Don't let it detonate and don't over rev it and it will live. It sounds simplistic, but those are the big killers, so if you don't allow them to happen, then the old girl will die from wear and tear.
Obviously (as has been pointed out) controlling detonation will be the big achievement.
Your intended exhaust manifold design is good and will help keep combustion chamber temps as good as you can keep them (no excess back pressure).
If you have the option, maybe go for a .86 A/R ratio turbine housing. This will tend to bring boost on a bit further up the rev range, but the lower back pressure on the engine should also help keep combustion chamber temps down/less chance of detonation.
I would look at water injection as a must. It is a much more effective detonation supressant than excessively rich mixtures. It would be great if Greg Gordon chimed in here, he's experianced with water injection and has done much research on it's effectiveness having gone thru many NACA documents on the subject when he wrote his book on supercharging.
If you do insist on using a a purely mechanical ignition system, look at finding a boost retard distributor that you could make fit to your NORD engine and have recurved to suit your needs. I personally would go a Microprocessor controlled system as I mentioned in Storm-X's thread. To me it helps elliminate 1 of the big causes of drivabillity and detonation issues in carby-turbo set ups.
If you can get decent air/fuel ratios and still have detonation issues, then ignition timing will be your engines saviour.
You must have control of your ignition timing.
Also, I would only look at machined or different pistons if your engine is in pieces already unless you are higher than 9:1 compression ratio to begin with.
I would reccomend that you make absolutely sure that your valve guides and valve stem seals are in top condition, especially on the inlet valves. Oil in the combustion chamber has an octane reducing effect on the fuel. It also leaves carbon deposits inside the combustion chamber that can be hot enough to ignite the air/fuel mix.
Water injection has a nice combustion chamber cleaning effect as every combustion event that has some water in it, the chamber/piston crown get a nice little steam clean.
Same said for crank case ventilation. It must be as effective as possible and either vent into an (illegal) atmosphere venting catch can or have very effective oil mist trapping baffles. I made 1 that was full of stainless steel pot cleaners to litterally scrub the oil from the blow by gas.
Really good ring seal from a propper run in (not some namby pamby 'treat it like a little girl' run in
) will be the best way to prevent blow by from occuring.
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so question is how to i controlle detonation and how do i lower the compresion ratio?,
Linear Mode
