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  #21 (permalink)  
Old 11-19-2020, 02:56 PM
eschaider's Avatar
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The only way you can get away with 10 or 11:1 compression and a supercharger is very low boost and or timing. The detonation we all can hear occurs much later in the ignition event than incipient detonation.

Detonation in an n/a engine is tantamount to a tack hammer. Detonation in a blown gas engine is equivalent to using a short handled 5lb sledge hammer. Incipient detonation is undetectable by the human ear and falls somewhere between the carpet hammer and the 5lb sledge (but favors the sledge) and can do both impressive and considerable damage over time to pistons, blocks and heads.

This is what incipient detonation does to pistons over thousands of miles;



This engine did not smoke, felt responsive to the throttle but not surprisingly a little lazy. The thing that saved the throttle response was a PD blower. BTW notice how good the skirt looks. This was an example of a tuner (a big name one) who early on in his professional career subscribed to the mean is lean school of thought and produced tunes that felt very responsive to the throttl, until you put the engine under load. Then it was, well not so much ...

Over time, the slightly lean mixture, the occasional tank of not so good gas etc, etc slowly will eat away at the pistons. If this happens in an iron block you have the extra added attraction of ultimately cracking the block between the cylinders and/or down into the main webs.

In the end everyone is entitled to their own opinion about what is safe. The ultimate arbiter however is the engine. If it doesn't like what you are doing or how you are doing it, it will not matter what anyone says, thinks, or writes or who you are ... The incipient detonation will eventually catch up with the engine and cost someone a fair amount of cash to repair the damage.

The small amount (if any) of additional power obtained by engaging in an unscripted dance of death with detonation is vanishingly small compared to what the motor is capable of when built, fueled, and tuned correctly and safely.

There is no need to play Russian Roulette with a blown gas engine especially with more than one bullet in the gun.


Ed
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  #22 (permalink)  
Old 11-19-2020, 03:59 PM
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Quote:
Originally Posted by eschaider View Post
The only way you can get away with 10 or 11:1 compression and a supercharger is very low boost and or timing. The detonation we all can hear occurs much later in the ignition event than incipient detonation.

Detonation in an n/a engine is tantamount to a tack hammer. Detonation in a blown gas engine is equivalent to using a short handled 5lb sledge hammer. Incipient detonation is undetectable by the human ear and falls somewhere between the carpet hammer and the 5lb sledge (but favors the sledge) and can do both impressive and considerable damage over time to pistons, blocks and heads.

This is what incipient detonation does to pistons over thousands of miles;



This engine did not smoke, felt responsive to the throttle but not surprisingly a little lazy. The thing that saved the throttle response was a PD blower. BTW notice how good the skirt looks. This was an example of a tuner (a big name one) who early on in his professional career subscribed to the mean is lean school of thought and produced tunes that felt very responsive to the throttl, until you put the engine under load. Then it was, well not so much ...

Over time, the slightly lean mixture, the occasional tank of not so good gas etc, etc slowly will eat away at the pistons. If this happens in an iron block you have the extra added attraction of ultimately cracking the block between the cylinders and/or down into the main webs.

In the end everyone is entitled to their own opinion about what is safe. The ultimate arbiter however is the engine. If it doesn't like what you are doing or how you are doing it, it will not matter what anyone says, thinks, or writes or who you are ... The incipient detonation will eventually catch up with the engine and cost someone a fair amount of cash to repair the damage.

The small amount (if any) of additional power obtained by engaging in an unscripted dance of death with detonation is vanishingly small compared to what the motor is capable of when built, fueled, and tuned correctly and safely.

There is no need to play Russian Roulette with a blown gas engine especially with more than one bullet in the gun.


Ed
Sure. That is why about 90% of all the supercharged/turbocharged LS engines are running boost with almost 11:1 and greater. Because it doesn't work. Looks more like the tuner doesn't know how to tune the engine properly.

As i stated, 8-9 psi is easily obtainable without the need for water/meth injection. Thousands upon thousands of people are doing it in daily drivers with no issues and have a lot of miles on their cars already.
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  #23 (permalink)  
Old 11-19-2020, 06:37 PM
eschaider's Avatar
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You are missing the point here. I am not attempting to convert you to anything. I am offering you information you might find useful. If you want to boost your engine to what ever manifold pressure you like, I think you should absolutely do that. It's your engine, your parts, your money and most importantly your rules. Definitely go for what ever you think is best for your personal situation.

You should also remember a turbo does not hit the engine as hard on the bottom but hits it much harder on the top and of course you can't hear incipient detonation at lower engine speeds so you definitely can not hear it at higher speeds.

Like the song says, 'don't worry be happy".


Ed
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