Huntsville Records Trial November 11-13, 2005

[Geraghty]

I've found out way back when I was running nitro trucks that the little engines can really kick in once they get to the point where a tuned pipe is doing its job, kind of like cruising along in your car and stomping on the pedal using a Holley 4-barrel spread-bore carb.

Once you guys figure out what's going on, you'll have my full attention, like you don't already have it!

Some of the Aussies have been using the Jett cannisters and got great results from them in boats.

The problem with the "car pipes" is they have absolutely no torque but they don't need it in cars.

With transmissions and adjustable clutches the motor is always in its powerband.

 

[Tim_Duggan]

The problem with the "car pipes" is they have absolutely no torque but they don't need it in cars.

With transmissions and adjustable clutches the motor is always in its powerband.

Rod,

Don't know for sure if this is relevant but your posts reminded me of something I stumbled accross years ago.

I've never played with .12's in boats but did a little testing in a car once with a side exhaust .12. Going to a smaller ID header with the same motor / pipe / gearing gave a noticable increase in bottom end (torque) AND an increase in upper rpm limit without altering the pipe length. It surprised me as to how effective it really was. I assumed that this was due to the huge difference in exhaust port area verses header cross sectional area.

I'm now wondering if it's a total volume of the header and the pipe being closer to correct?

 

[Geraghty]

The problem with the "car pipes" is they have absolutely no torque but they don't need it in cars.

With transmissions and adjustable clutches the motor is always in its powerband.

Rod,

Don't know for sure if this is relevant but your posts reminded me of something I stumbled accross years ago.

I've never played with .12's in boats but did a little testing in a car once with a side exhaust .12. Going to a smaller ID header with the same motor / pipe / gearing gave a noticable increase in bottom end (torque) AND an increase in upper rpm limit without altering the pipe length. It surprised me as to how effective it really was. I assumed that this was due to the huge difference in exhaust port area verses header cross sectional area.

I'm now wondering if it's a total volume of the header and the pipe being closer to correct?

Tim,That certainly is a plausable possibility.I don't know for "absolute sure" why you saw the performance increase.I suspect what happened is the reduced volume in the header/pipe combo caused an increase in motor exhaust temperature and as a result the wave speed increased and the motor found its sweet spot and staged up.

Your experience is just one more indicator that there is something in the pipe/cannister performance spectrum that has not being understood by us RC nitro boaters.

I can get .12/.21 motors to pretty much stage up at will these days by controlling the motor temperature so I do know where to start.What I don't know is how much effect the pipe/cannister "volume" fits into this equation.With the O.S. outboard I know volume plays a part in the overall picture,but just how much I don't know.

I don't know if it is wave speed,wave length or possibly wave pressure drop or something else that makes a motor stage up as hard as we saw this weekend in the .12.

The O.S. outboard muffler on the K&B test will tell us a ton about where to start to understand this phenomenon.

Rod Geraghty

 

[Tim_Duggan]

The problem with the "car pipes" is they have absolutely no torque but they don't need it in cars.

With transmissions and adjustable clutches the motor is always in its powerband.

Rod,

Don't know for sure if this is relevant but your posts reminded me of something I stumbled accross years ago.

I've never played with .12's in boats but did a little testing in a car once with a side exhaust .12. Going to a smaller ID header with the same motor / pipe / gearing gave a noticable increase in bottom end (torque) AND an increase in upper rpm limit without altering the pipe length. It surprised me as to how effective it really was. I assumed that this was due to the huge difference in exhaust port area verses header cross sectional area.

I'm now wondering if it's a total volume of the header and the pipe being closer to correct?

Tim,That certainly is a plausable possibility.I don't know for "absolute sure" why you saw the performance increase.I suspect what happened is the reduced volume in the header/pipe combo caused an increase in motor exhaust temperature and as a result the wave speed increased and the motor found its sweet spot and staged up.

Your experience is just one more indicator that there is something in the pipe/cannister performance spectrum that has not being understood by us RC nitro boaters.

I can get .12/.21 motors to pretty much stage up at will these days by controlling the motor temperature so I do know where to start.What I don't know is how much effect the pipe/cannister "volume" fits into this equation.With the O.S. outboard I know volume plays a part in the overall picture,but just how much I don't know.

I don't know if it is wave speed,wave length or possibly wave pressure drop or something else that makes a motor stage up as hard as we saw this weekend in the .12.

The O.S. outboard muffler on the K&B test will tell us a ton about where to start to understand this phenomenon.

Rod Geraghty

Rod,

Perhaps this would be a good candidate for the Kavan Prop test with a handheld tacho? Anyone got a set of Kavan's? Some numerical data would make for some interesting reading.

Tim.

 

[Geraghty]

Rod,

Perhaps this would be a good candidate for the Kavan Prop test with a handheld tacho? Anyone got a set of Kavan's? Some numerical data would make for some interesting reading.

Tim.

