old school V8 jet boats

pavulon · 01-16-2019, 04:51 PM

Always loved the things. Having a shaft and prop hanging (V-drive) low on a boat makes me nervous. Beyond overall condition considerations, brands/equipment (pumps...) to seek or to avoid? Dunno how serious I am, just think I don't know enough about them.

BeyGon · 01-16-2019, 04:55 PM

Great fresh water fun, I used to work for a guy named Penhall that raced different versions, we spent a lot of time at races with them.

sammyg2 · 01-16-2019, 05:08 PM

How fast can you flush a toilet?

The boat in the top picture with the blown big block would go about a mile on a gallon of gas, tops. Half that if going over 30 mpg.

The performance of a jet boat suffers and the mpg is usually horrible.
Why? because people don't match the pump to the motor and versa visa.
You can bolt up a 500 hp motor to a 200 hp pump and all you do is waste gas. Too much pressure, not enough volume, thrust is not maximized.

They are not true centrifugal or axial flow pumps, kind of a hybrid mix of the two. But they do have pump performance curves and best efficiency points. An RPM where the pump moves the most water for the given power input and impeller diameter and discharge nozzle diameter.
Rev it higher and the efficiency falls way off.

if you can get a true pro to engineer the engine/pump combination, it will be much better.
it'll still cost 3 times as much in fuel and an outdrive or v drive would and will go half as fast, but that's better than 4 times as much fuel.

The Berkeley pump is best IMO, with a droop snoot.

pavulon · 01-16-2019, 05:17 PM

Was thinking a modern and mildly modded LS7 (aluminum 7L) could be a good engine for a reliable, fun, jet boat. The things make 600hp without working very hard and the displacement makes for really good torque as well. I could be way off on that reasoning.

sammyg2 · 01-16-2019, 05:18 PM

BTW, if you can find one in decent shape they are usually dirt cheeeeep.

sammyg2 · 01-16-2019, 05:19 PM

BeyGon · 01-16-2019, 05:25 PM

Quote:

Originally Posted by BeyGon

Great fresh water fun, I used to work for a guy named Penhall that raced different versions, we spent a lot of time at races with them.

I was just talking about the type you had pictured.

pavulon · 01-16-2019, 05:35 PM

Quote:

Originally Posted by BeyGon

I was just talking about the type you had pictured.

Sure. Love the idea of a bug-catcher on a blown big-block...not convinced I could stomach the reality of it for very long though. Tough to argue with the beach appeal!

URY914 · URY914's Garage

Like a Pit Bull on water. Seems safe.

Drbraunsr · 01-16-2019, 06:57 PM

Ran a big block flatbottom (V-drive prop) for 30 years.
Are you skiing ? lake or river, both, -- the low freeboard (side) makes for an exciting time on a rough lake.
Have you owned a boat before ?

Drbraunsr · 01-16-2019, 06:59 PM

by the way …. those headers will peel the hide right off you. I think those are more likely to hurt you than anything else.

Cajundaddy · Cajundaddy's Garage

I spent a lot of time in the waterski community and the low profile jet boat was usually all foam, no beer. There were exceptions to the rule but often a V drive will generate more hole torque, go faster, and burn 1/2 as much fuel as the V8 Berkley Jet on the same hull. I always wanted a lot more freeboard when the thunderstorms popped up so leaned more towards Donzi or Ski Nautique.

For that visual appeal of small boat/huge motor the jet boat was king.

LakeCleElum · 01-16-2019, 09:26 PM

Talked to a guy with one on Lake Chelan once.....Said it used 58 gallons/fuel/hour.....

onewhippedpuppy · 01-17-2019, 02:57 AM

I see them at the lake occasionally, seems like a novelty that would wear off very quickly. Can’t haul people, not really that fast, can’t handle rough water, can’t do water sports, uses a ton of gas, not good for lounging and drinking beer.....what’s the point? Sorta like a Harley for the water I guess. Personally if I wanted to go fast I’d pick up an older Formula offshore style boat instead. Stick an LS7 in THAT and you’ll have something.

ckelly78z · 01-17-2019, 03:10 AM

You will need to buy a SPEEDO, and start sporting a mullett.

ckelly78z · 01-17-2019, 03:13 AM

What interests me is the new Mercury 400R outboard motor....one of these on a bass boat, WOW.

sammyg2 · 01-17-2019, 06:13 AM

Quote:

Originally Posted by Drbraunsr

Ran a big block flatbottom (V-drive prop) for 30 years.
Are you skiing ? lake or river, both, -- the low freeboard (side) makes for an exciting time on a rough lake.
Have you owned a boat before ?

Good to know I wasn't the only one with questionable judgement

Had an 18' stevens, supercharged hemi built to the hilt. But it was practical!

sammyg2 · 01-17-2019, 06:16 AM

If I ever got the itch to own another high performance lake boat (shoot me if I do) I'd prolly want to get a tunnel with outboard. Relatively efficient and quiet, can handle a little rough water, stable and faster than snot.
Yes, you can blow one over but you have to do something wrong to do it. Most of the time it won't do it by itself.

dad911 · 01-17-2019, 06:40 AM

I had a Yamaha LS2000, twin 135hp. Wide open could watch the gas gauge go down.......

Only data point I have.

ckelly78z · 01-17-2019, 06:48 AM

A buddy 20 years ago was flying down the Detroit River in his 21' Champion bass boat with a 175 Merc, doing about 70 mph. He didn't do anything wrong, but still hit an unseen, submerged object at that speed...it sheared the lower unit off of the motor (never to be found again), and almost nose dived the front of the boat under the surface. Luckily he had a seat belt on, in a wrap around bucket seat, so no injuries. Be careful out there.