Mercury EFI Motors! ???

[Wario]

Has anyone ever notice this? I was researching buying a 60Hp mercury & then compared it to the bigger motors (just for interest sake) ie. the Mercury EFI 75, 90 or 115 Hp motor. I did a comparison of all four on the USA Mercury website. The 60 is obviously a very different motor as it only has 2 valves per cyclinder (whereas the other 3 have 4 valves) But as far as I can tell there is no difference between the 75, 90 & 115 Hp motors. They are identical in terms of bore/stroke & gearing (the gearing on all of them is also the same as the 60 Hp Bigfoot @ 2.33 instead of 1.83:1). The only difference would appear to be prop. Can this be right?

It would then seem (to me) that the 90 Hp Mercury (being the same engine - bore & stroke wise) is just merely revving its guts out to produce the 90 Hp). Perhaps the EFI is set differently? If this is correct it seems a cheap way of getting a 90 (by buying a 70) if you can get the emgine mapping software to change if (through a friendly mechanic)? What else is there that can cause the increase in Hp? What do you guys think?

[Wario]

Having a second look at the 40 - 60 Hp motors I've discovered that they are the same as well (bore/stroke etc). Interesting.

[smokindrags]

Yes it is always done
Then they don,t have to make 1 new motor for each size HP
in older mercs/2 st 75-90 they used to run different carbs and jetting which was the difference i the hp
also one another motor they had different jetting and intake plate/ larger bore for air flow.

you need to do our research such as how much it would cost to get
ECU rechipped if it can be.
if they run different size injectors or air intake plates and another differences
if any others

[Fishigan]

Yep, same CCs different HP. I was under the impression that the older ones had different powerheads. Years ago, a mate of mine had his 40hp rebuilt with a 50hp powerhead which gave it the extra 10 HP.

[Ben]

The diff between the 60 and the 60 bigfoot is gear box and propeller.
Bigfoot gives a stack more torque, designed for displacement hulls and large loads generally.

[Andrew7]

The porting and ECU's are all different on each model as far as i know....

[leachy]

Its similar to the Yamaha CV25 & CV 30 but on a smaller scale. The differenece between these two motors is the reed valve spacers and the engine timing.

[Dean Titmuss]

I looked into the same thing about the 75, 90 and 115 hp mercury engines. I rang a local dealer and asked the same very question, are these the same engine? The answer quite simply was yes, except for the computer. The computer is the governing factor. If for example you bought a 75hp engine and bought a 115hp computer for it then your engine would become a 115hp engine, except you would not have any warranty. You would only possibly think of doing this outside of the warranty period and even then it would be still a bit dodgy.

I found this information whilst looking to repower my boat. My boat has a max hp rating of 80hp. Since there are not too may 80hp engines built these days I started to look at the current crop of 75hp engine and stumbled upon the same information about the engines being the same weight , size, stroke and bore. I asked the question of a dealer and got the above reply about the possibility of changing the computers to up the hp rating of the engine without disclosing the true indentity of the engine. The would give you increased hp but would possibly then void any insurance claim should you have one. A 90 hp motor on my boat would be great, but a 75hp engine i could not see delivering the required performance for the dollar outlay price to upgrade from the current 60hp efi 4 stroke.

I just stumbled upon your post about the topic and thought i would share my information.
cheers