I'm thinking for doing some kind of force induction but I heard with a greddy turbo kit you can't go over 7000rpm's but I was on the mazdatrixs site and they have 2 superchargers. So my question is what should I go with

 

greddy just needs a few fixes to work well. Best if you replace the blower with something bigger. Twin turbo should be possible but no real reason to use it, single should work just fine. really depends on your price range and how much power you're looking for.

 

who told you that you can't go over 7,000 rpm?

if you run the greddy kit at 6 psi, it will hold 6 all the way to redline. if you raise boost, at 7k the turbo doesn't flow to keep up with the engine demands, and so it peaks at 7 and declines slowly after that.

Check it out:

https://www.rx8club.com/attachment.p...3&d=1189649274

Right now there isn't a SC kit available for the RX-8 that would be overall better than the greddy (and the greddy is the lowest powered turbo kit available for the RX-8!). Just look at where the torque numbers are at 3,500 rpm, and compare to the SCs.


anyway, back to your question:

1. You can twin turbo your RX-8, but it's no more logical than it is to quad turbo your RX-8.

2. You can go over 7,000 rpm with the greddy, but you're going to see diminished returns. If this is an issue, drop the $1,000 and upgrade to a larger turbo.

 

but what about a supercharger???

 

You can twin turbo or supercharge any car. I believe MadDog is putting a custom twin turbo system in his 8 and he had shown some time ago that if he used twin GT20's he could get as broad of a powerband as a GT3071 while remaining in some better efficiency islands than the 3071. The question is do you want to put the money down to make a twin turbo system work?

Now people bitch about the Greddy not holding full boost to the redline, but they overlook some things:

It's a fun turbo on the street. It spools up quick and 280 whp on an RX8 will outrun a stage II Sti.

It gives the RX8 a much fatter torque curve allowing you to better exploit its great chassis.

It's still the cheapest route to go.