E85 vs 93oct
No. The ECM will adjust short term and long term trim to adjust for the fuel unless it requires more than 20% rich to solve the imbalance. I have lots of practice with Supras.
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Lead Lap
Joined: Aug 2014
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From: sc
I didn't say "when" I said "why". Fatigue is a combination of both...
Given the stress of these events, one might assume the exhaust stroke would be easiest on the connecting rod. The objective is simply moving the piston to push the spent gasses through an open exhaust valve. This, in fact, is the most dangerous time in the entire combustion process for a connecting rod. As Manley’s Michael Tokarchik explains, “The reason why is there’s no cylinder pressure buffering during that cycle.” With many camshafts having at least some type of intake and exhaust valve overlap, there is no cushioning pressure to slow the piston down.
As the crank makes the turn again over and past top dead center, inertial forces continuing driving the piston on it’s upward journey. This is the end of the exhaust stroke and beginning of the intake stroke. At this point, the rod is stressed in a tensile fashion. The big end must comply with the crank and begin the journey back in the opposite direction, while the small end wants to stay with the piston and continue upward. According to Tokarchik, this is actually where Manley sees the most failures occur in connecting rods.
During all of these directional changes, both ends of the rod are stressed, which can eventually lead to ovaling the bearing bores or complete failure.
As the crank makes the turn again over and past top dead center, inertial forces continuing driving the piston on it’s upward journey. This is the end of the exhaust stroke and beginning of the intake stroke. At this point, the rod is stressed in a tensile fashion. The big end must comply with the crank and begin the journey back in the opposite direction, while the small end wants to stay with the piston and continue upward. According to Tokarchik, this is actually where Manley sees the most failures occur in connecting rods.
During all of these directional changes, both ends of the rod are stressed, which can eventually lead to ovaling the bearing bores or complete failure.
All very true and consistent with my experience as well. IME, the engine blows when you lift off the gas from high rpm, not from too much compression loading, and never related to fuel unless you're running nitromethane.
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Lead Lap
Joined: Aug 2014
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From: sc
the engine didn't stop running after ventilating the block 
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Lavrishevo
LS - 3rd Gen (2001-2006)
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Nov 6, 2016 07:33 PM
