need higher rpm range on chrysler 318

anyone have any after market solutions to increase max by 2000

 

Where would that put your redline?

 

First of All,reliability would suffer, unless 6000 - 6500 was only an occasional Burst.

If you're willing to go to a smaller prop, very little need be changed. Perhaps, nothing.

If you're looking at a 2000 RPM increase with a 40% to 50% increase in speed, HP will need to be More than DOUBLED.

Required HP increases expodentially with speed. This would require a TOTAL rebuild of motor - Higher compression, stronger crank, Rods, Higher flowing Heads, complete valve train change, cam , carburation etc. Not exactly an Inexpensive operation.
Less expensive to go to a larger motor.

 

Any thoughts on rebuiding small bloch to 350-375hp so I have more tourque and losing the 2:1 reduction?. I'm thinking this would double my prop turns without the need for 5-6000 rpms. I would be happy if I could spin this four blade @ 3000 rpm, which means docking at idle im still turning 750 prop revolutins. hmmm

 

between 5-5500 rpm

 

yeah smaller prop =higher rpm =same boat speed right?

 

Depends on how much power your engine produces at 3000 vs 5000 rpm. I'd say you're over-propped.

 

You will not be able to spin the same prop at twice the speed by changing to a 1:1 gearbox. If you motor is in Good operating condition,tune etc. and you are currently wide open at 3000 -3500 RPM, you are Overproped. Operating speed should be 4000 RPM plus. Yes, you can get 350-375 HP, but, at a cost.

 

Am I over proped if I can red line the engine?

with the engine @ 4000 rpms ( max recommended is 4200) shaft turning 2000
the boat moves nice, not fast but nice. anything less than that is too slow

 

5000 RPM is way too high for American iron. The RPM needs to be right on the max HP. Why take it higher, your running out of steam up there.

 

Wait, I thought you said you could only turn 3000-3500?

Anyway, the only way you're going to get that engine to 350-400 hp is with a supercharger. If you do a lot of part-throttle cruising, the supercharger might be more fuel-efficient, but for mostly wide open throttle it would be cheaper to just buy a bigger engine.