I am going to build another engine for my Bugeye Sprite. It currently has a stock 13B in it now. I don't have room for a turbo or a supercharger, so I am looking for different porting options. I have heard some mention of using turbo housings with 89-91 rotors. I am open for all suggestions.
Thanks,

 

I know the 13b rotors got lighter in 86 then even lighter in 89.

 

what kind of power are you looking to make?

 

Those housings and rotors are a good combination for any type of N/A porting. Are you going to use a certain intake and if so what is it? That might limit what type of porting will work best for you. Also whats the running weight of your car?

 

What year is the 13B you have? Is it a 4-port form a 70's car or is it 86-91 rx7? That can make a big difference.

May I ask, did I see that car on ebay a couple months ago? Did you buy it or are you the seller and decided to keep it? Very cool project any way.

 

I have had the car for ten years, my 13b is a low mileage '88. I have been running a weber dcoe (45). The weight of the car is approx 1400 lbs. Car has a lSD from a 1st gen rx7. I'd like to have a lot of power.

 

If you want lots of HP for your lite weight car then bridge porting is the way to go. With its light weight you won't suffer as much in the midrange since there is less mass to move. My engine builder has got almost 260HP on an engine dyno with what he calls a street bridge. A street bridge doesn't cut into the rotor housings. We are currently duplicating that engine for a racing buddy of mine that has a miata with a 13B in it. He had many FTD in that car with a low compression engine and expects to be much faster with the BP engine. That engine will actually let him accelerate from feature to feature unlike the no-compression engine he use to run.