exhaust mods

[dart]

hey guys
r.e modding stock outboard stinger manifold pipe and megaphone.
i have a 50 hp mercury(tohatsu) hort shaft 3 cylinder/3 carb with plenty of mods done
i have the earlier d1 exhaust which is a little larger diameter than the late model stinger!!
can you shorten or lengthen the stinger ?
what will this do ?
and the megaphone,can you remove it altogeather or shorten it ?
what does the megaphone actually do ?
your thoughts/ideas please .
thanks

[dart]

can any one please help advise ?????

[Tim Kurcz]

can any one please help advise ?????

Hey Glen,

Attached are images of my 45SS expansion chamber Mod engine from 2010. The Ski-Doo pipe is large and requires a custom headpipe and mid section to keep it clear of the water.

Note the difference in pipe position from driveway shots to lake: The headpipe and chamber required serious shortening as indicated by test wheel pulls (peak RPM too low). After a year's worth of building, testing, and development, the engine delivered 4.2 MPH better than my best 45SS Mod. It needs additional work - 2more MPH are needed to be competitive in class.

As stated in PM, there is no commercially available expansion chamber for your Tohatsu, and no single solution whatsoever. To achieve your goals, the research, mods, and development need to be done the good old fashioned way - by you!

Good luck with your quest for speed,

Tim

[dart]

g,day tim
wow great pics mate!!
a credit to you on all the awsome work you have done!!
thanks for your kind encouragment mate!!
so you dont use and run a top engine cowling when on water ??
i have alloy ram tube velocity stacks on my engine,no air box any more and i also have 3 cut thri air vents on front of cowling to let air into carbs better!!
what rpm range does your pipe start kick into ??
is a end bleed or centre bleed type pipe better ??
im modding/designing my pipe that will have both end bled and centre bleed an will block one bleed of while trying the other bleed!!
also r.e stinger inner diam for correct back preasure,im going to make a couple of various inner diameter stinger outlet sleeves that i can slide into end of pipe stinger.
any info pls re. questions above on stock stinger please ??
the exhaust i have got and been modding is a " westcoast " jet ski brand perf pipe.
quite short,not as long as your pipe,decent size diameter belly
will get pics for you once all modding,fitted and painted
hey tim,can you please check out " westcoast" performance brand jet ski pipes pls,tell me what yo think ??
cheers

[Tim Kurcz]

g,day tim
wow great pics mate!!
a credit to you on all the awsome work you have done!! Thanks!
thanks for your kind encouragment mate!! You're welcome.
so you dont use and run a top engine cowling when on water ?? Nope: We call it Mod (modified)
i have alloy ram tube velocity stacks on my engine,no air box any more and i also have 3 cut thri air vents on front of cowling to let air into carbs better!! Sounds good.
what rpm range does your pipe start kick into ?? Mid to 7250 where it hits the wall (needs to be shorter).
is a end bleed or centre bleed type pipe better ?? End.
im modding/designing my pipe that will have both end bled and centre bleed an will block one bleed of while trying the other bleed!! Good luck with your development.
any info pls re. questions above on stock stinger please ?? Nope. Just gotta try it and document results A-B-A
the exhaust i have got and been modding is a " westcoast " jet ski brand perf pipe.
quite short,not as long as your pipe,decent size diameter belly They are all different.
will get pics for you once all modding,fitted and painted Sounds good!
cheers

Good luck with your build. Just be sure to keep notes and change only one variable at a time....

Tim

[dart]

i heard apparently r.e expansion pipes,the longer the cone,the more low end/torque you will have,but less rpm.
the shorter the cone more rpm/top speed power you gain ??

[Mark75H]

Two Stroke Tuners Handbook, the best source to understand all these variables

[dart]

hey tim,
in your pics of the seadoo exhaust,what are those two grey bands around the pipe ??,are they too help strap and secure it to the engine ?
is your pipe quite secure and you dont get any side movement ?
is your pipe a "dry set up" or a "wet set up " ?
how did you strap it to which part of the engine ?
thanks

glen

[Tim Kurcz]

hey tim,
in your pics of the seadoo exhaust,what are those two grey bands around the pipe ??,are they too help strap and secure it to the engine ?
is your pipe quite secure and you dont get any side movement ?
is your pipe a "dry set up" or a "wet set up " ?
how did you strap it to which part of the engine ?
thanks

glen

Hey Glen,

Those are springs which hold the pipe snowmobile style. Expansion chambers must be allowed to move or they will break: After all they are acoustic chambers and experience a wide range of vibrations (up and down). The pipe is dry, though a diffuser cone water injection point was tested. It did improve midrange and quieted the pipe ever so slightly - it's pretty raspy. The pipe was attached by four springs at the inlet, and two springs around the belly. Attach your pipe anywhere there are strong points.

Tim

[dart]

hi mate
so where would i fit my brass 360 degree spray fine nozzle that is attached to the brass barb and the water comes from above from the tell tail outlet to make my pipe into a wet pipe ?
i was thinking to fit it on top of pipe at the start of the first large belly cone ,will this be ok ?
thanks tim
cheers

[Tim Kurcz]

hi mate
so where would i fit my brass 360 degree spray fine nozzle that is attached to the brass barb and the water comes from above from the tell tail outlet to make my pipe into a wet pipe ?
i was thinking to fit it on top of pipe at the start of the first large belly cone ,will this be ok ?
thanks tim
cheers

The objective of water injection is for pipe tuning, not cooling, in the case of my 45SS, a "dry" snowmobile pipe. The personal watercraft "wet" pipe you chose has a water cooling jacket for below deck operation. I can't tell from your questions if you're talking about tuning or silencing, presumably not cooling.

As stated several times before, there is no single answer to your question(s). YOU are now a development engineer and must make decisions, test, and compare. For more help, take Bill's suggestion and search the thead, or read Blair, Bell, or Jennings if you want to learn more on the subject. Like the rest of us backyard mod guys, you're on your own!

Tim

[dart]

The objective of water injection is for pipe tuning, not cooling, in the case of my 45SS, a "dry" snowmobile pipe. The personal watercraft "wet" pipe you chose has a water cooling jacket for below deck operation. I can't tell from your questions if you're talking about tuning or silencing, presumably not cooling.

As stated several times before, there is no single answer to your question(s). YOU are now a development engineer and must make decisions, test, and compare. For more help, take Bill's suggestion and search the thead, or read Blair, Bell, or Jennings if you want to learn more on the subject. Like the rest of us backyard mod guys, you're on your own!

Tim

i was talking about the wet pipe r.e cooling and tuning!!!
any way as you said on my own now,so i wont ask any more questions....