20-11-2017, 11:59 AM
(20-11-2017, 10:02 AM)bobthompson Wrote: Controversial question - I hope! Is there a better type of cylinder head than an Ally 9E to use on my Mag engined trials car. Phoenix crank, Pigsty trials cam and indeed built by them about 12 years ago. I get about 125 psi and 30 bhp now,not sure how that calculates as a compression ratio?
I was thinking of changing to a new Ricardo one, will there be any more power for my money?
According to Stuart Bonney in a 2006 paper 'Compression Ratios and Cylinder Compression Testing in Ford N Series Tractors'- compression pressure checked with a Compression Tester will be 17 to 20 times the compression ratio with a standard street type cam.
If you take an average of 18.5 for a 6.2 : 1 CR you get 115 PSI at a cranking speed of 120 rpm (The Ford specification)
Cheers, Tony.