methanol and boost... compression ratio limitations

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Hello all,

I've been playing around with numbers and researching for quite some time, so I figured I'd see what you all thought.

The engine in question is a low deck 470 big block stroker with a 10:1 static compression ratio and stealth aluminum heads.

With the implementation of a methanol injection system such as a Snow Performance kit that utilizes a 50/50 water methanol mixture, would 6 lbs of boost be attainable on 91 octane pump gas without detonation issues?

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I have ran as much as 7 lbs boost on a iron headed pump gas 426 hemi street hemi motor with no problems. You shouldn't need to add the injection at that level of boost The best thing to do is to start with the total timing limited to 22 degrees before top dead center(with a very cold spark plug) at WOT and then slowly, one degree at a time advance the timing until you start to see black or shiny specs on the center porcelyne (SP?) in the spark plugs, once you get it there then back the timing up 1 or 2 degrees Another good option is to use a boost timing retard module that will back the timing up for you automatically so it will drive nice under vacume and still protect the motor under boost

Quote:

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Hello all,

I've been playing around with numbers and researching for quite some time, so I figured I'd see what you all thought.

The engine in question is a low deck 470 big block stroker with a 10:1 static compression ratio and stealth aluminum heads.

With the implementation of a methanol injection system such as a Snow Performance kit that utilizes a 50/50 water methanol mixture, would 6 lbs of boost be attainable on 91 octane pump gas without detonation issues?

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Assume you are adding a blower to a already built motor - 10:1CR? Also don't know where you are getting your 50/50 mix from unless it is an aftermarket mix from Snow, etc, cause windshield solvent is about 32% - and that's for winter blend. At any rate, the big variable is the pump gas #. I have seen it all over the place - and that's all over the place. So, you better cut yourself a level of margin. Are you running a blower cam - 114LSA or there abouts? To answer your question, yes, you can run 91 with injection and the timing cut way back - IMO. The question you have to ask yourself is the power gain trying to accommodate 91 octane fuel worth the cost of adding a very under utilized power adder - blower. Of coarse there is always the "WOW" factor.