March pulleys

jajwrigh · Post by **jajwrigh** » Mon Aug 08, 2005 8:18 pm

How difficult are the pulleys to install? Do the gains seem worth the time?

coffeedrnkr · Post by **coffeedrnkr** » Mon Aug 08, 2005 10:19 pm

http://forum.zr2.com/ubb/noncgi/ultimat ... 004186;p=1

this thread on zr2.com tells a lot about them, if you do a search you can find a lot of info on them too.

I have been seriously thinking about getting them but I never got around to it.

quickbiker · Post by **quickbiker** » Tue Aug 09, 2005 9:45 am

You talk'n bout underdrive pullies? I knew someone had them in a Mustang and it had trouble charging the battery unless you race all the time. lol

jeggers · Post by **jeggers** » Tue Aug 09, 2005 10:40 am

how much power?

top_sgt · Post by **top_sgt** » Wed Aug 10, 2005 5:25 am

another mod to think about!!!!!

bwenny247 · Post by **bwenny247** » Wed Aug 10, 2005 4:02 pm

i have them

you get a smaller crank shaft pulley and alternator pulley to eliminate the charging issues. you will of course need a new belt because the loop becomes smaller.

as far as installation goes the crank pulley we had a hard time with because of the radiator and clutch fan in the way. but, for all intensive purposes, it's a belt off, un-bolt/bolt on, belt on installation.

as for power, it's hard to say....i did all my upgrades at once (K&N FIPK, Throttle Body Spacer, Hypertech, Exhaust) all combined i'm positive i've made power. I can break my 33's loose with the 3.42 gears on dry pavement

and still manage 17+ MPG on the Highway/Freeway

Ben

jeggers · Post by **jeggers** » Wed Aug 10, 2005 7:11 pm

bwenny247 wrote:as for power, it's hard to say....i did all my upgrades at once (K&N FIPK, Throttle Body Spacer, Hypertech, Exhaust) all combined i'm positive i've made power. I can break my 33's loose with the 3.42 gears on dry pavement and still manage 17+ MPG on the Highway/Freeway

dude that is sweet i cant break my 32"'s with 373s. i need some more mods

Post by **Walt** » Thu Aug 11, 2005 7:05 am

I couldn't break my stock tires loose on dry pavement, now my 31's are certainly no exception

bwenny247 · Post by **bwenny247** » Thu Aug 11, 2005 2:03 pm

dude that is sweet i cant break my 32"'s with 373s

jeggers i think that's because of the limited slip incorporated with the 3.73 gears....i think, somebody double check me.

Steve2003 · Post by **Steve2003** » Thu Aug 11, 2005 5:19 pm

bwenny247 wrote:
dude that is sweet i cant break my 32"'s with 373s
jeggers i think that's because of the limited slip incorporated with the 3.73 gears....i think, somebody double check me.

Joe according to my RPO codes I have the G80 lockers which I believe is the limited slip. I can bark my tires also. Maybe you should try the HPPIII and a good exhaust set up. I have the flowmaster deltaflow with the 2 1/2 inch custom pipes. Just a thought

Steve

jeggers · Post by **jeggers** » Thu Aug 11, 2005 6:16 pm

Steve i dont have a muffler may be i need some more back pressure.

Post by **Walt** » Sat Aug 27, 2005 11:12 am

Ok, on Zr2.com, they say that the correct belt size needed is actually 91.5" 6 groove. Is this correct?

Post by **HenryJ** » Sat Aug 27, 2005 2:26 pm

I just want to offer some advise , or words of caution in regards to pulleys.

Don't assume that the March pulleys will be steel. Most of them are aluminum. Aluminum oxidizes more readily. Belts can tend to slip, and in a dirty environment they wear out fast.

When building Streetrods I always substitute the crank pulley in a show quality aluminum set for steel. The crank drives everything else and really needs to hold well.

Next thing is the alternator pulley. Our stock 54mm pulley is borderline for providing enough rpm at idle to keep things charging. make darn sure you can spin it fast enough after slowing everything else down.
This could pose a problem should you decide to get a higher amp alternator as the smallest pulley available is 49mm.

Just words of caution. Personally if you are wanting the horsepower and throttle response from a mod like this, you really need to go to an electric fan first. Ditching the clutch fan will help way more than the underdrive pulleys , IMO.
I have not used them though, so I may be way out of line here.

Post by **Walt** » Sat Aug 27, 2005 8:26 pm

HenryJ wrote:I just want to offer some advise , or words of caution in regards to pulleys.

Don't assume that the March pulleys will be steel. Most of them are aluminum. Aluminum oxidizes more readily. Belts can tend to slip, and in a dirty environment they wear out fast.

When building Streetrods I always substitute the crank pulley in a show quality aluminum set for steel. The crank drives everything else and really needs to hold well.

The set I bought are steel

HenryJ wrote:Next thing is the alternator pulley. Our stock 54mm pulley is borderline for providing enough rpm at idle to keep things charging. make darn sure you can spin it fast enough after slowing everything else down.
This could pose a problem should you decide to get a higher amp alternator as the smallest pulley available is 49mm.

Ok, this is where I'm confused.... March advertises that the alternator is driven exactly the same as standard pulleys, it's just the other stuff that is underdriven, so why would the truck not be able to spin the alternator fast enough if the overall gear/belt ratio for the alternator remains the same?

Don't look at me like I'm stupid

I have probably just missed something in your post....

HenryJ wrote:Just words of caution. Personally if you are wanting the horsepower and throttle response from a mod like this, you really need to go to an electric fan first. Ditching the clutch fan will help way more than the underdrive pulleys , IMO.
I have not used them though, so I may be way out of line here.

I have everything here, and will do the install on Monday at work, if Katrina doesn't blow us all away

Post by **HenryJ** » Sat Aug 27, 2005 9:57 pm

wamason wrote:Ok, this is where I'm confused.... March advertises that the alternator is driven exactly the same as standard pulleys, it's just the other stuff that is underdriven, so why would the truck not be able to spin the alternator fast enough if the overall gear/belt ratio for the alternator remains the same?

From the testing that I have done on the "bigger alternator" , the stock ratio is borderline. Slightly faster is much better. In order to run the alternator at the same speed with a smaller crank pulley they have supplied you with a smaller alternator pulley in an attempt to maintain the same ratio.
The problem lies in that 49mm is as small as you can get, or I could find that would still work.
If this set includes that pulley you have no option to go faster if needed. The CS144 conversion does require a 2mm smaller pulley to allow it to produce 110 amps at idle speed.

Don't feel that I am saying this is not workable, only that it may have other consequences.

Sounds like you have the bases covered, let us all know how it works for you. Give it a few weeks for the "new mod" to wear off though

jeggers · Post by **jeggers** » Sun Aug 28, 2005 8:04 am

good luck

killian96ss · Post by **killian96ss** » Mon Aug 29, 2005 9:36 am

If you are getting a smaller crank pulley and a smaller alternator pulley then your only hp increase is coming from slowing down your power steering pump and your water pump which doesn't amount to much. You will be decreasing your cooling efficiency and possibly your steering assist, although I think it should be ok. If I were seriously going to do this mod I would get a higher flow water pump, maybe even aluminum if they make them, and a dual fan set up like HenryJ has. I have been wondering lately if our water pumps are interchangable with the Vortec V-8's like the older V-6 & V-8's were?

My stock fan comes on all the time in weather above 90*, and if I slowed down my cooling system any more I would surely have a melt down.

Steve