Compression ratio for LS-V with CTR pistons
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Compression ratio for LS-V with CTR pistons
I know all builds are different, but what is the average compression ratio for an LS-V with CTR pistons. I want to go turbo, but some people on here said the CR is too high. I guess it all depends on the head gasket but I'm not sure what was put on, I bought the car this way. Any help would be appreciated.
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From: Paradise, Newfoundland Canada
Re: Compression ratio for LS-V with CTR pistons (merepink)
Uh, boosting a motor with a 12:1 CR is asking for it.
Your tune better be bang [freak]ing on or your gonna pop something. Also, if he's got CTR pistions, he's likely got stock slevees too. Some how I don't see that bottom end lasting under boost.
Your tune better be bang [freak]ing on or your gonna pop something. Also, if he's got CTR pistions, he's likely got stock slevees too. Some how I don't see that bottom end lasting under boost.
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From: Holiday, FL
Re: Compression ratio for LS-V with CTR pistons (dc2ls-vtec)
OP, If you ask me, its pretty risky to use those pistons in an LS/V with a stock gasket thickness while boosting.
I found this from Garrett Turbo's website Turbo Tech 101-103
http://www.turbobygarrett.com/...tml#d
There are numerous factors that affect the maximum allowable compression ratio. There is no single correct answer for every application. Generally, compression ratio should be set as high as feasible without encountering detonation at the maximum load condition. Compression ratio that is too low will result in an engine that is a bit sluggish in off-boost operation. However, if it is too high this can lead to serious knock-related engine problems.
Factors that influence the compression ratio include: fuel anti-knock properties (octane rating), boost pressure, intake air temperature, combustion chamber design, ignition timing, valve events, and exhaust backpressure. Many modern normally-aspirated engines have well-designed combustion chambers that, with appropriate tuning, will allow modest boost levels with no change to compression ratio. For higher power targets with more boost , compression ratio should be adjusted to compensate.
There are a handful of ways to reduce compression ratio, some better than others. Least desirable is adding a spacer between the block and the head. These spacers reduce the amount a "quench" designed into an engine's combustion chambers, and can alter cam timing as well. Spacers are, however, relatively simple and inexpensive.
A better option, if more expensive and time-consuming to install, is to use <U>lower-compression pistons</U>. These will have no adverse effects on cam timing or the head's ability to seal, and allow proper quench regions in the combustion chambers.
Good stuff, and I would trust there knowledge and recommendations anyday over any trial user/noob advise on HT
Modified by DC_Legacy at 11:40 AM 8/7/2008
Modified by DC_Legacy at 2:49 PM 8/7/2008
I found this from Garrett Turbo's website Turbo Tech 101-103
http://www.turbobygarrett.com/...tml#d
There are numerous factors that affect the maximum allowable compression ratio. There is no single correct answer for every application. Generally, compression ratio should be set as high as feasible without encountering detonation at the maximum load condition. Compression ratio that is too low will result in an engine that is a bit sluggish in off-boost operation. However, if it is too high this can lead to serious knock-related engine problems.
Factors that influence the compression ratio include: fuel anti-knock properties (octane rating), boost pressure, intake air temperature, combustion chamber design, ignition timing, valve events, and exhaust backpressure. Many modern normally-aspirated engines have well-designed combustion chambers that, with appropriate tuning, will allow modest boost levels with no change to compression ratio. For higher power targets with more boost , compression ratio should be adjusted to compensate.
There are a handful of ways to reduce compression ratio, some better than others. Least desirable is adding a spacer between the block and the head. These spacers reduce the amount a "quench" designed into an engine's combustion chambers, and can alter cam timing as well. Spacers are, however, relatively simple and inexpensive.
A better option, if more expensive and time-consuming to install, is to use <U>lower-compression pistons</U>. These will have no adverse effects on cam timing or the head's ability to seal, and allow proper quench regions in the combustion chambers.
Good stuff, and I would trust there knowledge and recommendations anyday over any trial user/noob advise on HT
Modified by DC_Legacy at 11:40 AM 8/7/2008
Modified by DC_Legacy at 2:49 PM 8/7/2008
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Re: Compression ratio for LS-V with CTR pistons (DC_Legacy)
I'll listen to Garrett, they have a little experience on the subject. I actually bought a Greddy turbo kit on ebay 2 days ago, but cancelled the order b/c the guy tried to charge me $200 to ship it. It's good that I didn't go through with it or it looks like I would have blown my engine.
My engine runs very good as it sits, so I'll probably just keep it NA and build another specifically for boost.
My engine runs very good as it sits, so I'll probably just keep it NA and build another specifically for boost.
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Re: Compression ratio for LS-V with CTR pistons (dc2ls-vtec)
It's also been shown and calculated that the actual CR with CTR pistons in an LSVTEC is much higher than what the c-speed calculator shows.
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From: Holiday, FL
Re: Compression ratio for LS-V with CTR pistons (dc2ls-vtec)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dc2ls-vtec »</TD></TR><TR><TD CLASS="quote">I'll listen to Garrett, they have a little experience on the subject. I actually bought a Greddy turbo kit on ebay 2 days ago, but cancelled the order b/c the guy tried to charge me $200 to ship it. It's good that I didn't go through with it or it looks like I would have blown my engine.
My engine runs very good as it sits, so I'll probably just keep it NA and build another specifically for boost. </TD></TR></TABLE>
Yeah I originally setout to build my setup with a Vortech SC w/Aftercooler but after I bought the kit used on CheapBay it came with a few missing parts that were going to cost more new from Vortech then what I paid for the entire setup used, so I sold the kit as I received it and went the NA route.
I think I made a wise choice for my daily driver. You could always get some ITB's and some descent cams that'll get you in the 200whp range.
My engine runs very good as it sits, so I'll probably just keep it NA and build another specifically for boost. </TD></TR></TABLE>
Yeah I originally setout to build my setup with a Vortech SC w/Aftercooler but after I bought the kit used on CheapBay it came with a few missing parts that were going to cost more new from Vortech then what I paid for the entire setup used, so I sold the kit as I received it and went the NA route.
I think I made a wise choice for my daily driver. You could always get some ITB's and some descent cams that'll get you in the 200whp range.
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