Gas props on nitro rigger

[dwilfong]

Here is a run of the 2818. And a few more props.

 

[Ian Inverarity]

David,

Interesting stuff. Quite a difference in RPM variability between the different props, were the water conditions the same for all tests? If so it would seem that both the H667 and 7023/3 stay 'hooked up' better than the 1667 on your setup, with the RPM spiking up from unloading of the prop. 26000rpm may not thus be appropriate for calculating the 'slip' for the 1667.

 

[dwilfong]

Here is a pic of all the props tested. 2818 1st and last 7025/3 2nd from last.

Will break them out more. still going over it.

The power supply took a crap at the pond could not get them in a different named file.

Still trying to remember which ones are witch :wacko: Dumb ass didn't wright it down.

Add 3-4 oz of weight near the engine bay and see if it handles better but does not slow down . i think it will .

Will give it a try when I land on the right prop.

Got more prop on the way with some new cuts to try.

When it says uncle I will slap the nitro to it and slam the pipe in. Will need the weight then. :lol:

David

 

[dwilfong]

David,

Interesting stuff. Quite a difference in RPM variability between the different props, were the water conditions the same for all tests? If so it would seem that both the H667 and 7023/3 stay 'hooked up' better than the 1667 on your setup, with the RPM spiking up from unloading of the prop. 26000rpm may not thus be appropriate for calculating the 'slip' for the 1667.

All test where done in a 1hour time spand. wind about 10 15MPH nice 3 4" chop. The h667 did not look good on the boat.

All the low speed spikes where full rudder turns as tight as it would go.

The H667 lost lots of speed in the turns. to little blade.

You can see what the blade area dose real good with this loging. less blade area on the 2818 should make a diffrence.

Now I can see the changes as there made to the blade.

Going to try Prpo Shop next.

David

 

[Ian Inverarity]

David,

Interesting stuff. Quite a difference in RPM variability between the different props, were the water conditions the same for all tests? If so it would seem that both the H667 and 7023/3 stay 'hooked up' better than the 1667 on your setup, with the RPM spiking up from unloading of the prop. 26000rpm may not thus be appropriate for calculating the 'slip' for the 1667.

All test where done in a 1hour time spand. wind about 10 15MPH nice 3 4" chop. The h667 did not look good on the boat.

All the low speed spikes where full rudder turns as tight as it would go.

The H667 lost lots of speed in the turns. to little blade.

You can see what the blade area dose real good with this loging. less blade area on the 2818 should make a diffrence.

Now I can see the changes as there made to the blade.

Going to try Prpo Shop next.

David

David,

So these plots show the results from driving circuits at full throttle? Interesting that the speed changes with some props from corners to straight runs shows almost no connection to the RPM plot, that is the boat could slow dramatically without the RPM coming down significantly. As you say it does show some props are better in the turns than others.

 

[dwilfong]

Just shoot me a number. Never thought it would be free.

Just remember this is a toy boat not a NASCAR team. :lol:

Unless you want to sponsor the first 100MPH heat racing boat.

David

David

so how fast are you going now?

regards Aaron

only a estimate rite now. still have to get the gun on it . so lets just say fast.

I will hook up the eagle tree next week to get some data logged.Getting the new V4 with the power panel this week.

If you do the math 4.56 lead in pitch at 23500 RPM=101 MPH

O and this is right now not soon

YA YA I know far from 100MPH. I could have just typed I went 100MPH.

Keep watching. I'm not done yet. Got a bigger prop on the way.

Only got 16MPH to go :lol:

If I do it there will be no BS involved.

David

 

[dwilfong]

David,

Interesting stuff. Quite a difference in RPM variability between the different props, were the water conditions the same for all tests? If so it would seem that both the H667 and 7023/3 stay 'hooked up' better than the 1667 on your setup, with the RPM spiking up from unloading of the prop. 26000rpm may not thus be appropriate for calculating the 'slip' for the 1667.

All test where done in a 1hour time spand. wind about 10 15MPH nice 3 4" chop. The h667 did not look good on the boat.

