Pulley question?
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12 Second Club
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Joined: Jan 2004
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From: Palos Hills, IL
Pulley question? ok so looking on LS1speed.com....im looking at pulleys....basically im planning out everytrhing now...and then purchasing it as money comes around...im making my list lol...
so im looking around and all these pulleys say SFI appoved (whats SFI) but ASP pulley is not??!?! i dont get what it is...is that good or bad?....also what is this whole 10% 25% deal stuff or whatever? would an alternator pulley be better as well? (needsa be a daily driver very streetable and do good in all weather conditions) will tuning be needed?....should i get an ARP crank bolt as well?
what brand to get? ASP SLP whatever else there is?
so im looking around and all these pulleys say SFI appoved (whats SFI) but ASP pulley is not??!?! i dont get what it is...is that good or bad?....also what is this whole 10% 25% deal stuff or whatever? would an alternator pulley be better as well? (needsa be a daily driver very streetable and do good in all weather conditions) will tuning be needed?....should i get an ARP crank bolt as well?
what brand to get? ASP SLP whatever else there is?
The common brands are ASP, March, ATI, SLP. Most people use the ASP like me.
The NEW model of the ASP pulleys are SFI appoved. SFI is some group of people that certify aftermarket parts, not sure what it means. Anyways, the pre-SFI appoved ASP pulleys are just as good as the new ones.
25% means how much the pulley is smaller than stock. ASP pulley is 25% smaller than stock, so it makes all the stuff spin 25% slower, freeing up some power.
The alternator pulley is an overdrive pulley, meaning it's larger than stock and spins the alternator faster than stock, to keep the battery charged. You use this with the underdrive crank pulley, if you have charging problems are a big stero system. I dont have the overdrive Alt pulley and havent had any problems.
Tuning is not needed. However, some people get knock retard with an ASP pulley, which is usually due to an unbalanced pulley. This may or may not need tuning. I dont know the details of fixing KR.
ARP crank bolt is good, but a NEW stock one will work fine. I got one for like $4 w/ tax at the dealer.
The NEW model of the ASP pulleys are SFI appoved. SFI is some group of people that certify aftermarket parts, not sure what it means. Anyways, the pre-SFI appoved ASP pulleys are just as good as the new ones.
25% means how much the pulley is smaller than stock. ASP pulley is 25% smaller than stock, so it makes all the stuff spin 25% slower, freeing up some power.
The alternator pulley is an overdrive pulley, meaning it's larger than stock and spins the alternator faster than stock, to keep the battery charged. You use this with the underdrive crank pulley, if you have charging problems are a big stero system. I dont have the overdrive Alt pulley and havent had any problems.
Tuning is not needed. However, some people get knock retard with an ASP pulley, which is usually due to an unbalanced pulley. This may or may not need tuning. I dont know the details of fixing KR.
ARP crank bolt is good, but a NEW stock one will work fine. I got one for like $4 w/ tax at the dealer.
11 Second Club
Joined: Feb 2003
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From: The South
Don't get an underdrive alt pulley. If anything, people with systems, etc get an OVERdrive alt pulley to avoid charging issues. The vast majority of the parasitic loss comes from the crank pulley. What happens is the crank is connected to the serpentine belt via the pulley, and you get a different pulley (diff diameter) to reduce the loss of power from the crank to run the power accessories such as the compressor and power steering. ASP is the most highly recommended pulley for the LS1 F-body at this point in time. The 10% vs 25% is the percentage reduction vs the stock pulley I believe....and I also believe most people get the 25% 
Edit: Damnit, ferocity replied while I was still typing mine
Edit: Damnit, ferocity replied while I was still typing mine
