I was looking for you input, thx. Replaced all the o-rings with new ones after the pipe got hot and no noticable water coming out of the Cooper. The pipe was no hotter than a nitro pipe and the head was the same as always heat wise. It's a dual pick up system so the hesd gets cooled by itself! It was just the pipe that was not being cooled. Could it have something to do with the exhaust being burnt more efficently? 6 mile an hr is a big gain!!!!!

:dash:

ottie44 wrote:
Did you READ the responses ? .... Under stand what was said ?

Sorri not really after 30 yrs of racing nitro I'm lost!!!!!!! Never had a pipe get weak or even heard of it? If the power comes from the pipe should we not be timing and porting the pipe and not the head??????

ottie44 wrote:
Let me see if I can put this all in perspective :?

Your engine has an optimum rpm it can run at if all the tuning parameters are near 100%, Carb mixture, engine load, operating temp, pipe settings etc ...

What you describe in your FIRST post is that of a boat where you LOOSE exhaust system cooling and engine push's the boat faster than it ever had before ... Right ?

What this tells us is:
#1 your set up was not 100% in the pipe tune department, this by maybe tuned length, operating temp etc.

If pipe type fitted is running too cool, at the incorrect length for the engines rpm potential, or just not tuned right for the engine load.
Under your set up you had maxed out the performance, The unfortunate cooling system failure of pipes added greater performance to the attached engine changing it effective "Tuned Length" and BTU input back to engine.

The engine simply reacts to the BTU input from the tuned pipe and changes it peak HP rpm as the pulse signal of the pipe sped up under the increased operating temperature of it.


Does this help :?

Thx Scott. I hav tried the pipe in all the way to the elbow, Im running a four inch offset and it still does not want to get up on pipe the way it did b4 I put the Cooper muffler on? When I lost cooling I had the muffler on with great power and speed? I have tried both the T mod and Cooper but I would really like to go quieter without lose of power? I have even sent the pipe and header out and had it chromed to raise my BTU's! Does anyone make a pipe for gas like the old Irwin pipe? With an OPS .90 it was so quiet in my CAT u ciuld hear the waves hit the hull with no power lose!

:dash:

Sorri bad pic !

I see with the wide band of pipe & header offset, the overall tuned length IMO is too long.

Hey Ottie I had the same thing happen to me last week. One of the water hoses came off. I noticed my boat got louder then all of a sudden it got really fast. I had a gps turned on but the battery died so I don't know how fast it actually went. I to burned up my o rings on the pipes. I had also asked on another forum why the increased speed when the water hose came off. I was told that water cooled pipes slow some of the heat pulses(not sure if that's correct) and the water does some type of muffling. Not sure if thats correct I'm still learning the gas stuff. I'm still adjusting pipe length on my avenger so I haven't hit top speed for my boat yet. I'm glad I'm not the only one that this has happened to.

pcg33k wrote:
Yikes !! ... Yes your pipes OAL is WAY TOO LONG !!

** Both of you can get a better idea how much too long your set up's are
If you measure down the MIDDLE of the head pipe starting at the flange that bolts onto the cylinder ... measured to the START of the rear cone, you should be in the @ 12 1/2 to 14" range.

I am no expert on this subject by any means, but I understand all sides and what they are trying to get across. I also crossed from nitro to gas - and have tried to apply what I learned running nitro boats to gas, and have learned a lot - especially from MGB. With a nitro boat - the length of the tuned pipe increases timing and RPM -too long, and the motor "comes on the pipe" at the end of the straight, so you shorten it until you see no more gain in RPM and power. The pipe will be on almost all of the straight, and it will carry RPM thru and out of the turn. Switching to gas, the pipe has a similar effect, longer seems to make more torque, shorter raises the RPM. One thing about gas boats is that they are way more forgiving than a nitro boat. When it comes to heat and power, I have a good analogy: Ever watch a drag race and see a crew get upset when the other car is taking a long time? The opponent breaks their rhythm when their car is staged or ready to stage. The setup is designed for a specific time, the longer the engine runs, the hotter it gets, thus it makes more horsepower. Now the setup could be junk! The timing is all off. Going back to the pipe losing a water line, you just changed the setup... The temperature got much hotter, the exhaust gases moved faster, and the output was increased as evident by the large increase in speed. Ottie44, looking at your setup, the 90 deg header is long, due to the offset. You simply cant get the pipe close enough to duplicate the effect of the heat increase. I dont think it has anything to do with your muffler. You would need a 90, 100, or 105 deg header and slide the pipe down towards the flange. It would change the whole setup - including taking the exhaust out from underneath the deck, and rerouting it up thru the cowl. Aluminum dissipates heat quickly compared to steel, water cooling brings the temp down as well. Steel holds heat and increases the flow~ A steel pipe in your current configuration may be possible, but you would need to get everything away from it, and expect anything near it to get hot or burn as well - including your paint! You may be a little slower at 58 MPH, but I'll bet its fun to run, and it looks good, too. It probably handles chop well, and that could be an advantage itself.