88mm supercharger pulley
 

Would anyone know where I can find a 88mm stage two pulley for a rotrex supercharger

rotrex.com?

I think gtm pulley is custom from rotrex pulleys ...gtm uses 6 bolt 7 rib .......not sure what would be capatable with it

I think its custom only, the only pulleys rotrex makes are 8 rib. ( could be wrong )

But it shouldn't be much from a machine shop, maybe 1-200 bucks.

Gamma doesn't carry any ?

They do ... $299 for one ... They will be my last resort .... Hoping to find someone with one .... And I got dibs tiller lol

Haha no problem,my car won't even be on the road probably till may,it's -1 here right now,iam already thinking about a built bottom end for an upgrade lol and haven't even tuned my car or even started it,watch the $$$$$ disappear

I wouldn't upgrade bottom end out unless you are having problems with it ....you can get a lot of power still.......but I'm a run it till it blows kinda guy ...gives me a reason to upgrade then ...also not sure how much power you can get with our super chargers ....I would assume we would be to the upper limit with a 88mm pulley ...unless you risk overspinning the charger .....only thing I thnk we can do is supporting mods to maximize the setup ..and maybe get alittle over 500 at best .....and if that is e case ....bottom end should be ok

Oh ya I agree,I won't touch it till it's blown,car only has 7000miles on it,been collecting dust since 09,just once the mods begin it becomes a disease,I think with an 88mm pulley and a good tune we should easily hit 500whp,guys with the old 1.5 kit were hitting just over 500whp,and it's not always the number it's how you get what your making to the pavement.

I can't promise anything right now, my car is torn apart but I have 2 pulleys currently.
One I know is 88mm the other is unknown, need to measure it, I need to decide which pulley I will keep.

[QUOTE=theDreamer;3426451]I can't promise anything right now, my car is torn apart but I have 2 pulleys currently.
One I know is 88mm the other is unknown, need to measure it, I need to decide which pulley I will keep


That would be great Just let me know

Piggybacking on this thread, going from lets say a 92mm to 88mm, would that require a belt change or is there enough for the tensioner to pick up the slack?

From my understanding.... You don't have to change the belt ... And from looking at it there should be plenty of room

Hey bud, I'm going to be in their area tomorrow. If they have one in stock I can pick it up for you. (31O)eight nine three-42O7

http://www.the370z.com/members/pokey...2-mm-pully.jpg. This one is 82mm the 92mm is next to it.

That's waaaay to small for gtm kits

http://www.the370z.com/members/pokey...6-sc-speed.jpg

http://www.the370z.com/members/pokey...644-c38-81.jpg

Falls on the 70% line and makes more power on the way to 7K than the other pulley at 7500.. I shift at 7 and have more HP and torque sooner.

I like it and have over 25K miles on this set up. All based off a dyno tune done at Z1 on another car with a 88mm pulley making 517 RWHP boost at 11 PSI.

current set up, GTM 1.5 kit 750cc injectors and some day digital NOS.

Maybe I'm not looking at this right .....from my understanding the 88mm will be at 11lbs at around 7k rpm and would be just over make for the supercharger........and the 84mm is 14 lbs at the same point and even overspinning more .....so a 82mm would be like 17lbs at 7k and way above max range of supercharger .....I realize you are getting boost sooner in the rpm range but should be limited on how high you can run the engine rpm without risk of blowing supercharger/motor ......also if you don't rev to the upper limits of the rpm range would torque be lost even at a higher boost ?

Also I have the 38-91 stage two supercharger not the 1.5

OK, I don't do math, I just works for me. I even ran this with my 1.0 set up. That system made only 8 PSI due to restriction in the intake. 38-81 compressor

Hmmm that sounds strange for a 82 mm pulley .... I'm at 8lbs with my 92mm pulley now ....at what rpm did you hit 8lbs and how high did you rev to ?

I had 8 @ 5000 and it stayed at 8 until 7500. All with the stage 1 intake and the small charge tubes

That's strange ... Either super charger was maxed out or something was wrong ... Super chargers are based on engine rpm so the rpm increase should have increased the boost from 5k-7.5 k .... Sounds like supercharger was over spinning and couldn't produce anymore boost .... Killing the life of the charger and borderline blowing it.

