o.s outboard,stock exhaust or pipe

[mark james]

Hi all,,Has anyone ran a stock o.s (3.5)and upgraded to a pipe exhaust..If so what was the improvement?

Ive heard good things about the stock set-up useing the stock exhaust but,,alway looking to improvement.

Ive run many tunnels over the yrs but this is my first o.s powered tunnel.(going on the lynx hull)..

Also,,if piped,,what pipe for this mtr ??

Thank you for any help and comments

mark

BTW, any set-up info as per head clearance (via head shims,ect will be very helpful too!! thanks again!!

 

[Howard Welch Jr.]

Hi all,,Has anyone ran a stock o.s (3.5)and upgraded to a pipe exhaust..If so what was the improvement?Ive heard good things about the stock set-up useing the stock exhaust but,,alway looking to improvement.

Ive run many tunnels over the yrs but this is my first o.s powered tunnel.(going on the lynx hull)..

Also,,if piped,,what pipe for this mtr ??

Thank you for any help and comments

mark

BTW, any set-up info as per head clearance (via head shims,ect will be very helpful too!! thanks again!!

hi for head clearence take the shim out as for a pipe the stock works very well so as for a tuned pipe i couldnt tell you

 

[topfuel443]

Plenty of people run a pipe on an os succesfully. The stock muffler works very well with just removing the head shim, and running high nitro. In order to get a pipe to run any better than the stock muffler, you will have to raise the exhaust timing. This is fairly easy to do if you have done it before. The optimum number is around 180 degrees (stock is 160), but you could run a little more or little less with similar results.

The best pipe I have run on an OS is the Silver Bullet HP pipe. The Irwin stamped pipe also works well if you shim the stinger down to about .280" id.

Definitely remove the head shim, and run as much nirto as your wallet will allow, 50-65% is best. A lower pitch prop at about 38-39 mm is also good, it lets the engine rev more freely.... and they do like to rev when set-up right.

If you bolt on a tuned pipe without raising the timing, you are waisting time, effort, and money.

~James

 

[GRoth265]

James is correct, If you don't change the exhaust timing it won't work. I use the Irwin pipe with the stinger reduced. My timing is more than 180 degrees but I use a plug a run. The stock motor runs well with the head shim removed on my LYNX with high nitro. You have to put the motor high and let it sing.Greg

 

[Ronald van Essen]

Maybe a good thing to remember-------stock pipe gives you automatic lubrication.

Ronald.

 

[mark james]

Hey thanks for the fast repleys guys!! Guess Ill try first running the stock pipe and test.

ILike I said,,I do run diff.mtrs,,k&b and also I run a rossi power head on my leecraft wth a silver bullet pipe amd lawless lower.

NOTE,,

RON,,is the tube from the right side of the muffler used to lube the drive shaft?..(just a new set-up and curious to know..Yes I will still pull the drive shaft,clean and relube it ..

Top,,thanks for all the info..its very helpful

. thank you all very muck,,will check for any more repleys..!! cant wait to get er done and test!

Need to get hooked up with a few props too!!(mark HINT!!

 

[davidwhipple]

Hey mark, I have an o.s and im gettig ready to increase the timing, did you get yours done yet. Godd luck and let us know how it turns out

 

[bzubee]

Remember the IMPBA SAW record for the Sport 20 tunnel hull class was set using a lynx with with an O.S. Outboard it is over 60MPH! I'd say without a pipe works pretty well.