srupp1969

Hi,

are there any experiences in using a rotrex c38 supercharger in a kit for the 928.
As I have learned yesterday from the passenger seat of a BMW M5 V8 with twin rotrex-setup these chargers are really small, quiet and deliver an absolut scary amount of power.

Cheers,
Stefan

ceedee

it looks pretty neat.

Vilhuer

There is work in progress in Finland to install their largest model into '90 GT. In this installation it will be low down where alternator is and smaller diameter alternator will be where air pump is normally. This allows Rotrex to be mounted so that rotation direction is correct. If its mounted in way which Murf and other kits are done outside of the belt would need to be used to pull it instead of inside.

srupp1969

Hi Erkka,

thanks a lot. This is interesting info. Sounds like a very tidy installation. I think lot of us would be very interested in beeing kept updated in this project.

Cheers
Stefan

ceedee

i've seen a vette last night with the charger turned, facing the engine.
never seen that before. but i bet it helps with some mounting problems

FlyingDog

Doesn't Rotrex make SCs that turn in both directions like Vortec? Maybe I just saw that on smaller ones.

Ceedee, standard Prochargers turn the opposite direction from Vortecs, so they are mounted reversed.

hans14914

To my recollection, rotrex only spin clockwise. They are fantastic units, and I have considered their use on the 928. The only "problem" is the current sizing. Even the largest unit wont provide the same outputs as the vortech or autorotor. Its advantage is mechanical and thermal efficiency.... so, it would have a niche as perhapse a moderate boost, non-intercooled system available for a reasonable price. If you could figure out how to mount a C38 on a 928, then you could plumb similar to an early murph kit with no intercooler and safely run around 7lbs or maybe a bit more. Would require new injectors, but with the sharktuner, that really isnt an issue. Other issues stem from the price. The head unit and oiling system alone cost $2000, even at dealer pricing. They are much more expensive than competing products. In order to get numbers to compete with the existing 928 boost options, it would require a pair of rotrex, which would bump the price of just supers alone to $4k.... add brackets, filters, intercoolers at this point.... It would be a very expensive option. There would be enough "breath" for the possibility of 900+ RWHP on a 5.0 if you could build a drivetrain strong enough to take it.

In summary, rotrex units are great. They are small, near silent, and very efficient. However they are very expensive, and really not sized ideally for a monster 928 setup. It is possible, and the bracketry shouldnt be too hard to contstuct, but with the current available kits from DR, Murph, and others, why spend the time and effort to re-invent either a more expensive or less powerful kit? The advantages of a twin rotrex setup would only reveal themselves on a built motor (pistons, rods... $$$) and a single wont out-huff the vortex. If someone were to release a kit, the only viable market would be the non-intercooled budget market, and even then it would be a struggle to market. Raw costs of the kit alone would be at least $3500 without making any profit or accounting for labor or develpoment costs. I am looking into it for a personal project, but it probably is not a commercially viable idea at this time.

Imo000

Sounds like they are desined to be used on V6 engines. Internally thye are very simmilar to the planetary drive Paxton I have and this makes it very compact

Vilhuer

Reason for GT setup is stealth installation. It will also utilize pipe type intercooler hidden inside intake tubing. IC setup is somewhat different than what Lindsey racing is selling. This has several straight pipes inside larger pipe which contains water.

Its possible to install Rotrex same way as Vortech by using couple of extra rollers and two sided belt.

hans14914

Sounds like you are using laminovas. I use them too, great product. What is your target output for the gt, 450hp?
Hans

Vilhuer

IC will be custom made locally. It is not like Laminova. Maker has done these for years already. Mainly for tractor pulling tractors.

Niklas who develops SharkTuner together with John Speake did calculations and Rotrex should support 600+ levels. Unit is C38-81, largest they are currently offering and rated to 630hp. It will be run slightly faster than recommended making 650 possible. Key is to always keep SC oil under 80C temp.

928DK

Let me know the progress of the project, i have a C38 that is just wating to get on my 928 when the repairs are finished