air fuel ratio with boost
#41
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They way I see it, whatever the engine, whatever the combination, its all about preventing failure. If an engine can run at 12:1 and not fail, then thats good. If another engine needs 10.5:1 to not fail, then thats good as well.
My goal is not to speculate on GM on what they did wrong, nor mercury racing, or what they did right. I aim my posts at the average do it yourselfer, like myself. For the guy building a home built supercharged marine engine. Some of these topics, can be beneficial to them. While the 1075 lives at the air fuel ratio it does, it is certainly not the target for the guy running a 177 blower on a 502 with a carb and no knock protection, no intercooler, poor fuel distribution, etc. Many guys over the years have burnt pistons, valves etc, due to lean conditions before widebands were available. They thought the plugs looked fine, so it had to be something else causing it. Next thing they are running 28* timing, to keep it together, which really was a band aid to the tune.
My goal is not to speculate on GM on what they did wrong, nor mercury racing, or what they did right. I aim my posts at the average do it yourselfer, like myself. For the guy building a home built supercharged marine engine. Some of these topics, can be beneficial to them. While the 1075 lives at the air fuel ratio it does, it is certainly not the target for the guy running a 177 blower on a 502 with a carb and no knock protection, no intercooler, poor fuel distribution, etc. Many guys over the years have burnt pistons, valves etc, due to lean conditions before widebands were available. They thought the plugs looked fine, so it had to be something else causing it. Next thing they are running 28* timing, to keep it together, which really was a band aid to the tune.
Last edited by MILD THUNDER; 01-28-2015 at 07:48 PM.
#42
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one thing that has not been mentioned yet is the heat soaking of the innercooler and the combustion chaimber. in a v btm boat with throttles at wot for longer runs.an engine may be fine at 3 minutes of wot but what about 10 or 15 minutes?
#44
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#45
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I'll take a stab at it, but it probably only takes 35-45hp for a Vette to cruise at 65mph. So,,,,very light throttle, very high vacuum, very little oxygen/fuel in that combustion chamber....ie:very low cylinder pressure.
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#49
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i,m pretty sure those ratio,s are at wot,yes if you are crusing at 4000 rpm and not at wot i think the a/f ratio will go much leaner.
#50
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I would wonder what the AFR's are for the Vette to pass emissions for CA & Carb testing. There is no way being street legal in CA running in the 10's AFR.
Last edited by BUP; 01-29-2015 at 12:09 AM.