Engine revs at a rally cross

Scott Johnson · **Posted:** Mon Jun 28, 2004 2:14 pm

How much spinning of the tires goes on in a traction limited car? I'm planning to run the old Celica in august, and am just trying to figure out where to put the rev limiter. If it's just going to spool up to 7000 rpm then I'll lower it to something a little less destructive (I don't accelerate any faster with the tires slipping at 6000 rpm than I do with the slipping at 7000 rpm).

Obviously there is some throttle modulation invoved, but I'm trying to pretect the equipment here.

Scott

PS: I'm going to own SO2.

Carl Fisher · **Posted:** Mon Jun 28, 2004 2:43 pm

Well, obviously some wheelspin is likely as you're exiting slow corners, but you may also find you get some in faster corners when the rear end is stepped out about 15 degrees and you're absolutely floored and a testosterone-fueled euphoria washes over you and it just feels so right that you just can't make yourself lift. It's the latter case that you have to watch out for.

But seriously, the traction on grass/dirt is great enough that even in wheelspin situations the revs don't wind up fast enough to catch you by surprise.

Aaron Buckley · **Posted:** Mon Jun 28, 2004 2:55 pm

Carl Fisher wrote:

But seriously, the traction on grass/dirt is great enough that even in wheelspin situations the revs don't wind up fast enough to catch you by surprise.

Obviously Carl has never driven a Celica GT-S on a slippery asphalt surface

- AB

Scott Johnson · **Posted:** Mon Jun 28, 2004 3:28 pm

Carl Fisher wrote:

you may also find you get some in faster corners when the rear end is stepped out about 15 degrees and you're absolutely floored and a testosterone-fueled euphoria washes over you and it just feels so right that you just can't make yourself lift. It's the latter case that you have to watch out for.

So what you are saying is that every one of my runs will begin with the comment "Hey yall, watch this!"

Hmm, easier to set it low then raise it than to set it high and blow up...

Looks like I'll set it high.

Scott

Carl Fisher · **Posted:** Mon Jun 28, 2004 4:44 pm

Aaron Buckley wrote:

Obviously Carl has never driven a Celica GT-S on a slippery asphalt surface

- AB

That's true- and I accept your offer of a fun run at the next Sanford event.

Interestingly, though, the difference between the coefficients of static and dynamic friction on dirt seems to be a lot less than on asphalt- that is, grip doesn't drop off so radically when the wheels start to spin. So I stand by my original statement.

Addition: The same factor is also why sliding the car on dirt is not a bad idea as it is on asphalt...

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Engine revs at a rally cross

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