Hey all from melb aus,

I took my car down to a local workshop today to get it checked up before i sell it. The results were abit worrying, but im not sure if he is full of it or not.

The car is a 1988 series 4 turbo 2. Engine is stock.

Compression was lower than normal, he didnt say by how much, he just said it was low. The engine was rebuilt only 30,000km ago, and ive heard from other sources taht turbo cars should have a lower compression.

He was also concerned that the car was burning oil, he was only basing this on the reading off the dipstick. I start my car early in the morning, so its fairly chilly.

He also told me taht the spark plugs put in by another rotory workshop were incorrect and only used to mask the oil burning.

thanks for any light people could shed

 

well chances are, the mechanic you took your car to didn't know his ****...

Your compression readings should be at about 110 I believe...someone correct me if i'm wrong...

All RX7s burn oil...expect about a quart every 1000 miles...

there is only one kind of plug that I've seen for rotarys. NGK makes them and they're flat. meaning you don't have to gap them. the plugs will have an 'L' and a 'T' designation on them . Basically the 'L' and 'T' are there to remind you that one set is leading and the other is trailing. Look for those designations and you'll know whether or not they're the right plugs.

 

the motor is designed to burn off enging oil; "by how much over a period of time" is the factor here

the plugs for rotory are special, and as for colour, the tip of the surroundings should be black and dry

 

I'm a friend of malich's and have a bit more rotary experience..

From what I've heard, that guy seems to be full of it..

The plugs in the car are the right flat ended ones, slightly different between leading and trailing. I think one set is BR8EQ cant remember the other..

Rotaries burn oil... if they didn't they wouldnt last, or get as good compression! Burning oil is a good thing lol. No burn oil = no drive for more than 10000km

And I thought turbo blocks had lower compression (decomp rotors) because they have to deal with a lot of boost from the turbo at times... whereas an N/A block relies on the rotors alone for the compression, turbo blocks pass this task onto the turbo itself. - so when your cranking over the starter motor doing a comp test, you will read lower figures as the turbo is not contributing its part, as compared with an n/a rotor with normal rotors.

Him not even giving specific details is just dodgy.. saying 'compression is low' doesnt mean a thing. Compression just has to be even between all faces and relatively close between both rotors.

I reckon he is full of it, but share your thoughts ppl..

 

as for compression, read up: http://fc3spro.com/TECH/FAQ/compress.html

 

Turbo engines have a lower compression ratio than a non-turbo, but the pressure numbers from a compression test are about the same. Without the numbers his test is pretty useless. You need to compare them to the factory minimum spec.

This guy doesn't seem to realise that rotaries consume oil by design (~1L per 1500km to lubricate the internals). Worrying...

Sounds like a load of BS to me; plugs can't mask that. Take them out and read the numbers on the sides. The leading (lower) plugs should be NGK BUR7EQ's and have an "L" on them, and the trailing (upper) should be NGK BUR9EQ and have a "T" and two stripes on them. There are a few other okay selections so let us know what they are.

This guy sounds like trouble. I really think you should take engine-related problems or work to a rotary specialist.

 

this guy sounded like he was way to vague. i agree with funk, he doesn't have the slightest idea what he's working with. ask him if the head gasket could be the problem, if he says anything but "there are no head gaskets", find a new mechanic.

 

Hey NZConvertible, What other plugs can you use?

sorry to threadjack....

 

Nader

HKS, densos and a few others but I've named the big ones.

 

Stan

Thanks...

 

You're correct, but as NZConvertible has mentioned, it's almost insignificant.

IME, I've seen S5 non-turbo engines hit 130psi.
I've never seen an S4 turbo engine hit more than 120psi.
Sorry for the imperial units, but it's going to be maybe 5psi...10psi maximum difference between turbo and non-turbo rotors.

As you've already mentioned, having the face even is more important.
If the faces are all even and close front versus rear, the engine should be okay.


-Ted