with a Rover/Buick 215 V8 and a Magnacharger 110.
Magnacharger is running with 60% overdrive and with the stock heads it delivered 6.2psi boost.
I changed heads for the new Merlin F85 high performance heads which flow significant better than the old stock ones and now my boost readings dropped to 3.5 psi. Yess I know this is normal with better flowing heads.
My question is:
With the old heads I had a cr of 9.4 : 1 + 6.2psi = about 13 :1 corrected compression ratio.
With the new 33cc Merlin heads I have a cr of 9.02:1 + 3.5 psi (measured) = about 11 :1 corrected compression ratio.
Is this true and does it mean I can raise boost now to get beack to my old 13:1 corrected compression ratio or do I see it all wrong ; the new heads flow better and the boost readings I now read are not accurate for calculations.
Your are correct that to equal your compression back up just change pulley to get you back to 13:1 if it was safe running then it will be the same now.
Just wondering!! What kind of times are you running and what track is it so I can correct for altitude. I had the same car 20 years ago and put a Buick 3.8 with a Paxton blower. Thanks
I did 15 sec with damaged rotors earleyer this season. Running it with 3.09 :1 gears and 5 speed LT77 gearbox.
Blower is repaired now by BDS agend UK Blowers.
I am running it with those long gears as we don't have a race track in Holland annymore. I have to drive it 500 miles to Great Britain ( UK ) to make some runs thats why the long gears are suitable for me.
As I experiance the new heads do deliver more horsepower with the same overdrive ratio ( had 256 bhp on the wheels with the std heads).
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