Best motor for a 15' hydrostream viper

[john rowley]

I have a 15' hydrostream viper that I want to put a motor on. What is the best hp motor and brand to put on this boat. I want it to go around 70 mph max. I have a mid to late 80s 100 hp mariner inline 4 cylinder and a 2005 mercury 90 hp 3 cylinder. Can either of these motors be made to run 70 mph on this boat with the right setup and prop? How would a 150 hp mercury do on it? Please give me some advice. thanks!

[Pro300x24LD]

I'm not a viper guru but the old inline 4 will look cooler on it due to being the correct era IMO. Should run pretty decent also, not sure how fast, but I would guess close to that 70 mark you want with proper set up

[specboatops]

Mercury 1500xs...............................:thumbsup::thumbsup::thumbsup:

Chris

[1BadAction]

I'm not a viper guru but the old inline 4 will look cooler on it due to being the correct era IMO.
no. you're thinking of the wrong inline 4... he has the bastard inline 4 that idles on 2 cylinders.

Bad idea using that I-4 on a viper, you'll never be able to keep it in the RPM range its intended for. Use the I-3, or even better, pick up a cheap 2.0L V6. :thumbsup:

[Pro300x24LD]

no. you're thinking of the wrong inline 4... he has the bastard inline 4 that idles on 2 cylinders.

Bad idea using that I-4 on a viper, you'll never be able to keep it in the RPM range its intended for. Use the I-3, or even better, pick up a cheap 2.0L V6. :thumbsup:
ahhhh


yeah I think the 2.0 150 is a great idea also :thumbsup:

[Bruster]

:iagree:
or, if a 1500XS isn't in the cards, a late ADI 115 inline 6 on a short mid. It's easy enough to make the 115 look like an XS, and it will run as well on the top and I think it even has a little better mid range. :thumbsup:



Mercury 1500xs...............................:thumbsup::thumbsup::thumbsup:

Chris

[JustMercMe]

Throw a 2.4 135 or 150 on it.....That way if your not happy with 70 mph you got something to work with.

[beer30]

Put a Merc 280SS Offshore, just don't go over 70!!!!!!:thumbsup::thumbsup::DChuck

[pyro]

no. you're thinking of the wrong inline 4... he has the bastard inline 4 that idles on 2 cylinders.

Bad idea using that I-4 on a viper, you'll never be able to keep it in the RPM range its intended for. Use the I-3, or even better, pick up a cheap 2.0L V6. :thumbsup:

Completely agreed. The inline 4's are better suited for a pontoon or a tri-hull. They have lots of torque, but they won't stay together if you turn them harder than 5400 RPM.

Hang a 2.0 Merc 150 on it.

[Jason Johnson]

A V-4 is the best engine, even one of them white ones. My choice is a 130 Yamaha, mine was stock with LWP 72mph.

[stvhelm]

I'd go with a V6. I remember making the switch on my viper from a 115 I6 to a V6 150 and the boat handled so much better afterwards. then it wasnt long before I got my hands on a 200:reddevil:

[Raceman]

Mercury 1500xs...............................:thumbsup::thumbsup::thumbsup:

Chris

No doubt about it......... Viper/1500XS is one of the best matched combinations anybody ever dreamed up. A 20" V6 with sloppy stock mounts and a typical stock V6 gearcase isn't a good option on a Viper, so if you're going that route I think you'd need at least solid mounts, and some type of upgraded or modified gearcase, and preferably a cutdown mid..................... just my opinion.

[Jeff_G]

That boat was originally rated for a 70hp IIRC. Any V6 will be too much for a pleasure boat, dangerous in inexperienced hands and a liability.
The late model 115 inline 6 would be lighter and still get you where you want to be, with better handling. You would still have a liability problem though.
The 3 cyl. OMC 70 HP with the proper set up and depending on weight, accessories etc will get you very near the 70 mph mark and relatively safely, cheaper, and dependable.
In the hands of an experienced driver go with the 115. Inexperienced, 70. Another option would be the 3 cyl. 90 Yamaha, another very good engine choice.

