Mazda Rotary Club

General => General Queries / Hints and Tips on purchasing a rotary => Topic started by: Rich Cheung on November 24, 2004, 12:19:19 PM

Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 12:19:19 PM
Hi Guys,

I\'m going to see a really nice black R1 on Saturday.
The dealer has just taken it to Roteknics to get a compression test done. These are the readings.

Front Chamber
92psi
92psi
90psi
Rear Chamber
91psi
92psi
92psi

Car has covered 60,000. Cat back system, HKS filters, Apexi ecu.

Does this sound like a reasonable engine given the mileage ?
Dealer said Roteknics thought it was healthy.
What are your thoughts?

Cheers,
Rich
Title: Compression Readings
Post by: 88GT-R on November 24, 2004, 01:09:10 PM
Hi,
That is fairly good and even for 60grand. Generally, below 80psi is looking tired and in need of a build.

John
88 GT-R
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 01:10:27 PM
So this is about 6.3 bar.
I read on another thread 8.5 bar for recently rebuilt engine
7.0 for an engine with 35k on the clock.

So really how far is 6.3 away from re-build time ? I guess the fact the numbers are all even is a good sign.

Rich
Title: Compression Readings
Post by: 88GT-R on November 24, 2004, 01:25:36 PM
Hard to say... generally, all being even, rebuild time is about 80grand. All depending on the rate of wear etc.

John
88 GT-R
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 01:39:25 PM
John - I appreciate there are a lot of factors that contribute to how soon a rebuild may be needed.

Are there any procedures I can do to improve the longevity of the engine ?

Regular oil changes I guess with a good mineral oil
Spark plugs - any particular rating ?
What other practical things can you guys suggest ?

Cheers,
Rich
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 01:55:48 PM
Whats the price of the car Rich??? As this would give a better indication if the car is worth having, even if the rebuild is like 15k away???

Also any pic of the car???

Gurj
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 02:17:30 PM
Can get the car for £6.8k.
How do I post pics m8 ?

Rich
Title: Compression Readings
Post by: Martiny on November 24, 2004, 02:20:45 PM
When you post a reply, use the ATTACH FILE button at the bottom:D
Title: Compression Readings
Post by: petemillis on November 24, 2004, 02:23:01 PM
Year?
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 02:27:09 PM
L plate, 94.

QuoteWhen you post a reply, use the ATTACH FILE button at the bottom

Thanks but I tried that. It doesn\'t seem to like the file format.
I\'ll try and save it as something different and try again.

Rich
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 02:34:53 PM
Pic of car
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 02:35:34 PM
pic of engine
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 02:46:11 PM
Looks a nice car Rich, i guess if you can budget for a rebuild then it should be ok, just remember the rebuild could be in 5k or it could be 20k???

Does that include the FTO exchange.
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 03:07:03 PM
Pains me to do it but I\'m selling the FTO to a trader via ebay for 3.4k :(

So this is just a straight cash deal.
Going to see it on Saturday.
If anyones in the Reading area and could meet up with me to view it that would be great.

Rich
Title: Compression Readings
Post by: Freddy on November 24, 2004, 03:24:02 PM
Hi Rich,

Nice looking car but for that price. It is slightly high considering the engine. 6.8k plus 3k for rebuild.

Regular servicing can only add to the longetivity. But Gurj bro, theres no way, this is good for another 20k miles. 8k miles tops imho and that is being very optimistic, but being realistic; I would say 5k miles.

Rgds
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 03:50:35 PM
Freddy,

was just saying you dont know if it would last 5k or 20k as even good compression readings aren\'t that accurate.

