Underdrive pulleys?
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Underdrive pulleys?
Guys,
Has anyone ever seen some good results from underdrive pulleys? I still have the big old beasts on my car, do you think I could pick up a .1 sec or anything for that matter with some underdrive pulleys?
I would like to see some good data, like we did with the header tests if possible. Thanks :cheers:
Has anyone ever seen some good results from underdrive pulleys? I still have the big old beasts on my car, do you think I could pick up a .1 sec or anything for that matter with some underdrive pulleys?
I would like to see some good data, like we did with the header tests if possible. Thanks :cheers:
Pro
Joined: Jan 2003
Posts: 567
Likes: 0
From: Oswego Illinois
Re: Underdrive pulleys? (ski_dwn_it)
It couldnt hurt the worst that could happen is that you improve your times as much as you would like to. Lots of guys on the forum are runing a crank underdrive pulley.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Underdrive pulleys? (ski_dwn_it)
I picked up maybe 4mph from the March underdrive crank pulley from their Power & Amp set. And the engine does seem to spin up a little quicker.
I had charging issues till I installed the over drive alt pulley and now charging is like stock.
Coolant temps will rise a little on a long idle unless I raise idle to around 1,000rpm but I can live with that.
I had charging issues till I installed the over drive alt pulley and now charging is like stock.
Coolant temps will rise a little on a long idle unless I raise idle to around 1,000rpm but I can live with that.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Underdrive pulleys? (ski_dwn_it)
My L98 has essentially stock internals; mods at the time of the underdrive pulley install are on my site though the times there include a copla other mods.
The best pass just after the underdrive crank install was at the end of June, 2001 at Raceway Park:
Raw time slip:
ET=13.47sec @101.77mph; 77deg F, ??RH, 28.72 baro, ??coolant temp.; with
3,360lbs launch weight = 276chp.
Normalizeded for climate:
ET=13.26sec @103.32mph; = 289chp
This was up from a few weeks earlier (with stock crank pulley) where the normalized data bave 285chp.
The best pass just after the underdrive crank install was at the end of June, 2001 at Raceway Park:
Raw time slip:
ET=13.47sec @101.77mph; 77deg F, ??RH, 28.72 baro, ??coolant temp.; with
3,360lbs launch weight = 276chp.
Normalizeded for climate:
ET=13.26sec @103.32mph; = 289chp
This was up from a few weeks earlier (with stock crank pulley) where the normalized data bave 285chp.
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Underdrive pulleys? (65Z01)
Where did you guys get yours? And how much were they? I called Summit a while ago and they wanted like 200+ dollars for a set :eek:
And wonder if they make more of an effect on a lesser HP motor?
[Modified by ski_dwn_it, 2:18 PM 4/29/2003]
And wonder if they make more of an effect on a lesser HP motor?
[Modified by ski_dwn_it, 2:18 PM 4/29/2003]
Burning Brakes
Joined: Feb 2000
Posts: 871
Likes: 1
From: Westland MI.
Re: Underdrive pulleys? (ski_dwn_it)
I can't answer how much they improve performance, but I can say they hurt boost levels. When I installed my Procharger I forgot I had underdrive pulleys on. When I went to replace my belt I remembered, and put the stock pulleys back on. My boost came up about 3psi on the gauge.
I guess what I am trying to say is if you want them, we can work out a deal. I think it's a 2 piece set, maybe 3. I know at least crank and alternator. They're not doing me any good anymore, maybe you can use them.
I guess what I am trying to say is if you want them, we can work out a deal. I think it's a 2 piece set, maybe 3. I know at least crank and alternator. They're not doing me any good anymore, maybe you can use them.
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Drifting
Joined: Jan 2002
Posts: 1,606
Likes: 1
From: Las Cruces NM
Re: Underdrive pulleys? (ski_dwn_it)
I haven't installed them on my '88 yet, since I haven't seen the car (just over 4 weeks till life back in the states!!!!), but I picked up the MR Gasket 3 pulley set new on ebay for about 70 bucks.
Search around and you can find deals, especially if you're the ebay-aholic like me.
Chris
Search around and you can find deals, especially if you're the ebay-aholic like me.
Chris
Racer
Joined: Jul 2001
Posts: 443
Likes: 0
From: Tampa FL
Re: Underdrive pulleys? (ski_dwn_it)
ASP makes a 40% underdriven "race" pulley. Most street pulleys are around 20%. I was wondering if there would be cooling issues if used on the street? Heres a link- http://www.aspracing.com/frame.htm
Burning Brakes
Joined: Oct 2002
Posts: 835
Likes: 3
From: Water Winter Wonderland
Re: Underdrive pulleys? (ski_dwn_it)
No experimental data to report, but most say around 5-10 HP. I've used the one-pulley type since 1990. Power steering is a little harder, but electrical, cooling, and A/C are fine. THe downside is that the one-pulley setup uses a belt that's different size than the stocker. For that reason, I carry a spare down by the ABS controller.
:cheers: -Bill
:cheers: -Bill
Racer
Joined: Oct 2000
Posts: 476
Likes: 0
From: Socorro New Mexico
Re: Underdrive pulleys? (ELEVENS)
I have had the ASP crank pully on mine for few years now. No problems. I don't do the drag strip, but I took it with me on a 2000 mile vaction back home to mom and dad. Installed it while back there, my dad thought that I was nuts, to head back with it virtuialy untried :D .
Going back home I was a solid 2mpg better. Now that is performance :D :D
I highly recomend the ASP 40% pully, based on my personal experience.
Going back home I was a solid 2mpg better. Now that is performance :D :D
I highly recomend the ASP 40% pully, based on my personal experience.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Underdrive pulleys? (BOBA VETT)
BOBA VETT, you will no doubt see some charging issues with s 40% underdrive pully and maybe some minor cooling, even in Toledo, OH.
Ski-down-it, I got the March Power & Amp 3-pulley set two years ago for $135, and think it was through Summit.
Ski-down-it, I got the March Power & Amp 3-pulley set two years ago for $135, and think it was through Summit.
