Pre Turbo Injection - How Much and When to Inject

[rotrex]

don't think so. I gain power with every degree advance I add.
We talk 14 deg of advance here with plenty of water/meth and 102 octane fuel on a 4 valve pent roof engine. Without water / meth I am stuck at about 10 degrees.
I map myself. I know how power develops as I advance ignition.
I also have a J&S safeguard knock control system with a display. Beside this system, knock is also easily audible in a Elise. With both I can map it right to the knock limit myself and observe changes by butt and by data logging.
Power changes are also easy to feel as the car weights less than 800kg.

I have build the engine with a 1mm copper shim to protect the cylinder ahead against indentation. Rover K heads tend to turn soft over time in high power mid engined applications, especially around the exhaust valve area. This is caused by insufficient coolant flow at idle and low revs after a high load situation.The MLS head gasket seals with a very sharp edge against the hardened alloy cylinder head.
I installed a electric water pump and controller to manage the heat in low rev and idle situations. Works a treat.

Thing with the shim is that I forgot to chamfer the lower edge of the cylinder bore of the shim. I had specified the shim with a inner bore diameter of 80mm, same a cylinder bore diameter to distribute forces uniformly. the firer ring has a diameter of about 83mm. Normally the shim also has a bore of 83mm. This puts the lower edge of the shim in the quench zone near the head gasket seal area.
I believe this exposed edge together with the reduced squish is responsible for the tendency to knock.
To fix this I need to replace the head gasket with a N-series head gasket, it employs a flat seal area with a larger surface, and remove the shim. that's it. Compression will still be a reasonable 9.2:1.
It is a full day of work. I just don't have the time or motivation to do it in the moment as the car is plenty fast as is.

https://youtu.be/onYUHH0muNc?t=25
To put it in perspective: The yellow Elise in front of me is powered by a supercharged Honda K20A2 engine from a Civic Type R with 280HP. On the Radiation straight I just left in it 5th gear.