Turn a 70HP into a 90HP??

Power_Dr · Jul 29, 2008

Hello All,

I heard someone saying that there is some adjustment or something that you can do to a 70 HP Evinrude outboard that will make it a 90 HP. He didn't have any of the details but was told this by some boat mechanic. Has anyone heard of this or is this just BS.

Thanks,

Dhadley · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

Very easily done but the details depend upon which series of motor you're talking about. If you're refering to the later model carb'd versions it's very easy. Undo the 4 bolts in the stern brackets of the 3 cylinder 70 and insert them thru the stern brackets of the V4 90. Naturally you'll have some wiring and hoses to deal with too.

Seroiusly, there's usually a lot more to increasing horsepower by over 25% on any motor than a simple adjustment. What year 70 do you have in mind? Remember, torque is what moves a boat, not horsepower.

Power_Dr · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

I will have to check what year they were talking about. I was think it would be like a gov'ner or something like that, but all that would do is increase the RPM's not the HP. I wasn't really bevlieving what they were saying.

Thanks,

Dhadley · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

Some models have a rev limiter, some don't but it'll still won't be just an adjustment.

iwombat · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

No no.

If you look right on top of the powerhead there's a little knob you can turn with numbers beside it. It should go from 50-150. Just ease it up to 90.

Dhadley · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

I thought you used the tire valve on the black box (cylinder). Just inflate to the desired level.....

iwombat · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

That's only if the knob is broken. Of course, you'll need to wrap a paper clip around the spark plug on #1.

Silvertip · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

Yet another third party fairytale! You can certainly get 90 HP out of a 70 but it isn't going to be with an adjustment. You also need a very thick wallet and that 90 HP motor will likely need to be rebuilt every month or so -- if it would last that long. And you'd better like going wide open or not at all as that's the only RPM it would be useful.

iwombat · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

Power Dr, we're not making fun of you. We're just having a snicker at the originator of the story.

Welcome to iboats.

Tacklewasher · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

iwombat said:
No no.

If you look right on top of the powerhead there's a little knob you can turn with numbers beside it. It should go from 50-150. Just ease it up to 90.

My knob must be broken as it only goes to 115.

Can I just get a new knob that goes to 150?

iwombat · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

That 115 knob was superseded in 1991 by part# 0387451.

Tacklewasher · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

iwombat said:
That 115 knob was superseded in 1991 by part# 0387451.

Cool.

Off to the local BRP dealer.

Can't imagine the look I'm going to get based on the dumb look I got just trying to get a prop out of them.

Benny1963 · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

HEY I JUST TURNED MY 150 INTO A 175 ,
all i had to do was spend 2500 on a new powerhead take out 6 bolts 4 nuts and wireing harness,wish i would have know about the switch ,thanks alot guys for keeping me in the dark

WTL · Jul 29, 2008

Re: Turn a 70HP into a 90HP??

No, but they do make a carburetor that you can add on to the engine which will increase fuel efficiency to 100 mpg. It would have been sold already but the government, oil companies and evinrude bombadier are conspiring to keep it off the market with a system of kickbacks so complicated only I understand it.

Turn a 70HP into a 90HP??

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