Underdrive Pulleys
Thread Starter
Drifting
Joined: Aug 2000
Posts: 1,614
Likes: 0
From: Colleyville Texas
Underdrive Pulleys
Know underdrive pulleys have created alot of discussion over the years. Went ahead and put the two piece ASP pulleys for the 93-96 LT1 on my 396. The new ASP balancer was 4LBS-5 ounces less than the factory one.
Thanks to Nathan Plemons for the AC Delco belt number that fits right.
The Gates belts on the ASP site would not have worked.
Driving home from the shop today the car seems to idle alittle higher now? Plan to race this weekend with the new pulleys as the Texas Muscle Car drag racing season starts. Also plan on doing a dyno.
Thanks to Nathan Plemons for the AC Delco belt number that fits right.
The Gates belts on the ASP site would not have worked.
Driving home from the shop today the car seems to idle alittle higher now? Plan to race this weekend with the new pulleys as the Texas Muscle Car drag racing season starts. Also plan on doing a dyno.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Glad the belt worked for ya. I don't know why their recommended one isn't correct.
Be sure to keep us posted.
The idle should be the same. Only thing I can figure is if the IAC is stuck and can't close as far as it needs to?
Be sure to keep us posted.
The idle should be the same. Only thing I can figure is if the IAC is stuck and can't close as far as it needs to?
Intermediate
Joined: Sep 2010
Posts: 40
Likes: 0
From: Goodyear Arizona
I've been thinking about doing this mod, i've tried looking up parts but always come up the same....with nothing. can someone point me in the right direction? I've even tried the brand mentioned above.
Team Owner
Joined: Sep 2003
Posts: 20,172
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
I for one am very glad that Nathan is back. His knowledge and friendliness are an asset to the C4 CF.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Thanks for the kind words. According to one or two on here I'm simply ignorant and combative. Apparently it offends these people to answer questions that an original poster asks instead of making fun of them.
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Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Mine came with steel under drive pulleys do not know who made them other than at night with ac and headlights voltmeter goes painfully low a tiny bit of rpm and all reads right. Personally i consider it a very unfriendly mod for very little gain.
Dave
Dave
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
May not be the best thing in the world for a strictly street car but if you're trying to get everything you can out of your engine it's worthwhile. 10-15 RWHP and .1 in the quarter mile is significant to a drag racer.
Race Director
Joined: Jun 2004
Posts: 13,939
Likes: 705
From: WI
I was all gungho about under drive pulleys years back but now not so much. Glad I had them for saving the power steering pump on the track, didn't like that they slowed the water pump. Check alternator max speed too. Some speed it up and if you run high RPM the alt revs can get to high. Other kits leave it to low for decent charging.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
I did run exclusively Chevron for a year back in the day to see if it made any difference in MPG.
The ASP kit actually slows the alternator down, hence the possible charging problems at idle. Since the LT1 isn't a belt driven water pump you don't have to worry about that. Personally I love the set. Yes the power drops low at idle but it hasn't caused me any trouble. I tend to spend more time moving than I do idling.
Now if I drove it every day in gridlock it might be a different story.
The ASP kit actually slows the alternator down, hence the possible charging problems at idle. Since the LT1 isn't a belt driven water pump you don't have to worry about that. Personally I love the set. Yes the power drops low at idle but it hasn't caused me any trouble. I tend to spend more time moving than I do idling.
Now if I drove it every day in gridlock it might be a different story.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Hi Nathan we have never met and from following things in the last few posts you are a legend here is that transferable? LOL.. condesation is common and mods only work for specific applications different horses for different courses. 15 rwp for 10% under drive even 25% is substancial. If 25 % underdrive you are suggesting it take 25% of the load off that means if a 10 hp rwp gain 100% of the load is 40 hp and if 15 rwp a 60 hp one. total does that really pass the smell test for you and the belt used to drive the load. even more when you hear the commonly quoted 15 to 20% loss from flywheel the rear wheel hp. That would mean the belt has to handle 50 to 70 hp from accessories.. a bit unbelieveable for me. It is good to know my L98 is actually 320 hp at the fly wheel or wonder if depressing it is less that the 200 hp v6 in my gran prix...
I think YMMV is the byword here..
Dave
I think YMMV is the byword here..
Dave
Thread Starter
Drifting
Joined: Aug 2000
Posts: 1,614
Likes: 0
From: Colleyville Texas
PM'd the serious drag racers on this forum before adding the pulley's. Most agree .1-1mph was realized. Bought the Pulley's direct from ASP racing in Conroe, TX for $185.00. An idle of 950-1000 RPM's on my 396 should minimize the underdrive.
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
i got a three-piece March kit , i love them ! Power and Amp series
Alternator works just fine !
http://www.summitracing.com/parts/MCH-4445/
Alternator works just fine !
http://www.summitracing.com/parts/MCH-4445/
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Not only is it lighter, the smaller diameter means that the weight is concentrated more towards the center. This would make it easier to turn even if it wasn't driving any accessories. Rotational inertia is fun.