superchargedZ

Here:
http://www.vortechsuperchargers.com/...pspeedv-1.html

Crank Pulley Diameter 8.5 inches,

Engine RPM at shift 6200,

Supercharger Pulley 2.75,

Impeller Speed 66114.55.

It was Mike at RMCR. I was thinking of upgrading my G-Trim to a T-Trim. They have a kit to upgrade.

<small>[ October 29, 2002, 01:13 PM: Message edited by: superchargedZ ]</small>

SJH

The crank pulley is only 8" in diameter.

30thta436

iTrader: (10)

I thought the crank pulley was 8.5".
I have been over spinning for a year. I'm running the 2.75" pulley and revving to 7100rpms. That comes up to 75700 rpm impeller speed. I was having oil in the tubes pretty bad, even the tubes before the s/c. But putting the BOV on there took care of the oil problem.
I can't tell you it is safe to overspin it,just that I have been doing it for a while without problems. I think Vortech is conservative on there #'s.

1dirtyZ

iTrader: (1)

from what i heard that the max impeller speed is the speed where no more boost is produced and actually could be lost due to cavitation of the air at that impeller speed( think of it in terms of boat propeller speeds and what not).

superchargedZ

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 30thta436:
<strong>I thought the crank pulley was 8.5".
I have been over spinning for a year. I'm running the 2.75" pulley and revving to 7100rpms. That comes up to 75700 rpm impeller speed. I was having oil in the tubes pretty bad, even the tubes before the s/c. But putting the BOV on there took care of the oil problem.
I can't tell you it is safe to overspin it,just that I have been doing it for a while without problems. I think Vortech is conservative on there #'s.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I thought it was 8.5 as well?

Are you still making boost at 7100rpm? If so the max impeller speed is alot higher than 65,000. I was thinking about putting a 2.65 pulley on. Looks like it will be ok to put it on.

You must have a solid valvetrain to support 7100rpm. What do you have?

Jason

30thta436

iTrader: (10)

I'm not sure if I'm making boost up that high,but I would guess so because the graph is still climbing.
The Valve train is stock except for the 01 LS6 Springs.

superchargedZ

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 30thta436:
<strong>I'm not sure if I'm making boost up that high,but I would guess so because the graph is still climbing.
The Valve train is stock except for the 01 LS6 Springs.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I can't believe you are reving to 7100rpm and all you have is springs. I would think the ls6 cam would flatten out at that high of an rpm. Looks like a good setup.

30thta436

iTrader: (10)

Boost is the determining factor not the cam.

superchargedZ

Just need to get the story straight. I have been told the max impeller speed for the g-trim is 65,000. With my 2.75 pulley I shift at 6200 or so. Which puts me over impeller speed by 1100 rpm.

I have been told that I could exceed impeller speed by 4-5k rpm. Without hurting blower. It won't hurt anything but only when V.E. is reached it will only stop producing boost. Can anyone confirm or deny??

Thanks Jason

SJH

I come up with 62225 rpm for your 6200 shift point.
How do you figure you are 1100 rpm over max?

Also who told you it's Ok to exceed max speed?
Steve

SJH

you don't measure across the pulley flange.
Wrap a tape around the pulley where the belt rides and then divide by Pi.
Unless when I measured it I was on crack, it's 8".

I'll remeasure this weekend as now some of you have me second guessing myself.

30thta436, at what engine rpm do you flatline the maf at 58lbs/min?

30thta436

iTrader: (10)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SJH:
<strong>30thta436, at what engine rpm do you flatline the maf at 58lbs/min?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm not sure exactly, But I know it is over 6k. I'm thinking at about 6.5k.

SJH

you may want to check again as that sounds sort of high for a 2.75.
I hit 58lbs by 5400rpm with a 2.85.
I am going to try a 2.75 and add a mondo bypass to help keep the stress off the blower at these speeds when the throttle gets shut.

I may even go a 2.65 if ASP still sells them.

What I am trying to do is create maximum boost by 6200 engine rpm MAX.
What I don't want to do is spit g-trim guts through my motor with a bearing or gear failure.
But yours seems to be holding up very well.

Has anybody ever talked to Vortech about over spinning these units?
Steve

Gold Phoenix

iTrader: (1)

Max Impeller Speed is the max speed before the impeller flies apart. Turbo max speed are up to 120,000 rpm

superchargedZ

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SJH:
<strong>you don't measure across the pulley flange.
Wrap a tape around the pulley where the belt rides and then divide by Pi.
Unless when I measured it I was on crack, it's 8".

I'll remeasure this weekend as now some of you have me second guessing myself.

30thta436, at what engine rpm do you flatline the maf at 58lbs/min?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Just wondering if you have remeasured the crank pulley?

Jason

SJH

I measured it today again.
Circumferance is 25.125"
divide that by Pi and you get 7.99"
It is a 8" pulley guys, so redo your calculations.
Steve