SPP RS or NR muffled pipe for CMB 21 BETA EVO

[normlee]

Any input would be great please, hull is JAE 21.

 

[timothy johnson]

Why not a CMB Nitro pipe or a Bouchie if you can find one.

 

[Brandon Atwell]

The RS pipe is considered the faster pipe, the NR easier to throttle and heat race with. Either is a great choice, but I believe those pipes were more so designed around the wrap around exhaust systems.

 

[Tom David]

I run my JAE 21 CMB 21 EVO with a CMB 21 NITRO Pipe.

Please watch both videos. 

It is an excellent all around pipe. Even for heat racing. 

Watch first video at the start. I am early (on purpose) Boat has great acceleration off pipe! 

 

[ALLAN YUEN]

Tom  very good speed 

what size of prop did you run 

thanks 

 

[Tom David]

Tom  very good speed 

what size of prop did you run 

thanks 

First Video:

abc 1817-19-38

pipe at 7 3/4 inches

Second video:

cooler air (good air density)

abc 1819-19-38

pipe at 7 1/2 inches  

Fuel—John Otto   65%

 

[Greg Wannamaker]

Something really wrong with your boat, it’s going way too fast!!!!!!!!  You definitely got it flying.

 

[Tom David]

Something really wrong with your boat, it’s going way too fast!!!!!!!!  You definitely got it flying.

Thanks Greg

Waiting on old man winter to leave Evansville so I can test some new ideas on this set up. 

 

[BobBonahoom]

First Video:

abc 1817-19-38

pipe at 7 3/4 inches

Second video:

cooler air (good air density)

abc 1819-19-38

pipe at 7 1/2 inches  

Fuel—John Otto   65%

Tom,

Impressive that you can pull those props with a 7-1/2" pipe.  Is the pipe measurement from center of the engine to the weld, (accounting for the S bend in the step-up header)?, or is it plug to weld in a straight line?

 

[Tom David]

Bob, the measurements are a straight line from center of bore to weld on pipe. 

The offset header that I use will add about 3/16 inch in length but I still reference everything in a straight line measurement.

Air density is everything—-especially on our little 21’s. 

The little 21’s really wake up when air temps are in the 50’s or cooler.

You probably won’t pull a 1819 in the 80’s.

Almost all records are set in cool temps. 

I do heat race with the 1817 and pull out the pipe in hot temps.

If your looking for optimum performance at each race, adjusting to air density is a must on our 21’s.   

I posted my opinion about the cmb nitro pipe to illustrate it is capable of obtaining very good results if you test and learn from that testing.

More time testing = more races won.

I also use different heat range plugs and less water during my testing   

I will also add that my cmb 21 is all stock except with a small removal of brass on the ramp fo the boost port. Timing was not changed.  

I was not able to keep my squish very tight on the stock turbo head button without detonation. I am opening the bowl and testing more in this area.   

 

[Tom David]

I run my JAE 21 CMB 21 EVO with a CMB 21 NITRO Pipe.

Please watch both videos.

It is an excellent all around pipe. Even for heat racing.

Watch first video at the start. I am early (on purpose) Boat has great acceleration off pipe!

I have noticed that a video was removed from this post by the moderator.

Was the video too offensive???

Tom David

 

[David Ashcroft]

Thanks for info Tom...

 

[Tom David]

Thanks for info Tom...

Your welcome David.

I am going to repost video to support performance of CMB 21 Nitro Pipe tuned for heat racing.
This video was deleted in post # 4.



TD

 

[dr gary turner]

You need to bring that boat to the Internats in Huntsville

US 1 looks like it could be yours

 

[Tom David]

You need to bring that boat to the Internats in Huntsville

US 1 looks like it could be yours

Going to try and make it.
Need to work on my driving skills.

TD

 

[dr gary turner]

Great. Plenty of room on the Huntsville lake.

 

[darryl whitman]

21 nitro pipe with a 707 stringer on my beta evo it rocks, I am almost afraid of it .lol Im a noobie