All the low speed spikes where full rudder turns as tight as it would go.

The H667 lost lots of speed in the turns. to little blade.

You can see what the blade area dose real good with this logging. less blade area on the 2818 should make a difference.

Now I can see the changes as there made to the blade.

Going to try Prop Shop next.

David

David,

So these plots show the results from driving circuits at full throttle? Interesting that the speed changes with some props from corners to straight runs shows almost no connection to the RPM plot, that is the boat could slow dramatically without the RPM coming down significantly. As you say it does show some props are better in the turns than others.

Yes that is on a course run. that is what is great about this logger you can see what the prop is doing.

Best Dino there is. load changes in real time not on a static Dino run on a bench. the load is changed with the prop an how it hooks up.

This is the real word. not a lab or a key board.

Will try and link it with goggle maps that way you can see it on the pond running the course.

Still trying to figure it all out. This thing dose all kinds of crap.

David

 

[Ian Inverarity]

Yes that is on a course run. that is what is great about this logger you can see what the prop is doing.

Best Dino there is. load changes in real time not on a static Dino run on a bench. the load is changed with the prop an how it hooks up.

This is the real word. not a lab or a key board.

Will try and link it with goggle maps that way you can see it on the pond running the course.

Still trying to figure it all out. This thing dose all kinds of crap.

David

Absolutely, now you have some real data on RPM and peak speeds as well as the lowest speeds thru turns, and you can do developments to try to improve all those things and verify the testing with real data. No more guessing RPM's and speeds! B)

 

[julianconde]

26000 thats good RPM. You can talk about dyno and tech talk and puch everything here on the keyboard but everything is proven in the water. just like i did with my Twin hydro great job david. bring that boat to me so i can drive the hell out of it in Huntsville Record trials.

Julian

 

[BigChuck]

What you are seeing is the Plus or Minus of your hull. I have tried,tested,run more..............way more. You have just see above the surface of this iceberg. Your hull and hulls of that style will benefit from what you are testing. The hull that I run and hulls like it............well let just say that expodition has move on to a different location.

Keep up the testing.............You are creating good reading...

 

[ALLAN YUEN]

Did you try run test 6720/2 diameter 67mm/ pitch 135mm and 7022/2 diameter 70mm/ pitch 154mm from Prop Shop in US? I knew that hardy get them :blink: so it already sold out of stocks

 

[Joe Warren]

Thats correct. Compare an exhaust that is oval shaped at the top with one that is flat across the top & it can easily been seen which one has the greater time area number in the blow down area. You will definitely want this if the tuned pipe is really doing its job.

I do make the top of the ex flat but the different angle sounds real nice. I was always on the mind set that the ex should come out all at once to get that high pressure wave moving all in one shot. So 80% of the timed area should be the number of the wide area that is above the transfers and the the rest of the window should make up the rest? With a total area of the ex to be 30% of the combined transfer and boost area? Just got my new mill set up to day will mess with some old sleeves and do some test cutting. The bottom of radius on the piston should line up with the bottom of the ports. what kind of transition to the transfers would work best. Should the sleeve be a sharp edge on the OD or should this be a transition radius? then again the piston dose not spend much time at the bottom.

I think we have a little misunderstanding here. The 80% number shows the relatonship between the exhaust width at its widest point & the engine bore diameter. For example; a K-90 has an exhaust width of .895" & a bore of 1.0635", which equals 84%; OS MAX .91 has a .902" wide exhaust & a bore of 1.090" which gives 83%; CMB .90 has a .968" wide exhaust & a bore of 1.102" which gives 88%; Rossi 1.05 has a 1.096" wide exhaust & a bore of 1.1425" which gives 96%. Whats interesting here is that some of the most powerful piped engines such as K & B .40 & .82, Nelson .45 & Picco hydro .90 have exhaust widths that do not exceed 75%. Could excessive exhaust width & poor exhaust port shape coupled with poor transfer geometry restrict the main transfer areas & cause HP killing short circuiting? Dyno testing says the answer is a definite yes!! The radius is applied to the top edge of the piston only. Jim Allen

Jim, I don't think the KB40 KB82 and Picco 90 hydro are some of the most powerful piped engines and probably the reason is that the exhaust width is too little. You talk about trying for maximimum blowdown time area without increasing exhaust duration but the only way to do that is to either widen the exhaust port or narrow the transfers. Are you suggesting we narrow the transfers? I don't think thats an option or the right way to go. Most of the regularly used marine motors have gradually had the exhaust width increased over the years and power has steadily gone up.

