A/C Delete and Underdrive Pulleys

I was planning on doing these both at the same time, I know if I put the underdrive pulleys on I need to get a new belt for my serpentine set up. Now if I get rid of the A/C compressor is it necessary to have the A/C delete pulley? Since I need to get a new belt anyways is it necessary that I run the A/C delete pulley?

Thanks
Jason

 

Let us all know how the underdrives work out for you, and how many times you need a jump start this winter.

Incidentally, don't expect a lot of gains, since the electrical load of the alternator will actually increase with the underdrives (due to alternator efficiency losses at low RPM). You'd probably gain a lot more by changing to an electric water pump drive and leaving the rest alone. The AC sheave is nothing more than an idler unless the AC compressor is turned on, and the parasitic load from the idler is so insignificant with a poly-V belt that it isn't even worth calculating. Check with your local industrial power transmission suppliers on the load and loss calculations, like Bearing HeadQuarters/Headco in the Chicago area. You'll be enlightened, for sure.

I don't mean to be completely negative, but check out some direct dyno comparisons with street underdrives versus stock steel sheaves. I'll bet March won't let you see what THEY tested. I just hate to see people waste their efforts when there are far better ways to gain performance for the same cost.

 

So basically I will be wasting my time and money? I won't see the 10 horses that they claim and the pulleys will just wind up giving me a charging system problem?

What if I just put the crankshaft pulley on and not the alternator one? Would this do anything and not disrupt my charging system?

 

i would do what Vader said and leave em alone

 

Greek,

That quoted 10 HP is probably like all the other advertised gains from most other aftermarketers. It's a best-case scenario, derived from a test engine where everything else is prepared and modified to take the best advantage of the advertised modification. Like the 5-8HP gains advertised by the sellers of intake airfoils, few if any of us ever realize that gain.

For a true 10+ HP gain as confirmed by independent dyno results, change to synthetic lubricant in your engine. For another free 6-8HP, change the transmission and differential as well. SLP had a SBC 350 dyno test posted on their site showing the gains simply by changing to synthetics. They picked up 17HP by changing from NEW "premium" mineral oil to synthetics through the engine and driveline. They don't sell synthetics, so they had nothing to gain but knowledge through the testing.

 

WOW vader thanks for the information. I'll go see if I can find that test. I probably won't see 17 HP but I've been thinking of changing to synthetics anyway.

Bill

 

I got mine tested on a dyno after putting in the March Crank pulley only, I found that I was making a good 10 more ft/lb of torque at peak. HP on the other hand doesn't change much, that's really dependant on how well the the torque curve stays flat.

My only complaint is the alternator pulley is crap. You have dangerously low charging capability with that. With my stock alternator pulley, its fine until I toss on the a/c max and lights and idle, but even then its running a tad above 12 V.

A lot of others I know run the pulleys and we all happen to be making higher than stock torque flywheel numbers AT the rear wheels. With drivetrain loss a dyno usually shows lower than stock torque numbers at the rear wheels.

Try it out and see if you like it, return if not satisfied.

Things to note, I'm running warmer than prior to putting them in, doesn't matter to me, I have my own fan swtich in the car. I usually keep the car running at about my stat, 180. The charging issue was solved by popping in the old alternator pulley. A/C is not as effective at idle, so I leave it in neutral when I'm at stop, 750 rpm in neutral/park, 500 in drive.

 

AC Delete Pulley is #10055890
$36.74 at gmpartsdirect.com.
-Rich-

 

Back from the dead! Anyway, back to a question posted above, what if...only the crank pulley were used and the alternator pulley was not used? I should contact March to see what they "say" too but i was just wondering if anyone could tell me some consequences to this. Also, if i were to change the alternator pulley, how the hell would i get the old one off? It is killing me. The alternator is off of the car by the way. We tried an air gun with no luck. Any tips? thanks for any help guys

 

here is something that people aren't mentioning buy removing conponent pulleys from you engine (ie alt, water pump, and so on) you help in the the power loss called Parasitic power loss. this is the loss of power from the turning of conponents or going through things. ie the power goes from the engine through the trans. then through the driveshaft then throught he rear end and ending up at the tires. also the engine losses power through all the stuff you have for up front (a/c, alt, power steering, water pump, and son on.) now buy using the under drive kits you can gain some power maybe not 10 hp but some. now march makes two different kits. the one everyone is talking about is the Performance Series. now they also make the Power and Amp Series (Recommended for Automatic Transmission Vehicles). i took these names from there webpage word for word. now this package still gives you your power witht the added performance gains but not as much as the performance system. hope this helps some. My 2 cents

Nick

 

I got the same dyno results as Slade1 (about 10-15 RWTQ, nothing noticable for RWHP). Torque is what counts anyway so I think it is a good mod for the price. I didn't change the alternator pulley. I only changed the crank pulley. If you change the alternator pulley, I have heard your alternator has a hard time keeping up. I would change the crank pulley and stop there. It is worth it.

 

Thanks for responding guys. So, there were no ill effects from just changing the crank pulley jfreeman? Anyone else wana chime in? Thanks again for your time fellas. later

 

i would go with the under drive pulleys, in GM high tech performance magizine (july 2003) they said this concerning the jet performance under drive pulleys " The majority of personnel on hand were not expecting much, myself included, but JET saidthe pulleyss were worth 10-30 horsepowere depending on the application. When the first pull was finished, the SupereFlow showed 236.9 horsepowere and 303.8 lb.-ft. of torque. Yes that's at the rear wheels and yes that is a gain of about 17 horsepower and 13 lb.- ft. of torque." so you decide.

 

I had no problem from only replacing the crank pulley. The alternator pulley is a little larger than the stock pulley. This causes the alternator to turn less which causes the charging problems that you hear people talking about.