Planning out the convertible TII supercharged project.

Are the 8x-88 and the 89-92 TII drivetrain's the same strength?

Obviously the 8x-88 years are cheaper and readily available.

Thanks

-- Clayton
1992 FC3S Turbo II Midnight blue

 

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anyone?

 

I'm really not sure on this, but I think they are very similar in durability. The reason I'm responding is.... why would it matter? You say you're superchargin a T2? What compression rotors are you using? Superchargers usually aren't pushing more than 10-12 lbs of boost. On 1 bar you will make more power with 9.7:1 rotors than you would with T2 rotors. As long as it's properly intercooled, and you run 93 octane you will not have detonation problems. 10-12 lbs should be no problem for you! With that said, I'm guessing you will not be making more than 250 ft/lbs of TQ, meaning ANY year T2 tranny will suffice.... that I am postive on. What are the details of this project?

-Brian

 

I would venture to guess that the drivetrains are basically the same in terms of reliability and durability. What year vert are you planning on modding? I'm asking this because it'll be easier to stick with the series 4 or 5 engines and trannys in respect to the convertible body you plan on using. The 87-88 TII engines are a bit longer lasting due to their lower-compression rotors not to mention they're more common, thusly cheaper.

 

I definately would not 8.5:1 rotors if you plan making good power. 8.5:1 is too low on these cars even for very high boost applications (22-28 psi)! 9:1 rotors are best for any amount of boost, on pump gas, with good tuning. 9.7:1 rotors are good for lower boost applications, but can be used efficiently at high boost with race gas. If reliability is your main concern go with the earlier T2 rotors... but if realiability were your main concern, you'd probably be sticking with an N/A

-Brian

 

They are the same strength. I don't know of any difference other than the 5th gear ratios of the transmissions.

One thing that you need to be careful of is the driveshaft. Due to the design of the 2Gen's drivetrain layout (both NA and TII), the stock driveshaft eventually binds at the U-joint, causing really bad things to happen if you don't replace it. Of course, it would be too easy to replace the U-joint, so Mazda makes you buy the entire shaft. If the donor car that you get the TII transmission from has any more than 120K miles on it, I can almost guarantee that it is going bad. You can get a driveshaft custom-made, or you can get the Mazdatrix replacement driveshaft for $242. The Mazdatrix driveshaft won't last any longer than a replacement from Mazda, but at least you can rebuild it.

I'm not sure what inspired the rotor compression discussion, but IMO anyone who is building a convertible instead of a coupe, and installing a supercharger instead of a turbo, is more concerned with style than they are performance. In other words, just use whatever rotors you like, and have fun.

 

relvinnian, ZachSpazz, Evil Aviator,

This is my winter project rx-7. I'm sticking to the 89-92 years for the convertible.

For the doner TII, guess your right on sticking with the same year as the convertible. All the bolt holes allignments & minor incompatiblies would be a mute point

Not planning on making more than 8PSI of boost with the supercharger. Note I already have a 92/91 TII.

The supercharged setup is for maximum streetability/nimbleness. Nothing line instant boost

Someone mentioned the NA engine may be a better canidate for supercharging as backpressure is greater providing more low end torque (max streetability). Need more opinions on that before making a decision.

The trick is going to be avoiding the supercharger heating the air too much. Need to R&D all the different types of superchargers and weigh intercooled vs not.