Hi..
Have been tuning up 4- and 6 piston engines with a lot of turbo boost, and as you all know when you do this,
the engineŽs compression has to to be lowered or youŽll have a big pile of junk on the road when you step on gas...

So my questions are:

How much boost can a 13B handle?
and if necessary; what can you do to lower the compression?


And please, no laughing out loud...(beginner)

(And IŽll send my pet polar bear to bite yer *** of...)

Thanks.....

 

I'm not sure if there is any way to lower the compression on a rotary. I think the compression on a rotary is determined by the size and/or shape of the cupped part of the rotor face. Since nobody makes aftermarket rotors, I think compression stays the same. That's the only way I can think of a rotary making compression, I may be wrong though.

As for boost, if you get 3mm apex seals and have the car tuned correctly, I think you can make about 20 psi of boost. It could probably make more easily, but it wont be very reliable.

 

There are too many variables to give set number.

Crispeed was running upwards of 40 psi

 

I can make an engine running under vacuum detonate It's all in the TUNING, both hardware and software...

 

you don't need 3mm apex seals. The 2mm ones will handle the boost it's just a myth that they can't because there are many people on this forum that run more than 20psi regularly but they have tuned them right and that makes all the difference.

3mm seals are for PU$$ys that can't tune their car correctly so they have to get big damn seals that rob both power and RPMs and have bad wear on the rotor housings and bad sealing. All they are good for is if you are getting spark nock and they will handle a little more than a 2mm will but not much.

BTW they do make lower compression rotors and sell them through companies like racing beat.

 

Nice one dick.

You can run as much boost as you want, as long as the engine is built right and you have the injectors to flow the fuel you will need.

 

i think the true answer to this question is........

a) how much boost can your fuel supply handle
b) what will your intake air temperature be
c) what octane is the gas you plan to run

Those three things are the factors that limit how much boost a 13B will handle, not the engine itself

 

a rotary engine 13B, have seen handle 2.5 bar boost. This was on NB 2mm seals.

You can get low compression rotars, but that still wont change what the seals can handle..

Jason
www.jt-imports.com

 

They're also for people who enjoy '74-85 engines
Someone with a single-dizzy 12A or older 13B doesn't really have a choice in the matter.

 

Q. How do I lower compression?
A. you need to get a set of internal rotors out of a 86 or later rx7 motor that came from the factory with a turbo. The stock compression ratio on an NA motor depends on the year of the engine but is usualy around 9.2 to 1. Someone feel free to correct me if i am wrong but i think the stock turbo rotors are like 8.7 to 1? The other way to get lower compression is to pay a rotary shop to dish out your NA rotors. this means they take material out of the face of the rotor. I know there is a rotary shop close to me in Seattle who does it and they can do it to 8.2 to 1 or 8.5 to 1. your choice.


PJ: Thanks for standing up for us old 4 port 13b and 12a guys. I like the old motors, it makes getting side plates for my 13b very easy since there is about half a million 12a's out there.

CJG

 

The rotors can be machined for lower compression. I've heard of compression as low as 7:1 after milling enough metal from the bathtubs.

However, many people will tell you that, with proper tuning, not only will you not need the lower compression, but that it's detrimental as well.