9" crank pulley in progress.

entirelyturbo · Post by **entirelyturbo** » Thu Jul 06, 2006 3:02 am

Smaller pullies on the supercharger make higher boost

.

He's pretty much doing the same thing, just the other way around.

Murphy · Post by **Murphy** » Thu Jul 06, 2006 3:35 am

yeah smaller s/c pulley or bigger crank pulley

its all the same ...sorta

douglas vincent · Post by **douglas vincent** » Thu Jul 06, 2006 3:56 am

I am using a SC with an electric clutch, therefore cannot change the SC pulley.

The other way to do it is use a stepper pulley, but I tried that and it didnt work so hot.

bmxpunk · Post by **bmxpunk** » Thu Jul 06, 2006 4:03 am

THat would be a smaller pulley on the super charger itself. it has the same effect as using a larger crank pulley.

THink of it like a mountain bike doug's pulley is the front sprocket. On a mountain bike their are 3 sprokets. the difference between the three is very dramatic. Going to a smaller pulley on the superchager itself would do something similar, just not as drastic.

so for every 1 time dougs crank goes around, his SC is going around alot(!) more

Brat4by4 · Post by **Brat4by4** » Thu Jul 06, 2006 2:07 pm

azn2nr wrote:um quick question.

why is it that some people seem to say that smaller pullies are better for superchargers (more boost) yet yours is hooooogggggeee

Ummm... remember your bicycle. If you want the rear wheel to go faster you switch to a smaller gear (pulley) at the rear wheel to make it go faster or a bigger gear (pulley) at the crank.

sammydafish · Post by **sammydafish** » Thu Jul 06, 2006 3:13 pm

OK... so the last 5 posts responded to azn2nr 's post and said the exact same thing... why the hell would you litter a thread like that....... post whores!

anyway, Doug, you get that thing bolted on yet?

bmxpunk · Post by **bmxpunk** » Thu Jul 06, 2006 5:27 pm

apparently we were all posting at the same time, casue i posted right after his went up. man we are good at this!!!

IronMonkeyL255 · Post by **IronMonkeyL255** » Thu Jul 06, 2006 9:26 pm

Get that thing bolted on already! I wanna see some pics and see if it blows something up!

douglas vincent · Post by **douglas vincent** » Fri Jul 07, 2006 2:48 am

ITS HERE!!!!!!!!!!

9 inches Baby!!!! Weighs less than stock even.

Project_Legacy · Post by **Project_Legacy** » Fri Jul 07, 2006 6:23 am

SWEET~! lets see what this thing can do!

douglas vincent · Post by **douglas vincent** » Fri Jul 07, 2006 8:25 am

I am holding it in my lap and just admiring it right now. Its a piece of freaking art!

The pulley started as an EBAY donor underdrive pulley and a 1" thick piece of 12"x12" square aluminium stock from McMaster Carr. The outer ribs of the donor pulley were turned off. The block was turned round and an opening was turned into it.

Then the donor pulley was frozen and the outer section heated and then they were press fit together. Once they came back to room temperature, they were not going anywhere! To top it off, the machinist then put 4 pins in the ring section to tie them together 100%. He also turned it down to about 5.5 pounds, although I have yet to weigh it, although it weighs less than whatever the stock 5.25" stock pulley weighs.

I may lighten it a tad more, by installing it in a mill and rotating vice and drilling holes in it. We shall see. Depends upon how much free time I have tomorrow.

douglas vincent · Post by **douglas vincent** » Fri Jul 07, 2006 10:53 pm

Installed and running!

8 psi at 2000 rpm, 10 by 3000 rpm and 14-15 max!

Ways more than I expected. I hoped for 11 psi, up from 8-9. I would have been pleasantly surprised with 12. 14? YESSSSS.

BANG!

IronMonkeyL255 · Post by **IronMonkeyL255** » Fri Jul 07, 2006 11:40 pm

Holy crap that looks nice.

5.5 lbs? I think that's a little more than stock, at least my stock pulley was ~4.5 lbs.

jnorion · Post by **jnorion** » Sat Jul 08, 2006 4:17 am

Must be fun to drive at 14psi. Now I REALLY need to come check it out.

Subtle · Post by **Subtle** » Sat Jul 08, 2006 6:00 am

As you may have checked out, the more the weight in the rim the higher the inertia when trying to spin the wheel up.

jnorion · Post by **jnorion** » Sat Jul 08, 2006 6:03 am

Do you have to buy a new belt every time you change the pulley around or does the tensioner move that far?

sammydafish · Post by **sammydafish** » Sat Jul 08, 2006 10:58 pm

wow... so how much faster is it? Getting any detonation at that boost level? That works out pretty well as that's about the max boost you can run on a modified roots type compressor (the get stupid inefficient after PRs over 2)

douglas vincent · Post by **douglas vincent** » Sun Jul 09, 2006 2:38 am

I bet I will be close to 13.99 on boost alone finally. Barely. The extra boost is good for maybe 25-35 whp (7 whp per psi, 14 psi * 7 = 98 whp plus stock 100 whp = 198 whp estimated, 10 bhp per psi, 14 psi x 10 = 140 plus 130 = 270 bhp). I did a "Fremont Run" test last night and wow! 4th gear felt like nitrous.

I AM GETTING detonation, just in 5th, but because I finally out of the stock ECU AF ratios. Currently, I have to simply blow in raw fuel with a solenoid and nitrous fogger to be safe. Very very ghetto but it works. I will be "fine tuning" it so it works slighly better until I get those damn 430 cc injectors reinstalled again.

Using the same belt. relocated the tensioner.

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

9" crank pulley in progress.