www.RX7fb.com

syebba wrote:I'd like to know at what approx readings a wankle goes pop!

& what are compression readings on a new engine

Me too.... I'm trying to find out what represents a healthy engine and what readings constitute a shagged engine.

syebba wrote:If engine still starts & runs fine,not worth worrying about,you'll probably get years out of it yet.

Keith how much does the proper mazda compression reader cost?
Probably £Hundreds?

ta stu..

Mine runs and starts fine so I'll just run it until it gives up the ghost then drop my other RX Motors rebuilt engine in... a dead simple job.

Keith was telling us he got a special deal on this tester and it still cost £1100 !!! Great bit of kit though and if he takes it to a few meets, he'll get his money back eventually doing comp tests for people for a few quid. Even if you're not really into engines, tuning and performance, it's still nice to know how your engines bearing up.

Jeepers £1100 for the proper mazda tester,no wonder no one else apart from the specialist pro's have one!

Keith a G8 little sideline business is ripe for exploiting at car shows!

How long did it take to get the compression readings on both rotors?start to finish.

Still wonder when a wankel will go pop,maybe readings around 0.35 on the rotors.

ta stu..

syebba wrote:Jeepers £1100 for the proper mazda tester,no wonder no one else apart from the specialist pro's have one!

Keith a G8 little sideline business is ripe for exploiting at car shows!

How long did it take to get the compression readings on both rotors?start to finish.

Still wonder when a wankel will go pop,maybe readings around 0.35 on the rotors.

ta stu..

5 mins each car.... drop a plug out of each rotor, unplug the ignition coils, connect the tester and then spin it over.

What the manual says


Would be good to know when one becomes a non runner.

If i was near you keith & looking at buying an RX7 i'd pay to get this test done.

Surprising how few owners bother & how often the engines do go pop!

myatt1972 wrote:What the manual says


Would be good to know when one becomes a non runner.

interesting.....

according to this, my readings break down as:

Rear rotor:

4.7
4.6
4.5

gives an average of 4.6 which is running at 77.66% of the maximum

Front rotor:

5.2
5.3
5.4

gives an average of 5.3 which is running at 88.33% of the maximum


dunno what it all means though!!!

I think the 1.5 permissable is between chambers on one rotor rather than between rotors.
Its like voodoo magic this stuff.

Stu, I think you might be getting your keith's mixed up, ive not got the tester, its Trind-fd (keith).

myatt1972 wrote:I think the 1.5 permissable is between chambers on one rotor rather than between rotors.
Its like voodoo magic this stuff.

oh yeah, you're right.... I'll edit my post.... I'm nowhere near 1.5 .... yet!

myatt1972 wrote:I think the 1.5 permissable is between chambers on one rotor rather than between rotors.
Its like voodoo magic this stuff.

Stu, I think you might be getting your keith's mixed up, ive not got the tester, its Trind-fd (keith).

Yes Keith i thought you had the tester kit,just seen it's another keith over on mrc

After talking to a couple of rotary engine builders, opinion seems to be:

Fresh rebuilt motors comp tested will give you 10 plus on all faces,once the motor has run it will give you 8's all the way round.
so new engines around 8's.
7's are fine then around 6's means its getting tired. The rear rotor normally goes first.
They both also say, don't worry about a bottom compression figure.... as long as it starts ok, just run it.... you know when it's knackered when it won't start.

Interesting stuff... I'd never really thought about it before.