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Re: Increasing compression ratio 20vt
[Re: paddy]
#423014
28/08/2007 02:39
28/08/2007 02:39
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Joined: Dec 2005
Posts: 12,295 Sandhurst
Begbie
Ex El Presidente
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Ex El Presidente
I AM a Coop
Joined: Dec 2005
Posts: 12,295
Sandhurst
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You would be better to skim the block, than the head to raise the compression
Your car is Usain Bolt with wellies
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Re: Increasing compression ratio 20vt
[Re: Begbie]
#423036
28/08/2007 03:20
28/08/2007 03:20
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Anonymous
Unregistered
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Anonymous
Unregistered
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yeah, but this means an engine out job. Thinner gasket as well will help, I did block, head and thin gasket and I'm rather impressed with the way the car picks up (mind you 16vts have 8:1 compared to the 8,5:1 for the 20vts) (estimated comp at the moment at 8.7-8:1) V.
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Re: Increasing compression ratio 20vt
[Re: ]
#423336
28/08/2007 19:50
28/08/2007 19:50
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Joined: Dec 2005
Posts: 3,158 Near Reading
JohnS
I need some sleep
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I need some sleep
Joined: Dec 2005
Posts: 3,158
Near Reading
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The other alternative is forged high compression pistons or a thinner gasket (which is available). I think the thinner gasket bumps it up to 9.5:1 but also gives better squish properties
Higher CR makes a big difference to off-boost performance, and the engine responds well to it. I run a higher than std compression ratio.
But don't expect to run the same boost if you go over 9:1 and also to ensure ECU compliance you will have to run SUL. The SUL this isn't a problem as it will also make the engine more efficient/economical which will probably totally offset the cost of the fuel
Former low boost hero - 616BHP@1.5 bar. 2.4 20VT RIP
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Re: Increasing compression ratio 20vt
[Re: JohnS]
#423410
28/08/2007 22:18
28/08/2007 22:18
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Anonymous
Unregistered
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Anonymous
Unregistered
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But don't expect to run the same boost if you go over 9:1 Does that mean run less boost for the same power, but with a better curve, or run more boost for the same power, or something else?
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Re: Increasing compression ratio 20vt
[Re: paddy]
#423517
29/08/2007 00:42
29/08/2007 00:42
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Joined: Dec 2005
Posts: 3,158 Near Reading
JohnS
I need some sleep
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I need some sleep
Joined: Dec 2005
Posts: 3,158
Near Reading
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Same power for slightly less boost generally. The VAG 1.8T engine uses higher comp and lower boost.
Squish is all about forcing the combustion gasses into the centre of the combustion chamber to improve combustion. Because the head gasket 'hole' is wider in diameter than the cylinder it slightly impacts the overall mixture. The smaller height of the higher comp head gasket means that less gasses can be diverted in the direction of the gasket section.
The head gasket is more likely to fail actually to be honest but still v unlikely as it is still a metal gasket with integral fire rings.
Former low boost hero - 616BHP@1.5 bar. 2.4 20VT RIP
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