Re: 232 Engine
Here's an interesting tidbit I pilfered from an automotive forum where a Mike Brown era crew member was discussing problems related to this engine:
"It is in fact an 18 cylinder Wright R-3350(-93) engine with mechanical fuel injection. After a $175k engine overhaul last year, we replaced two more sets of pistons/cylinders (@ $54k/set) due to detonation. The net result was a racer that could not race and a pile of unserviceable parts. The boss is still a little pissed! The solution looks like it could be had with a relatively small number of (cheap) parts. I was wondering if the solution was as simple as a knock-sensor. Unfortunately there is relatively little data available on what a knock-sensor does and what the wave-form of a knock looks like. I have read some data that suggests that the knock looks like a spike in the 3kHz region. The article did not mention the number of cylinders in the test engine. Is the phenomenon independent of the number of cylinders? I am trying to figure out what the 'event' looks like so that I can 'capture' it in some form when it shows up.
Wow! there are so many good ideas I do not know where to begin. To "flesh-in" the detail ... here goes ...
The 3350-93 is not the same engine that appeared in the B-29. The -93 is mechanically fuel injected (like the Daimler DB-603) whereas the the bomber motor was carbuerated (but still fed a supercharger). The fuel in WWII was typically 145/160 octane (purple color), enhanced primarily with benzene. The fuel consumed for normal flying in the race plane is 100LL which is adequate for the task. For racing, we use the VP Racing Fuel with a performance number (octane) of around 160 (at $6.00/gallon - ouch!). This gets "hot-rodded" with the addition of CI3, a very high manganese solution which the Air Force abandoned in the 1960's because it was too hard to mix in the normal fueling process. This yields a performance number around 200. This allows manifold absolute pressures (MAP) in the range of 65 to 100 in-Hg. This high MAP increases (virtually guarantees) the problem of detonation; which is the reason I got on this board. We are currently using anti-detonation injection (ADI) to combat the detonation. The ADI is a mixture of methanol and water injected into the induction system downstream of the supercharger. The latent heat of evaporation of the ADI sucks the extra heat out of the combustion charge before it enters the cylinder. The problem with this engine installation is that you cannot hear a knock like you can in my '84 VW Rabbitt. So we are back to figuring out how you can listen for these events."
Here's an interesting tidbit I pilfered from an automotive forum where a Mike Brown era crew member was discussing problems related to this engine:
"It is in fact an 18 cylinder Wright R-3350(-93) engine with mechanical fuel injection. After a $175k engine overhaul last year, we replaced two more sets of pistons/cylinders (@ $54k/set) due to detonation. The net result was a racer that could not race and a pile of unserviceable parts. The boss is still a little pissed! The solution looks like it could be had with a relatively small number of (cheap) parts. I was wondering if the solution was as simple as a knock-sensor. Unfortunately there is relatively little data available on what a knock-sensor does and what the wave-form of a knock looks like. I have read some data that suggests that the knock looks like a spike in the 3kHz region. The article did not mention the number of cylinders in the test engine. Is the phenomenon independent of the number of cylinders? I am trying to figure out what the 'event' looks like so that I can 'capture' it in some form when it shows up.
Wow! there are so many good ideas I do not know where to begin. To "flesh-in" the detail ... here goes ...
The 3350-93 is not the same engine that appeared in the B-29. The -93 is mechanically fuel injected (like the Daimler DB-603) whereas the the bomber motor was carbuerated (but still fed a supercharger). The fuel in WWII was typically 145/160 octane (purple color), enhanced primarily with benzene. The fuel consumed for normal flying in the race plane is 100LL which is adequate for the task. For racing, we use the VP Racing Fuel with a performance number (octane) of around 160 (at $6.00/gallon - ouch!). This gets "hot-rodded" with the addition of CI3, a very high manganese solution which the Air Force abandoned in the 1960's because it was too hard to mix in the normal fueling process. This yields a performance number around 200. This allows manifold absolute pressures (MAP) in the range of 65 to 100 in-Hg. This high MAP increases (virtually guarantees) the problem of detonation; which is the reason I got on this board. We are currently using anti-detonation injection (ADI) to combat the detonation. The ADI is a mixture of methanol and water injected into the induction system downstream of the supercharger. The latent heat of evaporation of the ADI sucks the extra heat out of the combustion charge before it enters the cylinder. The problem with this engine installation is that you cannot hear a knock like you can in my '84 VW Rabbitt. So we are back to figuring out how you can listen for these events."
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