Questions about underdrive pulley systems
Thread Starter
Racer
Joined: Sep 2002
Posts: 357
Likes: 0
From: Sayville New York
Questions about underdrive pulley systems
I was considering getting an under drive pulley set for my 81. I have a few questions about them though.
1- Ecklers sells a kit that comes with an underdrive crankshaft pulley, if I just get that will I have charging problems and over heating problems because my water pump and alternator won't be turning as much.
2- will it actually make an improvment in power?
3- They also sell a kit that comes with the underdrive pulley and the other pulles so they will turn the other accessories at there regular speed. Isn't that defeating the purpose.
4- Is any one running this set up and if so do you just have the underdrive pulley of the hole set?
5- any opinions on what I shpuld do go for the hole set or just the single pulley?
thanks for any help you guys could give me.
1- Ecklers sells a kit that comes with an underdrive crankshaft pulley, if I just get that will I have charging problems and over heating problems because my water pump and alternator won't be turning as much.
2- will it actually make an improvment in power?
3- They also sell a kit that comes with the underdrive pulley and the other pulles so they will turn the other accessories at there regular speed. Isn't that defeating the purpose.
4- Is any one running this set up and if so do you just have the underdrive pulley of the hole set?
5- any opinions on what I shpuld do go for the hole set or just the single pulley?
thanks for any help you guys could give me.
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
Re: Questions about underdrive pulley systems (jaybird81)
This is just my opinion.
If you have a special application (like your car is primarily used for drag racing), then a underdrive system might be of a small value in saving power.
The stock accessory drive system was optimized for best performance on the street and for typical everyday operation. All of the accessories, (i.e. power steering pump, alternator, AC compressor, water pump, etc) were evaluated and released for production to provide the best overall performance with the belt and pulley ratios that came with the car.
For instance, the following could occur if you change the pulley ratio and you drive the power steering pump at a much slower speed than normal. With the engine at idle, if you try to rapidly rotate your steering wheel, you might experience an abrupt lack of power assist because the power steering pump is not providing sufficient flow at slower pump rpms.
If you have a special application (like your car is primarily used for drag racing), then a underdrive system might be of a small value in saving power.
The stock accessory drive system was optimized for best performance on the street and for typical everyday operation. All of the accessories, (i.e. power steering pump, alternator, AC compressor, water pump, etc) were evaluated and released for production to provide the best overall performance with the belt and pulley ratios that came with the car.
For instance, the following could occur if you change the pulley ratio and you drive the power steering pump at a much slower speed than normal. With the engine at idle, if you try to rapidly rotate your steering wheel, you might experience an abrupt lack of power assist because the power steering pump is not providing sufficient flow at slower pump rpms.
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Questions about underdrive pulley systems (jaybird81)
I have the March underdrive pulley system on my car. When I got my engine rebuilt the original pulleys were almost touching so I pretty much had to. I have had no charging, cooling or power steering issues. But I don't think there was much if any horsepower gain. But since they are polished they do look cool.
Melting Slicks
Joined: Aug 2003
Posts: 3,416
Likes: 291
From: dayton oh
Re: Questions about underdrive pulley systems (jaybird81)
:iagree:
I've got the March setup too. The only side-effects I've noticed is the battery warning light coming on at idle while at a light (slower spinning Alt) and the engine running hotter while at above mentioned stoplight (slower spinning H2O pump). Since my Alt and pump were original, I had no qualms about replacing them with hi perf stuff to compensate--cheap insurrance IMHO. Other than those 2 annoyances, you'll notice a quicker rev and less engine load when turning on headlights, using AC, or firing up a killer sound system.
I've got the March setup too. The only side-effects I've noticed is the battery warning light coming on at idle while at a light (slower spinning Alt) and the engine running hotter while at above mentioned stoplight (slower spinning H2O pump). Since my Alt and pump were original, I had no qualms about replacing them with hi perf stuff to compensate--cheap insurrance IMHO. Other than those 2 annoyances, you'll notice a quicker rev and less engine load when turning on headlights, using AC, or firing up a killer sound system.
