressure gauge in hot pits Again my experience is on an E90 m3 not g80 but 39-40 is what michelin recommends for Cup2's which is what we run. Not greasy at all. Maybe PS4S is a lot different in terms of recommended tp/temp. Will see when mine gets here I have a set of cup2s waiting for it but will check with PS4S also.
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      09-28-2021, 02:43 PM   #8
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Quote:
Originally Posted by BMWRacer523 View Post
Quote:
Originally Posted by beachBmmr View Post
39-40 hot is WAY too hot. The car will feel greasy at this pressure.

I ran on my MPS4S before my track tires came, and got excellent wear at 34 hot. Would start at 29 cold and get the tires to 160 degrees and see what your pressure does.

BTW - The in car pressures and temps are not that accurate, especially the temps, they read about 25 degrees cooler than actual, since they are measuring air temp inside the tire, and not the tire temp itself. I know this because I run the cup2 connects which has the sensor actually against the physical tire and it reads hotter.
We have crew measure with pyrometer and external pressure gauge in hot pits Again my experience is on an E90 m3 not g80 but 39-40 is what michelin recommends for Cup2's which is what we run. Not greasy at all. Maybe PS4S is a lot different in terms of recommended tp/temp. Will see when mine gets here I have a set of cup2s waiting for it but will check with PS4S also.
Cup2 recommended on g80 is 32-33 hot.

39 is insane and perhaps on a much lighter car

Call jackson motorsport, thats who michelin directed me to for temps and pressures, they will ask your car, tire size, and track, and surface type and give you recommendations

Edit: Rennlist GT3 forums poll - https://rennlist.com/forums/991-gt3-...ith-mpsc2.html
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Last edited by beachBmmr; 09-28-2021 at 03:49 PM..
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      09-28-2021, 03:50 PM   #9
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Quote:
Originally Posted by beachBmmr View Post
Cup2 recommended on g80 is 32-33 hot.

39 is insane and perhaps on a much lighter car

Call jackson motorsport, thats who michelin directed me to for temps and pressures, they will ask your car, tire size, and track, and surface type and give you recommendations
Yeah we are running gutted race cars so lighter. But still your running too low. In any case, temps are a better indicator of grip level. around 180 is where you want to be.

https://www.pca.org/sites/default/fi...r-TTW-2018.pdf

Page 23 there for Michelin's own recommendations.

Last edited by BMWRacer523; 09-28-2021 at 03:57 PM..
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      09-28-2021, 04:06 PM   #10
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Quote:
Originally Posted by BMWRacer523 View Post
Quote:
Originally Posted by beachBmmr View Post
Cup2 recommended on g80 is 32-33 hot.

39 is insane and perhaps on a much lighter car

Call jackson motorsport, thats who michelin directed me to for temps and pressures, they will ask your car, tire size, and track, and surface type and give you recommendations
Yeah we are running gutted race cars so lighter. But still your running too low. In any case, temps are a better indicator of grip level. around 180 is where you want to be.

https://www.pca.org/sites/default/fi...r-TTW-2018.pdf

Page 23 there for Michelin's own recommendations.
This was where I ended up after checking temps across tread and looking at my chalk line wear indicators.
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