GPS is a humbler for sure

[bighead]

Got some GPS #s friday after the pump rebuild, 55.4 mphwith a aa AT imp, inducer and stuffer at 3900 rpm, boy it felt a lot faster than that!!!! Previous best was last winter at 61.7 mph at 4600 rpm with a a berk imp. On sat installed a rpm air gap with a 1" stepped spacer in place of the factory low rise cast quadrajet intake with a P.O.S. adapter for a Holley and gps on sunday was 57.6 mph at 4100 rpm. The boat is a 20'6" Commander open bow heavy cruiser with a BBC 325 rated hp Hardin Marine motor and crappy truck heads.Next step is probably carb set up, it has a 4150 750cfm vac secondary carb. Right now it runs pretty good as it has no stumble hesitation or any problems I know of. I am pretty green at carb tuning so it is time to start researching this too.

[Jetmugg]

It sounds like that AA impeller may be holding you back. The engine can't reach its power peak working against that big impeller. A smaller impeller might help you the most - at least to get back to where you were.
Other than that, you just need more power. If it's running good now, there is probably not much to gain by a carb change. You would need a big infusion of power to make a significant difference (i.e. compression, cam, heads) to get that AA impeller to spin into the4600-4800 rpm range where your engine can make its peak power.
My 2 cents
SteveM.

[dmontzsta]

It is the humbler for sure, the thing is it probably feels like 100mph. Most people think they do close to 100, unless they have other people to correct them. The feeling on water is different. But then again, if I was driving down the freeway at 55mph and had no windshield or doors, it would feel pretty fast too. :)

[Squirtcha?]

But then again, if I was driving down the freeway at 55mph and had no windshield or doors, it would feel pretty fast too. :)
There's something else at work though. I rode street and dirt bikes for years. I've gone 126 mph on a street bike with no windshield or fairing, and it didn't feel as fast as 85 in a boat. Not sure what the dealio is, but that's been my experience.

[bighead]

Maybe it is the rapid deceleration that the drag of the water causes that gives the illusion of much greater speed or the rushing sound of the water. Who knows but it sure is addictive as hell and a lot of fun, I like it and need more horsepower.

[dmontzsta]

There's something else at work though. I rode street and dirt bikes for years. I've gone 126 mph on a street bike with no windshield or faring, and it didn't feel as fast as 85 in a boat. Not sure what the dealio is, but that's been my experience.
That is true. Maybe it is the sliding across the water? I will have to think a little more. :D

[Brooski]

I will have to think a little more. :D
<Note to self: Hurry up and buy lots of stock in Bayer aspirin and Tylenol>
:D

[Brooski]

Got some GPS #s friday after the pump rebuild, 55.4 mphwith a aa AT imp, inducer and stuffer at 3900 rpm, boy it felt a lot faster than that!!!! Previous best was last winter at 61.7 mph at 4600 rpm with a a berk imp. On sat installed a rpm air gap with a 1" stepped spacer in place of the factory low rise cast quadrajet intake with a P.O.S. adapter for a Holley and gps on sunday was 57.6 mph at 4100 rpm. The boat is a 20'6" Commander open bow heavy cruiser with a BBC 325 rated hp Hardin Marine motor and crappy truck heads.Next step is probably carb set up, it has a 4150 750cfm vac secondary carb. Right now it runs pretty good as it has no stumble hesitation or any problems I know of. I am pretty green at carb tuning so it is time to start researching this too.
Thats good info about the RPM air gap giving you 3 mph more. I am running one on mine with a double pumper 800, and it runs like a champ. (Mild engine).

[Wally_Gator]

I think it has more to do with the proximity of the water...
The closer you are to it the faster it feels. Perspective...
I used to own a Porsche 914 (Yes poor mans) fun car and felt fast.
I thed bought a truck and the difference was amazing..

