Underdrive Pulleys C5
Drifting
Joined: Jun 2002
Posts: 1,945
Likes: 41
From: Corinth TX
Sorry for getting back to you so late. I didn't end up getting a cam installed when I had my pulley installed. Mine was wobbling like me after a few too many.
It was so bad that it was causing the belt to be thrown off. I didn't even think about the cam change until it was too late. All I was thinking at the time was that something was wrong with my baby. I went with a Powerbond pulley. TSP had a pretty good price on them when I bought mine, I'm not sure how much they are going for now though. As LonestarFRC stated, I haven't had any problems whatsoever with undercharging or alternator problems. When you compare the two, you will see how much nicer the replacement is. I do regret not getting the cam changed out at the time though but it was a necessity to get the car back up and running. It was my daily driver at the time.
Here is a good thread on the same topic. When I saw mine wobbling it had me all nervous esp thinking about the thing coming apart like in the pic.
http://forums.corvetteforum.com/show....php?t=1872301
It was so bad that it was causing the belt to be thrown off. I didn't even think about the cam change until it was too late. All I was thinking at the time was that something was wrong with my baby. I went with a Powerbond pulley. TSP had a pretty good price on them when I bought mine, I'm not sure how much they are going for now though. As LonestarFRC stated, I haven't had any problems whatsoever with undercharging or alternator problems. When you compare the two, you will see how much nicer the replacement is. I do regret not getting the cam changed out at the time though but it was a necessity to get the car back up and running. It was my daily driver at the time.Here is a good thread on the same topic. When I saw mine wobbling it had me all nervous esp thinking about the thing coming apart like in the pic.
http://forums.corvetteforum.com/show....php?t=1872301
Last edited by NocarbutaVetteforme; Nov 28, 2007 at 03:28 AM.
Team Owner
Joined: Nov 2001
Posts: 34,124
Likes: 105
From: Pensacola FL
It will cause your marginal water pump to become even more inefficient. 
It will not allow your alternator to put out the amperage that GM designed it to put out at the low RPMs we see in 5th and 6th gear.
It will reduce the ability of the power steering pump to keep up with your turning demands.
IMHO - Underdrive pulley are not a well thought out idea.
It will not allow your alternator to put out the amperage that GM designed it to put out at the low RPMs we see in 5th and 6th gear.
It will reduce the ability of the power steering pump to keep up with your turning demands.
IMHO - Underdrive pulley are not a well thought out idea.
I don't know if the Z06 draws much more than a comparable LS1 F-body, but voltage/amperage has never been an issue either.
The power steering pump might be a concern as they are pretty weak to begin with. Any other input on this?
IMO, on F-bodys, the pulley is a good mod. Is the Vette install any worse? thanks in advance.
Pro
Joined: Jun 2005
Posts: 734
Likes: 0
From: Austin TX
Hmmm. My "marginal" water pump (with ASP pulley) has been cooling my hi-po LSx 383 for years with no issues.
I don't know if the Z06 draws much more than a comparable LS1 F-body, but voltage/amperage has never been an issue either.
The power steering pump might be a concern as they are pretty weak to begin with. Any other input on this?
IMO, on F-bodys, the pulley is a good mod. Is the Vette install any worse? thanks in advance.
I don't know if the Z06 draws much more than a comparable LS1 F-body, but voltage/amperage has never been an issue either.
The power steering pump might be a concern as they are pretty weak to begin with. Any other input on this?
IMO, on F-bodys, the pulley is a good mod. Is the Vette install any worse? thanks in advance.
BTW, I'd previously had bad luck removing powerbond pullies on F-bodies. Don't know if the C5 design is any better.....
Former Vendor
Joined: Nov 2005
Posts: 8,995
Likes: 2
From: Spring Texas
St. Jude Donor '08
The entire cooling system is marginal. If you were to switch out to a aftermarket 2 row radiator (and perhaps a SPAL fan kit) your cooling system's capacity would increase. Under these circumstances a slower water pump could actually help. Since water has a high specific heat, it would stay in the engine longer and absorb more heat per unit volume, then would stay in the radiator longer to dissipate that heat.
Thread Starter
Instructor
Joined: Nov 2007
Posts: 198
Likes: 0
From: Lodi New Jersey/New York
The entire cooling system is marginal. If you were to switch out to a aftermarket 2 row radiator (and perhaps a SPAL fan kit) your cooling system's capacity would increase. Under these circumstances a slower water pump could actually help. Since water has a high specific heat, it would stay in the engine longer and absorb more heat per unit volume, then would stay in the radiator longer to dissipate that heat.
Pro
Joined: Jun 2005
Posts: 734
Likes: 0
From: Austin TX
Drove my car about 180 miles today. I saw the coolant temp get to about 185 once. The average was about 172.
Oil temp was between 180 and 185. Battery voltage was at 14.4 minimum in 6th gear at about 1500-1800 rpm.
Oil temp was between 180 and 185. Battery voltage was at 14.4 minimum in 6th gear at about 1500-1800 rpm.
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Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
Been running a 25% underdrive Powerbond for over a year now, no cooling/charging/steering issues whatsoever.
Engineer scare tactics are always wonderful...but more useful are the hundreds of reviews from people actually using and enjoying the product.
One look at the quality differences between stock and aftermarket pulleys, and there is no doubt which one you'd want on your car.
I wouldn't bother with the effort needed to install one though, unless you are already in there for a cam swap, or your stock pulley is junk and wobbling (not uncommon).
Engineer scare tactics are always wonderful...but more useful are the hundreds of reviews from people actually using and enjoying the product.
