Just wondering what you guys think of underdrive pulleys, what are the best for the money, and where is the best place to buy them?

------------------
1990 Iroc convertible,305 tpi,Black with black leather interior,lowered

 

I got my moroso 4" dia crank pulley from summit ($35), though you can find them at swap meets. I got my 7.5" waterpump pulley from the junkyard (cutlass cruiser wagon), and my alternator pulley from a junkyard ($2 each). Then I got a short V-belt from Auto-Zone for $4

and yes it was very worth the money adding about 25hp to the rear wheels.

------------------
*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305/383 with Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, 3.25:1 rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, .462/.470 lift @1.5:1 ratio. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch.
N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99

[This message has been edited by The ODB (edited February 05, 2001).]

 

25 RWHP?!?!!?!? Who told you that?? March claims "up to 11". Are these Dyno results?? Man..if I can get 25 RWHP I buying pulleys today! Pulleys are good if you have a good charging and cool system..if they are flakey then you should hold off on pulleys.

------------------

• Red '88 IROC 5 Speed 305 TPI w/3:08
• Dual Friction Centerforce Clutch
• Accel 300+ Racing Ignition
• Accel 300+ Pro Sleeve Plug Wires
• Accel U-Groove Plugs
• Flowmaster Force II 3 Chamber Cat Back Exhaust
• Hypertech Chip
• Hypertech Airfoil
• Removed, Then Re-installed (out of fear) MAF Screens
• Gutted Air Box
• Best E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 MPH 93.91
• Best 60' 2.17

 

LOL ODB!!! 25RWHP!!! Not saying you didn't get that many horsies from your pullies, but coming from a guy who doesn't think his drivetrain constitutes much of a horsepower loss during acceleration that's pretty damn funny!

 

I'm just telling you the results I got. I only run a waterpump and alternator as accessories.
My power figure comes from an equation (hp is always based on an equation) that I use given vehicle race-weight and 1/4 mile trap speed. My car shows a trapspeed difference of 2.46 MPH which under the same air density conditions equals aprox 25 horsepower.

I told you exactly how I did it, so take it or leave it.

good luck

 

ODB:

What diameter alternator pulley did you use.. did you just search for one of that size off of any GM vehicle? I was gonna go to the junkyard pretty soon, and while im at it i might as well pick up a "underdrive" alternator pulley..

How did you get the pulley off of the alternator? Impact is usually the only way to do it... or did you get one that was already pulled by the yard?

I don't think i'll do it.. but what size water pump pulley did you use?

I am assuming you can't get an underdrive crank pulley from the junkyard...?

Thanks.. feel free to email me if you like.

ahartoun@ucsd.edu

 

Everyone I know that used underdrive pulleys on their cars (F-bodies, Mustangs, etc.) has had charging problems. My buddy's Firebird died at every red light.

 

89gta,
I thought I stated the crank pulley is a 4" Moroso. The waterpump pulley is 7.5" junkyard-technologies, and the alternator pulley is the smallest I could find in an alternator rebuild shop 1.3" and was basically given to me, though I have found others in the junkyard like it.
Impact is the best way to get the pulley off, or just walk into a rebuild shop and pick up a loose one. If you don't have an impact then Auto-Zone would probably do it for you.
Oh and in case you didn't pick up on this my alternator pulley is smaller than stock so it charges just fine. I use an alternator cutout switch at full throttle so there is very little drag.

It doesn't matter at all what vehicle the things come from. If they don't fit then make them fit... drill holes or whatever, and if that doesn't work toss it and try another. I have both patterns drilled into my waterpump pulleys so I can use them on different styles of waterpumps.
good luck

 

I'm about to install a Bose system with an aftermarket amp, and 4 stock Bose amps. If i get pullies, will my alternator take a dump?

------------------
-80 Camaro 350, Carter AFB, headers, dual exh, ram air, all sorts of crap
-88 Iroc-Z 350tpi, 3.27 gears, 4 wheel disc, MSD 6a, tpi airfoil, k+n's, white gauges, accel coil, flowmaster, pretty quick

 

THERE IS NO WAY THAT YOU SAW 25 H.P. GAINS. THERE ARE TOO MANY VARIABLES TO CALCULATE HP GAINS THE WAY YOU DO, EVEN W/ THE SAME AIR DENSITY, THERE ARE WAY TOO MANY OTHER VARIABLES. THE ONLY WAY YOU COULD PROVE THAT IS IF YOU DYNOED THE CAR AT THE SAME ENGINE TEMP, ON THE SAME DAY W/ BOTH SETUPS. AND I GUARENTEE YOU'LL ONLY SEE A FEW HP. BESIDES, YOUR MOTOR IS NOWHERE NEAR STOCK, SO EVEN IF YOU SEE A LITTLE MORE HP GAINS THEN EVERYONE ELSE, THESE GUYS W/ 305'S CAN'T EXPECT THAT. I PERSONALLY THINK PULLEYS ARE A WORTHLESS ADDITION FOR PRICE/PERFORMANCE. I DIDN'T GAIN ANYTHING IN THE QTR. W/ THEM, BUT THEN AGAIN, LIKE I SAID BEFORE, THERE ARE SO MANY VARIABLES, THAT MAYBE THEY DID HELP. BUT W/ ALL THE RUNS I'VE DONE, I DOUBT IT. MAYBE A HALF OF A TENTH. ANYWAY, I THINK THEY ONLY HAVE COSMETIC VALUE.

------------------
SUPERCHARGED 87 GTA: Blk/Gld w/Superam, 355cid Trickflows, forged pistons 9.5:1. Auto 2,600 stall, 3.45 9 bolt disc, Best time & mph (Naturally Aspirated): 13.567 @ 101.900 w/ a poor 60ft. Best mph: 104.3 *This car is 100% NYS emissions legal, w/ all emissions controls!* "If you want to have a fast car, hang out w/ those who do!"
http:// www.community.webtv.net/munks87/JustinsGTApage.com
VORTECH S-TRIM, INSTALLATION IN PROGRESS: 10 & 15 LB> PULLEYS, CUSTOM HKS RACE BYPASS, CUSTOM DUCTING W/ COLD AIR, SWAPPING TO SERPENTINE, & MANY EXTRAS! BEST TIME: 11'S I GUESS. WE'LL SEE IN SPRING!

 

ok



------------------
*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305/383 with Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, 3.25:1 rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, .462/.470 lift @1.5:1 ratio. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch.
N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99

 

Justin, they do have some value that varies based upon the accessories you have and their parasitic drag on the engine. For example, most water pumps require anything from 5 to 11hp to spin at higher RPM, so if you can reduce the speed of them by 30% you will gain some flywheel horsepower. Ditto for other engine driven components. It really just depends on your setup and how major of a change you make in pully size.

ODB - Sorry about that remark earlier, but I just couldn't resist .