[dmontzsta]

<Note to self: Hurry up and buy lots of stock in Bayer aspirin and Tylenol>
:D
LOL.
Hey, I am not the one that plays grown up bumper cars! :D

[dmontzsta]

I am thinking it is a sensory overload that causes people to think they are going faster.
You have alot of factors tricking your mind. First you have the wind rushing in your face, second you have a motor loud as hell behind you, then you have no doors and you are sitting slighty above the water. It is just alot of things for your brain to process and makes it feel like it is going insanely fast. :supp:

[BigDoug]

Plus the fact the boat is running some what loose and dancing all over the place, where as we have control in the car with the steering and shock absorbers (smooth) i think dmont is right with censory overload, plays a huge factor when your not used to it, open cock pit, loud motor, etc etc.
This my friends is what is bitchin about boats. :cool: :cool:

[roostwear]

I guess I was lucky. I started working on my boat before I ever GPSed it. I never saw how slow it was in the beginning. Ignorance IS bliss.........

[bighead]

Rootswear I hear your circus boat is a mover.

[roostwear]

It's an open bow with an E pump... how fast could it be? :D

[bighead]

Mine is a open bow with a E pump too so yours is way faster than mine, from what I heard.

[dmontzsta]

Mine is a open bow with a E pump too so yours is way faster than mine, from what I heard.
of course...he is running the blue oval!
:2purples:

[bighead]

shoulda seen that one coming !!! I guess if I wanna go fast I need a smaller boat built for speed and leave the cruising for cruiser.

[SmokinLowriderSS]

Personally, I think your next biggest gain would be to get a set of Large Oval port heads (but not the rectangles) AND a stouter cam. You may well find nearly another 100 HP depending on what cam you are running now. I would think your cam (if original) is similar (if not identical) to my old one (Indmar 330HP 454).
Other option is I believe you are over-impellered. you're gonna need about 200 more HP to do that AA justice IMO.

[LVjetboy]

"There's something else at work though. I rode street and dirt bikes for years. I've gone 126 mph on a street bike with no windshield or fairing, and it didn't feel as fast as 85 in a boat. Not sure what the dealio is, but that's been my experience."
I'd agree. I ran a vette to 150 mph. Not as exposed as a bike, but also somewhat low to the ground. That said the vette experience was nothing like 100 mph in a low profile jet on the lake. Someone mentioned engine noise. There's that, certainly with the power it takes to move a jet to 100 mph...over double the vette needs for 150. But noise alone doesn't capture the experience. At some point in the jet...maybe 90-95 mph? Wind noise starts to mask engine noise at least w/o a helmet. Above that the experience becomes somewhat detached or surreal. As if there's a disconnect between what you feel and your chances of controlling or influencing the outcome. Not connected. Hard to explain. Except to say I've never experienced anything like it.
I think both your mind and senses know you're closer to the edge than a low profile car running 50 mph faster on a smooth stretch of solid pavement. No unexpected rollers on asphalt except maybe Ca in a earthquake. A performance car just feels more stable connected and controllable, even at much higher speeds. I'm sure also a 30' cat or v on the water. But a small tunnel or v? Nope.
jer

[roostwear]

[i]A performance car just feels more stable connected and controllable, even at much higher speeds. jer
Yah, my roadster only chine walks when I bang second gear......

[Aluminum Squirt]

It also feels way faster when you are going 70 and the water suddenly becomes 4" deep. I spent my whole life paranoid about shallow water and watching out for rocks, now with an aluminum jet sled, I crave the shallow water. It really freaks people out when you take regular boater in shallow water and then do it fast, it definetly feels way faster than it is-Aluminum Squirt

[blender over]

I am thinking it is a sensory overload that causes people to think they are going faster.
You have alot of factors tricking your mind. First you have the wind rushing in your face, second you have a motor loud as hell behind you, then you have no doors and you are sitting slighty above the water. It is just alot of things for your brain to process and makes it feel like it is going insanely fast. :supp:
When that happens, just look over at the shore, it will give you a check on how fast you are really going :cry: