performance form?

[adam98]

first off this is me just thinking out loud and do apreciate any input even if its not what i want to hear. I value all opinions! so dont take this wrong but...

Why when i see or ask about changing something to gain performance most say dont do it you are crazy (cost to much) and everyone is just happy with a boat the gets them from point a to point b and starts on easy....

I have messed with all forms of engines and never seen a type of motor that cant be easy to improve with some minor tweeks and some like myself value that time learning and testing/ building as much or more then time on the water. yes my boat runs but can get more out of it without spending to much money. all things can be improved here and there unless all outboards are gods gifts to man.

I drive a $55,000 diesel truck and have a few more for work... the work ones are wot all day and still strong 200k miles ( loaded over there cap.) with only 4-5 oil changes in there life, only problems have been trans, a rad. and a/c... I change my oil every 30k-50k miles!!!! I take these and other motors apart so i know this doesnt cause problems, but if i made my living selling Gasoline or oil and filters i would say ur crazy. give me some more money......... my wifes car has 0-5wt oil in it stock. thats nuts.

i find many people just dont understand and never will. so they play it safe. but a few people know alot and some try and learn. and there should be a form for performance for just that DIY performance so you can get feed back on ideas and mods that did and didnt work.

i dont plan on keeping the motor for thousands hours or and wish people tryed to get more out of there motors for fun. or is it crazy to get more performance out these outboards?

 

[JB]

Re: performance form?

The reasons most of us do not recommend "hopping up" 2 stroke outboards is that it is far easier to ruin an engine than to increase output, there are essentially no bolt on goodies in the market and most people buy outboards that fit their applications already.

It is certainly possible to greatly increase output. It usually costs much more than simply upgrading the engine. It almost always makes the engine unreliable and short lived. Racing is the only application in which I would consider it.

My experience modifying 2 stroke engines was almost all making kart racing engines out of used chainsaw powerheads. A 5HP @3600rpm engine could be made to make 15-20HP @10000-12,000rpm on methanol/nitromethane. They frequently failed spectacularly.

You are welcome to experiment in that area, but don't expect enthusiastic involvement from guys who simply want a user friendly outboard to take them fishing or pulling the kids on skis or tubes.

 

[Chris1956]

Re: performance form?

As JB said, whenever you modify your motor for high performance, you trade something else off, usually longevity. As an example, Indy cars get tremendous maintenance and repairs between races. Some are completely rebuilt or get new motors. If you took that example and (loosely) adapted that to your OB, you would need to rebuild it after every 5 fishing trips or once a year, but you would get to the fishing spot real fast. Is it worth it?

 

[Chris1956]

Re: performance form?

BTW- There is a high performance OB forum called "Screamlandfly". Those guys will give you all kinds of ideas for increasing performance, although they tend to concentrate on V6 Outboards. To borrow a phrase, "When in doubt, Dry-stack that baby!"

 

[Boss Hawg]

Re: performance form?

Strongly agree with JB-
Also remind me not to buy any used motor from you

 

[Frank Acampora]

Re: performance form?



2 cycle outboards are set in horsepower range by the "timing" of the ports. They are not like older lower tuned auto engines that will benefit from something as small as a carb change or like newer engines that can be upped by a chip in the computer. Thus: while it is not as easy to improve performance of a 2 cycle, it can be done. It just takes more time.

I do port work on my personal use engines and will recommend it to those who ask. HOWEVER-- It is relatively easy to actually degrade performance so you need to do your homework BEFORE digging into the engine.

Hey Chris: Do you recognize this? Waretown and Barnegat township ramp. The inlet and lighthouse would be off the stern in the last photo

 

[Frank Acampora]

Re: performance form?



Adam98: Here are a couple of photos of port work and other mods I have done on older Chrysler engines. Newer engines and other brands already incorporate these mods into their design. Thus, I am simply taking old school design and bringing it up to current standards. For example: My Chrysler 90 horsepower engine is highly modified and now puts out an honest 90. It can now compete with Merc and OMC 90 engines while before it was 5-8 MPH slower.

 

[Chris1956]

Re: performance form?

Frank, The only real time I was in Waretown was when my Fat-fifty broke down (broken point wire, as I later discovered), and I was towed to Ahern's dock, and given a ride to the Waretown Wawa. From the Wawa, I shared a bus ride north on rt 9, with Ocean County's finest folks, jogged from rt 9, back to my house and grabbed the car and trailer.

 

[adam98]

Re: performance form?

Great info! thanks and thanks again.

i dont expect to double the output of the motor but a little here an there or maybe less timming for these conditions and more timing plus a recomended simple mod might wake up the motor for your needs. a 115hp running at real world 100hp that can be tuned up to 120hp and in a range your looking for or even a few hundred rpm wot could be a world of difference. and Shouldnt kill the motor like Im running 75hp shot of NOS.... at 8500rpm.

my johnny 115 v4 has a timing base advance. can i put more timing into it and find when i pings then back it off a few degrees? I added 5 degrees today and helped out entire rpm range. if its not pinging i dont see the problem do you?

 

[Frank Acampora]

Re: performance form?

Your V4 can be modified, but timing advance is asking for trouble. Outboards make a lot of noise and sometimes you just don't hear pre-ignition. If you want to jack up timing, don't go more than 32 (if it is crossflow) and at least, use premium fuel. However, remember that even top fuel dragsters only use about 36 degrees total advance.

I believe your 115 is a crossflow engine and porting will increase power. Reeds? There are various opinions on aftermarket reeds. If your 115 is a bubble back, you can also clean up the exhaust runners. Fair them and remove extra casting flash. I'm not too familiar with OMC but you may also be able to change lower unit gear ratios.

You will probably get better and more detailed info at the OMC forum

However, before you go into mods, play around with engine height and setback on the transom. Using a jackplate and raising the engine usually results in some real speed gains without modifying the engine. Then, play with props--pitch, diameter, and blade area. Cupping for better bow lift, and venting for hole shot.