Kevinb
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Hello all.
Just bought a Dynamite Mach 2 21.
I checked the squish band height, factory is at 23,000th and 26,000th with the extra shim.
I have been reading about pre detonation with this particular engine.
Usually all my other 3.5cc engines are between 16,000th to 22,000th they all run fine on medium plugs, 40% and slightly longer pipe lengths.
I never ran low nitro content in 40 years.
For this engine in a Ofna Ultra MBX R2, I'll be running 30%
Medium plug
slightly longer pipe.
8.5 insert
And both shims to give me 26,000th squish band height.
With all the talk about how this particular engine is prone to pre detonation I noticed that it was from people who installed this 6 port .21 engine in place of a lower RPM 3 port and or, started out running the recommended 20% and bumping up to 30% without retuning the pipe length.
Something tells me they didn't lengthen the pipe to compensate for the faster sound/shock wave from the higher RPM due to the higher nitro content. I'm wondering if it's because no one actually tunes the pipe because I haven't read anyone talking about pipe length when taking about pre detonation.
Is this particular engine that bad with pre detonation? I just don't understand how it could be any different from other engines. I mean as far as stroke and chamber volume. Heck even the 23,000th squish band height is about right. Mine is more 22,600, not exactly 23,000th.
So I'm wondering why this particular engine is prone to pre detonation or is that just a myth lol.
All my ot
Just bought a Dynamite Mach 2 21.
I checked the squish band height, factory is at 23,000th and 26,000th with the extra shim.
I have been reading about pre detonation with this particular engine.
Usually all my other 3.5cc engines are between 16,000th to 22,000th they all run fine on medium plugs, 40% and slightly longer pipe lengths.
I never ran low nitro content in 40 years.
For this engine in a Ofna Ultra MBX R2, I'll be running 30%
Medium plug
slightly longer pipe.
8.5 insert
And both shims to give me 26,000th squish band height.
With all the talk about how this particular engine is prone to pre detonation I noticed that it was from people who installed this 6 port .21 engine in place of a lower RPM 3 port and or, started out running the recommended 20% and bumping up to 30% without retuning the pipe length.
Something tells me they didn't lengthen the pipe to compensate for the faster sound/shock wave from the higher RPM due to the higher nitro content. I'm wondering if it's because no one actually tunes the pipe because I haven't read anyone talking about pipe length when taking about pre detonation.
Is this particular engine that bad with pre detonation? I just don't understand how it could be any different from other engines. I mean as far as stroke and chamber volume. Heck even the 23,000th squish band height is about right. Mine is more 22,600, not exactly 23,000th.
So I'm wondering why this particular engine is prone to pre detonation or is that just a myth lol.
All my ot
