questions on pulleys, stock and underdrive

95cobra68camaro said:

i have a 95 cobra, and i was assured by many and also beleived that the GT and cobra shared the same pulleys, but the part number is 100% different for a serp. belt for a cobra and a GT, i mistakenly got a GT belt and it was 6-8"+ longer then the cobra whats the deal????? and also i might as well do underdrives on my car since my cobra is pretty slow, these cars run warm as it is anyone notice a sunstantial difference in engine temp?? also how bad is the charging sitaution at idle i know its a frequent question by newbe's, also i was thinkn abotu getting ASP's or march's, anyone expeirenced or heard bad things about either company i know march stuff is usually good but figured id ask u guys b4 i bought it

thanks !

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First, the water pump pulley is different from that of the GT. It is overdriven slightly to accomodate the factory oil cooler. My 94 Cobra runs at 184* at its hottest point. You can underdrive, but I wouldn't. I went to extremes to get the pulleys chromed so they would look good. Underdrive won't cause much more heat, it will just make your fan run more which puts more strain on the alternator which if underdriven starves the car for power. WOW. Say that twice fast.

A great upgrade would be a PA performance 200 amp alternator. Then you could underdrive it and still have a lot of power to spare.

Hope that helps - PA PERFORMANCE LINK

Loudtoy from my understanding the pa alts (and others) are not at full amperage/charge until about 1,000 rpms. U/D pulleys are rated at full charge at 950 rpms. So at idle both would still be under charged until about 950+rpms.

wytstang said:

Loudtoy from my understanding the pa alts (and others) are not at full amperage/charge until about 1,000 rpms. U/D pulleys are rated at full charge at 950 rpms. So at idle both would still be under charged until about 950+rpms.

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True, I was leaning on the 200 amp Pa alt. Then you would still be higher than factory even if it was underdriven. At idle the do 100+ amps. They under rate them a little. I had a 160 amp on my old GT under driven, and it made a big difference. Had a huge stereo then also, not like now. Interests have change. It might just take someone to do a real comaparison.

ANYBODY - It nobody does, I will do a comparison on the stock alt with stock pulleys, and the PA 200amp unit. I should pick it up in mid August. I will post idle results of each, and we will see if there is a difference. For the money, I hope so.

I would agree with your understanding if using the smaller alt. Personally I don't care much for under drive, but to each there own. I guess if I was 5-7hp shy of 300rwhp I might change my mind though - -

If you could do a comparison at idle on both that would be awesome. Look forward to your findings.

I have underdrives. I'm going to buy the cobra waterpump pulley soon. I have a temp sensor in the back of my intake along with factory in the front. When idleing in traffic the back will reach 215 or more even though the front flutuates with the fan running. As soon as i get moving for a little the back will come down to 185 and stay there.

I have a tweecer and datalog the ect so I know the front gauge is accurate. The only thing I can assume is that due to the bad coolant flow in th rear of the motor along with the slower water pump speed it causes this.

If anyone else has seen this or has a better explination of this please chime in.