[Henry Schmidt]

Answers in red.

Originally posted by Jeff Alton
What are the unnecessay challenges that should be avoided? Hot spots, carbon deposits, lower compression from machine work, plugs notorious for falling out. What CR and cylinder bore can one get away with while not twin plugging? Or, what would you say the safe thresh hold is for not twin plugging when running pump gas? There are too many variables to define a specific c/r that works in every instance

Is there a rule of thumb for cam/cr/bore that can be applied to avoid the cost of going twin plug? same answer

I always assumed (and quite probably incorrectly) that if the bore was 95 or above, one would be "pushing it" with a higher than 10.3 "euro" CR. (on pump gas) And even that may be pushing it. I realize running a bigger cam can help get away from detonation issues, but how big? Static compression is only part of the equation. Dynamic compression is varied by cam configuration. Overlap is the key. More overlap = less compression.

Anyone out there know of PROVEN high performance combos that work with out twin plugging that are not "mild" motors? There are literally 100s. A thread all it's own. Compression, ignition timing, mixture, fuel octane, chamber shape and dome configuration all need to be considered to prevent detonation.

I know, a bit of topic of the thread, but it would still be good info to have.

Cheers