viper/engine question

[boater4040]

I have recently purchased a late 70s model viper that I want to have restored. I have two engines that I am thinking about putting on it. One is a late 80s model 100 hp Mariner inline 4 cylinder and the other is a 2005 90 hp Mercury 3 cylinder inline saltwater series. I want to go 70 mph? Will either of these engines bre capable of making it run 70 mph with the right setup and prop? If not, how fast would either of these make it go? If either of my two engines will not make it go 70 mph, what is the best engine choices to make it go 70 mph?

[Hippie459MN]

200 will make it go 70 and then some I bet.

Really though, I am no expert on the viper hull motor combos but im sure someone here will be able to help ya out. There are a few viper guys here.

Also, Welcome.

[Blue]

I had a viper with mod 140 ran 76.7 gps. But 130 yama hammer is what you would like.

[77viper]

If I had to choose I would go with the 100 just to get it on the water. I'm only guessing but it should put you into the upper 50's low 60 with a good set up. A 3 cyl just doesn't have the tourque and will cost more, neither engine is a performance powerhouse. If the 100 gets you up and running it will be more motivation to get more power. Look for at least a 115 inline, there are upgrades you can do but it's a little before my time.

Welcome and good luck, check you're core

[Maple Leaf]

Neither of them, They are both big heavy turds. And either of these motors will NOT get you to 70mph. You could be lucky to get at least 60mph. I would sell both and find a 1984 or later Mercury inline 6 115. They have the better ingition and are Hp rated at the prop. With a BIA Mid and built in Power trim. Or find a OMC or Yamaha V4 115hp or 140hp etc. Hope this helps. Brandon

[HST4ME]

The 100 will get you to 70, but has to be propped stiff at around 5400, no more. The problem with both those motors is the flabby mounts and horrible gearcase profile. They are going to make you drive to get the results. FIRST make sure the boat is solid with no core rot and a good transom. In my personal experience there is maybe a handfull of original boats out there that are solid, They were built like **** unfortunately, and a delam will hurt you or worse at top speed.

[boater4040]

What is a delam, just curious..

[77viper]

Delamination is when the outer fiberglass is torn away from the core. It is caused by a weak bond between the core and the outer fiberglass, of a rotted core. If it happens the outcome can be dangerous and the boat can sink fast.

[Vegas XT]

I have a Johnson GT200 for sale. Make an offer.......