Compression Loss

ClassicAU · 07-02-2007, 10:06 PM

Hi all
I just got a bit of bad news tonight. I had a feeling that something was a bit off after the last couple of poor showings i have had at the track, and i was right. It turns out that i have lost 60% of the compression in my engine. How does this come about? Would it be because i have a heavy foot, or do i just have a Friday afternoon motor? I am a little disappointed, but i guess its no ones fault but my own. Is there any way i can redeem my motor, or is that it for it?
Cheers
Evan

p.s. Yes Woosha, you were right! :P

JC · 08-02-2007, 02:40 AM

Engine bits wear out - simple as that. Every engine needs a rebuild at some stage, or replacement. It's probably the EF lid that's done it - made the engine feel older than it really is. LOL.

The good news is that turbos like low compression!

Seriously, you can pick up a second hand AU engine for around $600 (talk to FTG, or just search on ebay), then just have to get it installed. Or get a rebuild for around $3k to $5K for something half decent (maybe mild cam, bit of headwork, better pistons/rings etc) - actually if you get it rebuilt, may as well drop the compression ratio properly and bolt on a turbo. Not much change out of $10k though.

chief · 08-02-2007, 07:20 PM

I will have an I6 motor for sale within a month. Runs very well, always serviced Mobil1 oil and premium fuel. PM me if you like.

Casper · 08-02-2007, 07:27 PM

This must have happened pretty quickly then. To pull 120+rwkw late last year means you certainly were not losing compression at that time.

GK · 08-02-2007, 07:40 PM

Sorry to hear the news Evan.

GK

NeishaXR8_347 · 08-02-2007, 08:34 PM

Not good news, but can i ask what is the actual problem? did someone do a cyl leak down test and tell you what the issue is ie, rings or valves not seating 100%, maybe just a reco head will set you off again.
I have done engines at work with over 200k on them that come in for a headgasket and the valves are usually never seating 100%, i new valve job and it will still have about 90% of original comp as no rings seal 100%.

Racecraft · 08-02-2007, 08:40 PM

AU i6 engines are everywhere.. Don't fret about it.. A good set of leads and plugs will cost you half as much as a 2nd hand engine does..

I pay $500 inc. GST and just bought another 2 yesterday. One has 46xxx and the other 63xxx klms.. Great value. 2 engines delivered for 1k

NeishaXR8_347 · 08-02-2007, 09:33 PM

Quote:

Originally Posted by Racecraft

AU i6 engines are everywhere.. Don't fret about it.. A good set of leads and plugs will cost you half as much as a 2nd hand engine does..

I pay $500 inc. GST and just bought another 2 yesterday. One has 46xxx and the other 63xxx klms.. Great value. 2 engines delivered for 1k

Whats the reason for stocking up?

Racecraft · 08-02-2007, 10:15 PM

I like to put a fresh engine into my cabs when they retire.. I usually sell them to my own drivers and for 5 hundred bucks + 3 hours fitting it is a nice bonus to make sure they have that tight feel..

ClassicAU · 08-02-2007, 10:46 PM

Thanks for the replies guys. The reason i asked was when i got home from work last night my old man hit me with this news. I don't know if he got it tested or anything like that. I did, however, call my mechanic this morning to ask what the deal was, and he had no idea what i was talking about!!
The only reason i believed him was because that last couple of times i have been on the track it has pulled really bad numbers. At the time it was put down to the conditions though. But as Casper mentioned, only three months or so ago it pulled 121rwkW after an edit. Hence why i am so puzzled! Is there an easy way of testing this to see how the motor is going, or do i need to go and see my mechanic?

Evan

FS5 · 09-02-2007, 05:17 PM

Quote:

Originally Posted by ClassicAU

Thanks for the replies guys. The reason i asked was when i got home from work last night my old man hit me with this news. I don't know if he got it tested or anything like that. I did, however, call my mechanic this morning to ask what the deal was, and he had no idea what i was talking about!!
The only reason i believed him was because that last couple of times i have been on the track it has pulled really bad numbers. At the time it was put down to the conditions though. But as Casper mentioned, only three months or so ago it pulled 121rwkW after an edit. Hence why i am so puzzled! Is there an easy way of testing this to see how the motor is going, or do i need to go and see my mechanic?

Evan

like neisha said you can get a leak down test done ,this will let you know whats going on .

just remember when running at the drags your times will vary a fair bit depending on conditions .its not uncommon to loose 2/3mph and .4/.5 of a sec in ET's going from winter to summer.

mik · 09-02-2007, 08:53 PM

is it using oil?

AU2PWR · 09-02-2007, 08:57 PM

Dont Tell me where not going to run each other at Heathcote now evan ,,,

ClassicAU · 10-02-2007, 01:07 AM

I will check the oil tomorrow, but i don't think it is. Would that be an indicator of compression loss? I will try and get a test done tomorrow if i can, if not next week.

Quote:

Originally Posted by AU2PWR

Dont Tell me where not going to run each other at Heathcote now evan ,,,

Well Daniel, if the motor does turn out to be shagged, then h'm afraid that wouldn't be much of a match up then would it? But if all goes well then its on like Donkey Kong buddy!!

au2sw · 10-02-2007, 08:16 AM

good luck man, i hope its nothing serious that a head job wouldnt fix.

mik · 10-02-2007, 05:10 PM

if its using a fair bit of oil is and its not leaking you could bet its pretty tired, but usually if they use excessive oil they also blow some blue smoke, some times if its a small amount of blue smoke that clears after a while, thats worn valve guides /stem seals if it blows smoke all the time rings are sad as well, thats my understanding of it anyway, someone will correct me if i`m wrong no doubt :yeees:,compression test will tell, if the engine gets cooked (overheated)that will suck the life out of the rings as well,
good luck

ClassicAU · 10-02-2007, 06:14 PM

Thanks for that mik. I did check the oil, and the dip stick is actualy over full, and the oil was changed over 2000kms ago. So it doesn't look like it is using any oil. But you did mention overheating, and that reminded me of a bit of an incident that happened a while ago. I blew the top radiator hose on the way to work, and didn't notice until the car actually cut out on me. I ended up almost emptying the radiator, as i had kept driving with no hose for about ten minutes. But my mechanic checked it and he said it was fine, and it was over a year ago anyway.
I think i am just being paranoid. I will try and get a comp test anyway, just so i feel better!

Evan

mik · 10-02-2007, 06:21 PM

actually we should be ok in think these, au`s have the fail safe cooling..... forgot about that, but anyway it sounds like another issue to me, not using oil, no smoke will something small and cheaper i think ,
cheers