Dishoner

[Aqua Zombie]

Last weekend, my friend ragged me so bad that I almost went to the E.R. to have a specialest look at my wounded pride. It all started a few years ago when I found him a good outboard for his first boat. My other friend had the motor, but never used it, and was ready to sell it. It was a Seahorse 6hp that they bored a plate behind the carb to match the carb bore. That single mod, seemed like the equivilent of adding nitrous, running nitromethane, with 18 pounds of boost from a roots charger... and the **** thing hangs together just fine. Just draw the starter cord back and its running from dead cold. Same thing when its hot. It just doesn't care. So with his "pro mod, top fuel, mountian motor" he ran circles around me all day on the river. Not just circles around me, but circles in a flat bottom 16' overpacked johny with 2 people, around my 12' V bottom with just me a tank of gass and a motor. So I need help. I must make my 1978 6hp Evinrude fishing motor outrun his 6hp motor. Where to start? I am entertaining any and all Ideas. This includes powerhead swaps. It just has to look like that ole 6hp that I own. Any help would be greatly appreciated. Ill have many pics of mods and parts that anybody may sugest to mod on this thread. So for entertainment value, stay tuned and watch this evolve to something way bigger than the wife is going to tollerate!

[Guest]

6hp is that even a motor????

Last weekend, my friend ragged me so bad that I almost went to the E.R. to have a specialest look at my wounded pride. It all started a few years ago when I found him a good outboard for his first boat. My other friend had the motor, but never used it, and was ready to sell it. It was a Seahorse 6hp that they bored a plate behind the carb to match the carb bore. That single mod, seemed like the equivilent of adding nitrous, running nitromethane, with 18 pounds of boost from a roots charger... and the **** thing hangs together just fine. Just draw the starter cord back and its running from dead cold. Same thing when its hot. It just doesn't care. So with his "pro mod, top fuel, mountian motor" he ran circles around me all day on the river. Not just circles around me, but circles in a flat bottom 16' overpacked johny with 2 people, around my 12' V bottom with just me a tank of gass and a motor. So I need help. I must make my 1978 6hp Evinrude fishing motor outrun his 6hp motor. Where to start? I am entertaining any and all Ideas. This includes powerhead swaps. It just has to look like that ole 6hp that I own. Any help would be greatly appreciated. Ill have many pics of mods and parts that anybody may sugest to mod on this thread. So for entertainment value, stay tuned and watch this evolve to something way bigger than the wife is going to tollerate!

Where to START? Get a bigger frinking motor and get the lead out of your .......

[Aqua Zombie]

I have bigger frinking motors prohydro... I have twin 40's. A small collection of kg7's. Including hydro quickies to go along with them at the H length. And I am the kind of guy to try clamping both 40 horse mercs on the back if my tin can just to be that guy. But the problem is that my friends 6hp Is NOT allowed to outrun my 6hp. plain and simple! sort of?

[B Walker]

There is no truth in advertising for outboard manufacturers. Not all motors with a sticker on the side that says "6HP" are created equal.

The only way to compare the two motors for real is by comparing bore and stroke.

Some manufacturers use the same bore and stroke in the 6HP, 10HP and even 15HP models then use detuned ignition systems, rev limiters, and smaller carbs to "choke down" performance.

I would not be suprised if your friend had one of these wolves in sheeps clothing.

More info is needed to help you out here. Lets start out with both motors bore and stroke.

If you cant find that out then the make and model and year of manufacture would be quite helpful.

If his 6HP seahorse is really a 15HP with a really small carb (before the mod) and you have a for real 78 Evinrude 6HP you may be s.o.l.

Easy fix: get a 10HP or 15HP that your 6HP evinrude cover fits and swap em....you will not be the first person to do it

good luck
BW

[pirata]

Get a better prop and add some octane boost from an autoparts store to your gas tank, just be careful not to burn up the engine. ..

[Mike45]

Without changing the gear foot and type of prop you may never beat him. But if all else fails put some alcohol or ether in your fuel. However I am not recomending this because it may only beat him once.

[Aqua Zombie]

My Evinrude...

ok.. here is the mill I am working with...

[Aqua Zombie]

B Walker, Pirata, and Mike 45... I am fully prepaired to bore, stroke, change octain, and nitro, ethenol, methanol, "leafblowersupercharger", nitrous, intercooler, what ever. Not afraid to turn money into noise at this point. I'll get some teardown pics on here soon. I had a look at the reed cage yesterday, then had to screw it all back together to get my workbench back. but its "On" at this point.