One look at the quality differences between stock and aftermarket pulleys, and there is no doubt which one you'd want on your car.
I wouldn't bother with the effort needed to install one though, unless you are already in there for a cam swap, or your stock pulley is junk and wobbling (not uncommon).
Former Vendor
Joined: Nov 2005
Posts: 8,995
Likes: 2
From: Spring Texas
St. Jude Donor '08
I just installed headers-cam-valve springs-and 25% underdrive pulley and have a 160°stat.Now on the same ° day it is running 20°higher.Did yours do the same?Today it is 35° and it would run 165°and now at the same temp it is running 187°at highway speed.I am still running the stock plugs and have not changed my tune yet.Do you think that would change the temp much.Also while I was doing the cam swap I cleaned the ac condenser and radiator.Car has 15,000 miles.
It's normal for the car to run as hot as 210. If you have a Highway temp of 187, you're doing well. Just because you have a low temp thermostat doesnt' mean it will run cooler, it just means the coolant will circulate at a lower temp. The underdrive pulley may actually help because it makes the water pump turn slower. This means water spends more time in the block sucking up heat and more time in the radiator dissipating it.
Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
what mix are you running in your coolant? Usually us Texas guys run a 25% coolant/ 75% distilled water mix cause it's so hot. However with this freakish cold a 50/50 would be better.
It's normal for the car to run as hot as 210. If you have a Highway temp of 187, you're doing well. Just because you have a low temp thermostat doesnt' mean it will run cooler, it just means the coolant will circulate at a lower temp. The underdrive pulley may actually help because it makes the water pump turn slower. This means water spends more time in the block sucking up heat and more time in the radiator dissipating it.
It's normal for the car to run as hot as 210. If you have a Highway temp of 187, you're doing well. Just because you have a low temp thermostat doesnt' mean it will run cooler, it just means the coolant will circulate at a lower temp. The underdrive pulley may actually help because it makes the water pump turn slower. This means water spends more time in the block sucking up heat and more time in the radiator dissipating it.
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
I installed the 160 stat at the same time as the pulley/cam...so I can't say what my temps would be with a stock pulley and 160 stat. (if you are suspecting the pulley for the temp difference). I assume you are running the same 160 stat before and after the h/c?
What heads did you put on? Since the coolant temp sensor is located in the head, perhaps an aftermarket head of slightly different design could possibly affect temp readings. I don't know, seems possible. 20* difference is quite a bit though.
if that.
Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
Mine runs consistently at 175-180 on the highway. Tops out at 200 idling or in traffic.
I installed the 160 stat at the same time as the pulley/cam...so I can't say what my temps would be with a stock pulley and 160 stat. (if you are suspecting the pulley for the temp difference). I assume you are running the same 160 stat before and after the h/c?
What heads did you put on? Since the coolant temp sensor is located in the head, perhaps an aftermarket head of slightly different design could possibly affect temp readings. I don't know, seems possible. 20* difference is quite a bit though.
I installed the 160 stat at the same time as the pulley/cam...so I can't say what my temps would be with a stock pulley and 160 stat. (if you are suspecting the pulley for the temp difference). I assume you are running the same 160 stat before and after the h/c?
What heads did you put on? Since the coolant temp sensor is located in the head, perhaps an aftermarket head of slightly different design could possibly affect temp readings. I don't know, seems possible. 20* difference is quite a bit though.
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
I did H/C and underdrive pulley at the same time. I have a 165 degree stat. Before the change my temps would be about 180 at highway cruise (below 2000 rpms). Now they are about 190-195. It has to be the slower circulation. When I keep the revs above 2000 rpm my temp drops back to 180. A third gear pull today started at 195 and when I let off I saw that it was down to 183. With stock pulley and stat it was always just below 200. I think it must be normal. I'll see what the summer time brings.
Former Vendor
Joined: Nov 2005
Posts: 8,995
Likes: 2
From: Spring Texas
St. Jude Donor '08
I did H/C and underdrive pulley at the same time. I have a 165 degree stat. Before the change my temps would be about 180 at highway cruise (below 2000 rpms). Now they are about 190-195. It has to be the slower circulation. When I keep the revs above 2000 rpm my temp drops back to 180. A third gear pull today started at 195 and when I let off I saw that it was down to 183. With stock pulley and stat it was always just below 200. I think it must be normal. I'll see what the summer time brings.
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
A H/C swap produces more power because of the burning of more fuel/air in the combustion chamber. This results in a hotter running engine. It may be advisable to invest in an aftermarket radiator. The OEM radiator is a rather small single row and an aftermakret aluminum like the one from De-Witts would provide significantly better cooling. You may also want to consider the SPAL fan upgrade for optimum cooling even in heavy traffic.
Team Owner
Joined: May 2006
Posts: 21,473
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
LS6 Manifold and a handheld programmer to make better use of the mods!
Highflow airbridge and a VARARAM will add some extra RWHP!
Thanks,Matt
Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
I did H/C and underdrive pulley at the same time. I have a 165 degree stat. Before the change my temps would be about 180 at highway cruise (below 2000 rpms). Now they are about 190-195. It has to be the slower circulation. When I keep the revs above 2000 rpm my temp drops back to 180. A third gear pull today started at 195 and when I let off I saw that it was down to 183. With stock pulley and stat it was always just below 200. I think it must be normal. I'll see what the summer time brings.
When I would do a WO blast it would cool down to 178° to 180°.But after I would pull into my shop and let it idle it would creep up to 194°and then creep back down to 187°idling.Guess I will see what happens when it warms up and can use the ac!
