New to Supercharger

Good morning all,

My name is Stephan, I am new to the Supercharger scene, always had Turbo before.

My car is a slightly different set up than most pony and muscle car on this site however I have a few questions related to my SN92.

I own a SN92 and was wondering what are the differences and benefit , if any, of the SN2000 as opposed to the SN92.

My understanding is that both can be upgraded with a slightly larger impeller without any other modification, now if we compare apples to apples, does the SN200 really blows more than the SN92 (psi), or this is just a myth?

My dilemma is that: I am leaning toward the complete rebuild of my SN92, however I could purchase an SN2000 but if the performance and longevity benefits are pretty much the same as mine I would not invest into the more costly SN2000, but rather go with the rebuild. My understanding is that they all use the same internal parts, the only visual difference are the outer casing configuration. So, why different version of the same supercharger not offering anything really different?

I have researched this on various online sources and there appears to have a wide arrays of opinion on that. I am just reaching to you for your professional opinion on this matter.

Hi Stephan, welcome to SuperCharger Help.

To answer your question re: the difference between the SN92 and the SN2000, the truth is there is very little difference between the two superchargers. Virtually all of the internal components are exactly the same, including the impeller, ball drive, races, input shaft, etc... I believe the chief differences are the seals - the SN2000 may use redesigned/newer seals. As such, if there is a difference in the amount of boost the SN2000 makes when compared to the SN92, the difference would be negligible (if any) indeed.

You are correct in saying that either supercharger can be outfitted with a "high-output" impeller (not a 'larger' impeller, but one with redesigned air-veins to improve airflow) which would provide about 6.0-6.5psi of boost from either an SN92 or an SN2000 (or any other 'SN' unit for that matter).

For serious horsepower junkies, the only major upgrade worth considering for an SN unit is the conversion to a VR4. This upgrade provides a radically redesigned impeller and a much larger rear scroll, and facilitates considerably more boost (14-16psi) and higher supercharger RPM. Not an inexpensive upgrade though (somewhere between $750-$1,000 just for the VR4 kit) and it's not very easy to find either.

IMHO, I wouldn't waste my time or money for an SN2000 since the performance/life expectance is virtually identical to the SN92 you already have. If cost is an issue, I would opt for the upgraded impeller during the rebuild (it's an easy way to gain 1-1.5psi of boost), and if you don't already have it, get an oil cooler for the supercharger as well. This will help extend the life of the supercharger considerably. If cost isn't an issue, start hunting for a VR4 kit. Talk to the folks at Paradise Wheels or at CUNDN Racing - they may have a kit available for sale.

Hope that helps.

Thanks Michael for the substantive reply with complete info.
I have already contacted several expert (CUND, Superchargerrebuild, and Paradise wheels) it's funny how I got 3 different answers, but none were as complete as yours.

As for the advise, it is very helpfull.

I do have an oil cooler plumbed into my SC with a very slick oil pump and in-line filter I just bought from Craig at Paradise W.

I am already getting a steady 5lbs and will probably go for the upgaded impeller. It is still pushing good boost and not leaking, but is it wise to go for a full rebuild at this time even though nothing is wrong with it ? Or should I just wait and go for the rebuilt when something happen?

Thanks

Stephane

Don't fix it if it is not broken.
Just go with the upgraded impeller and expect about 1 psi more (at the most).

Quote:

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Originally Posted by pavement pounde

Don't fix it if it is not broken.
Just go with the upgraded impeller and expect about 1 psi more (at the most).

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I agree with pavement pounde, if the supercharger is working fine, then I wouldn't do a full rebuild. As long as the seals are fine and you stay on top of the fluid changes, it should give you plenty of years of service without problems. But the upgraded impeller is definitely worthwhile, especially considering it's cost (and if I'm not mistaken, Paradise Wheels offers an exchange for your old impeller which lowers the cost of the new impeller even further) and the fact that you already have an oil cooler plumbed in.

Incidentally, what did the other three people/places you contacted say about the differences between the SN units? What did they suggest you do?

BTW - your 911SC looks FANTASTIC! I've always loved the classic air-cooled 911s, and after reading the book The Gold Plated Porsche by Stephan Wilkinson my admiration for the 911 - particularly the SC - grew even more. Thanks for sharing the photos with us.