FWD vs RWD: Adders, Subtractors, and Weight, Oh my...!

[JeffYoung]

That's true isn't it? Curb weight/race weight is going to have a significant impact as well, just like horsepower. A heavier FWD car 'suffers" more, right, regardless of power?

[Xian]

Assuming both the cars run the same size front tire. Personally, tire size options is the main reason I think an ITR RSX (can fit 245's or possibly larger up front) has a better chance than an ITR Type R (225's up front are pretty much the max).

Christian

[Andy Bettencourt]

FYI: Current process

ITA, ITB and ITC FWDers get a 50lb deduction just for being FWD.

ITS and ITR FWDers get a 100lb deduction.

Straight up, off the top, no questions asked.

[hondaracer48]

Andy,
Are you saying that SCCA is working on giving the ITS GSR's another 100lbs off in addition to the 100lbs it received in 2007? I love the sound of that.

I do have some comments on what I read earlier on this thread. First, someone please explain why with everything mathematically pointing to the RWD as being superior, that the FWD cars are able to out brake the RWD cars? And I don't think that is just a personal opinion either. Second, I think the most important advantage to a road race car, whether it be a 1500lb or 3500lb one, is the balance of the car (with comparable horsepower of course). The more balanced the weight, the less amount of weight transfer that can push the tire beyond its cornering limits, at the same time the longer or earlier the driver will be able to accelerate. The longer the acceleration, the faster lap times. Lastly, I do believe that math is a priceless tool we can use in preparing a car or predicting its tendencies, but there is no one formula that will be consistant. There are just too many factors, which explains why many pro teams take their winning formula back to the same track, try all weekend making adjustments, and still end up in the back. It is however, our best shot, by repeating success. I think the current method of taking an educated guess, group these cars together, and see what happens works just fine. Until someone does come up with a 100% built ITS GSR (I'm almost there, but moving is forcing the sale of the car), it would be wasted time to argue about FWD/RWD advantages. I still personally believe that a 100% built ITS GSR at 2590lbs will be a dominating car.

Ed Chang
San Francisco Region

[Andy Bettencourt]

Andy,
Are you saying that SCCA is working on giving the ITS GSR's another 100lbs off in addition to the 100lbs it received in 2007? I love the sound of that.

No. Just describing how it works currently.

[Chip42]

First, someone please explain why with everything mathematically pointing to the RWD as being superior, that the FWD cars are able to out brake the RWD cars? And I don't think that is just a personal opinion either.

1 - they weigh less, due the the -100/-50lb "adder" for FWD.
2 - dynamics, spring rates, and static mass are very different, usually.
3 - apex may differ slightly, especially for low speed corners, exagerating the accordian effect - watch the exits of the same corners where the FWD cars appear to be outbraking all the RWD cars...
4 - not always true, anyhow.

Until someone does come up with a 100% built ITS GSR (I'm almost there, but moving is forcing the sale of the car), it would be wasted time to argue about FWD/RWD advantages. I still personally believe that a 100% built ITS GSR at 2590lbs will be a dominating car.

Scott Seck in the CFR has a very good GSR. one of the Ira brothers does too, somewhere in the Carolinas, I think. I believe that both would agree that a built to the hilt GSR can't compete over a race length at most tracks with the RX7s and Miatas - they may get a lap, but pretty much can't get the race. just too much work for the tires over the long run. a weight break would help, but this info is available now - there's no one holding a gun to anyones head demanding that they build these cars. the club gives us a place to race with no promisses as to the competitiveness of the car as classified (though they do try)

EDIT - I just read greg's post above and wanted to add the following about FWD in braking:
most of the cars built that fit into ITA/B/C over the past 20 years or so have been FWD. this is a fact of market conditions and industry paridigm. new cars have MUCH better braking systems than older ones, and more sorted suspension geometries as well. this could go a long way to making the FWD cars look better in braking. not that the miata, as greg points out, has great brakes. it's really the only modern RWD ITA car in the same power/wt range as the good FWD cars in the class... and it often walks all over them.

[lateapex911]

So, is the answer to grab a "median" car, assign it a weight value, say 100 pounds as it's 'adder', then apply it to other weights via a percentage?

So a car that would hit the class at say 2500 gets a 100 pound break, but a car that is 2800 before adders gets 112 pounds?