I'm trying to choose a compressor blade and housing for my supercharger project. I am making my own supercharger from the front half of a turbo. I'm trying to get my gearing down to get 10psi at my desired RPM.

I cannot find any formulas on how much pressure a turbo will create at given turbine revolutions. Yes, i know there are many factors in this... But if someone can point me in the right direction, that would be great.

 

Most compressor maps have a compressor wheel overlay. its not very precise, but it will narrow it down within a few thousand rpm.

What wheel is it?

-Jacob

 

GT30 hybrid knock off at first... Which is more like a GT35 front really. I'll check the Garrett website to get me in the ballpark.

inducer 61.40mm, exducer 82.00mm


I will use an eBay chinese knock off at first so I don't mess up exspensive parts on my prototype.

 

Something tells me your superturbo is gonna eat bearings.

 

something tells me you dont know my plans...

I am a machinist. I will not be doing this with a drill press and a file.
.

 

70-90k would be my estimate

-Jacob

 

Garrett sells a RPM sensor for compressor wheels, find someone that uses one or maybe just check with them.

 

You probably wont be able to figure it out based on RPM...boost is a measure of resistance and is different on every engine. 10 psi on a rotary isnt the same as 10 psi on a 2.0L honda. therefore turbo RPM will be different. then you have to factor in engine rpm, blah blah blah.

 

I'm not sure if this is the right way to go about it but I would figure out where your engine is going to make max power and make the gear hit the desired RPM based on compressor map for that engines peak power RPM.

Example, lets say 90,000 compressor RPM @ 7,200 engine RPM? I think that would be a good place to start but this is just going off assumptions, I have zero supercharger experience. After the first prototype, you can see where it lands on the map and then pretty accurately guess the correct gear ratio.

Just make sure you have an anti-surge housing to broaden the map.



thewird

 

I've had a (turbo compressor wheel based) centrifugal supercharger in my hands. 2 of my mates bought the kit and installed it onto a big piston already with plentiful torque.

It took the power from 120rwhp to 200+rwhp at which time the guy doing all the work who was a turbo guy convinced him to put a gt35/p-trim on it so he could **** in 400rwhp with the barely a few more psi boost.

Anyway my impressions from looking at the thing. The guy who installed it told me it came with a 3:1 gearbox, I never counted it so but I assume that is correct. All the other speed change was achieved using pulley sizes, again I never looked into that, but he told me he worked out what pulley gave what boost, installed it tested it and got that boost. Anyway, the compressor wheel in said blower that was making no power was like 100+mm in size. I'm pretty sure you can't spin them fast, and something like 20000rpm is already pushing it.

The other thing is the boost response is a linear ramp its not like a turbo or a roots/screw supercharger where you build the boost and it goes up early and stays up for 3000rpm.

I never drove it but apparently it was completely underwhelming. I'm sure if you looked hard enough you could find good used eaton blowers sized to make 400-500rwhp cheap enough.