Weight & Laptime

M3E30 · #1 09-13-2007, 12:05 PM

Hi,

Does anyone know what influence an extra 400 LBS ballast has compared to the laptime of a stock E30 M3 Sport Evolution (2700 LBS) at Top Gear test track?

So how many secs do you reckon this stock M3 (E30) will be slower due to the 2 extra passengers (about 180kg/400LBS)?

BTW, the car is very well driven, by former DTM champion Steve Soper.

Thanks a lot

Regards

admin · #2 09-13-2007, 02:33 PM

I heard PCA racers say 25lbs was .1 sec around Road America (Jim Bryant). in a 944s2 or class H

JimLill · #3 09-13-2007, 05:09 PM

If I knew what that track was like, in terms of a more well known one that I have data on, I could run you a simulation.

kbrew8991 · #4 09-13-2007, 08:18 PM

you could place the weight properly and not slow the car down, thats a large variable

Stack · #5 09-13-2007, 10:03 PM

Quote:

Originally Posted by M3E30

Hi,

Does anyone know what influence an extra 400 LBS ballast has compared to the laptime of a stock E30 M3 Sport Evolution (2700 LBS) at Top Gear test track?

So how many secs do you reckon this stock M3 (E30) will be slower due to the 2 extra passengers (about 180kg/400LBS)?

BTW, the car is very well driven, by former DTM champion Steve Soper.

Thanks a lot

Regards

I find myself very confounded by your posts... they are at once very specific, yet extremely vague and almost unanswerable.

But I'll give it a shot anyway.

1) Any car with another 15% of its weight added, will be slower
2) HOW much slower will vary. In your specific instance, on Top Gear's test track driven by former DTM champion Steve Soper, I would venture a wild guess that he would be slower anywhere from .5 second to 1.5 seconds. My gut tells me it would be closer to the .5 second because of the complete lack of elevation changes, and that it is a wide-open momentum track.

BTW... Jeremy? Is that you?

M3E30 · #6 09-14-2007, 06:19 AM

Quote:

Originally Posted by JimLill

If I knew what that track was like, in terms of a more well known one that I have data on, I could run you a simulation.

Hi,

Yes, I'd love to have a simulation of this.

But I don't know what tracks you've got??

Just try one with quite a lot of straights, and quite a lot of slow corners.

Thank you in advance.

@Kbrew, yes I know, if you 'd put the weight in the right place it won't influence the cornering speeds (much). But you will have a disadvantage when braking or accelerating...

@Stack, thank you for your try. And yes I've got very specific Q's...

Thanks for helping me anyway!

Regards

JimLill · #7 09-14-2007, 06:56 AM

I have most popular F1 and Pro Sportscar tracks...

M3E30 · #8 09-14-2007, 07:12 AM

Hi,

Do you have the Top Gear testtrack, you know, the track where the Stig does the powerlaps?

Or something that is equal to it?

Snetterton in the UK? Or something else with some straights, slow corners and average laptimes 1:30-1:40?

I also don't mean I want an exact number, just an indication is more than satisfying enough!

Thanks

M3E30 · #9 09-14-2007, 07:57 AM

Here is a picture of TG testtrack:

So they actually use that diagonal twice

Regards

JimLill · #10 09-14-2007, 09:25 AM

Not much time to spend on it today, but........

I took the model of a 2001 M3 and reduced the vehicle weight to 2700 + driver + gas. The model uses street tires. I then increased weight to 3100.

At Sebring, there's a 3 second difference

At WGI, 2.5

There is no way to accound for lowered CG easily, than would make the spread bigger.