zahndok

So the original cam doesn't seem that aggressive. If I have already added an intercooler and bumped the boost to 7lbs with ecu reprogram, would a more aggressive cam wake up the motor more or would I need different heads also. Looking at the recent thread on the 500efi cam it appears much more agressive than the 575 cam. Am I comparing Apples to Oranges since one is a efi and the other a blower motor? Which cam specs should be changed from oem to hop up this motor?

Quiet Storm

Biggus

I spoke to my engine builder about the cam selection and he asked me not to share the information. He said that there are so many variables involved in the changes to my original engine set up that it may not work as well for your engine. I guess it's like one of those trade secrets too.

Cam selection seems like black magic to me. I know just enough to know I don't know enough but I'm learning a lot here.

Good luck with your selection. I wish I could have been more help.

jdnca1

Look how much more agressive (relatively speaking) the 500EFI cam is compared to the 500HP cam to make the same power......kinda shows you how much MORE power an old school carb and dart intake make over the EFI stuff....

PatriYacht

Mercury's cam choice for the 575 goes against everything I know about supercharger cams.It should have 8-10 degrees more exhaust duration to help rid the additional spent exhast gasses and it should have 112-114 lsa to shorten the overlap period. More hp could be gained by using a roller with higher lift and more time open "under the curve". The Crane 741 would be a good choice but I would have one ground at a 114 lsa and retard it a bit to make up for the 5 degrees of advance that they grind into it.

zahndok

The lobe separation of 110 is what has me confused as well. rmbuilder stated in another thread that a blower motor likes a late intake opening and a good exhaust flow or duration and a lobe separation of 114. Mercury seems to have chosen the exact opposite extreme of 110. It would help to understand their reasoning here.

RichardCranium572

I'm not saying this is why Merc did it, but keep in mind the overlap cycle in blown applications help cool the surface temperature of the piston and combustion chamber thereby helping to control heat.