Gas props on nitro rigger

[julianconde]

28000.

Julian

 

[aaron alberico]

David

If your pulling that much leading edge pitch and turning the rpm's your talking in your oval boat,

You should play SAW, because in a lot lighter SAW rigger you should be able to turn even more R's and L/E pitch you will smash the current records to bits!!!!

Regards Aaron

 

[dwilfong]

David

If your pulling that much leading edge pitch and turning the rpm's your talking in your oval boat,

You should play SAW, because in a lot lighter SAW rigger you should be able to turn even more R's and L/E pitch you will smash the current records to bits!!!!

Regards Aaron

I hope to be heading that way will see how much time and money I have when it comes around next time.

I think I will give the boat to my buddy Julian to run the oval. he is one heck of a driver.

We are working on a CF boat now to put the belt drive in. this boat will run the VAC 1.05 with more RPM than a amp eater.

This is just a test boat .

 

[BigChuck]

Thanks Arron

David If..............If that number is correct than what Arron said is correct. But what I have to say is not going to make any difference is it???? Do what you think you need to do. If.......... we get a chance to race again.....You can show me............or not. That simple. B)

 

[dwilfong]

28000.

Julian

well maybe not that much. will see.

I guessing about 23500.

 

[dwilfong]

Thanks Arron

David If..............If that number is correct than what Arron said is correct. But what I have to say is not going to make any difference is it???? Do what you think you need to do. If.......... we get a chance to race again.....You can show me............or not. That simple. B)

Chuck

Chill dude it is what it is. we will race again and I will probly crash out. But I will have one heck of a good time doing it.

David

 

[BigChuck]

David

Nothing ment.........Just that I will be doing most of racing on On Bridgestones,not water. So, if we get that opporunity we can expand the theoy further.

 

[dwilfong]

David

Nothing ment.........Just that I will be doing most of racing on On Bridgestones,not water. So, if we get that opporunity we can expand the theoy further.

We will race again I am sure of that. will have a good time shooting the shib also.

But if you get too unruley. I will get my friend with the pink too too after ya!

David

 

[BigChuck]

David

Nothing ment.........Just that I will be doing most of racing on On Bridgestones,not water. So, if we get that opporunity we can expand the theoy further.

We will race again I am sure of that. will have a good time shooting the shib also.

But if you get too unruley. I will get my friend with the pink too too after ya!

David

I will be sure to give him a ride at 160 so we can hear him sream like a girl...!!! :lol: :lol:

 

[Jeff Lutz]

David

If your pulling that much leading edge pitch and turning the rpm's your talking in your oval boat,

You should play SAW, because in a lot lighter SAW rigger you should be able to turn even more R's and L/E pitch you will smash the current records to bits!!!!

Regards Aaron

I hope to be heading that way will see how much time and money I have when it comes around next time.

I think I will give the boat to my buddy Julian to run the oval. he is one heck of a driver.

We are working on a CF boat now to put the belt drive in. this boat will run the VAC 1.05 with more RPM than a amp eater.

This is just a test boat .

The 1.05 thing was done many years ago. It was first done on Rossi 90's with the ducted fan 105 sleeve. I started converting a k90 years ago and never finished the project. Both the Rossi 90 and the K90 have the same stroke as the vac 91.It could be very powerful with the right combos.

 

[DickJones]

28000.

Julian

well maybe not that much. will see.

I guessing about 23500.

I believe u are within the the 2 % range based on fuel, pipe, and pipe legth.

 

[dwilfong]

28000. Julian

well maybe not that much. will see. I guessing about23500.

I believe u are within the the 2 % range based on fuel, pipe, and pipe legth.

Thanks for the input Dick. I am just doing a calculated estamat. always nice to have a back up opinon on the calculations.

My math is not always the best.

This is what I call a resinable RPM. don't whant to go over 24000. need a little cushion for unhooking over rev.

Funny when I use to street race as a kid. My dead square 455 had no problem with the little 302's

David

 

[dwilfong]

David

If your pulling that much leading edge pitch and turning the rpm's your talking in your oval boat,

You should play SAW, because in a lot lighter SAW rigger you should be able to turn even more R's and L/E pitch you will smash the current records to bits!!!!

Regards Aaron

I hope to be heading that way will see how much time and money I have when it comes around next time.

I think I will give the boat to my buddy Julian to run the oval. he is one heck of a driver.

We are working on a CF boat now to put the belt drive in. this boat will run the VAC 1.05 with more RPM than a amp eater.

This is just a test boat .

The 1.05 thing was done many years ago. It was first done on Rossi 90's with the ducted fan 105 sleeve. I started converting a k90 years ago and never finished the project. Both the Rossi 90 and the K90 have the same stroke as the vac 91.It could be very powerful with the right combos.

The long stroke will make lots of power I hope. Have all the numbers just need a VAC case. the HR I have is not as good of a breather.

The 1.01 P/S will get the same mod in the VAC case. With the .588 drum ID a bigger carb will work real nice.

As soon as Stu gets the cases in I will giving it a try.

David

 

[Jeff Lutz]

David

If your pulling that much leading edge pitch and turning the rpm's your talking in your oval boat,

You should play SAW, because in a lot lighter SAW rigger you should be able to turn even more R's and L/E pitch you will smash the current records to bits!!!!

Regards Aaron

I hope to be heading that way will see how much time and money I have when it comes around next time.

I think I will give the boat to my buddy Julian to run the oval. he is one heck of a driver.

We are working on a CF boat now to put the belt drive in. this boat will run the VAC 1.05 with more RPM than a amp eater.

This is just a test boat .

The 1.05 thing was done many years ago. It was first done on Rossi 90's with the ducted fan 105 sleeve. I started converting a k90 years ago and never finished the project. Both the Rossi 90 and the K90 have the same stroke as the vac 91.It could be very powerful with the right combos.

