ITS 240sx Gearing

[TBreu007]

I know most people recommend 4.36 gearing for an ITA 240sx with 225/45/15 wheels. What about a ITS 240sx with 225/45/16 wheels? I wanted to go with 16" wheels for an extra little bit of rubber on the track and for looks, but if an ITS 240sx is making power somewhere between a E36 BMW and a RX7, would that be enough to offset the gearing change of the bigger wheels?

Thanks,
Tim

[TBreu007]

I guess I'll have to find out in testing

[Banzai240]

Originally posted by TBreu007:
... but if an ITS 240sx is making power somewhere between a E36 BMW and a RX7, would that be enough to offset the gearing change of the bigger wheels?

Thanks,
Tim

The ITS 240SX making power between the RX-7 and the E36 BMW??? I need to talk to your engine builder!

------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Auburn, WA
ITS '97 240SX

[erlrich]

Originally posted by TBreu007:

...would that be enough to offset the gearing change of the bigger wheels?

Tim -

Not sure if this will help, but I can tell you what the change will do to top end. In 5th gear (.76 ratio on the 240SX) at redline (6500 rpm) each 1" of OA tire diameter will net you approx. 5-6 mph of top speed. On the other hand, changing from the 4.08 to the 4.36 gears will cost you approx. 9-10 mph. Changing from the 4.36 to the 4.63 gears will cost you approx. 8-9 mph. So, with respect to top speed, changing gearing should more than offset the change in wheel size, assuming the overall tire diameter is also increased by 1".

(Btw, if your engine is making power somewhere between a BMW and an RX7 I would also like to get the name of your engine builder!)

------------------
Earl
ITA 240SX in process

[This message has been edited by erlrich (edited February 10, 2003).]

[murphyd]

You may want to check the Hoosier specs on their website. They are listing an approximate dia increase of 2" from the 225/45-15 to the 225/50-16. I chose to run the 15" in ITS to aid in gearing (and the availability of good used tires!).
In regards to the engine making power between the RX7 and the E36 are you refering to the ITS or ITA model? I'm not sure what numbers the RX7 produces (I've seen many different numbers) and have seen what the e36 is supposedly producing. I've yet to dyno an ITS engine, but have talked to a very reputable engine builder who has dynoed ITA engines producing 175+ hp at the flywheel. Don't ask what type of dyno and conditions I don't know. Call Rebello and ask for HP estimates from their ITA engines. I was told with their exhaust system, ECU mods and everything else to expect right at 190hp!!! I know of Rebellos rep for high claims, just passing on info!!

[Joe Harlan]

Something else to consider when choosing gear ratio's is that there is a powerloss when using an overdrive gear. You may find on some tracks that gearing for 4th gear as the top gear is a better choice.

[TBreu007]

Thanks for the help on gearing. I don't know if the 4.36 will be any good with 16" tires. I may get a cheap used set of both before making a final decision.

I've seen dyno numbers from people with the earlier KA24DE engines in street cars with the larger stock cams ('91-'92) putting ~170hp and 170lb/ft of torque to the wheels with just intake, off the shelf headers/exhaust and a JWT ECU. The later motors ('93+) seem to have a hard time making those numbers...probably because of the cams.

With a balance/blueprint, proper race header and a few more tweaks, this motor should be able to make alot more.

My motor is being built by a very reputable motor builder. If the HP numbers do come in where expected (between E36 and RX7) I'll let you know. I plan on doing my own dyno to find definite RWHP.

[handfulz28]

Are the 91-93 and 95-9x cars on the same spec line?
I don't have a recent GCR. Hmmmm, maybe they're not because of the wheels. But if they are, the 91 cams would be legal in 95+ cars......
Michael

[Banzai240]

Originally posted by handfulz28:
Are the 91-93 and 95-9x cars on the same spec line?
I don't have a recent GCR. Hmmmm, maybe they're not because of the wheels. But if they are, the 91 cams would be legal in 95+ cars......
Michael

I don't have my ITCS handy, but I don't think these cars are listed on the same line. Totally different body styles might mess with the "update/backdate" rule! (Though I suppose one might argue that you could replace the whole body/chassis as an "assembly"! )



------------------
Darin E. Jordan
SCCA #273080, OR/NW Regions
Auburn, WA
ITS '97 240SX

[TBreu007]

Nope, the S13 and S14 are on different lines.
At least the S14 gets the monster brakes.

[murphyd]

Hey TBreu007 how about sending your email address. I've just about finished "stage 1" of my 95 ITS 240 and have a few questions for you.

[dspillrat]

Originally posted by murphyd:
Hey TBreu007 how about sending your email address. I've just about finished "stage 1" of my 95 ITS 240 and have a few questions for you.

David,
I'd sure like to see some PICS of your new project. Will it be ready for VIR this spring? Glad you turned away from the "darkside" >)
David Spillman

[bbp]

S14 Monster brakes? I don't know that I have the monster setup, "maybe" adequate. The S13 must really suck!

I would like to get together with you guys as well. I ran my S14 last year here in Cendiv. my email is [email protected]

[murphyd]

Spillman, Where having a slight oil pressure problem, but if it is fixed we'll be at VIR in March. Will I be chasing any of my old Z stuff? Check out my website for some early pics of the sx. www.murphymotorsports.net

------------------
David Murphy
Murphy Motorsports

[TBreu007]

Originally posted by murphyd:
Hey TBreu007 how about sending your email address. I've just about finished "stage 1" of my 95 ITS 240 and have a few questions for you.

[email protected]
Anyone can drop me a line any time. I'm fairly new to the game, but I've done a TON of research and I have a friend from a pretty successful team helping me out with questions I might have.
I'll have some questions for you as well I'm sure

Tim

[dspillrat]

Originally posted by murphyd:
Spillman, Where having a slight oil pressure problem, but if it is fixed we'll be at VIR in March. Will I be chasing any of my old Z stuff?

yea,I swapped out my 73 doors the other day with some Hotwheels doors
I think, maybe the doors...wheels if it rains,diff.several odds and ends. To stay in the Nissan camp,my next one will be a 240 SX S car. I can't wait to see some of those beasts on the track"240sx" Appear to have some potential.....Guess I'm hoping you guys get all the bugs worked out........Back to the garage,working on some wrinkled fenders.

David