Dave

I agree with Dave. You are limited on Ex timing. I have seen most Big Block engine improve with HP & Performance by making the exhaust port wider. We used this same mods yeas ago in the picco`s. Crowher used the mod by Sub porting the ex port hole. Todays thinner cases you have to do it a little differently.

 

[stan simpson iv]

Just shoot me a number. Never thought it would be free.

Just remember this is a toy boat not a NASCAR team. :lol:

Unless you want to sponsor the first 100MPH heat racing boat.

David

David

so how fast are you going now?

regards Aaron

only a estimate rite now. still have to get the gun on it . so lets just say fast.

I will hook up the eagle tree next week to get some data logged.Getting the new V4 with the power panel this week.

If you do the math 4.56 lead in pitch at 23500 RPM=101 MPH

O and this is right now not soon

YA YA I know far from 100MPH. I could have just typed I went 100MPH.

Keep watching. I'm not done yet. Got a bigger prop on the way.

Only got 16MPH to go :lol:

If I do it there will be no BS involved.

David

ONLY 16 MPH???? My father and Andy Brown worked on my 45 EAGLE for over a year just to get 2 mph at one time...I wish you luck,hope your not on the naughty list.I would wish for a prop from A.B.and some 70% MHO

 

[Terry Keeley]

Told ya you'd like the Eagle Tree.

Any chance you could trim some of the plots to show just a few of the peaks and valleys? Kinda hard to see what's going on when it's all on one page.

Can you change the "x" axis to seconds?

 

[Terry Keeley]

Double post, sorry...

 

[stan simpson iv]

What up Terry K.have not seen you in quite awhile.I hope to see you at the Nitro Nats. in S.C. Hope you are thinking about coming...

 

[Terry Keeley]

What up Terry K.have not seen you in quite awhile.I hope to see you at the Nitro Nats. in S.C. Hope you are thinking about coming...

I'll be there buddy!

You got a 40 hydro these days?

 

[DaveMarles]

Here is a run of the 2818. And a few more props.

You are only running in the 21 to 22000 rpm range which is too low. I'm not a hydro expert but I would think the fast hydro guys are running more like 24000-25000. Perhaps you need a bit less blade area than those big propshop props and a shorter pipe. Dave

 

[dwilfong]

Thanks every one for making this a very good thread. Lots of good info and discussion going on.

I am going to test as many different props as I can with out changing the set up for now.

the more info I can acquire the better idea I will have on the best way to go.

The question is how much blade area is the best to hook up the boat compared to the pitch.

I will be looking at the lead in pitch and see what correlation it has with the speed.

If I can unload the larger props and get to the RPM range that will keep the eng alive with moderate nitro. I think this will make for a easy tune for the eng with out burning it up or smoking a bearing.

85MPH is no slouch on a heat race boat! especially when most all are toping out at 78MPH or less!

Also landing on a prop that needs little work will make for easy replication of the set up.

This is not all in vain there is a method to my madness. All heading toward a bigger eng and the power needed for the belt drive. I need power not RPM to do it my way.

Will see if it all pans out.

Thanks again David

 

[Jim Caldwell]

David, change the x to seconds and click on the Chart Setting Icon lower left corner on the chart, set the points per page to 200 or 250 to start and play with from there to get the detail where you want it.

Also, under Advanced you can set Logging Triggers to say 18,000 RPM so your Ave. speed and rpm will be closer.

Once you set the Paging you can change down to say 100 and look at the prop just in a corner or just on the straight.

As You have discovered the E/T will open lots of new horizons!!!

PS You can do the paging options on your existing charts.