Turbojack

For comparison, my AFR CNC 335 @.600lift 28in = 396 on short port, 378 on long port. I agree that motor needs better head, I had the same merlins & changed to the AFR's. What are specs on cam. I agree with cobra's HP numbers.

z.zuperboat

Hows The Bottom On The Boat.my Bud Had One,the Boat Had A Bad Hook And Once Removed It Picked Up.needed Less Trim To Carry The Nose.

articfriends

iTrader: (1)

tubojack,cam is a cam motion hyd roller,can't find spec sheet but roughly remember .598/.628,228/236 at.050 duration,idles at 675 rpms at 10 in vac in gear,it seemed pretty small to me but went with crocketts reccomendation on it (he had to be able to tune it and make it idle on dyno),i'm not dissappointed with performance of motor in it's present state of tune,just wondered what best gues of my hp is,if i had much more torque,it would break outdrive everytime out. So far outdrive casualty list-1.set stock bravo gears,1 set of xr gears,1 set lower xr gears,1 hd aftermarket vertical shaft,iv'e resigned to fact you must have a spare beefed up outdrive,called b-max-4 wk wait (boating season is short in michigan),gear ratio was too far off for my collection of props also. Hook-boat doesent have much more than 1/16 inch variation with straight edge,thanks guys

tomcat

It is interesting how bigger cubes and bigger cam drop the boost. Boost is just a measure of how restrictive your heads/engine/exhaust are. You had the same blower pulley so you would expect the engine to at least make the same power, but sometimes it makes less.

A friend with a M-1 Procharger on a carb engine had a similar experience. On a 454 Magnum he had 6-7 psi. Putting the same system on a new 502 with Merlin heads and a slightly bigger cam, he only got 4-5 psi. In both cases the boat went about 77 mph. He was pissed! Instead of increasing blower speed with a smaller pulley, we replaced the restrictive Procharger intercooler setup with an Rtech supercooler. Boost went up dramatically to 8 psi and the boat gained 8 mph. If you don't want to change heads, change intercoolers. The improvement in air flow is just as dramatic and the result is the same; more power without spinning the blower any faster (just adds heat).

P.S. Those poor injectors!!

articfriends

iTrader: (1)

Tomcat,i'm running m-3sc procharger,it has a HUGE intercooler,the m-1 has a real small one,they claim the aw-504 intercooler is one of the least restrictive on market.Might be a interesting experiment to measure inlet press vs. outlet pressure though. I can feel for your buddy,seems like modifying boats is always 1 step fwd,2 steps back!! Thanks for your input,Smitty

502procharger

i have a 548 bbc with dart pro 1 heads 335 cc cnc ported, single nickerson carb, 30 deg total timing and i made 945hp with 9-10 lbs of boost with an m3 procharger 504 intercooler at 5600. seem to me your numbers a a little low. i can post my dyno sheet it those numbers will help for a comp.

502procharger

cobra marty

BSFC of .25 !! Yikes that is lean!

Turbojack

Is that correct on dyno sheet 254lbs/hr @ 942HP? I just looked at what my efi is using @ it is at 602lbs per hr @ 5700rpm. I knew I was rich but I did not think I was that rich. At 4200rpm with a a/r ratio of 12.53 I am at 292lbs/hr

502procharger

yeah i forgot to mention that the wire fell off fuel "b" so double that fuel number atleast