underdrive pully questions

[quackmandude]

what r the pros and cons of under drive vs stock size? any less voltange at the alternator or something likew that? horpower differences?? thanks

[91STT]

Pros:
Lighter weight
Smaller diameter = less inertia
Smaller diameter = reduced parasitic drag from alternator
Looks nicer than stock
Gain back a few hp

Cons:
Smaller diameter = less voltage from alternator
Not dynamically balanced (may not be con depending who you talk to)
Non-standard belt

Those are the pros and cons I can think of at the moment, I think I got all of them though.

[Hans_GZP]

no harmonic balancer either. Could cause potential premature bearing failure. Not really worth it for the hp gained.

[quackmandude]

so the 3sx stock size liughtweight pulley has a harmonic balencer?

[91STT]

nope

[quackmandude]

is there anyway to be sure that the bearings wont fal without a harmonic balencer? or should i just no get one?

[Polygon]

Originally Posted by quackmandude

is there anyway to be sure that the bearings wont fal without a harmonic balencer? or should i just no get one?

There is no solid evidence I've seen to support either side of that argument. That being said, it's better to be safe than sorry IMO.

[jason_bet]

I have one.. Underdrive FTW.. Great HP to $ ratio.. Look at all the fast ass cars.. they all have them..

[Hans_GZP]

Originally Posted by jason_bet

Look at all the fast ass cars.. they all have them..

are you serious?

[AutostradaVR4]

this topic has been debated quite a bit. i'm sure a brief search on 3si will get you dozens of pages of arguing, with some good info sprinkled in between.

[Hans_GZP]

I don't see any of the top guys running them though. If you are making 1000 awhp, what the hell is 1 hp difference from a pulley going to do. I would rather have the peace of mind knowing that I have a harmonic balancer (would be an aftermarket one at that power level).

[jason_bet]

Originally Posted by Hans_GZP

are you serious?

lol the way I worded that it did sound kinda retarded.
Look at some of the fastest 3ks out there.. Matt from Dynamic runs one on all of his stealths. and also recomends it.
I believe Trever with the red stealth (E16G record car) runs one..
I am just saying... I mean I have one on both my my vr4s.

Jason

[Hans_GZP]

Originally Posted by jason_bet

lol the way I worded that it did sound kinda retarded.
Look at some of the fastest 3ks out there.. Matt from Dynamic runs one on all of his stealths. and also recomends it.
I believe Trever with the red stealth (E16G record car) runs one..
I am just saying... I mean I have one on both my my vr4s.

Jason

I would call up Matt and double check your info. Definitely not correct. I would be willing to bet that Trevor doesn't run one either.

I have about 6-8 of these pullies for sale. Anyone want to buy one? I have a couple for the 91 models, a couple of the new style ones, and a bunch of old style ones.

[jason_bet]

Originally Posted by Hans_GZP

I would call up Matt and double check your info. Definitely not correct.

lol.. ok..
Go to matts site. Click DR project cars His red stealth and his white stealth both have them on it. And I quote-
"The first trip to the El Paso track with those first modifications pitted Matt up against a modified (headers, exhaust, DRM chip, air intake, ported intake manifold, and drag radials) 1992 ZR-1 Corvette. The supposed “King of the Hill” -- went down hard on numerous back to back passes. The Stealth emerged the victor, each and every time. The best pass for the ZR-1 was a 13.5 at 109 MPH. Needless to say, Matt was impressed, and the ZR-1 owner was shocked. When told what mods were on the Stealth, the ZR-1 owner could not believe it. A valuable lesson was learned by the ZR-1 owner that day, power is worthless unless you can put it down to the track.

From this point, the die was cast, and Matt, a long time drag racer was extremely impressed by the performance of this platform.

The next modifications added were an underdrive pulley, 13G turbos, Denso fuel pump, and a G-Force ECU upgrade. This level of modifications gave Matt a best of 12.64 at ~108 MPH (~4800 ft. elevation). "




NEXT we have his red stealth and I quote-
"A short list of modifications was then installed:

Stillen air intake, Stillen down pipe, Blitz DSBC, Unorthodox Underdrive Pulley."





NEXT-
follow this link to his "Staged Upgrades"

http://www.dynamicracing.com/custome...&cat=49&page=1

[jason_bet]

LOL I have plenty more..

How about Nelsons car? Here is his old set up-

http://www.dynamicracing.com/mw/inde...lson_Bernardes