Speeds to be expected with a 150 xs on a 15 ft Allison

[mrcrsr]

What kind of speeds would a 15 or 16 ft Allison do with a warmed over 150 xs? Let's say 15" mid, gearcase with low water pickup and a chopper?

[FUJIMO]

The 1500XS came with the 15" mid & low water XS gearcase. Define "warmed over". On many properly rigged J powered boats, swapping out the XS gearcase, for the standard gearcase of the day, was faster. The XS pickups had a tendency to introduce air into the slipstream. They had other issues as well.

[largecar91]

80+

[mrcrsr]

Would the Allison be the fastest choice, or possibly a hydrostream or something else might be faster with the xs? Thinking about doing something vintage eventually, always liked the xs

[JWTjr.]

mid to high 70s in circle race trim--realistic, real speed. 80+ jacked to the moon not for turning corners. JP kilo record was just under 87 mph set by Louis Collins with a 16' Laser/1500xs.

[JWTjr.]

Would the Allison be the fastest choice, or possibly a hydrostream or something else might be faster with the xs? Thinking about doing something vintage eventually, always liked the xs

Allison 15' is likely fastest in dead calm conditions. But those conditions don't exist on a race course after 1 lap. 16' Allison, 16' Laser or HydroStream Ventura are the best bets for roughed up courses.

[mrcrsr]

I'm looking for something that would look cool, be vintage that I could take on some of the river runs. I figured I could put some modern technology in the old inline. I don't necessarily think I would start with an xs, but an 83 and up 115, because of the modern ignition and integral power trim, and then modify from there. I would need to do some research and see if I can use that powerhead with the 15" mid but keep the integral trim. Does everyone agree that the later 115 would be a better way to start, and then port/modify and rebuild from there? I rebuilt a few in lines but that's over 25 years ago!

[FUJIMO]

J motor/16 Action.

[mrcrsr]

I'm not really an action person. I remember riding in a brand new hydrostream viper back in the day, it had a 115 Mariner, if I remember right it was a 65 mph boat. I'd like to at least be able to run 80

[2us70]

Does anyone know the difference in prop shaft horse power between the 150xs and the later year I6 motors?

[specboatops]

I had a 1500xs on a 15 ft. G.W. Invader that ran right at 77.8 on gps, if you search Vintage Merc on youtube there is some video of it...

[2us70]

The Action Marine version of the "Ventura" is about as fast as anything with a 150 inline. It is also probably the easiest to drive in varied conditions. I worked part time at Action in the mid 70s and drove several of these boats. It was noticeable that these boats seemed not to suffer as much from prop blowout as the Allisons and Checkmates. Oldgator ran a 15 Hydrostream in JP in 1975 it looked like a handful but he did pretty well with it as I recall. I saw a picture in one of the Rabe's batches of that one.

[W2F a V-King]

This is a Viper with an XS 1500, doesn't say how fast in the comments.

https://www.youtube.com/watch?v=e3_fWI-fbnQ

There is another member on here with a light vector and an XS 1500 runs 80.
Maybe he will read this and chime in...

[FUJIMO]

Nice little set-up. This HydroStream Ventura ll is what the first Action came from. Or was it the Ventura l Jim? Yeah, I think it was the Ventura l...lol

[FUJIMO]

original ventura l..was a slightly smaller/narrower version of the later Ventura ll... What Action Marine used as a base, with minor improvements. Lots of Action 17's still out there. But those are not what you want. You want one of the original Action 16's, for a short shaft inline. Not easy to find.