250 vs 420 blower
11-13-2013, 01:54 PM
#24
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That is my engine Bob posted above. It is 25% overdriven.
Last edited by DirtyJohnson; 11-13-2013 at 02:16 PM.
11-13-2013, 05:40 PM
#26
Fires up like stock and the idle is pretty much like stock (around 800 rpm). No problems at all around the docks. As far as how much more fuel burned I haven't really tracked it, since I still have some prop tuning to do and I really didn't get to use it that much this summer. If I remember, the dyno sheet had it burning around 25-30gph around 3500-4000 rpm. I am also running the v6 module on my tbolt 4 ignition.
Last edited by wayne272; 11-13-2013 at 05:44 PM. Reason: add'l info
11-13-2013, 10:37 PM
#27
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wait till you see the EFI setup, I will post up some pics when I get it completed.
11-14-2013, 06:49 AM
#29
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No. There's a reason tons of people use them. From the average boater upgrading, marine engine builders, Mercury marine, etc. Properly setup , they work great. You can rotate a blower with little effort. Actually, a low compression supercharged engine will crank easier than a high compression N/A engine
11-14-2013, 10:36 AM
#30
MarineKinetics
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Heads
Mike,
The cylinder heads were box stock AFR 325 cc with the CNC chamber port option. This head is the base casting for the 335 fully CNC head with the exception of the porting program run only through the combustion chamber, seat, throat, and bowl area.
Ultimately the decision was made to go these heads due to the fact that I had seen them support well in excess of 1100 hp in prior testing. The efficiency of this exhaust port is certainly key in handling the volume of spent charge at outputs of exceeding 1000 hp. The fact was, at some point we would run out of blower before we would run out of cylinder head. While there may have been some incremental gains to be had by expanding the cylinder head program, given budgetary considerations, and that the target 1000 hp was obtained, the “bang for the buck quotient” for this package is right on the money.
To reiterate what MT has already mentioned, the Imco manifolds exceeded everyone’s expectations. Given the capability of the selected head easily surpassed the target for the project, the additional resources available from utilizing this head were diverted toward valvetrain optimization.
The valve size is the standard 2.300” intake with the SS exhaust swapped out for the proprietary 1.880” Ferrea tulip valve. The spring package was also optimized toward stabilizing the dynamic mass of the valvetrain. The fuel curve is confirmation the valvetrain was very “quiet”.
Bob
The cylinder heads were box stock AFR 325 cc with the CNC chamber port option. This head is the base casting for the 335 fully CNC head with the exception of the porting program run only through the combustion chamber, seat, throat, and bowl area.
Ultimately the decision was made to go these heads due to the fact that I had seen them support well in excess of 1100 hp in prior testing. The efficiency of this exhaust port is certainly key in handling the volume of spent charge at outputs of exceeding 1000 hp. The fact was, at some point we would run out of blower before we would run out of cylinder head. While there may have been some incremental gains to be had by expanding the cylinder head program, given budgetary considerations, and that the target 1000 hp was obtained, the “bang for the buck quotient” for this package is right on the money.
To reiterate what MT has already mentioned, the Imco manifolds exceeded everyone’s expectations. Given the capability of the selected head easily surpassed the target for the project, the additional resources available from utilizing this head were diverted toward valvetrain optimization.
The valve size is the standard 2.300” intake with the SS exhaust swapped out for the proprietary 1.880” Ferrea tulip valve. The spring package was also optimized toward stabilizing the dynamic mass of the valvetrain. The fuel curve is confirmation the valvetrain was very “quiet”.
Bob
