I know to raise compression in an engine you can shave the head,
but how can you lower the compression?
current compression is 8.0:1
and I want to know how to get it to 7.5:1
4agze....
Lowering the compression ratio
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Lowering the compression ratio
by no_8wire » Wed Jul 13, 2005 3:04 pm
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no_8wire - Toyspeed Member
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by Akane » Wed Jul 13, 2005 3:20 pm
Low compression pistons.
No "stance", no "hellaflush", none of that bullshit. Nothing but no grip on full boost.
http://www.lol.co.nz/ random shit.
http://www.lol.co.nz/ random shit.
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by RomanV » Wed Jul 13, 2005 3:29 pm
Double up on head gaskets, and machine down the top of the pistons. 
Dont actually try this.
Why do you want your comression lower than 8:1 anyway?
If you are after higher boost levels, isnt the 4agze supercharger the main problem?
IIRC it produces too much heat at high boost levels.
Dont actually try this.
Why do you want your comression lower than 8:1 anyway?
If you are after higher boost levels, isnt the 4agze supercharger the main problem?
IIRC it produces too much heat at high boost levels.
Last edited by RomanV on Wed Jul 13, 2005 3:30 pm, edited 1 time in total.
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by Mr Revhead » Wed Jul 13, 2005 3:29 pm
thicker headgasket. maybe
why do you want to lower it?
compression is good!
why do you want to lower it?
compression is good!
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by Adamal » Wed Jul 13, 2005 3:36 pm
If you're planning on sticking a turbo on it, then 8.0:1 should be fine.
Motorsport is like sex. You could take it to track and have a long, enjoyable session, or you could take it to the strip and get it over with in less than 20 seconds.
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by EVLGTZ » Wed Jul 13, 2005 3:47 pm
Shouldnt need to change compression unless your going for a very serious setup
Compressions good as others have said. Means need less boost for more power and better off boost driving
Compressions good as others have said. Means need less boost for more power and better off boost driving
EVLGTZ
Ex 4AGTE AE101 Levin - 13.3@173km/hr
Ex BPT BFMR Familia - 13.8@168km/hr
Ex 4AGZE AE82 - 14.2@163km/hr
Current - 2000 Toyota Caldina GT, 2008 Ford Territory FPV
Ex 4AGTE AE101 Levin - 13.3@173km/hr
Ex BPT BFMR Familia - 13.8@168km/hr
Ex 4AGZE AE82 - 14.2@163km/hr
Current - 2000 Toyota Caldina GT, 2008 Ford Territory FPV
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by no_8wire » Wed Jul 13, 2005 6:25 pm
well.... I thought if I am going to do something I might as well make it good.
I was reading somewhere that if I lower the compression I would be able to run 260 degree cams and 20psi without a worry, which would give in the high 300hp bracjet (apparently)
7.5:1 was what was recomended...
I was reading somewhere that if I lower the compression I would be able to run 260 degree cams and 20psi without a worry, which would give in the high 300hp bracjet (apparently)
7.5:1 was what was recomended...
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by Mr Revhead » Wed Jul 13, 2005 8:34 pm
well EVLGTZ has 250hp at the wheels on 18psi with 8.9:1 compression
so you will need more than 20psi to make the high 300hp mark....
i know of a 20v turbo that runs 25 iirc and has around 320hp at the fly.....
and its had some big bucks spent on it.
i think you may need to lower your goal a bit!
if your set on that figure, and are prepared to spend the $$ then good on ya.
but youll be wanting more compression and a GOOD ecu as starting points!
so you will need more than 20psi to make the high 300hp mark....
i know of a 20v turbo that runs 25 iirc and has around 320hp at the fly.....
and its had some big bucks spent on it.
i think you may need to lower your goal a bit!
if your set on that figure, and are prepared to spend the $$ then good on ya.
but youll be wanting more compression and a GOOD ecu as starting points!
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Compression lowering
by GOLDAE86 » Wed Jul 13, 2005 8:46 pm
Either skim the pistons to the compression ratio desired, or machine out the hemispheres in the cylinder head
To finish first, first you must finish
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by Mr Revhead » Wed Jul 13, 2005 8:50 pm
skimming 4agze pistons removes the coating.... and by all accounts its better than HPC stuff......
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Lowering compression
by GOLDAE86 » Wed Jul 13, 2005 8:52 pm
Whats the coating on the pistons, cause there is nothing wrong with HPC
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by Mr Revhead » Wed Jul 13, 2005 8:58 pm
i dont know, and know ones been able to tell me. some kind of ceramic stuff, looks similar to the stuff that coats the s/c rotors
note i dont know for sure its not as good, but iv been told by a few ppl i trust.
sbut still, not gospel!
note i dont know for sure its not as good, but iv been told by a few ppl i trust.
sbut still, not gospel!
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