But for the fee of £9k or £10k a much better rx7 could be bought.:)
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 03:57:37 PM
OK guys so if it was your money you\'d probably leave it and keep looking yes ?
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 03:59:52 PM
Rich, have a look at the following:

1995 Rx7 in Black with chrome 17" alloys with recent rebuild reading 50000 miles on clock, £9595 - 07814 019599
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 04:01:23 PM
Or

1995 RX7 in Red, rebuild 2k ago reading 45000 miles on clock £6995 - 07973 471637
Title: Compression Readings
Post by: sadgoth on November 24, 2004, 04:08:41 PM
there\'s a few of us in Reading and surrounding PM me and I\'ll see if I\'m around
Title: Compression Readings
Post by: Rich Cheung on November 24, 2004, 04:39:27 PM
Cheers Gurj.
I\'ll give the guys a bell and get some info.

Rich
Title: Compression Readings
Post by: grinder on November 24, 2004, 04:44:41 PM
if i had 6.8K i know what i would buy :)

there are 2 in the for sale section here - one is 6.5K and is a corking example ( i would love to buy it ) and one at 5K that needs about a grand spending on it - im sure thats had a rebuild aswell

happy hunting

Stu

( and for an FD engine - i would expect a rebuild at anything between 40K and 60K - anything above that is rare - but thats only my opinion )
Title: Compression Readings
Post by: Freddy on November 24, 2004, 04:56:29 PM
Sorry Gurj, think I put my msg the wrong way. What I was saying, is even it has 60k with good readings. Has anyone known a FD to last 80k miles without a rebuild. The most I have seen was 70k. I know a mate was selling his FD last year with compression test being great. Took someone for a test drive, came back, parked up, fire her up again - kaput engine.

The above give food for though however, if a RX had a rebuild at 50k and the other at 45k miles. Surely that gives a good indication of how long the engine lasts in relation to how well its been looked after.

Rgds
Title: Compression Readings
Post by: gsb876 on November 24, 2004, 06:00:16 PM
I guess usually about 60k and the rebuild in just around the corner??? depends on how the engine has been looked after.

Cool freddy i know what you meant, gonna try and make the next northern meet if i can:)
Title: Compression Readings
Post by: 88GT-R on November 24, 2004, 06:54:00 PM
QuoteOriginally posted by Rich Cheung
John - I appreciate there are a lot of factors that contribute to how soon a rebuild may be needed.

Are there any procedures I can do to improve the longevity of the engine ?

Regular oil changes I guess with a good mineral oil
Spark plugs - any particular rating ?
What other practical things can you guys suggest ?

Cheers,
Rich

i know the other guys have pointed you in a couple of new directions with ref to other cars. I hope you find the one you are after. The white FD for sale on the forum looks like a good buy.

To anwer your question,
Spark plugs- go for 9`s all round, change every 3000miles
Oil change - i change mine monthly, but the limit is 2800-3000.

Practical stuff - Consider running premix with the oil injection. Mix ratio of 400:1 This will help with a cleaner burn and helps reduce carbon build up. As proof of this, when my engine was rebuilt at 130 000km, my builder reckoned it was the cleanest rotors and housings he had stripped.
Ensure you have stable boost control, and time is given for the oil to get up to operating temp.

I hope this helps,

John
88 GT-R
Title: Compression Readings
Post by: bnaellis on November 24, 2004, 07:05:03 PM
I know of quite a few that have done 70,000 + klm
and a few over 80,000 klm.
Apex seal wear is always looked at as the be all and end all of the rotary engine. Fact of the matter is the water seals go before the apex seals do alot of the time. From what I have seen from being involved in rx7s for about 8 years or so now is that alot of owners can\'t really afford their car so the maintenance is poor because funds are short or their car has a problem but rather than take it to a garage they continue to drive it and ignore the fault until the minor fault now becomes a £2,500 bill.
A customer left my workshop recently the engine was literally bone cold, he leaves wheels spinning up the road thrashing it.
I tell him that he should let the car warm up properly first before he thrashes it otherwise he\'s only reducing the life of his engine. He says oh I didn\'t know that. These are the kind of cowboys i\'m offering warranties to that don\'t care for their car I must be some kind of fruit cake.
Title: Compression Readings
Post by: 88GT-R on November 24, 2004, 07:23:20 PM
Of course you are a fruitcake... :D will you be needing a hand to fix them diffs again at RS??  :p

John
88 GT-R
Title: Compression Readings
Post by: Martiny on November 24, 2004, 08:44:06 PM
QuoteOriginally posted by BNA_ELLIS
I know of quite a few that have done 70,000 + klm
and a few over 80,000 klm.
Apex seal wear is always looked at as the be all and end all of the rotary engine. Fact of the matter is the water seals go before the apex seals do alot of the time. From what I have seen from being involved in rx7s for about 8 years or so now is that alot of owners can\'t really afford their car so the maintenance is poor because funds are short or their car has a problem but rather than take it to a garage they continue to drive it and ignore the fault until the minor fault now becomes a £2,500 bill.
A customer left my workshop recently the engine was literally bone cold, he leaves wheels spinning up the road thrashing it.
I tell him that he should let the car warm up properly first before he thrashes it otherwise he\'s only reducing the life of his engine. He says oh I didn\'t know that. These are the kind of cowboys i\'m offering warranties to that don\'t care for their car I must be some kind of fruit cake.

Geez, at last, someone on my side!!! I keep saying with proper maintenance and driven properly, the engine should go well beyond 60k.  Thanks Brian!!!! :) :)
Title: Compression Readings
Post by: bnaellis on November 24, 2004, 08:53:03 PM
QuoteOriginally posted by 88GT-R
Of course you are a fruitcake... :D will you be needing a hand to fix them diffs again at RS??  :p

John
88 GT-R

No chance I think i\'d rather use the car to start a bonfire rather than going through that again.
Title: Compression Readings
Post by: grinder on November 26, 2004, 05:26:30 PM
QuoteOriginally posted by Martiny
Geez, at last, someone on my side!!! I keep saying with proper maintenance and driven properly, the engine should go well beyond 60k.  Thanks Brian!!!! :) :)

i agree with the statement - but you would need to have the car from brand new - and make sure that it is servcied and treat nicely throughout its life

so if someone would like to buy me a brand new 8 - im happy to test this theory :)

so what are these like for figures then from an 52k engine :

Rear
6.95
7.05
6.90
@448rpm
Front
7.50
7.25
7.55
@448rpm

to be honest the 6.xx figures worry me - and again - i reckon that this engine will be lucky to make 60K

what do you guys think ?????

Stu
Title: Compression Readings
Post by: bnaellis on November 26, 2004, 05:44:34 PM
With those figues 60k will not be the slightest problem. Those figures are actually above average for 52,000 miles.
You can hardly find an fd in Japan that\'s got a rebuilt engine below 60,000 not unless it\'s a single turbo conversion and has been rebuilt & ported to match turbo.

rgds
Title: Compression Readings
Post by: petemillis on November 26, 2004, 08:33:28 PM
Grinder, why do the 6xx figures worry you? After all, 6.90 and 6.95 are 7 really, and your other figure on that rotor is 7 as well so what\'s the issue?
Title: Compression Readings
Post by: grinder on November 27, 2004, 01:08:30 PM
i thought they were low thats all ,  there is no proof of a rebuild on the car , so i was trying to gain how long the engine would last

does it take long for the figures to drop ? do they drop a certain amount per 1000 miles ?

i dont know much about FD engines , so how long would you guys expect it to last ?

or could you assume its been rebuilt ???

thanks

stu
Title: Compression Readings
Post by: grinder on November 27, 2004, 07:43:41 PM
after speaking to brian , yes , it sounds a good engine

its not usually the compression of the engine thats the prob , its the water seals holding pressure !!

at least i have a better insight into the FD engine

ta

stu
Title: Compression Readings
Post by: Ricco_04 on January 10, 2005, 09:47:42 PM
Not proud of my mileage at all but the only rebuild that it had done was at 99,700 miles!!! :D

Worth noting that It had a dealer service every year without fail!