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Duratec 3.0 v6
I Have raised my compression ratio from 10. 1 to 11.1 and Lots of other stuff cams slightly bored out,, forged pistons,, total seal rings etc
And after a spirited drive and I pull into a petrol station to fill up and restart quite quickly it doesn't like To restart spins over slowly
I have a Davies Craig ewp130 pumping coolant through engine for like 5 min after which has helped with the issue but its not fixed it, and ideas Is this down to inj prime, or too tight piston to wall clearece
I have factru gear reduction starter
And running a much larger optima red top battery 4.2u with larger cable
Any ideas as I know you can run near 15.1 to one one this engine is rally and race Car applications in the Aj30 jaguar version
Try a replacement starter. Slow cranking when hot is a symptom of a starter on the way out. For race cars we always have the next starter on hand.
Not familiar with the starter motor you mentioned, but considering you increased compression, it may give your starter a hard time when the engine components have reached operating temps.
In addition, piston to wall tolerances tighten up when the engine warms up, the material of the piston would typically dictate the piston to wall tolerance required to allow for this expansion. Double check that those were set correctly.
Did you upgrade all of your grounds to a thicker gauge wire?, i know you stated that you have put in an optima red top with a bigger cable, however did you do the same for all the cables?