m62 pulley sizes
well logic goes the smaller the pulley, the faster the supercharger spins. but the faster it spins, the less effecient it becomes by creating heat. knowing what pulley size you have and supporting mods you have could help a lot in determining where to go. i wanna know what you've done to reach this 270 hp on your 2.2 
Facts-
in a perfect world, 5 to 7 horsepower can be gained for every tenth decrease in pulley size.
however with the heatsoak factor, the curve is definitely not linear.
The m62 has a 3.35" pulley from the factory.
every tenth off your pulley size is roughly one psi increase
Personal Experiences-
Since the J body supercharger kit did not come with any cooling mods, you might be best off adding a methanol injection kit to drop those iat2 temps before you add any boost.
On the s/c'd j-body ecotec with no other mods the IAT2 reached temperatures upwards of 180 degrees. 160 was achieved with the addition of a small water to air heat exchanger.
in a perfect world, 5 to 7 horsepower can be gained for every tenth decrease in pulley size.
however with the heatsoak factor, the curve is definitely not linear.
The m62 has a 3.35" pulley from the factory.
every tenth off your pulley size is roughly one psi increase
Personal Experiences-
Since the J body supercharger kit did not come with any cooling mods, you might be best off adding a methanol injection kit to drop those iat2 temps before you add any boost.
On the s/c'd j-body ecotec with no other mods the IAT2 reached temperatures upwards of 180 degrees. 160 was achieved with the addition of a small water to air heat exchanger.
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From: O Fallon, MO
The hp and tq gains change in a non-linear fashion due to the fact that the m62 begins to lose efficiency after 12000 RPM due to heat and parasitic loss. Typically when going smaller than the stock pulley you can gain about 2.5hp/4tq per mm smaller as long as you can compensate for heat. Depending on what your RPM limiter is set to you don't want to overspin the blower either. At 7000 RPM I wouldn't go smaller than 69mm. At 6500 RPM I wouldn't go smaller than 64mm (as a side note - if you go smaller than 66mm you will need to machine the supercharger snout.
If you gave a little more information about what car and what was done we might be able to help a little more.
Thread Starter
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Joined: 03-10-09
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From: uk
thats my vx220
my list off mods are:
current mods
turbo spoiler
turbo side vents
turbo splitters
TAT long diffuser
fog lights converted to air brake cooling pipes
16/17 speedlines with r888 tyres
GAZ adjustable shocks
fast road GEO
engine mount poly-whatever inserts
mintex 1144 (soon to be 1155)
full 2.5" piper exhaust system with 200 cell cat and 4-1 manifold
ported head
+1mm wasted stem valves
piper cams (266)
m62 supercharger
75mm intake pipe with a KnN cone
courtenay sport custom remap
let injectors
Full aluminum radiator
full size aluminum charge cooler rad with twin fans
much bigger header tank for charge cooler rad
bosch water pump (for pre rad)
gearbox breather with air filter
oil catch tank with air filter
EGR cheater
near future mods
duel pass mod
eagle rods
wiseco pistons
balance deletion
lightened flywheel
4pot front brakes
harness bar
mog seats or similar
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Joined: 08-29-07
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From: "Central", PA
oh thank god it's a vauxhall. I thought this was another gay newbie thread....lol.
I think "Bika" 's response (post #6) was probably best. There are too many variables when dropping pulley sizes to really say what you'll gain.
For instance, when I dropped pulley's from a 2.9 to a 2.8, I had to change injectors to remedy my IDC's, I also went to step colder plug, and a heat exchanger because I knew my IAT2's were gonna go way up.
That said, I gained 15 horspower (and probably more cuz she was pulling timing on the dyno due to my water pump being off, causing my IAT2'S to sky rocket). But it's hard to say whether it was the lower temps made possible by the heat exchanger, which allowed me to run more timing, or if it was the injectors, or the pulley that allowed me to have the tune that I have and gain that much with "just a pulley change". so, calculating the size to hp change is hard.
I think "Bika" 's response (post #6) was probably best. There are too many variables when dropping pulley sizes to really say what you'll gain.
For instance, when I dropped pulley's from a 2.9 to a 2.8, I had to change injectors to remedy my IDC's, I also went to step colder plug, and a heat exchanger because I knew my IAT2's were gonna go way up.
That said, I gained 15 horspower (and probably more cuz she was pulling timing on the dyno due to my water pump being off, causing my IAT2'S to sky rocket). But it's hard to say whether it was the lower temps made possible by the heat exchanger, which allowed me to run more timing, or if it was the injectors, or the pulley that allowed me to have the tune that I have and gain that much with "just a pulley change". so, calculating the size to hp change is hard.
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From: "Central", PA
hatrickstu is running mid 12's with a 2.85.........don't have a clue how he does it, but he does.
I'd say with you car, running 12's will be no problem with a 2.8.
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i have a 2.8 and love it will hit 12s once i get my meth and intake and retune with good traction and the stumod. i beleive i 2.8 will be nice for your car. maybe with the dual pass and meth
Make sure you cool the thing off though. It is very hot at that point. You will need cooling and an awesome tune.
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From: uk
cooling is no problem as i have a full size charge cooler radiator, with twin fans. a large 1.5l header tank, duel pass mod is getting done very soon. thanks alot for all your help and compliments
@ Joe,
Most people here are used on WHP, and I know that your 270.13BHP was measured at the flywheel. (Before people get crazy about your 2,2 numbers.
)
You still run the stock pulley right? I think you should not go too small on the M62, otherwise you might get too inefficient at higher revs. From stock to a 3" pulley should be a nice upgrade. 2.8 will give you a lot of torque, but maybe loose too much top end in the VX
(You already had a dual pass chargecooler, right? You need cooling mods to cool down the hot air.)
Most people here are used on WHP, and I know that your 270.13BHP was measured at the flywheel. (Before people get crazy about your 2,2 numbers.
)You still run the stock pulley right? I think you should not go too small on the M62, otherwise you might get too inefficient at higher revs. From stock to a 3" pulley should be a nice upgrade. 2.8 will give you a lot of torque, but maybe loose too much top end in the VX
(You already had a dual pass chargecooler, right? You need cooling mods to cool down the hot air.)
Thread Starter
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From: uk
yeah at the flywheel, sorry dont tend to measure at the wheels other here!
im going to have to measure the pulley! as im doing a engine rebuild very soon to put the rods and pistons etc in so will measure it then
im going to have to measure the pulley! as im doing a engine rebuild very soon to put the rods and pistons etc in so will measure it then
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From: O Fallon, MO
Yeah, once you know what size pulley is already on there it will help to figure out how much smaller you can go and if you go smaller if you will need bigger injectors or anything like that.
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From: uk
you are all saying cool it down but surely a full size charge cooler rad (same size as my original radiator) with twin fans for extra cooling down with a remote so i can turn them on when i want. also with a 1.5ltre header tank aswell as all the water from front to rear of the car and a duel pass mod is surely going to be more than enough cooling for a smaller pulley? dont you think?
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From: st.louis
Wow get off the 2.8 pulley bid here people, a 2.7 is totally possible with a blower port and cooling mods and will run totally fine, on a stock M62 the limits are pushed, but get a port and rebuild then it will change your mind when you feel how cool the blower is compared to a stock M62. Joe your setup is totally fine, if anyone on here sees something work they swing from that persons nuts for awhile thinking they will have the same results(2.8 pulley since Hatrickstu runs 12's with one). With your built motor i would go 2.7 pulley and add some Meth and your car will be good to go!