1988 88hp motor vs 1992 115hp

[nastyquedawg]

Are there any advantages to upgrading to a 92 115hp motor other than 28 additional horsepower? I'm currently going about 32mph in my 17ft invader.

 

[SparkieBoat]

Re: 1988 88hp motor vs 1992 115hp

no advantage, unless it is a 60 degree OIS motor. it will idle idle better and run a little better than the 90 degree motors.

 

[BonairII]

Re: 1988 88hp motor vs 1992 115hp

What's it going to cost you to upgrade to the 115? Do you know the history of the 115?

How well does your current motor run?

 

[wired247]

Re: 1988 88hp motor vs 1992 115hp

You'll get there a little faster and youll use more gas. Your battery will live longer with the regulator.

 

[emdsapmgr]

Re: 1988 88hp motor vs 1992 115hp

They are not the same block. That will require a complete teardown and some significant block machining work by a skilled marine machinist. Not an inexpensive proposition. You'll have to purchase the larger carbs. Probably NLA, so you will have to find used ones. You will need an exhaust filler block kit, 392000, which was about $ 185-and it just went NLA. You'll also need the inner and outer exhaust covers. The inner is NLA (was $ 432) The outer cover is $146 and is still available. These parts are common and you should be able to find salvaged parts which will work. When you are all done, both engines on the same boat will run just about the same up to 32 mph, then the 115 will start to pull away. You'll probably get a 2-3 more mph out of it. Probably not worth the $ and the downtime.

 

[SparkieBoat]

Re: 1988 88hp motor vs 1992 115hp

he is not talking about swapping the power head, he is considering a complete engine swap..I think.....
by the way those old 88s were under rated in my opinion..you would probably only get about 5 HP with the 115..unless it is an OIS motor that I mentioned earlier.

 

[wired247]

Re: 1988 88hp motor vs 1992 115hp

There is a considerable difference between 88/90's and the 115s in power. Its not 4-5 HP. As far as the conversion of the block to 115 specs on the block it doesnt have to be a skilled marine machinist. Anyone with a vertical mill can do it with a set of 4 flute cutters. Less than an hour job. The 88/90 ports are about pinky sized on the intake . 115/140 ports are wider and higher but the 88/90 block can be used as a base quite easily. In any case once the case is apart the ports are easily cut from the side cover openings. The exhaust cut in the block is a 5 minute job on a mill. The bubble back is usually found under a hundred bucks for a complete set and theres no difference between a used set and a new set other than the cost. The carbs are run of the mill 1 5/16" and can usually be had for $50 a set on ebay. So for around $350 in parts ( gaskets, rings, carbs and exhaust stuff ) plus a 12 pack of beer for a buddy to do the mill work its an easy 25 HP . More if you want to add a set of 140 heads. The difference in the top end between the 88/90 and the 115/140 is astounding with very little given up on the bottom end. Add a set of Chris Carter reeds and the bottom end will feel the same.

On my best day with my old 90 I could hit 51 MPH going downstream with the wind with a 19 pitch OMC prop. With a 21 pitch Solas on a 140 spec crossflow OMC V4 I'm passing 60 without even trying hard.


FWIW I'll never understand the defeatist attitude given to people looking to upgarde their engines to more HP. "Oh. It will never work". "If you want more HP buy a bigger engine" Its a bunch of hooey especially when you are talking about hot rodding a crossflow 88/90 V. There is all kinds of potential HP sitting there just waiting to be released and without a lot of effort. Put a stock 90 next to a stock 140 in identical boats and the 140 will blow the 90 out of the water. Do a few simple mods to the 140 and it gets even better. These are quite possibly the simplest engines in the world to work on.