[modifiedoutboard]

Blue thunder

ok.. here is the mill I am working with...

Back in 96 I was running a trot-line "crabbing" on the Chester River in MD.
Saw a Sears 12' Semi-V with a 40hp bigtwin named USS Minnow.
It was fast compared to my 14' Jon with 15hp Evinrude.

A lot of hp is never enough while too much HP is just right.

[B Walker]

Generally, in a gasoline powered engine that is well tuned and optomized for performance 1 cubic inch is equal to 1HP.

Forget about the "6hp" stickers for a sec. If you have a 6 ci motor and your friend has a 15ci or even a 12.5ci motor there is nothing you will ever do to your 6ci motor to "catch up". Not even the most exotic mods will give you a 2hp to the cubic inch performance. Overboring, an alcohol conversion and a high compression head would maybe give 50% HP boost and I think that is a generous estimate.

You cant beat cubes.....even with a checkbook as big as Bill Gates. The laws of physics wont allow it.

Simple solution: get a 10HP-15HP of the same make and model year as your 6HP that the cowl fits on and make your own wolf in sheeps clothing.

Now if his Seahorse has the same or similar ci displacement as your motor it is on!

BW

[pirata]

Simple solution: get a 10HP-15HP of the same make and model year as your 6HP that the cowl fits on and make your own wolf in sheeps clothing.

Most definately a wolf in sheeps clothing. That would work too. Besides, who's to say your friend didn't already do this to you in the first place.

[D_Allen_III]

Plug the water passage. That's what we do in the stock outboards.

[johnsonm50]

There is no truth in advertising for outboard manufacturers. Not all motors with a sticker on the side that says "6HP" are created equal.

The only way to compare the two motors for real is by comparing bore and stroke.

Some manufacturers use the same bore and stroke in the 6HP, 10HP and even 15HP models then use detuned ignition systems, rev limiters, and smaller carbs to "choke down" performance.

I would not be suprised if your friend had one of these wolves in sheeps clothing.

More info is needed to help you out here. Lets start out with both motors bore and stroke.

If you cant find that out then the make and model and year of manufacture would be quite helpful.

If his 6HP seahorse is really a 15HP with a really small carb (before the mod) and you have a for real 78 Evinrude 6HP you may be s.o.l.

Easy fix: get a 10HP or 15HP that your 6HP evinrude cover fits and swap em....you will not be the first person to do it

good luck
BW

This is true & the guess part probably correct. If his motor had a restriction of less than the carb in the intake manifold, it would definitely be a de-tune of a bigger hp. Im not familiar with the 6's but know OMC uses the same basic block for 9.9's-15's & the 18's to 35's too of certain years. Heres a tip for parts ID..Armed with #s go to BRP parts catalogue & they have everything back to about 68. You could spend some time there & compare motors part for part. Did you look behind your carb?
When you mess with stuff like this your likely to lose performance till or unless you get the bugs of 'not designed for' worked out. Things like porting, fixed jets, exhaust flow all together make them what they are & usually theres no 1 -fast- fix. If there is a will, then a way.. You Can Do It ! LoLs on the Pride Dr.
Don't stop at the power head, look for difference below the waterline, many times the biggest best & most gain you'll see is the prop. [disclaimer: we're talking 6 ponies] If you cross reference midsections you might find what other power heads will bolt up. drive shafts can be cut & sleeved. Ya got options... If ya wanna go.

[Kev43V]

Plug the water passage. That's what we do in the stock outboards.

LOL you might have to explain that a bit... When we first got into stock. Someone asked us if the water passage was pluged on that motor. our ony reply. HUH?? what passage, where?

[PBRSpecial]

I have a Johnson (96) 3 hp, that is tricked out by Vic Brinkman, that we race once a
year in our 3 Horse Club Race. Run it on a 14 ft narrow bottom jon boat, 2 guys, 2 gals
of gas with squeeze bulb for refueling under way, 2 guys, 12 refreshments, etc, runs
anywhere from 13 mph to 14 mph on gps depending on setup...fuel is 119 octane, Klotz
racing oil, NGK plugs, we weigh in about 400 lbs total for race. we race about six lakes
marathon style..its a blast really..use automatic transmission fluid in gear case..even
have pipes made for this little runner..we have won our class 4 years running..just
saying, anything is possible with these smaller engines..