OMC 30 vs 35 hp

[Biddaddydan]

I presently own both a 30 (Johnson) and 35 hp (Evinrude) 1992 engines and I am at a loss trying to find where and how that 5 hp on the Evinrude  comes from.

As every critical components (Carbs, jets, intake etc.) seem (to me anyway) identical, I can only guess that the 35 would be allowed to rev an additional 500 rpms or so. OMC’s service manual (part 508142) does refer to the 35 hp occasionally but only gives engine specs for the 30 hp.

So I turn to you, my very knowledgeable friends, for an explanation of where those extra 5 hp come from and what hardware (if any) allows it

Regards !

There are no old outboards, just machines so well built, they have outlasted their owners !

[frankr]

I started to wade through the parts books, and got lost in the confusion.  But I think you will find the difference in the carburetors.  Guessing venturi size (?)

[fleetwin]

I was not aware that a 35hp was offered in 1992, just a 30hp, do you have its model number?

[billw]

Boy, I love a challenge but I don’t see any difference in parts, either. The whole carb, head, block, pistons, exhaust tuner, reed plate, reeds, ignition CD unit….all the same. That’s craziness. Like you say, maybe they just allow more spark advance on the 35. Maybe take a look at how the spark stop screw, #14 in the link below, is adjusted on each engine?

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1992&hp=35&model=E35RENR&manufacturer=Evinrude&section=CYLINDER+%26amp%3B+CRANKCASE

Long live American manufacturing!

[need2fish]

Maybe it’s just a difference in labelling ? 🙂

[Mumbles]

If all of the mechanical parts are the same, pistons, carb, head, etc. the power output may be determined by the alignment of the ports in the cylinder liner to the runners in the block. I’ve seen this done on other motors where the liner was cast or pressed  into place with the ports partially blocked off lowering the power output. A cheap and efficient  way to make different horsepower rated motors in the same family without having to manufacture different and expensive parts.

Remember, a motor has to be able to breathe to make power and if it can’t breathe properly, it just isn’t going to make the power it’s capable of.

[Biddaddydan]

Thanks for replying !  Venturi sizes measure the same on both and marineengine.com specifies the same jets for either engines.

There are no old outboards, just machines so well built, they have outlasted their owners !

[Biddaddydan]

Model ID is exactly the same on both except for the hp rating so one starts with J30… and the other with E35… !  Indeed my OMC service manual opening pages do state that it applies to both. Thanks for replying.

There are no old outboards, just machines so well built, they have outlasted their owners !

[Biddaddydan]

Thank you ! Your hypothesis warrants further investigation that I will conduct. Regards !

There are no old outboards, just machines so well built, they have outlasted their owners !

[Biddaddydan]

OMC was a serious manufacturer and I strongly doubt that the higher rating would only have been some marketing ploy. Maybe those different ratings could have been the result of different rating methods on various markets. I’m really at a loss here.  Thanks for your thoughts.

There are no old outboards, just machines so well built, they have outlasted their owners !

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