Not exactly, the stage 1 SC by GTM has a pretty terrible intake design.
There are 2 intake filters with a sharp bend along with a couple other 90+ turns before hitting the SC unit. It ended up restricting even the smallest pulley from going over 8PSI because of airflow restrictions.

And actually, the 1st design which I had we were topping out at 6-6.5PSI and they made some quick changes and sent out a new piece and we finally hit 8PSI.

I know of a 88mm pulley from GTM, like new.
How much is it worth to you and I'll present the offer

Might even have a 84mm too

Even still ....with intake restriction I can see the boost not going past a certain point ...but the supercharger is still spinning with rpm wouldn't it be still overspinning well over the maximum for the supercharger and running the risk of damaging the charger ?

I found Rotrex compressor maps as high as 115K for compressor speed still in the 65% or better range at our air flow, 38-81 compressor.

I don't know how to read them ...but from the rotrex website they all say 90k is max for them ...so I was using that as a reference for overspinning....I like the idea of boost sooner in rpm range as I don't like to redline the car .....was wanting to try to balance the pulley size to have maximum effiecincy of charger around 6800 rpm ......so I'm not sure which pulley size would be best or what the negative issues it would cause.

man you can really spin those rotrex's, my vortech is being over spun at 54,000rpm.

PR------Air Flow----RWHP Tgt------Stock HP
1.53------0.35----------400------------------300
1.73------0.38----------450
1.92------0.43----------500
2.01------0.44----------525
2.11------0.46----------550
2.20------0.48----------575

I don't do math, Excel is my friend.

This is using the Rotrex install information.
There are many other factors but it is a start
Use the compressor maps and find the intersection of the lines, that is the speed you have to spin the unit.
There is heat energy loss (that is % in the compressor map), intercooler pressure drop, intercooler temp drop

:confused: I can't even begin to understand how to read this lol

Pressure ratio on the compressor maps refers to the ratio of boost+atmosphere over atmosphere. so 1.0 on the map is ambient air pressure 14.7 + 0/14.7 or 1.0

so in terms of boost pressure:
1.0 = 0psi
1.5 = 7.3psi
2.0 = 14.7psi
2.5 = 22.0psi
3.0 = 29.3psi
etc

So if the 88mm pulley produces 11-12 PSI, you are at 1.5 to 2.0 Pressure Ratio, so for the c38-81 you are in the middle of the Compressor map just below the 70k line.

On the c38-91/92 compressor map you are at a similar spot but by the looks of it, the c38-91/92 compressor actually has a lower top spinning rate where the 81 can go a bit farther.

I think so, I am doing the math at all RPM's at all the pulley sizes. It may take some time.

Compressor Max Pressure
On the map, find the top-most point on the graph. The vertical coordinate is the max pressure ratio. For example, 2.8 pressure ratio at sea level is 1.8 times the atmospheric pressure, 1.8x14.7psi=26.46 psi.
Compressor max pressure is limited by compressor wheel speed. It's physically impossible to boost higher than this max pressure for one particular turbo. Plus the pressure drop in the intercooler system, the actual max boost reading from a boost gauge that's plugged into the intake manifolds maybe a few psi lower than this max pressure.

Yes, PR of 2.0=14.7 PSI of boost that is at the compressor outlet and very hot. You loose some of that as pressure drop across the intercooler.
More as the volume shrinks when the are is cooled by the intercooler.

So would the airflow at the bottom be rpm ? And since I'm running the 38-91 84mm would be the lowest I should go if I'm understanding the chart

Now that's a chart I can read lol that helps a lot .....so for the stage 1.5 charger the 84 would be best IMO. ANd for the stage two 88mm would be best IMO

I did find this 159-99-8507 - Pulleys - Performance / Accessories - KraftWerks USA
It's a 85mm with 6 bolt pattern for 85 bucks that might work out for my situation Any thoughts ?

I think so, I hate math. You can apply all the numbers to the 38-91 rotrex (stage 2) as well. I still need to do the math for the 82mm pulley I have. I just do not run to 7500RPM the motor might pop!

There are some Dyno charts with the 84mm ran to 7500 .... And was at like 523 hp ... I'm thinking I could use the 85mm .... I don't like running high rpms so 6k-6.5k I feel better at

No dyno near me, sorry