Replacement Rotrex Supercharger for the GTM Stage 1 kit
 

Can anyone confirm with certainty that the GTM Stage 1 kit uses the Rotrex C38-81 supercharger head? I am fairly certain this is the correct supercharger.

My car was in the shop for a yearly Rotrex service (unicorn blood based traction fluid and filter) and they diagnosed what I thought was a faulty idler as a rattle/grinding noise with the supercharger itself. When the tech drained the Rotrex filter into a container it was completely obvious the fluid was full of metal remnants.

So I am weighing replacing the supercharger versus returning the car back to stock. Sorry guys but going another FI route is not in the cards for me right now. I am a little leery going the replacement route as the original lasted 34 months and 27k miles with no track time and no auto-x. This car was only street driven and it is my DD.

From the site for a Stage 1 SC:



The GTM Supercharger kit has two different Rotrex compressors to chose from: the C38-81 trim and the C38-91. Combined with our custom compressor housing we will offer three different stages .

Stage zero up to 450 HP (CARB approval in progress)
Stage one up to 500 HP
Stage two up to 550 HP

Also from the site:

We are pleased to announce the GTM Stage 1.5 Supercharger Kit for the 370Z. The Stage 1.5 uses the same supercharger head unit as our Stage 1 Kit (the Rotrex C38-81) with the intake system of our Stage 2 Kit

How much do they want to rebuild the unit?

Thanks for the reply. I saw that on GTM's page. I still need to know the correct trim, C38-81 or C38-91.

From what I find online, the units are not rebuildable. There is an online vendor who advertises rebuilds but if I stay FI, I will just purchase a new unit.

My money is on the 81, just call GTM. It's hard to believe the Rotrex isn't rebuildable.

ETA...Sure enough, went on Rotrex's website and they can't be rebuilt. Score one more for Turbo set-ups

Does rotrex do a core credit on a new one? One would think there is a serial number on that bitch somwhere

Edit: googled it gonna throw this in here in case you need it Rotrex instalation guidlines

lol

The stage one is a C38-81, Stage 1.5- C38-81 with larger housing, and stage 2- C38-91. Sorry to hear about your troubles with your unit. I'll see if I can find the only company I know of that rebuilds Rotrex Superchargers. Even though Rotrex says the unit cannot be built, It can be done for a lot less than buying a new one.

Here is the website. I just emailed this company to see if they are still rebuilding C38 units. I Hope you decide to rebuild or upgrade your unit vs going back to stock. I suggest going with the C38-91 if you decide to buy new. More room to grow later, and you could go down on the boost to make similar numbers as you were making. Good luck.

Supercharger Rebuilds » Rotrex Repair C38, C30, C15, SP30

If stage II is really the C38-91 then I'm pretty sure you can't upgrade to that one without a new motor mount. GTM included it with stage II kit. They might sell you one but who knows when you would get it.

Yes, You are right. I forgot to mention that. I went from a stage 1 to 1.5 SC and had install the mount and buy the new air filter relocation kit. Looks like the best bet is for a rebuild or new C38.

When you upgraded to the 1.5 it is a different rotrex unit correct?
Do you by chance happen to know if the larger unit fits without requiring GTM motor mounts and filter relocation kit? I was always curious if a stage 1 owner could bump up one size without actually having to redo a bunch of items and then just throw on a smaller pulley and be done.

Mainly because I do not like the 1.5/2 filter location.

No my Rotrex 1.5 upgrade is the same stg1 sc C38-81 with just a larger housing. The larger Rotrex unit will likely not fit with the stg1 configuration. You could still always use a smaller pulley for more power on your current setup.

That was my plan, looking over the charts of the units at 8psi it is in the lower 50% so plenty of room to drop down a pulley size and bump up the psi to 10-11. Plus my other upgrade idea with that is e85 to squeeze out a little more that 93 octane lacks.

OK -81 is stage 1 and 1.5. You need the GTM kit to upgrade
-91 is stage 2 only

Next you can get a new unit from other non GTM source for $1800.

Last I think your unit may be under warranty contact rotrex direct to find out.

PM me if you want more data

Where did you find a Rotrex sc for $1800? Please do tell:) I believe the Rotrex sc's carry a 12 month warranty. I believe the op has owned his kit longer.