[stream18]

That boat was originally rated for a 70hp IIRC. Any V6 will be too much for a pleasure boat, dangerous in inexperienced hands and a liability.
The late model 115 inline 6 would be lighter and still get you where you want to be, with better handling. You would still have a liability problem though.
The 3 cyl. OMC 70 HP with the proper set up and depending on weight, accessories etc will get you very near the 70 mph mark and relatively safely, cheaper, and dependable.
In the hands of an experienced driver go with the 115. Inexperienced, 70. Another option would be the 3 cyl. 90 Yamaha, another very good engine choice.
The capacity plate on my 1974 Viper says its rated for a 120 not a 70:confused:

[Sonik]

I agree with Raceman wholeheartedly on this one. The XS motor on a viper is period correct for the most part and what I would also consider the ideal setup BUT, as has been said already, this hull can get you in trouble quickly with horsepower, improper setup, and and inexperienced pilot.

And yes, the vipers were rated for 120, not 70 as was posted earlier. And Jeff, I would have to argue with your claims of 70mph with the 3 popper OMC. The boat would have to be potato chip light, perfectly set up, and have an experienced pilot to run a number close to that.

I'm hanging an XR2 150 V6 on mine due to price and overall reliability. They are almost bulletproof and are missing a little bottom end grunt of a 2.4 or 2.5 which in the end I think will save your original transom if you arent replacing it. Keep in mind the weight differential between the 3 cyl,4 cyl, and V6 engines. With the 3 and 4 cyl motors (less weight on the transom to shift the CG rearward) the boat won't have the tendancy to porpoise as bad through the midrange as with a heavier motor i.e. the V6.

John, I had a V4 110 with a silly long 25" mid, and a propshaft height of around 7" below the pad and mine ran an honest 62-63mph with EVERYTHING in the boat set up completely wrong, including a rotten core. If your choices lie between the two motors you mentioned, I'd go with the 90 merc and hang it on a bobs convertible jackplate using the short setback and bring it as high as you can without losing water pressure. I'd bet it would run low 60's with the 90 if well setup and balanced with nothing but driver and a light fuel load.

Tell me the inline doesn't look cool.....

http://www.hydrostream.org/Specific%20Models/ViperCasper.jpg

[mrcrsr]

i wouldn't waste my time w/ the 2.0/150- it is the same weight as a 200 so why bother w/ the 150? as far as the coolness/optimum engine i would say an inline 150/preferably the later adi engine, and as said previously, it can be made up to look like an xs

[bernie]

I run a 1973 M115 flat on the transom now on my 1977 - just switched to a 15" mid this past winter, turning an extra cup 20" SS chopper. Still breaking in some new rings, but it will run around 6100. Added dual cable R/G also, trim buttons on the control handle (early control - had no buttons).
It will still trim to the moon but watch the water pressure - if you don't run a gauge, put one on. I have to top four holes plugged and have ground out the bottom pickup holes, but may still have to resort to scoops on the intakes.
Compared to the 20" mid, it now demands a bit of respect if the water gets choppy - will side hop if you're at WOT with trim running downwind in a 1' chop. Wakes need to be looked at also. Lanyard stop switch is good accessory, I wear mine always.
LOVE MY VIPER!!

[Jay R.]

out of the two you have listed, go with the 90. I'd like to see a V-4 looper on it, but thats just what i would do.

[transomstand]

According to RONNIE.........Champ motor:D:D:leaving:

[AirRide]

I run a 1973 M115 flat on the transom now on my 1977 - just switched to a 15" mid this past winter, turning an extra cup 20" SS chopper. Still breaking in some new rings, but it will run around 6100. Added dual cable R/G also, trim buttons on the control handle (early control - had no buttons).
It will still trim to the moon but watch the water pressure - if you don't run a gauge, put one on. I have to top four holes plugged and have ground out the bottom pickup holes, but may still have to resort to scoops on the intakes.
Compared to the 20" mid, it now demands a bit of respect if the water gets choppy - will side hop if you're at WOT with trim running downwind in a 1' chop. Wakes need to be looked at also. Lanyard stop switch is good accessory, I wear mine always.
LOVE MY VIPER!!Sounds like your get'n there Bernie, with the mods. Have you considered solid mounts? You should eventually be spinning a little more pitch too. Where did you get the old dual Ride-Guide? Good luck with that Viper.:thumbsup:

[BUSHWACKER]

According to RONNIE.........Champ motor:D:D:leaving:

:iagree:LMAO ya beat me too it, I was going to post, consider everything

that gets posted but not if it's by RONNIE! :nonod: :eek: :D

Also be sure to use an ARP bot and a locknut on the steering arm.

[Morgan B]

with a 90 55-60 ,115 68 ,150 72+ all speeds if engine set up 5" (15') with Bobs nosecone and chopper prop full interior 18 gallons gas.