I don't have a set of Kavans.The numerical data that you would compile would be interesting and it would accomplish one of two things..........either it would start to answering some questions or it would send you to the liquor cabinet,

 

[Don Ferrette]

I haven't seen Rod this fired up about somethin' in quite a while especially since he hates to type. :lol:

Seriously this is a great thread & I'm looking forward to the possibility of witnessing a sport 21 crack 60 when I'm there at Speedweek. If I can hit my mark early on I'll offer any assistance I can if you guys are gonna be there.

 

[Scooter12195]

Great reading guys. This type of discussion makes IW the kind of forum that is so beneficial to the Boating community!!! Please follow through with any results or observations that occur!!

Thanks to you all!

Scott Norris

 

[Geraghty]

I haven't seen Rod this fired up about somethin' in quite a while especially since he hates to type. :lol:

"Fired up" isn't an accurate description of anything I do anymore.Mental masturbation is more like it.

It isn't that I hate to type.........It is more like I can't type.I am absolutely horrible at it.

I will say this discussion has made me get off my dead axx and start on a "variable volume" cannister for the little twin .21.We know it will turn 45,000 with conventional tuned pipes.It will be interesting to see if there is an improvement with the VV cannister.

 

[Speed Jr.]

Thats awsome Rod! 45,000? ****!! Bet that sounds amazing!

-Larry

 

[VansRacing]

Rod,

I probably watched David's little 12 mono run every time it hit the water. After the boat got going and set on its pad, it would come down the shoot like a bullet. It was clear that it was very well balanced.

Eric, Allen, Rushing and myself saw it fly past the pit area in what I called "the scream of death" rpm and the boat actually stood out on the prop and flew for 35 or 40 feet without flying off or doing anything crazy... it was just flying perfectly thru the air on the prop. It was too cool!

Eric thought he had gotten this on tape but when we backed it up, it had cut off just before that point.

That little boat is cool...I hope you guys can get it faster but it is doing the big trick just like it is!

-Carl,

 

[Jerry Wyss]

"Fired up" isn't an accurate description of anything I do anymore.Mental masturbation is more like it.

:lol: :lol: Gawd Rod! I Broke 3 Ribs A Little Over A Week Ago, And THAT Just About DID Kill Me :lol:

 

[BigChuck]

Rod Question for you, If you will take the time, Thanks.

On the current tune pipes that we have, I have notice that one has more of a Peak at the cone connection points and one is more rounded at those same points. What is, if any, will be the effect on the motor...

 

[Geraghty]

Rod Question for you, If you will take the time, Thanks.

On the current tune pipes that we have, I have notice that one has more of a Peak at the cone connection points and one is more rounded at those same points. What is, if any, will be the effect on the motor...

I have noticed the same thing in the past but have always passed it off as nothing more than a pipe construction technique.

I have never ever give a thought to it possibly being a performance consideration.......in short I don't have a clue. :wacko:

 

[Geraghty]

That little boat is cool...I hope you guys can get it faster but it is doing the big trick just like it is!

-Carl,

There is no problem going faster........we were not even close to being out of prop or motor.

The boat was on the pipe 8" after being dropped in the pond.

Now keeping it on the water is another story.What we need now is some open water. We have a lot of motors and props to test.I told you the boat had a grand total of about 10 minutes of test time on it before last weekend.The setup we had on it was very conservative.

After all that is accomplished all we will need is a great weather day at Huntsville.

Noteavid and I have already been talking to Tommy and a better boat is already in the works.

 

[Geraghty]

Thats awsome Rod! 45,000? ****!! Bet that sounds amazing!

-Larry

I get a kick out of the "RPM spec"games that all the manufacturers play in their printed literature.

Until you hear 45K you don't realize how much of the 40K motor hype is nothing more than marketing BS.

David and I made several runs with the twin at the Internats in Evansville[inbetween Margaritas] 3-4 years ago and it did draw a crowd.Not one person watched the runs "without" their fingers in their ears.

45K is actually painful to listen to without hearing protecton.

 

[bzubee]

Hey Rod did you get the pictures I e-mailed you of David and I with our new Margarita cups ?

 

[Geraghty]

Hey Rod did you get the pictures I e-mailed you of David and I with our new Margarita cups ?

I sure did! You are going to have to put wheels and a handle on them when they are full.

The only problems I see with the cups are............

We will need a tanker truck of tequila to fill them,and the liver transplants you and David will need after you finish them. :wacko:

 

[bzubee]

I was more worried about all of the salt on the rims.

 

[Don Ferrette]

all you o/b guys can stop building those special boats for Speedweek & just order one of these-

http://cgi.ebay.com/NIB-NITRO-GAS-R-C-RADI...1QQcmdZViewItem

:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

 

[Scooter12195]

all you o/b guys can stop building those special boats for Speedweek & just order one of these-
http://cgi.ebay.com/NIB-NITRO-GAS-R-C-RADI...1QQcmdZViewItem

:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

WOW! A REAL GAS POWERED ENGINE AND 65MPH RIGHT OUT OF THE BOX!!! I'M ON THAT LIKE STINK ON S&%T!!!