Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Monty Goes To The Dyno

Thanks chaps, I appreciate your kind words of encouragement but clearly there’s something a miss at the top end.

My AFR is all good at 12.9:1 and I'm seeing zero air restriction (100 kPa) too, so that's all the fuel I need to mix with all the unrestricted air available in the atmosphere the engine can pull in, in theory that means it should just keep making more and more power, but cylinder pressures are clearly falling off over 6,500rpm!

So that just leaves ignition timing, perhaps I just need to keep lighting the fire earlier and earlier above 6,500rpm and onto 7,300rpm? The trajectory line definitely shows Monty is heading for a theoretical 200hp!



If I add 1 degree for every 200rpm above 6,500rpm that would see me 4 degrees higher at 32.5 degrees BTDC at 7,300rpm, which is probably worth another 10hp.

Or a destroyed engine from knock

I've just checked my log and at 6,500rpm where the power peaks I was running 28.5 degrees BTDC, from there on and all the way to/just past theoretical peak power at 7,300rpm the ignition curve remains flat at 28.5 degrees, there's zero ignition advance added from 6,500rpm up! For the last 800rpm it gets not a single degree more which was largely down to me not being brave enough, I really need to find out how much timing a Duratec can safely take at 7,300rpm under full load?

My other theory (read excuse ) is the rollers and my tyres were very wet, certainly when I entered to dyno cell it stank of hot rubber