crank pulley ??

[rkracing]

Does anyone know why Honda used a lightweight crank pulley on the 88'crx si motor and then went to the heavy, cast iron pulley on the 89-91's?

thanks

[Jon Nelson]

I thought they used the same for all years.

Can you send me pictures?

Jon

PS - They would have used the dampened pully for noise/vibration/harshness issues and crankshaft fatigue issues.

[rkracing]

Jon,

I do not have a digital camera, yet! A couple years ago, saw one on a guys ITA CRX si and I questioned him about it's origin and he swore up and down that it came from an si motor. And now a friend has one on a street crx and I'm just courious why honda made the change. I'll try to get a photo of it.

[Jon Nelson]

The reason I ask is that I searched up and down for a smaller, lighter, part that either:

A. Came from the factory on a CRX Si

or

B. Is made of steel and has the same diameter as a stock part.

Would fit the rules, and potentially save 4 or 5 pounds of rotating weight. The stock 1990 one weights 6.5lbs, I think.

J

[rkracing]

Jon,

Your correct, it weighs A LOT less. I called AEM just for fun to see if they sold a lightweight crank pulley and they don't for the reasons you stated. They advised not running the lightweight pulley on a car that would be at high rev's most of the time.
Thoughts anyone???

[CRX Lee G]

The early '88 cars had a smalled OD crank snout (same as the 84-87 cars) and they changed it to a larger diameter in late 88 or 89. I found out as I got light aluminum pulleys from Unorthodox and got the wrong one first for my '88 EP/FP car. Because of the ID of the pulley, they are not interchangable.

The stock pulleys are solid with no isolated damper so a lighter weight balanced pulley should be no problem. I was told that the stock Honda engine was so well balanced to begin with that it needed not isolating damper and therefore a good aftermarket one should be fine and mucho lighter. My car has not fired yet but I intend to see 9,000-9,500 rpm, much higher than an IT car would.

[B Breon]

Originally posted by CRX Lee G:
The early '88 cars had a smalled OD crank snout (same as the 84-87 cars) and they changed it to a larger diameter in late 88 or 89. I found out as I got light aluminum pulleys from Unorthodox and got the wrong one first for my '88 EP/FP car. Because of the ID of the pulley, they are not interchangable.

The stock pulleys are solid with no isolated damper so a lighter weight balanced pulley should be no problem. I was told that the stock Honda engine was so well balanced to begin with that it needed not isolating damper and therefore a good aftermarket one should be fine and mucho lighter. My car has not fired yet but I intend to see 9,000-9,500 rpm, much higher than an IT car would.


Lee is right. I had an early make 88 engine that got destroyed, whole nother story, anyhow, went to junkyard, got another 88 block, it didn't come with a crankshart pulley. Got the whole thing back together, went to put on the old pulley and it didn't fit, came to find out the hard way that there are two different snout sizes in 88. Am running the stamped one now (3 years, no problems), won't tell you how to make it work, but a good lathe, and a broaching tool can not only make it work but can also make it even lighter!!


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Brent Breon
Cendiv ITA #26
www.360racing.com (http://www.360racing.com)

[This message has been edited by B Breon (edited February 23, 2003).]

[HiRcc#21]

Brent is right. There is a different O.D. on the cranks, depending on if the car came with A/C or not. This determined the proper pulley between the Std (HF), DX or Si models.
I have run the pulley set up your inquiring about since 1996 with out a problem.

Here are the part no.'s you need to order from your local Honda Dealer.
Crank pulley- #38921-PM3-Y00
You will have to machine the I.D. of the pulley to mate it to the increase in size of the Si crank, about .60 thousands, and broach punch the key way to fit as well.
While on the lathe, you can also machine off the outside set of belt ribs that were intended for the A/C belt. You won't loose your timming marks either, and the marks are the same in configuration to the keyway as the O.E. heavy Si pulley.
Keyway part #-90704-634-000
Crank Nut #-90017-P01-003
Prices-
Pulley lists for- $78.58
keyway-$1.98
crank nut-$9.68
Machining about 20-30 bucks
I hope this helps you, if you need a pic, call me.
(866) 438-3966
Street-N-Track Autosports
Medina, Ohio
Chris Stiffler

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http://www.Street-N-Track Autosports- owner
ITA CRX Si #21
Central Division SCCA

[Jon Nelson]

So, this is a small, light, stamped, pulley? Is it the same diameter of the "stock" pulley?

I guess it might be just as easy to get one machined to fit the car (and the rules).

J

[HiRcc#21]

It is exactly the same diameter and all as the stock si pulley, except the true center of it is moved towards the block and the A/C part of the pulley is "outbound" which allows it be machined off with out ruining the pulley.
If you were to attempt to machine off the A/C part of the stock si pulley it would ruin it.
My pulley weighs around 2.5 lbs.
I haven't found a lighter, or more legal set up to run, and it turns alot of heads at the track for those that like to "peek" at my engine bay.

------------------
Chris Stiffler
Medina, Ohio
Street-N-Track Autosports
(866)438-3966
#21 ITA Crx Si
Cen Div
H4 Competitor in the 2003 NASA Midwest Honda Challenge

[benh82]

i have an unorthodox racing lightweight underdrive pulley on my street crx and i love it....its like a second flywheel. i talked to some ppl there and they can machine a stock diameter pulley that weighs mere ounces for $200+. not bad for what your getting. its all IT legal too!

[Richy Gonzalez]

unorthodox racing lightweight underdrive pulley...I could be wrong but (disclaimer) but I think your pulley is not IT legal.

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Richy Gonzalez
GB Racing - #24 ITA CRX (http://groups.msn.com/TheGonzalezFamilyRichySheilaandNyah/projectitacrx.msnw)
Racecar Sponsor: LAMIN-X Protective Films (http://www.lamin-x.com)

[Tom Blaney]

I gotta agree on this one, I believe the only pully dia. you can change is the alternator.



[This message has been edited by Tom Blaney (edited March 04, 2003).]

[HiRcc#21]

update and backdate rule applies here fellas. Unorthodox was not an O.E. parts supplier to Honda, so therefore, it is not allowed. The part must be O.E. Honda stuff, not alluminum, heck if your passing tech with that pulley, I want titanium valves and a JG throttle body too...just kidding.
I have had the pulley pass tech at the ARRC, and was able to prove it was a stock part, end of scrutineering issue. I took the honda part slip from the local dealer, per the part no.'s I posted above in my earlier post.
That was enough for them to pass the part.

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Chris Stiffler
Medina, Ohio
Street-N-Track Autosports
(866)438-3966
#21 ITA Crx Si
Cen Div
H4 Competitor in the 2003 NASA Midwest Honda Challenge