Thomas Knight Supercharger Kit, Eaton M90, 3000gt

[Outlaw1]

Are you sure this isn't a busted blower or a bad leak of some sort? With a 2.88 upper and any sort of typical lower pulley it's hard to imagine 3psi with any combination.

[Pushit2.0]

The drive ratio is only 1.5 or 1.6, the crank pulley is the inner 4 cog PS belt on the 3s which is about a 3" pulley. But with the 6" pulley that will be made this M90 will be spinning at 15,000 rpm, a drive ratio of 2.1 or 2.2. And I am sure the PS pump will like spinning almost twice as fast also.

~John

[Goat Blower]

Nah, there's no cancelling of boost to run the supercharger. It's only parasitic drag on the crank that cancels some horsepower, not boost.

I just read last night that a regular old centrifugal supercharger can use up to 50 horsepower to run it on a big block Chebby. They also talked quite a bit about the drag from the supercharger pulling crank pulley's apart. They also can bend a supercharger mount that's not strong enough. They use two 3/4" aluminum plates to mount the supercharger. Interesting.

Steve

The extra power produced by that 1-2psi (15-25hp) gets canceled by the supercharger stealing power to "compress" air. Or that’s how I would interpret it.

I think a nice pair of 13t’s or 15G’s would have done nicely. 14b’s probably would have been a bit excessive for the power range we were/are going for.

[Outlaw1]

Nah, there's no cancelling of boost to run the supercharger. It's only parasitic drag on the crank that cancels some horsepower, not boost.

I just read last night that a regular old centrifugal supercharger can use up to 50 horsepower to run it on a big block Chebby. They also talked quite a bit about the drag from the supercharger pulling crank pulley's apart. They also can bend a supercharger mount that's not strong enough. They use two 3/4" aluminum plates to mount the supercharger. Interesting.

Steve
You would be blown away if you saw the amount of deflection in a ProCharger D1-SC bracket setup on a Fox body Mustang. Within the last few years the craze has been to use a huge supercharger at a low boost setting to keep the intake charge dense. You should check out the belt tension it takes to get an 8-rib setup from slipping with a D1. It makes me feel very sorry for the supercharger bearings, engine main bearings, crank snout/pulley and brackets. Unless you go cog drive, you're stuck with serious belt tension with a big centrifugal and an 8-rib.

[niterydr]

Yeah this is a 4 rib setup, with an extreme belt tension. We aren't saying that it is canceling boost, just the 1-2psi worth of hp increase is being consumed by the supercharger.
We could do a boost leak test, but the gauge is plumbed into the supercharger manifold, not much room for the boost to leak out of, since its at the source.
John is right, im sure the ps pump will love life!

[Outlaw1]

Yeah this is a 4 rib setup, with an extreme belt tension.
A whole 4 ribs? I smell something burning. It's your blower belt! ;)

[JET]

Why not put a larger pulley on the PS pump too? There has to be some Mitsu application that could fit on pretty easily.

[Pushit2.0]

I have not tried myself but according to Knight you can not get that pulley off the PS pump with out cutting it apart. But if we are putting on a differnt pulley I guess it would not matter. The belt is not slipping I checked a few times on the dyno and it was just as warm as the AC/ALT belt. I know befor I modified the tensioner it was slipping, But a bolt tension set up similar to a 1g alternator tensioner fixed the problem.

~John

[Outlaw1]

I know befor I modified the tensioner it was slipping, But a bolt tension set up similar to a 1g alternator tensioner fixed the problem.
If the belt was slipping BEFORE it made 3psi, it's either a totally junk setup or the blower isn't turning as freely as it should. I'm still shocked someone would even drive a blower with a 4-rib belt. I've had problems with 6-rib setups, I can't imagine taking a step back from there. Sounds like something in the blower is binding.

[FattyBoomBatty]

maybe you guys forgot to advance the timing. turn that distributor to the left a bit. i gaurantee it'll help. :)