I don't have all the ratios at the ready, but since the overall diameter of the rear tires is 24.8-inches, what would happen to the gearing if an owner went down to say, a 23.8-inch tire? I know the speedo and odo would be off but I was curious how much difference it would make to the final ratio? I was just tinkering with time while bored and was imagining that the 1/4-mile time should be less and mph higher though top end would be reduced.
Curious.

 

This would be equivalent to increasing your final gear ratio by 4% (or 4.26:1 rear end). Your top end will not be reduced as the stock car cannot reach it anyway.

 

Thanks XViper but wouldn't the top speed of the car decrease? Not the top speed in theory, rather the car's actual attainable top end?

 

[QUOTE]Originally posted by Russ
[B]I don't have all the ratios at the ready, but since the overall diameter of the rear tires is 24.8-inches, what would happen to the gearing if an owner went down to say, a 23.8-inch tire?

 

[QUOTE]Originally posted by Russ
[B]Thanks XViper but wouldn't the top speed of the car decrease?

 

I believe that www.tirerack.com (site sponsor) has a chart of listing revolutions/mile for a bunch of tire brands/sizes. You should be able to do the math from there.

 

Top speed would be affected in two ways, I think, by the overall gearing being shorter by 4%:
1) Wheel torque is increased by 4% in each gear, which tends to allow a higher top speed (higher torque could overcome higher aero drag);
2) RPMs are 4% higher, meaning the engine is at a different point on the torque curve for any speed. Since the S2K's torque curve is typically decreasing above about 7500 rpm, the engine would be operating at a lower torque output for a given speed in that rev range, which would tend to reduce top speed.

I think #1 might be a stronger overall effect, since the torque dropoff is probably not 4% for a 4% rpm increase. (Although, above about 8600, the torque does drop sharply in many cars...)

So it would be close I think. How's that for hedging.

 

beware, you go too short and you'll need 5th by the end of the 1/4

 

I doubt there is anything to be gained in top speed by reduced gearing. Stock, max speed is on or beyond max HP. Torque is dropping real fast at those rev ranges. I mean, faster than drag is increasing, so no gains whatsoever.

A CAI with good ram air effect could change this (by extending the torque curve), as well as clocking max speed with your top down (by increasing drag and pulling back the max speed into a more favourable slope in the torque curve).

BTW, I've mean to venting this for a while... I have come across several posts/threads, usually exhorting the dramatic (sic) results of reduced gearing (final gears, etc) on acceleration. This is a misconception. In fact, it's a case of "horses for courses". What works on a track (or on a drag time measurement) may not work on another. When you increase gearing you are trading increased in-a-given-gear acceleration for a forced early upshift. This may work or not depending on specific conditions.

An example: You want to record your best 0-60mph. You reduce gearing by 5% and you can still hit 60MPH in 2nd. You clock a better time. You reduce another 5%. You no longer hit 60MPH in 2nd, and are forced into upshifting to 3rd. Your time worsens. Not only because it takes time to upshift, but because your reduced 3rd gear is less "pully" than your stock 2nd gear.

I would therefore caution advocates of the reduced final gear set by xyz to think before they buy .... The popularity of reduced gears stems from the fact that most roadworthy cars have somewhat longish gears in an attempt to increase fuel economy. Some cars will even sport a slower max speed on top gear than they do on the immediately shorther one.

This is definitely not the case with the s2000. Honda did the right thing AFAIC and for my conditions, the stock gearing is close to perfect.

... though I wouldn't mind a 7th gear for those long 200km/h drives on the freeways