Chrysler 90 HP ?

[rudedude]

I just picked up another outboard motor and I am a little confused about it. The tag inside is punched as a 90 hp ,the motor hood has Chrysler 90 super charger. Confusion comes in when I look for parts and can only find 90hp with 3 cylenders. This motor is the spitting image of my Force 125 hp,right down to every part and I can not find a listing for a 90 hp with 4 cylenders.

Was there some hankie pankie in the life of this motor with the hp rateing tag ? Could someone have maybe over powered there boat at one time and changed the tag out to avoid a rather large fine?

Or is it I need to research a little more?

 

[Frank Acampora]

Re: Chrysler 90 HP ?

No hanky-panky! The explanation is really quite simple. During the late '70s to early '80s--I forget which year exactly-- when manufacturers were required to rate their engines at the prop, Chrysler elected to re-badge the 105 four cylinder to 90 horsepower. It was only made for about 1 year so that is why you are having trouble finding it. Not many dealers will have manuals or reference it. Thus you have a four cylinder 90 horsepower "Charger" If your engine is from that timespan. (as a matter of fact, this engine is on the cover of the Clymers manual.)

Almost everything is interchangeable with exception of the piston size between every other 4 cylinder outboard Chrysler/Force block.

The four cylinder block was never changed externally, however, it did have four different versions:
1. The 105 which was 3.3125 bore and 2.80 stroke. (also Chrysler 120 HP)
2. The 3.3125 bore with a 2.875 stroke. (some Force 120 HP, Chrysler 125 HP)
3. The 3.375 bore with a 2.80 stroke. (Chrysler 115 HP)
4. The 3.375 bore with a 2.875 stroke. (Force 125 HP, Chrysler 140 HP)

 

[steelespike]

Re: Chrysler 90 HP ?

That description confuses me a little.while its true there is no 105 in 84 when the change was supposed to happen.there is also no 105 in 83.There is the 4 cylinder 100 in 83 and 84.Seems the 105 to 90 is a really big drop unless the
105 was overated.Did they bump all the motors down?I don't doubt the 4 cyl 90 In fact I did find 83 & 84 4 cylinder 90s in the NADA price guide.it just seems to me they would have dropped the 105 or made it the 100 and the 100 the 90 etc.Just trying to figure out the logic.Certainly easier to just drop the rating rather than trying to pump up the 105 to 105 at the prop.
but why skip over the 100.It is interesting to see the 90 re appear in 83,84 as a 4 cylinder after a 5 year absense.
I was surprised to see the 70,75,85,90.100,105,120,130,70-71 135,72-75 150 all seem to have the same bore and stroke.of course 100 up are 4 cylinder.

 

[Frank Acampora]

Re: Chrysler 90 HP ?

Well, when I listed the horsepower vs. bore and stroke, I only listed an abbreviated version. For example, I did not list any 3 cylinder engines. There was a high performance 85 made with a 2.70 stroke and approximately 69 cubic inch displacement instead of 72. Why? probably because a short stroke engine revs up faster.

I suspect the whole engine horsepower designation thing is driven by the marketing guys in an effort to gain market share, and therefore probably has no logic to it.

The original 105 was rated at the crankshaft and I can see a water pump and lower unit gears absorbing around 10 horsepower. Since ratings are a little bit pliable, I can see a rebadged 105 as a strong 90.

And, of course, when I wrote that the blocks were never changed externally I exaggerated a bit. For example, the bypass at the bottom of the block was eliminated, The tapped holes for distributor mount were left untapped, the stator mounting holes in the top of the block are different, and the waste oil recirculating system is different in later Force blocks. Later Force blocks also changed the water chest around the exhaust for better piston skirt cooling. So, they have a different bolt pattern on the exhaust cover. However, with a little work, all blocks can be adaped to all midlegs and almost all cranks are interchangeable--again, putting a short stroke crank into a long stroke block will work quite nicely, however you will lose about 10-15 HP due to the incorrect port timing and less displacement. A long stroke crank CAN be put in a short stroke block and if you raise the top of the ports about .0625 inch, the timing will be correct, and you will gain horsepower--provided that you use a TC carb

 

[eurolarva]

Re: Chrysler 90 HP ?

Merc site shows 83 and 84 chrysler 90s as 4 cylinder and the 75, 76 and 77 as three cylinders. Interesting is that force did not start making a 90 hp till 1990 then started making L drives out of them.

 

[rudedude]

Re: Chrysler 90 HP ?

Thanks guys. This one is stated as a 1984 or so says the title.

So I take this as a suped up 90 hp at the prop then?

I have a 125 force and it seems every thing is the same , I havent checked the bolt patterns but it seems the parts for the 90 are the same as the 125.

It has the same prop size and pitch as the 125. The L/U bolts right up and the splines on the shaft are the same.


This is important info as for the hp due to the fact I many put a jet pump on this motor. The boat is rated for 85 hp and a pump takes 30% of the hp, this will make it to where I wont get nailed for over powering the boat.


Thanks again. BTW The sturgon are biteing again so most of my time will be fishing , Monday and Tuesdays are my days off from the fish LOL.