Bouchie 21 Pipe Length?

[BobBonahoom]

We have been running our Bouchie 21 pipes at about 8 to 8-1/4" as measured from the center of the engine to the center of the flat band. I am just curious where others run theirs and how they measure. It seems like measuring to the rear weld at the converging cone instead of to the center of the flat band would be more comparable to pipes with no flat band. When I set the Bouchie at 8" to the weld, my JAE 21 picked up 10 mph but would not come back on the pipe when I slowed down. Just curious what others have found.

 

[dr gary turner]

I run 8-81/4.

What motor are you running?
Deck clearance
Stock head button

 

[dr gary turner]

Also what boat are you running?

 

[Carl Van Houten]

Doc, Is the Bouchie pipe giving you higher RPM or does it have more punch off the turns?

 

[Bradley Maglinger]

I run my hydro and my sport boat at 8.5” center band .011 head clearance on the hydro and .008 on the sport boat.

 

[dr gary turner]

I think both, probably more punch than RPM

Generally can run a bigger prop

 

[Bradley Maglinger]

I really like it bc I have mid range and consistent, it’s not a light switch.

 

[BobBonahoom]

I run 8-81/4.

What motor are you running?
Deck clearance
Stock head button

Doc, I am running a CMB Evo at 0.010" head clearance with the stock head button having 0.18 cc volume. I use 289 plugs and 65% nitro.
Where do you measure the 8-8-1/4" to on the Bouchie? The center of the flat band?

 

[BobBonahoom]

I run my hydro and my sport boat at 8.5” center band .011 head clearance on the hydro and .008 on the sport boat.

Brad, so you run 8-1/2" to the center of the flat band, or to the back weld?

 

[brad nichols]

Every boat and motor will have it's own sweet spot and through testing you will find it

Merry Christmas and Happy New Year!!

Brad

 

[Bradley Maglinger]

Brad, so you run 8-1/2" to the center of the flat band, or to the back weld?

Center of the flat band

 

[XtremeRcBoats]

Interesting topic, I recently bought a zippkits pipe. It will be on a JAE21 with a NR21plus35. First have to add a muffler, as we have strict noise restrictions. It is still WIP.

 

[dr gary turner]

Bob middle of flat band

No header pipe. Tune pipe goes right next to the exhaust opening of the motor

I run a 1819

I am running .006-.008 deck clearance. Dd 21

 

[dr gary turner]

I have a beta 21 but have not tried it yet

I am told the beta does not launch as good as the dd but dd will turn more rpm.

Of course the boat is the major variable

 

[BobBonahoom]

Interesting topic, I recently bought a zippkits pipe. It will be on a JAE21 with a NR21plus35. First have to add a muffler, as we have strict noise restrictions. It is still WIP.

That new Zipp pipe is very close to the same dimensions as a 21 Bouchie.

 

[BobBonahoom]

I have a beta 21 but have not tried it yet

I am told the beta does not launch as good as the dd but dd will turn more rpm.

Of course the boat is the major variable

Doc, we are running a DD in one of our 21 JAE boats (Greg's) and the CMB Evo in the other (mine). It does seem like the DD might have a little more torque at the launch, but we are running tighter head clearance with the DD so that could be the reason. I do think the CMB makes more RPM with the same prop and pipe set up. I just like the CMB because it has less moving parts to break, the bearings are not proprietary, flat top piston, etc. However, the inside of the case casting is rougher on the CMB and requires some work. Greg likes the DD because of its torque.

 

[dr gary turner]

Good info

 

[Terry Keeley]

Doc, I am running a CMB Evo at 0.010" head clearance with the stock head button having 0.18 cc volume. I use 289 plugs and 65% nitro.
Where do you measure the 8-8-1/4" to on the Bouchie? The center of the flat band?

Make a 0.13 - 0.14 cc button, run a hot plug like a 277 or 287 and cut back the water to about what you flow the needle at for starters.

I guarantee you'll mill down to a crawl and keep your 10 mph!

 

[dr gary turner]

Like Terry described I took .006 off of the squish band of my head button and kept the angle of the squish band

 

[BobBonahoom]

Terry,
Sounds like the concept is advanced timing (hot plug) and lots of heat = more burned nitro = more torque/power.

Questions:
1. Squish area % at 0.13 - 0.14 cc ?
2. Angle of squish or flat?
3. If angle, how far into the radius does it start?
4. If angle, how many degrees?
5. Material, Al or brass?
6. Head clearance?
7. If making your own buttons, assume you are using standard plugs, not turbos.
8. Run rich to keep plug and not detonate?
9. Do you pull the plug coil?