Nashua_Night_Hawk

Anyone has before and after 1/4mile times with the OBX headers?

Till Oct 12, I do not know how much improvment I can expect? Any clue?

Dom418

Actually... we're all waiting on YOU. :P

I'm getting mine in on Saturday, probably won't make it to the track for a little while...

Zapata

well,
if by obx you mean COMPTECH It really depends. I really didn't see too much of difference but i didn't run under ideal race conditions. Don't be disappointed if you don't see a huge improvement as you will only be in vtec 2.5x, through 1st and 2nd gear and half way through 3rd if you are lucky.

jucee187

arent the headers supposed to cut down the time by 0.4 seconds?

Nashua_Night_Hawk

if the gains are 0.4 sec... then I should expect 14.4s in 60s weather.

Dom418

That seems reasonable to me

Zapata

You should see less because of your wider rims/tires.

Dom418

I still don't understand this concept...

Wouldn't the additional traction off the line (from wider tires) be more beneficial than extra drag would be harmful??

Zapata

at the start yes but over th 1/4 his tires need to rotate more to travel 1/4 mile...hence slower times.


stock
215/50/17 792 revs/mile

NNH
235/40/18 794 revs/mile

jucee187

yes but what if the combined weight or rims and tires weigh less than the stocks?..

Zapata

That's a factor of course but in this case i know it isn't. As always less weight to move equal faster times....usually.

jucee187

so how much lighter does a 18 inch tire and rim combined have to be .. to be the equivalent to having on 17inch stock rims/tires? to produce the same numbers?

so the bottom scenario would be ideal?:

wider lighter rims/tires VS stock 17s?

Zapata

uhmmmmmm ssheesh well i'm sure there is a physics equation for this. Perhaps you could search for an ericL post?

Real quick though.....

optimal setup?
you'd want lightweight rims that are small in diameter but more wide than stock. You get traction off the line w/o compromising top end.

you can go to this site and check the difference between stock and aftermarket. It will give you the difference in the total revolutions/ mile. Then I know there is a equation or weight reduction to E.T. factor that EricL has posted a number of times.
http://www.miata.net/garage/tirecalc.html

Haus

Based on the increased rev's per mile...will this screw up the odo and give higher than actual milage?

TypeSKid

This is a thread for eric L! Where u at?

Zapata

Here are some good discussions:

http://www./tech/wheel_weights.html
http://www.mysportscar.com/features/wheelweight.htm
http://www.wheelweights.net


http://integra.vtec.net/wheels/rotation.html


http://www.acura-cl.com/cgi-bin/ulti...c&f=1&t=008076

http://www.acura-cl.com/forums/showt...light=unsprung

jimcol711

jesus christ, i should have paid more attention in calculus!!!! fuck that shit, someone have the cliff notes on this??

Zapata

cliff notes:


Lightweight rims OWNZ!!!! I'd say it's more worthwhile than headers. Get 17inch wheels. 18's look better but don't perform as well.

DISRUPTV

zapata's golden on this one

Lightweight 17s will kick so much ass that its not even funny...shit the Rota Battle (so what they are rotas) in 17x7.5 weigh 17.5 lbs which is pretty good, combine that w/a 225/45/17 tire and you will kick some major arse!

Dom418

seriously.. what kind of time differences are we talking here...

I mean going from 17's to 18's in the same wheel

Nashua_Night_Hawk

even 3%-5% is big! less MPG! BUt taking corners at high speed and beter steering feel... kick ass!

Wires

I watched an interesting show on this topic. Before I learned about the rotating interia crap, I always assumed that a car with lower profile tires would out-perform a car with taller sidewalls. My logic was you could corner faster on short sidewalls.

That's true. The catch is the more weight, the more HP it takes to spin that weight, so you lose power (proof is swapping a steel flywheel for an aluminum one). Dropping say 9 lbs off of the flywheel in a car (depends on the gearing of course), can make the car feel like it's gained 25HP!!!!!!!

They tested the same car with 15", 16", 17" and 18" wheel/tire combos on a road course. The 15" were slowest (do to the poor corning), but intereting enough, the 18" weren't much better. You picked up the cornering, but you couldn't accelerate as fast with the added weight! The 17" were marginally better than the 16"! Pretty cool and usefull info!