Props for 20 Hydro

[shoboat]

Preston,

With your 188 degree timings how short is your pipe? 6" ?

Is this on your little 12 motor? How much Nitro?

Wondering How You Achieve That,

Mark Sholund

 

[Preston_Hall]

I never said 188.

When we were running the 50X69 setup was critical. Ever since KP got the 1450s from Andy years ago we have never had a problem pulling the props. I don't know the overall pipe length but from the plug to the pipe belly is close to 3".

Nitro is a conservative 60%.

I hate to tell you but 21 records are set with heat racing motors that that Canadian guy does. It's all in the setup and prop. And some nitro.

 

[DON MAHER]

Yep that's right! Mark Grim just went 110mph with a 21 greenie, a prop & some nitro!!!!!

Don

 

[Charles Perdue]

Yep that's right! Mark Grim just went 110mph with a 21 greenie, a prop & some nitro!!!!!

Don

WOW 110 with a 21, Just imagine what he could have done with twins.

 

[DON MAHER]

Charlie,

Thanks for the " care " package. It's Sooooooooo Gooooooood.

Don

ps Just think what Scott would have done if he had tried his!!!!!!! :lol:

Check Race Results

 

[F.Orlic]

.The key is to get your pipes shorter and turn

more RPM fellas. 7" or less on the 21 and under 9" on the 45. RPM

is the key here for speed guys, and you will never get your pipes

short with high exhaust timing numbers. So back your 180+ timings

down to 175 to 178 degrees and shorten your pipes. Your motors

will then start to rev if you know what I mean?

Great Subject Guys,

Mark Sholund

From my experience it takes more than adjusting exhaust timing to have engine running well. With some engines 178 is high but some will run with 190 + with no ill effects.

What you need is to have an engine with very good torque and work on getting RPM's. Novarossi is one of them. I'm sure CMB or mac are good engines but not as much torque and the choice becomes what suits best your needs or budget. Just for example that high timing can work, I used 191 exhaust, 6 3/4" OPS 3280 pipe (or 2 1/8 from centre of the engine) on 75%nitro pushing modified X447 on mono, boat ran much too tight and flat on left side but still was clocked just under 65 MPH. Last time in Flint David Prusse ran almost 70 MPH with perfectly trimmed mono but I bet his OPS pipe was 3 1/2" long. Many ways to get the same results.

 

[shoboat]

Frank and Many Others,

I am no engine guy,but I think in general, higher exhaust numbers hurt the pipe

lengths that you can run. I have many engines and the ones that perform the best

have lower exhaust timings and run shorter pipe lengths. Frank, just a thought about

your set up,I think the OPS #3280 has it's limits, and I'm pretty sure you and Mike

Nowicki have reached that limit on lengths. We are working on quite a few new pipe

designs and we hope to solve this problem very soon. Propellers also have a lot to

do with the big picture on engine set ups,this is one of the reasons that this hobby is

so challenging and fun.

Have Fun And A Happy Holiday Season To All,

Mark Sholund

Owner Of : Props-4-U

 

[Marty Davis]

.The key is to get your pipes shorter and turn

more RPM fellas. 7" or less on the 21 and under 9" on the 45. RPM

is the key here for speed guys, and you will never get your pipes

short with high exhaust timing numbers. So back your 180+ timings

down to 175 to 178 degrees and shorten your pipes. Your motors

will then start to rev if you know what I mean?

Franco:

Interesting thoughts about exhaust timing. Would you expand on your thinking on this....

I also know that Rod Geraghty follows a similar belief about exhaust timing and short pipes.

Marty Davis

 

[Marty Davis]

Since this topic is Not About Props, why not start another thread on this topic. I will start it and if you would respond on the new thread, that would be great. I am anxious to hear the opinions of Rod and Andy Brown also.

Marty Davis