The long stroke will make lots of power I hope. Have all the numbers just need a VAC case. the HR I have is not as good of a breather.

The 1.01 P/S will get the same mod in the VAC case. With the .588 drum ID a bigger carb will work real nice.

As soon as Stu gets the cases in I will giving it a try.

David

I've looked at all that too.Good luck

 

[Jim Allen]

David I don't know about the grooves?? I see you still have a full liner?? We haven`t ran a 101 with a full liner in about 2 years.Put the liner in the case & take a look at the front intake port while you have it apart. Very Restricted.

Here is a better shot of the P/S.Kinda hard to see from the angle in the pic. the window is unsounded at BDC with this mod. The angle cut help with the flow more than the standard strait cut. Kinda swoopey. also the piston is very light. have bin using this mod on all RS eng and it dose wonders.

also running stock timing numbers on the liner. just flatten off the transfer port roof and make one cut on the bottom at the front.

After thousands of dyno tests looking at the influence of the types of changes to the liner & piston shown in your photo, I can say without a doubt, there has been no HP increase found, especially a higher RPM's (beyond 26,000). What has been shown to greatly improve & become necessary to increase the flow through intake ports is a radius on the entire inside wall. Examples can be easily found in the MB .40 cuin speed plane motor (32,000 to 35,000 RPM range) & racing two cycle engines such as the Aprillia, Rotax, etc.

The modification to the boost port's inside wall shown in your photo will make this port's flow decrease. The small radaii, which are ground on the main transfer window bottoms, that may or may not not be identical, serve no purpose in increasing flow at high engine RPM's. This is because the flow's speed is increasing as it approaches the top of the transfers, therefore if any radius is used, it should be increasing in size.

Concentrate on improving the time area numbers in the transfers; improve the time area number in the exhaust blow down period (without raising the exhaust timing); improve the carburetor's flow (,625+" bore for .90 cuin size engines) & provide a tuned pipe that can generate 100+ inches of water at WOT.

Jim Allen

 

[dwilfong]

Jim

Thank you for your insight it is very much appreciated as always.

I have a very good example of a port design that is optimal. I have bin studying it in depth. It is a IR .21 made in Russia. it is the only small eng I have ever seen with this type of porting.

The pic I posted is of my 91 cly. I have changed the way I do the boost in the new eng. I am limited with the narrow liner thickness in making the entrance to the transfers optimal. So I do what I can with them.

I am not worried about High RPM flow in the ports eng will not live at the 30000 RPM level. I have done what I do to shorten the distance the air travels in the restrictive ports. Most of what I am doing is to get more flow into the case and directing it in to the cly at the angel I want.

Now if some one would cast a cly like this we would have a whole different ball game.

Have the Eagletree all hooked up and will see what I have this weekend.

David

 

[Jim Allen]

David,

I'm not 100% sure that this type of porting is "OPTIMAL". Many non-mechanical things that work in one engine, do not work in another engine of similar design, but different size. It is definitely true that if the wrong inside & outside radaii are selected, there will be little if any HP improvement. Imagine how many different radaii would need to be tested to establish what is best. Some recently developed model motors such as the MV-40, QD Pioneer & the IR-21 show some promise. None of the presently available engines have shown large HP increases when this type of porting is used, especially at high RPMs.

One thing is certain, any motor that uses a liner as the inside wall of the transfers can be easily & cheaply changed if modifications are necessary. This would not be the case with cast in transfer walls.

Jim Allen

 

[jaxracer]

David I don't know about the grooves?? I see you still have a full liner?? We haven`t ran a 101 with a full liner in about 2 years.Put the liner in the case & take a look at the front intake port while you have it apart. Very Restricted.

Here is a better shot of the P/S.Kinda hard to see from the angle in the pic. the window is unsounded at BDC with this mod. The angle cut help with the flow more than the standard strait cut. Kinda swoopey. also the piston is very light. have bin using this mod on all RS eng and it dose wonders.

also running stock timing numbers on the liner. just flatten off the transfer port roof and make one cut on the bottom at the front.

After thousands of dyno tests looking at the influence of the types of changes to the liner & piston shown in your photo, I can say without a doubt, there has been no HP increase found, especially a higher RPM's (beyond 26,000). What has been shown to greatly improve & become necessary to increase the flow through intake ports is a radius on the entire inside wall. Examples can be easily found in the MB .40 cuin speed plane motor (32,000 to 35,000 RPM range) & racing two cycle engines such as the Aprillia, Rotax, etc.

Jim Allen

Hey Jim, could you possibly post a picture and elaborate on what you mean by cutting a "radius on the entire inside wall." Not intending to get this thread too far off track, but when analyzing the engine from the perspective of a dyno, what types of sleeve cuts and methods of enhancing flow within the engine have you found to be optimal?

Thanks for your insight,

-Mitch

 

[Jim Allen]

I have no pictures of what these type transfers look like, only the previous engine examples given. The sectional views in my possession are proprietary information.

When looking only at the different geometries that can be cut in sleeves during dyno testing, it becomes apparent that a minimum wall thickness is necessary in attempting to control scavenging flow & transfer flow, since the sleeve becomes the inner wall of the transfers.

As an example, from dyno testing, engines with flat top pistons should have their main transfers cut straight in on the top & bottom. The side geometry needs to direct the incoming flow towards the piston center. The incomming flows should collide in the center of the cylinder, cool the piston crown & move upward pushing the remaining exhaust out. If this is not done, the incomming flow cannot effectively cool the piston crown. The results will be detonation & holed pistons, especially when the compression ratio is raised. Could this be happening in some present day large size engines?

Jim Allen

 

[Steve Anderson]

mb .40