i think 4500 is a little low for a boat, my set up is a ford 460, c8 heads, dish pistons, big cam, 750 carb. running a berk 12 jc pump, with a loader under the boat snd ride plate. only getting 4500 rpm out of the boat. any way to get another 1000??


Sent from my iPhone using SoCal Jet Boats

Throw the 750 away, reduce the cam or increase the compression ratio, cut the impeller down and buy a 80 cubic foot bottle of nitrous oxide...


4,500 RPM is about right to be honest..

GT

i think 4500 is a little low for a boat, my set up is a ford 460, c8 heads, dish pistons, big cam, 750 carb. running a berk 12 jc pump, with a loader under the boat snd ride plate. only getting 4500 rpm out of the boat. any way to get another 1000??


Sent from my iPhone using SoCal Jet Boats

4500 is about right for a BONE STOCK, run-of-the-mill, used pick-up truck motor, with an "A" Impeller.

I run a 350 chevy @ 45-4600 rpm, "A" impeller. Mostly stock, BTW. (750 Holley and Headers)

4500 is ~ 325 hp (A imp.)
5500 is ~ 595 hp (A imp.)
There is no reason a mildly built 460 wont run 5K to 5100 rpm. (475 to 500 HP)

just my $0.02

Dan'l

What is your timing at ? What hull is it?

My bone stock marine  460 (back up motor) runs 4600-4700rpm on a tight pump and a stainless A  with a 750dp mech  secondaries. In my 600pound Daytona.   You are rite in the ball park. That engine with came stock with a dish (reverse dome) piston. Should be 10to1 comp .

but depends what material the impeller is made of . Alum will spin more rpms

i will have to check timing, what should it be at? and its in an 18ft brendella bubble deck.


Sent from my iPhone using SoCal Jet Boats

My bone stock 460 with a Berkeley E with an A turns 5200 in a 1000 pound Challenger hull

1977 Challenger

Time to build a pump or buy a new tach....

JMO

GT

what size carb gt?


Sent from my iPhone using SoCal Jet Boats

Can't miss with an 850, square bore double pumper. Quick Fuel, Holley, Pro Form are all pretty good. Drop the power valve 2" and one up the main jet sizes and it will be silly close...


JMHO

GT

Anyone can say completely untrue, let's hear some facts and data behind why you think that's untrue. @gtjets  I'm very curious .

i dont know, ill try taking the loader out and see what that does



Sent from my iPhone using SoCal Jet Boats

Anyone can say completely untrue, let's hear some facts and data behind why you think that's untrue. @gtjets  I'm very curious .

Show me on this chart where a stainless turns a different RPM than an aluminum or a bronze.......

I'm all ears.......


GT

I'm not trying to be a dick..

I just never heard of a 450 HP "Bone Stock 460"....

That engine made about 325 HP when it came from Ford.... Which would put you closer to about 4,600 RPM....

That's all I'm saying.  I feel the tachometer is off by 500 RPM...... Or that 460 is built better than you think it is.


GT

Not taken personally GT at all. Just saying dad bought the boat new the original Stewart Warner tach always would hit 5200 at WOT. When I swapped the parts from another Challenger with all stock parts I also swapped the tachs so it's now got the second tach in it exact same tach as the original stock tach still hits right at 5200 WOT. The original harman marine hit this and so does the second all original harman I have in it now from the swap. Idk maybe these SW tachs were prone to be wrong just odd that both original tachs and both original engines produce the same result. Again nothing personal just what I have seen this boat do both brand new in 1977 and to this day...you have a much broader knowledge then I do all I have is what I have seen.

1977 Challenger

If that has the bottom I think it does, that boat better be hitting 82 miles an hour.... Maybe more, at 450 HP with an A impeller....

GT

Lol GT. Now you know a Challenger would be hard pressed to hit that speed at any RPM it's a 1000 pound hull. If both tachs are wrong then they are both wrong is what it is. Your knowledge is very much appreciated.

1977 Challenger