Azki23

Hey all

2005 jap import rx8 @ 105,600kms

Bought 3 months ago at 86,000kms compression was 105,104,104,105psi

Today I got a test done 102-102-98-102psi

That 98psi is scaring me. Front rotor.

But 102? She ain't got much happiness left right? So I asked for a replacement of seals price. I found some online $570nzd. They agreed 570-2g depending on quality. But 5k after everything for standard seal replacement.

Is this price fair? Seems like alot when I can buy a new set for 4-600nzd for replacement Mazda 2mm seals... That labour cost though.

Thoughts?

At 102""98-102 should I be worried?

9krpmrx8

iTrader: (46)

Well there is some important info missing. Was the engine warm when this test was done? What was the cranking RPM of these results and where do you live?

Loki

iTrader: (1)

Problem with the price is that you have to take the motor apart entirely to get to the apex seals - which means you have to replace other seals as well AND you may find some of the big parts are out of spec. Don't think of them as seals, think of them as piston rings.

Also the compression results are weird, you should have 6 numbers, not 4. 3 chambers per rotor. If this test was done with a regular piston compression test, they're meaningless. Does this shop actually know what they're doing?

BigBadChris

iTrader: (4)

I was quoted $5400 for motor out, torn down, new seals and reinstalled. 5k isn't horrible. It can be done for less, but quality counts too.

Azki23

Heyy they said all 102. One pulse of 98. Hence I put " by 102.

Exactly Front - 102-102-102 Rear- 102-98-102 (I overheard the guy say @100rpm)

RIWWP

iTrader: (2)

250rpm is the speed it needs to be normalized to. The RPM speed should generally be between 200rpm and 300rpm.

The slowest tested starter I've ever heard of on the forum since 2007 was 170rpm. 100rpm doesn't sound possible.

98psi is passing if the testing speed is 260rpm or less. Failing if it's 270rpm or more. Assuming this is at sea level.

That speed really does matter.

Azki23

I'll give em a call now and verify

Azki23

Weird. He said. Doesn't matter what it's cranked at - the 98 discrepancy won't be different. Then said something about 400rpm. I'm so confused :/

9krpmrx8

iTrader: (46)

He doesn't know what he is talking about. The cranking RPM greatly affects the readings and there is no way it is cranking 400RPM. Typically with a healthy Series 1 starter it will crank about 245-260RPM. With a healthy S2 starter (larger), it will crank from 290-310RPM from what I have seen on our tester and the Mazda tester and the twisted Rotors tester. With a failing starter or weak battery they can crank as low as 150RPM. My guess is that he used a piston compression tester and so the results don't mean a whole lot other than the fact that you know the engine si not completely toasted.

Go to a Mazda dealer and pay $100-150 for a proper rotary engine compression test.

Azki23

I took it to a rotary mechanic. He did use the correct tool but I think he thought I was asking something else maybe about the cranking rpm. So without that info that reading is pointless?

Mysticstylezrx8

I bought an extended warranty through my local mazda dealer and it cover that

RIWWP

iTrader: (2)

Correct, the numbers aren't actually telling you anything without the RPM that the test was taken at.

If the numbers were under 78psi or so, we would say it's failing regardless of the RPM. Above 110psi, we would say it's passing regardless of the RPM. Between those numbers, pass or fail depends on the RPM of the test.


Note: All of these assumptions are assuming you are at sea level. If you are a couple thousand feet up, it changes things too.

RIWWP

iTrader: (2)

This chart I made a while back should answer a few things for you:

9krpmrx8

iTrader: (46)

"rotary mechanic".

Azki23

Thanks mate. Getting her retested in a week at a different place. Will be very specific.

Will probably go back to the original place for upgrades and service as their the highest rated for rotary engines in my country let alone city (Auckland New Zealand)

Will repost with my results next week. My original hopes for this jappy port was single turb. Exaust. Bridgey and looks. But it's definitely not healthy enough.

Saw a 32kms fd rx7 for a similar price. Would consider but. Ugh.
This 8 has burnt her nails into me
she's beautiful

RX8Soldier

iTrader: (24)

With the engine apart for rebuild, consider porting it. Though I strongly recommend you read up on porting the renesis. "Single turb" and "bridgey" suggests that you haven't read enough into the modding of this vehicle...