POLL: Alternate Crankshaft Pulley???

Banzai240

New member
I'm just curious.

A simple Yes or No will do...

QUESTION:
Would you support a rule change that would allow IT cars to substitute the crankshaft pulley, in addition to the current pulley substitution allowances?

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX
DJ_AV1.jpg
 
Yes.

For the SR20DE cars (NX2000 and SE-R) there are no alternate larger accessory pulleys. The main problem is that the factory accessory pulleys are crammed so close together on the end of the engine that there's very little room to make them larger as allowed by the rules.

Unorthodox Racing, the major supplier of this type of aftermarket part, makes a "kit" that includes nifty anodized power steering, A/C, alternator, and water pump pulleys for the SR20DE, but these pulleys are basically stock size, in some cases slightly smaller. Where these suppliers are making the difference is with a larger crankshaft pulley (where there's room to do it).

Take that physical limitation, couple it to a water pump that is very susceptible to cavitation at higher RPMs and a power steering pump that froths and overheats the P/S fluid at high RPM (to the point of melting the stock P/S lines), and the SR20DE has a distinct performance disadvantage and a very real possibility of engine overheating and/or puking P/S fluid all over the track.

Besides, looking at it from 30,000 feet, allowing accessory pulleys but no crankshaft pulley seems downright silly.

Greg
 
Originally posted by seamus88:
If it is leagal do not do it on a Honda it WILL wipe out your crank bearings and maybe the oil pump

Same thing on the Miata/Protege/Escort BP engine family.

Independently of that, I vote "No".

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Ony Anglade
ITA Miata
Sugar Hill, GA
 
since others have already broken the yes or no only request i will ask why was this limitation was put on in the first place. if you can change some pully sizes, why draw the line at the crank pully.

dick
 
<font face=\"Verdana, Arial\" size=\"2\">...more rules creep...!</font>

Taken to its idiot extreme, classifying any newer cars into Improved Touring is also "rules creep"...

Dick, judging from the attitudes in the mid-80's when IT was born (and when I started racing) I suspect it, as with coilovers, had to do with the state of aftermarket technology at the time. There was no Unorthodox Racing, there was no Sport Compact Revolution, but there was a crapload of cars out there with poorly-designed engines that had HUGE lead or heavy rubber vibration dampers as crankshaft pulleys. Given there was no easy aftermarket replacements, changing the crank pulley was an expensive and "high tech" effort.

For the most part, the cars we have racing in IT today are not necessarily victims of this concern (the above issues with Miatas and Hondas notwithstanding). In fact, it could very well be said that this would be a "vindication" of the ECU rule, as older cars would be able to take better advantage of this proposed rule than newer cars (which in general don't have as big a crank pulley)...

Ony and Seamus: I've been scratching my head trying to think about this, but WHY IN THE HELL would alternate crank pulleys have any affect on crank bearings and oil pumps? Are these cars so dependent on OEM crank pulleys for vibration dampening that they are detrimentally affected by harmonics? If so, you're allowed to balance and blueprint, so won't this balance out any production problems?

Greg
 
Maybe or maybe not (balancing correcting the issue), but allowing more modifications means more money to be spent to develop the car to the max of the rules. Also, cars for which the aftermarket doesn't have crankshaft pulleys would be put further behind (just like it happens with the current ECU rule).

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Ony Anglade
ITA Miata
Sugar Hill, GA
 
Originally posted by grega:
Ony and Seamus: I've been scratching my head trying to think about this, but WHY IN THE HELL would alternate crank pulleys have any affect on crank bearings and oil pumps? Are these cars so dependent on OEM crank pulleys for vibration dampening that they are detrimentally affected by harmonics? If so, you're allowed to balance and blueprint, so won't this balance out any production problems?

Yes Greg, there are indeed some cars out there that will go BOOM if you install an aftermarket pulley (supposedly the Bimmer is one of them
smile.gif
). I don't think it's simply a matter of balancing an engine because my inline 6 in my road Bimmer is absolutely the smoothest engine I've ever experienced.


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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com
 
Actually, it is my understanding that with the bimmer it is an issue only if you are running a single-mass, lightened flywheel, rather than the factory dual-mass.

Mike
 
No.

Rules creep is rules creep. If we're going to have it, why not start w/ some simple, non-performance things that make the cars easier to maintain or safer:

- Jack points
- roll cage mounts at the center of door bars
- removal of wiring for deleted accessories (power seats, A/C pumps etc)

Unless I have been reading most rules changes posts incorrectly, most of the requests for changes are to allow more equality and/or less money. Adding allowances in the performance dept hinders both of these goals.
 
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