How fast will my new boat go?

[SecondMonkey]

So I bought a boat today. :) It's a 1979 18' Sleekcraft with a 460 Ford and Berkely jet. I don't know much about the engine yet...it appears to be your average blinged out jet boat motor. The only performance parts I know of specifically are a new set of basset headers.
Anyway, she's still about 100 miles away and I won't be able to get it home for a few weeks. How fast do you think it will go? ~60 ish? This is my first jet boat.

[YumaBiesemeyer]

Congrads on new boat. Need more info on speed but should do 60-70. May do more depends on HP and set up.
Have fun with it.

[lilrick]

well if you bought it from ebay, it will definitely go 100!!!!!:D welcome to HB!!!

[Warlockjer]

60ish is realistic. 70 might be wishful thinking. Anyhow good luck and welcome :)

[SmokinLowriderSS]

Damit lilrick, that was the line I was going to use. :)

[SmokinLowriderSS]

Depends a great deal on hull condition and setup (and weight). Rough glass like I had may cost you 10 MPH. IMO a divertor is worth 5 to 10 MPH (maybe more at higher HP levels), just depends on how well set up to the boat the pump stuff is. Also impeller size/engine HP/RPM it will spin. A dozen variables in the speed number.
If you have a genuine 300 - 400 HP engine, no divertor, smooth glass, mid 60's maybe, divertor/rideplate/good loader, 70 is possible IMO.

[gochappy]

take it wide open through a no wake zone on a saturday about noon and I'm sure the watercops will ley you know exactly how fast it goes...

[TRUMP TIGHT]

I have a 76 18ft spectra w/ 460 bored to a 468 that was gps'd at 66.7 without being broken in. I would say you should get 60+. Welcome!

[TRUMP TIGHT]

By the way if you are within range on July 1 some of us ***boaters are getting together in the channel in havasu. All jets and v-drives are welcome! Good way to meet some peeps from ***boat with similar rides.

[SecondMonkey]

Thanks guys! It does have a nice smooth bottom and I'd guess the engine is around 300hp, but who knows. Does anybody know what the stock HP would be for a '79 460 in a boat?

[SmokinLowriderSS]

The Indmar 460's Taylor was using rated 320HP, and since the 330HP Chevys actually made about 270 to 280 according to peeps I know who dyno'd quite a few, I'm gonna guess the stockers at about 260 to 280HP.
That assumes iron manifold, single 4-barrell, and stock cam, log thru-hull exhaust.
With just the headers assuming no other changes, I'm guessing 280 to 300 HP. I doubt the headers help much if you have a set of the later manuf ford "smog" heads which have partly blocked exhaust ports. It really hurts them at RPM.

[SecondMonkey]

So if I was to assume that my Berkeley jet is original and probably somewhat worn out, would I be able to gain any MPH or fuel efficiency by rebuilding it? I was thinking about buying another used one to rebuild and then maybe install it this winter. Used jet drives are a lot cheaper than I thought. :)

[beerjet]

Anytime you can "freshen" something up . I cant see it hurting you IMO . When I did my pump , I noticed quite a bit of diffrence in how the boat accelerated and the diverter was another add that made a night and day diffrence .
Welcome and enjoy tinkering with your new boat !
-beerjet-

[48OFF]

IF you end up like most every other boater ,your new boat will go at least 10mph slower than you tell people it goes!

[castone001]

OK I REALLY liked the last one!! 10 miles slower !!! :)

[bulldawg art]

IF you end up like most every other boater ,your new boat will go at least 10mph slower than you tell people it goes!
Aint that the truth! I bought my boat through this site (AZ to CA) and was told it did 65. Pump ,jacuzzi wj with diverter, had some major issues so I had it gone through. Bent shaft, impeller was distorted, bowl was ground on pretty bad in a lot of areas, extremely rough cast in the suction and bowl. What I mean by rough is that there were bumps the size of peas all through out this thing and it was suppose to be blueprinted. After all the work, the boat should have run better right? Not! The best she could do was 55.9 in light chop. Can pump work slow you down that much??? At 65, freshening up the pump, an intake and carb change, dialing in the timing, indexing the plugs, would make getting to ~70ish not that difficult, right?. Now I am looking at trying to gain 14.1 mph and it doesn't seem likely.

[SmokinLowriderSS]

IF you end up like most every other boater ,your new boat will go at least 10mph slower than you tell people it goes!
The GPS musta been not working right that day either. I hear those things lie a lot. :p