BigJames

I'm currently looking at buying my first rotary, an FC Turbo II. The previous owner has mentioned that it recently had compression results and talks about them as though they are impressive and great - but I'm clueless. I spoke with a mechanic friend (V8 specialist, not rotary) and he thought that "good" compression for a 13B was much higher.
Compression results from the current owner: 7.2s on the front, 6.9s on the rear, even compression

Is that ok/good/need to start thinking about a rebuild?

Thanks in advance for your help

Aaron Cake

iTrader: (1)

Was this on the Mazda compression tester? If so, then that's right about where you want it to be.

BigJames

To be honest, I don't have a clue who did it, or which tools it was done with - but I hope to find out.
Incidentally, its a bit spooky that you've replied since I'm just on episode 12 of your Cosmos restoration videos on Youtube... Which I'm enjoying immensly! Thanks Aaron!

Eduardo Santos

The FSM states that a 1989 FC Turbo II has a compression ratio of 9.0:1 What year is the one you are talking about?
If you check this website you'll see that a good condition rotary engine should have at least 85 PSi of compression. Now, what is 7.2s and 6.9s ? I don't know what unit that is... You should clarify that in detail, before moving on.

BigJames

It's a 1991 Turbo II UK model.
I believe the 6.9/7.2 uses the bar unit of measurement. 1 bar = 14.503773800721815 PSi

So in theory this engine is running 7.2 bar/104.4PSi on the front rotor and 6.9 bar/100.07 PSi on the rear.

I'm also aware that I need to find out when the compression test was carried out, since these readings could be 5 years old!

Thanks for the link though, that gives me a great idea where the results sit on the scale of health!

Eduardo Santos

Well, if that was measured 5 years ago, the engine condition will be different, unless the car was rarely driven...
You said you were looking for your first rotary car. I recommend you to read this article:
http://www.aaroncake.net/RX-7/buy2.htm
It was written by Aaron Cake who is one of the most knowledgeable people here.

Good luck with that!

BigJames

Thanks Eduardo, that's really helpful. Also just to clarify, I meant that the results COULD be 5 years olf for all I know - since I don't know when the car was tested, or by who yet...

Eduardo Santos

Well, yes. Just try to find out when, and at how many miles that test was done.