Underdrive Crank/Alternator Pulley Question

**89LX** · 06-08-2006, 03:22 PM

If I opt to install an underdrive pulley on my LS1 2000 Z28 will I see an increase in RWHP? Is it woth the $$$ and which do you consider the best. Thanks

**mrr23** · 06-09-2006, 02:32 PM

you will see about 8-10 rwhp out of an under drive pulley set up. is it worth the money?? up to you. do you want to get all the hp you can? then, yes. is $100/hp a good buy? not really.

**89LX** · 06-09-2006, 03:12 PM

Good point on the $$$ to HP ratio. I have a lid, smooth bellows, K&N filter and Hooker CB. I was attempting to add a little extra without going internal or changing up my exhaust. Thanks for the reply.

**ProwlerZ** · 06-09-2006, 04:17 PM

Maybe I'm off, but isn't an underdrive pulley only like $200? And if that is the case, you'd be talking about $20/hp. Not the greatest deal, but once you're maxed on bolt-ons and too poor for power adders or cam/heads, it doesn't look too bad.

Btw, there's still a list of things to do before you hit serious money. Headers (which aren't cheap) should be a priority, ported TB with coolant bypass, gears, and a tune will all help, some a lot more than others.

**Mr. Luos** · 06-09-2006, 04:22 PM

If you gain 8-10 RWHP for a $200 pulley...you aren't doing bad in my opinion.

I did the ASP underdrive pulley (crank only) on my stroker. No idea what gains it gave me. Didn't have a before/after dyno.
I do know I had enough power to require a solid tensioner with that pulley though.

**mrr23** · 06-10-2006, 08:30 AM

Originally Posted by ProwlerZ

Maybe I'm off, but isn't an underdrive pulley only like $200? And if that is the case, you'd be talking about $20/hp. Not the greatest deal, but once you're maxed on bolt-ons and too poor for power adders or cam/heads, it doesn't look too bad.

Btw, there's still a list of things to do before you hit serious money. Headers (which aren't cheap) should be a priority, ported TB with coolant bypass, gears, and a tune will all help, some a lot more than others.

i was using a for instance on the dollar/hp thing.

**Aegnor** · 06-13-2006, 01:58 PM

and that's pretty much the ratio for headers.
$600/~20HP = $30/hp

**ninobrn99** · 06-15-2006, 12:36 PM

even if you dont notice a big gain in hp, you will notice faster revs...that helps out alot. You should only see 8-10 yes, but again, with these motors its not about what one mod does, but what the combination does

**breakparts** · 06-19-2006, 03:13 PM

I HEARD GOODTHINGS ABOUT THE SLP PILLEY 25% UD CUZ IT HAS EXTRA MATERIAL ON IT SO THE BELT WONT THROW. IM GONNA GET THIS ONE SOON. IVE HEARD MANY TIMES OF OTHERS WITH LS1 UD PULLEYS LOSING BELTS. F THAT ESPECIALLY IF YOUR OUT OF TOWN WHEN IT GOES. THAT WOULD SUCK

**Street Lethal** · 06-19-2006, 04:38 PM

Originally Posted by breakparts

I HEARD GOODTHINGS ABOUT THE SLP PILLEY 25% UD CUZ IT HAS EXTRA MATERIAL ON IT SO THE BELT WONT THROW. IM GONNA GET THIS ONE SOON.

SLP makes a great pulley!

**MadSeason** · 06-20-2006, 06:00 AM

I use a march pulley and saw a 2mpg increase in fuel economy on the HW

**89LX** · 06-20-2006, 07:07 AM

Ordered a SLP F-Body Underdrive Pulley (P/N SLP100221) from http://www.ls1speed.com/ for $213.16 and no S&H. Best buy I could find and a savings compared to other sites. Found the Gates belts on Amazon.com for $53.97 to the door.