Hello,

I have a 93 Riviera in great shape, and recently learned that while this car never originally came with a supercharger, the S1 3800 did in other cars. I was wondering if it were possible to slap on one of these (if it'* the correct supercharger) Eaton M90 Supercharger just to give it some much needed extra power. It feels rather anemic with the standard 174 hp and 4 speed automatic. These superchargers seem abundantly cheap?

Appreciate any insight.

Thanks

Sorry, but it don't work that way. Big difference between the Series I engine & the Series II */C engine that came with the M90. None of the parts are interchangeable.

There were two different superchargers that came standard in the series 1. The Eaton M90 was one of them, I believe.

I think this is more the answer you're looking for:

The naturally-aspirated engine has a higher compression ratio and weaker rods and pistons than the supercharged version of the same engine. If you slapped a supercharger on it and sorted out pulleys etc., it would run poorly due to the PCM'* programming based on non-supercharged values. If you got the PCM reprogrammed based on the supercharged version of your engine, it would still run badly, albeit less so, because of the higher compression ratio. It would also likely have detonation issue also due to the higher compression ratio combined with the extra air forced into the cylinders. If you got the PCM reprogrammed to accommodate the higher compression ratio and all other factors such that it runs perfectly in this configuration, it would thrash the main bearings, rod bearings, pistons, and rods. I'd be amazed if it made it 200 miles without bad sounds and/or failure of expensive parts.

Let'* say magic was used to enhance the main bearings, rod bearings, pistons, and rods . . . and they're as happy as they were before the supercharger arrived. The PCM is also programmed to work with this also. Now the transaxle has more power and torque to deal with than it was designed for. It would also have to deal with more power and torque than the transaxles on the factory supercharged cars of the time. This is thanks to the higher compression ratio combined with the supercharging. It would probably burn up clutches pretty quickly on its way to snapping parts inside. Maybe if the clutches slip a lot, the transaxle wouldn't be able to retain enough stress to snap anything, but that'* saving one part while ruining another.

I have no idea where you got that information that there were two different */C'* offered on the Series I engine. Where ever that info came from was totally bogus and lack of knowledge. The Series I */C "92-'95 was only offered with an Eaton M62. The Eaton M-90 was first used on the Series II engine beginning in 1996. Like mentioned, they are totally different engines.

The series 2 supercharged versions came with a 4T60-E HD (heavy duty) transmission as well.

I think I misunderstood and thought the M-90 was also for the Series 1. Apologies.

Hmm, I see. I was misled by this automotive enthusiast article. They make it sound like the L27 and L67 are not that different, and it would be trivial with some donor parts to slap on a supercharger on the L27. I have read that some have supercharged the L27, but it seems kind of stupid after digging deeper into it, as L67'* aren't exactly expensive or difficult to come by...would be better to just swap in the factory supercharged engine.

So, it would appear the answer would be "don't", and for good reason.

I'm not aware of how fragile the 4T60-E is, but I wasn't looking for any crazy power levels, perhaps 225 hp at the most. Makes me wonder what they did to make it stronger on the HD, though. Will see if I can find out.

The only difference between the 4T60-E & the HD */C version was the differential gears, housing & C/C joint. All internal parts were the same!