new style 350G compared to old style 350G

[JesseA420]

after testing of the new style compared to the old style 350G, the changes in shape and design have seemed to add a noticeable amount to the midrange/upper midrange. here are some comparison pics

old style


new style



old style


new style



as you can see there are almost double the amount of cone sections at the front. also the rear of the expansion chamber has been reshaped so it does not rub on the rear radiator hose.
pipe also comes with an exhaust stuffer as arlan calls it, basically an insert to reduce the ID of the stinger(back to standard ID of pipe instead of BB stinger ID) to raise exhaust temperature. i dont know or have the tools to fine tune to see if it would benefit my build or not, so i just left it out. i may throw it in, in the future to see how it effects the powerband but for now im not going to mess with it.
just thought i would post my thoughts for people interested in this pipe in the future. thanks.

[Tbone07]

Are you using the same silencer?

Did he add any mounting points? I'd like to see the second lower silencer mount added

[JesseA420]

same previous BB silencer.

unfortunately expansion chamber still only uses the top mount that hangs from the headstay bolt. i agree, having the lower mount added to the front motor mount would really solidify the mounting of the pipe, but i think i understand now why he has not. when adjusting the pipe in and out with the adjuster, the upper mount can swing forward and back to compensate for the adjustment in the length of the expansion chamber body, which then makes the front head pipe need to move slightly up or down to compensate for the length also. if the headpipe was mounted perfectly solid, when adjusting the body out it would push the stinger back that far thus throwing the silencer mounting way off.
thats my theory anyway lol.
also arlan noted that he took 1/4" total out of the center of the body of the expansion chamber to add some top end. there is in fact a bit more top end, but still not much over-rev. then again that is not what these pipes are designed for, so it doesnt bother me.

[Tbone07]

but i think i understand now why he has not. when adjusting the pipe in and out with the adjuster, the upper mount can swing forward and back to compensate for the adjustment in the length of the expansion chamber body, which then makes the front head pipe need to move slightly up or down to compensate for the length also. if the headpipe was mounted perfectly solid, when adjusting the body out it would push the stinger back that far thus throwing the silencer mounting way off.
thats my theory anyway lol.

No you're exactly right about why it's not mounted there. I would like to see the adjust-ability could be optional.

[Jerry Hall]

same previous BB silencer.


.........................also arlan noted that he took 1/4" total out of the center of the body of the expansion chamber to add some top end. there is in fact a bit more top end, but still not much over-rev. then again that is not what these pipes are designed for, so it doesnt bother me.

Shortening the center section 1/4" will usually mover the torque and power peak about 50 RPM higher.  I doubt that you would sense a 50 RPM change.  If you are feeling a RPM change using the butt dyno, I would guess that that there other dimensional changes in the pipe.  Also, you may be feeling a slight improvement due to the 5 added sections in the head pipe and diffuser section of the pipe.  

My experience has been that when hand coned pipes are really "right" for a particular engine package, the inside of the bends need to be as smooth as possible (without abrupt changes in direction a hand coned pipe has when the welds are not hammered over a mandrel).   Hammering the welds on the outside of a bend is not real time consuming and does very little to improve the flow and wave propagation but is more for cosmetics.

Hammering the welds on a hand coned pipe adds considerable time and expense, but is sometimes necessary to get to the next level of performance.

[JesseA420]

Hammering the welds on a hand coned pipe adds considerable time and expense, but is sometimes necessary to get to the next level of performance.

thanks for the info. when you put together a performance package do you build pipes like this to match?

[Jerry Hall]

thanks for the info. when you put together a performance package do you build pipes like this to match?

We have always built pipes for our engine kits. The economy/market place the last 7 to 10 years has not been able to support the necessary investment in R&D time to take the engine packages to the next level.  I think it may be time for me to go back to work and develop some new pipes for the latest big bore cylinders.

 Good hand built pipes are very expensive to produce once the testing and the design is finalized.  There are 3 advantages to hand coned pipes:  1,  If a better design is found during todays testing it can be implemented into tomorrows production at a much smaller cost than making new stamping dies.  2,  The wall thickness of the pipes usually varies because the metal does not stretch equally in all directions during the stamping process.    The metal often cracks where the metal is fatigued due to over stretching in some areas during the stamping process.  3. Stamped pipes have to use annealed (very soft) steel for the stamping process to minimize the problems in point #2.  The energy recovery on a hand coned pipe is slightly better because the cross-sections of the pipe do not have the seams that flex.  The soft metal also slightly hinders energy recovery from the exhaust. The metal will remain soft in the areas where the metal is not stressed enough during the stamping process.

We never produced stamped pipes.  Stamped pipes usually forces a company to continue to produce obsolete pipes when a competitor releases a better pipe.  The company needs to ware out the stamping dies before they will develop a new design and make new stamping dies.  There is a lot more to pipe development than buying one of the pipe software programs or using the free online pipe calculators and selling finished products with little to no testing and refinement of these software designed pipes.  The market is still saturated with pipes from this era that used these methods of design and production.

[udontknowme]

ive always wanted to try my hand at making a pipe. theres a ton of pipe calculators out there. some free and others cost money. im sure alot of them are useless but some are good (from what i hear) and based on very modern expansion chamber knowledge. of course it would be foolish to not do further development even after using the best of pipe calculators. i never rolled metal and welded it together so it may be a frustrating process at first

[etccb]

Mandrels are required to do a nice pipe.

[havinnoj]

Nice comparison pics [MENTION=540]JesseA420[/MENTION]