What is better, compression vs timing?
11-14-2001, 11:41 AM
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What is better, compression vs timing? This is sort of an offshoot of Vince's thread about flow and tumble and such.
If raising the compressin means you need to sometimes reduce timing to counteract detonation, is it still advantageous to raise it? Is it better to run more compression and less timing or run a lot of timing at a lower compression?
If raising the compressin means you need to sometimes reduce timing to counteract detonation, is it still advantageous to raise it? Is it better to run more compression and less timing or run a lot of timing at a lower compression?
11-14-2001, 01:31 PM
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Re: What is better, compression vs timing? NHRA Pro Stock engines run something near 20:1 compression ratios and about 10 degrees total ignition advance if that tells you anything.
On naturally aspirated, spark ignition, internal combustion engines, changes in compression ratio will result in higher cylinder pressure, thermal efficiency, and torque than changes in ignition timing. So, if your building the engine from scratch, add compression and drop back your timing.
But, it is obviously easier and cheaper to raise the timing on an existing engine, than tear it down and add compression.
On naturally aspirated, spark ignition, internal combustion engines, changes in compression ratio will result in higher cylinder pressure, thermal efficiency, and torque than changes in ignition timing. So, if your building the engine from scratch, add compression and drop back your timing.
But, it is obviously easier and cheaper to raise the timing on an existing engine, than tear it down and add compression.
11-15-2001, 12:38 AM
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Re: What is better, compression vs timing? I run higher CR (11.3:1) and less timing, it works for me. I don't know exactly how much timing as MMS did the PCM work for me, but I believe Mike took out almost 4-5 degrees from stock.
In Cali we also have poor pump gas (91 octane).
In Cali we also have poor pump gas (91 octane).
11-15-2001, 12:39 AM
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Re: What is better, compression vs timing? Thanks Crazy.. I started another thread about valve size as well, secondary to your comment in my post.. Now lets hope the gurus come in and share their secrets.. This is real important for the consumer to know. Keeping this information from us is like stealing. I should know if what I am paying for is beneficial in my plight for speed.. I remember going to buy car audio equipment and the guy selling me this huge high power amp. My car sounded awesome, but when I looked at what the gain settings were. They were 1/4th of what it could be. Turned them up and found out I was sold some cheap azz speakers.. Get my point..?
11-15-2001, 12:48 AM
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Re: What is better, compression vs timing? Stock average WOT timing on '97-'00 LS1s is 27 to 27.5 degrees usually.
[ November 14, 2001: Message edited by: 2quick4u ]</p>
[ November 14, 2001: Message edited by: 2quick4u ]</p>
11-15-2001, 12:52 AM
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Re: What is better, compression vs timing? [quote]Originally posted by 2quick4u:
<strong>Stock average WOT timing on '97-'00 LS1s is 27 to 27.5 degrees usually.
[ November 14, 2001: Message edited by: 2quick4u ]</strong><hr></blockquote>
Stock maf/stock tuning = 27.5*
Stock maf/hpp3 tuning = 29*
Ported maf/stock tuning = 29*-30*
Ported maf/hpp3 tuning = 31*
<strong>Stock average WOT timing on '97-'00 LS1s is 27 to 27.5 degrees usually.
[ November 14, 2001: Message edited by: 2quick4u ]</strong><hr></blockquote>
Stock maf/stock tuning = 27.5*
Stock maf/hpp3 tuning = 29*
Ported maf/stock tuning = 29*-30*
Ported maf/hpp3 tuning = 31*
