Turbo,

I talked to the builder today and got the head flow numbers:

Lift Intake Exhaust

.100 63 60
.200 129 118
.300 184 149
.400 223 164
.500 235 171
.600 236 175

Jeff,

I'm probably over-estimating on fuel (I keep getting different numbers for the weight per gallon). So at 70 gallons with the weight being 7.0 pounds per gallon, that makes the weight with a full tank of gas 3905 (please tell me if I have the weight of gas wrong). Add me to the mix plus misc stuff and at best another 300 pounds. So about 4200 pounds. Not bad. So where is my speed?? There's got to be something else going on here.

On the cam front.... I ran some info through Wolverine's old CamSelect program. There was a utility in there that applied to boat engines called the Marine Engine 60 Percent Rule. In order to acheive maximum HP at 5800 RPM (which is where my max comes in according to the desktop dyno), I would need at least 388 foot pounds of torque at 3480 RPM. I'm guessing that the 3480 is the 60% throttle setting which would be cruise. Any thoughts on that?

I think I'm still going to run that other cam. I might just run it like it is though for the rest of the season, and work on some other things that'll help get the boat flying (some weight savings, less fuel, etc.). I think I need to work on some trimming as well. One thing I noticed with the 17P was that it would cavitate with aggressive trim angles (Mirage) while the older 21P Quicksilver would not (I don't even think that the trim was working right when I went out... another problem). So many variables here...

Later,

Tom, are those flow numbers before or after porting? I can put those numbers in to desktop dyno and get a more accurate number. I can probably get them Sunday sometime. I have to go out of town so I'm be away from my tube.

I always figured 8 lbs for fuel. I know that is too much but I rather over estimate than under. I agree at 4200 you should be faster.

Yeah, those are the numbers after porting.

I'm going to work on some things over the weekend and see what it nets me.

Thanks!

Tom I put in the flow numbers in for your heads and you get an increase of 9 HP to 393 and 8 LBS. to 409. The curve stayed the same but just moved up abit.

Hope this helps.