Gas props on nitro rigger

[dwilfong]

Well just thinking out loud but if you have a ton of negative in the strut with your best prop might want to add /redistribute weight forward or change sponsor AA . Thats one of the things negative I have seen with sponsors with low AA is that the critical moment changes rapidly with small adjustments , some of the more popular sponsor designs /profiles out there give the hull more of an envelope of drive ability without making major adjustments even though top end speed may be sacrificed a bit . Keep on testing Dave !! Full Metal Jacket in Riverview for sure ! (I guess i should get off this stupid thing and start working on stuff !!)

thanks for the input Tom you always have good advice. I will mess with the strut when I land on a prop. Have a 1/4 steel rod to stick in the strut so I can put the magnetic angle finder on it. that way i can make adjustments and know exactly where I am at all times.

Imagine that me knowing where I am exactly at at any time. :unsure:

 

[aaron alberico]

David

ABC 3020 dam that's a lot of prop!!! If you where pulling that with any decent rpm's you should be well over 100mph with your heat race boat!

I must be doing something wrong as I only ran 2618 cut to 63mm on my oval heat race twin!

maybe that's why I never saw 100mph!!

Things to try!

Regards Aaron

 

[dwilfong]

David

ABC 3020 dam that's a lot of prop!!! If you where pulling that with any decent rpm's you should be well over 100mph with your heat race boat!

I must be doing something wrong as I only ran 2618 cut to 63mm on my oval heat race twin!

maybe that's why I never saw 100mph!!

Things to try!

Regards Aaron

Aron

Same RPMs as every other prop I have run with the MAC 1384 13cc pipe at 11 1/2". I launch the boat by my self so it is flat dropped in the water with the radio in my hand. This prop did not pop right off took a little to get it going.

Here some pick of the eng after the running tear down.

It is burring real nice and no piston wear. Bearings are like new and feel real nice.

O and the look thew the throat of the beast.

David

 

[Ian Inverarity]

David,

The inlet tract looks nice! B) What is the purpose of the long cuts thru the liner under the exhaust port?

 

[dwilfong]

David,

The inlet tract looks nice! B) What is the purpose of the long cuts threw the liner under the exhaust port?

thy hold the fuel oil mix and cool the piston face. also cuts down on the surface area to reduce friction at High RPMs. This is a variation on Some thing Marty showed me on a 21.

The spacer helps with the flow lines to the case. not just a dump in to the window from the carb bore. with a oval bore carb I can put the carb closer to get the same effect. The window is only .500 tall so a larger round bore carb would change the flow in two directions dropping the fuel out of the stream.

 

[shoboat]

David,

It looks like I will have to profile a few more blades

so the boat will launch easier. :huh: The other few changes

we talked about will help you carve the turn with even more

speed. The V-4 will give me the information that I would like

to see. I told you from the start there is a lot of different ways

to go fast.

Thanks For The Test Results David,

Mark Sholund

 

[dwilfong]

David,

It looks like I will have to profile a few more blades

so the boat will launch easier. :huh: The other few changes

we talked about will help you carve the turn with even more

speed. The V-4 will give me the information that I would like

to see. I told you from the start there is a lot of different ways

to go fast.

Thanks For The Test Results David,

Mark Sholund

Yes but using a slege hammer is so much fun. ^_^

Like I told you I will build the eng if you got the prop for it. B)

What the heck we going to do with a VAC 1.05!!!! :lol: :lol: :lol: :lol: :lol:

 

[shoboat]

David,

We will have to break out the jet ski impellers pretty soon.

Bring on the VAC 1.05 h34r:

Happy Holidays,

Mark Sholund

 

[Joe Warren]

David I dont 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.

 

[Jeff Lutz]

I bumped 99 mph heat race trim over 12 years ago. It was a 90 SG. Did that with a old 1 inch purple head cmb,ran a k 90 97.6mph heat race trim in that boat also. I did it with a prop that was around 5 " total pitch. Most of todays "prop polishers" would tell you the prop I did it with was a piece of junk.....I see you have played with 10" cup,quit wasting your time,that 10 lb sg boat will never need that much cup. Turn some freakin rpm !! Have fun, Jeff Lutz

 

[Elias Vazquez]

I bumped 99 mph heat race trim over 12 years ago. It was a 90 SG. Did that with a old 1 inch purple head cmb,ran a k 90 97.6mph heat race trim in that boat also. I did it with a prop that was around 5 " total pitch. Most of todays "prop polishers" would tell you the prop I did it with was a piece of junk.....I see you have played with 10" cup,quit wasting your time,that 10 lb sg boat will never need that much cup. Turn some freakin rpm !! Have fun, Jeff Lutz

Amen to that

2nd Amen to that!

 

[dwilfong]

David I dont 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.

 

[dwilfong]

I am tryiny to hold the RPM to a reasinabl level. I already got a crank with the rod blued up and spit the needls out.

David

 

[dwilfong]

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.

 

[Chris Wood]

have you had any issues ripping out the wrist pin boss? i am suprised if you havn't been how close you are cutting it to the piston

 

[Joe Warren]

David, How Much Nitro & Oil? if you think it runs good with 60% try 65%. Both will require a larger head button.

 

[BigChuck]

have you had any issues ripping out the wrist pin boss? i am suprised if you havn't been how close you are cutting it to the piston

Chirs

David has a catch22 there. If he increases RPM He will have a ripped Piston. But in order to turn the big ABC props he needs power....................But will not be as fast as turning the RPM.

There is a TON more to this Equation................Good luck with the Calculus...

 

[dwilfong]

I have bin using this mod in many eng for the last 3 years. in my 45RS in my mono.

This eng has bin logged at 29000RPM and 65 mph.

This is also the mod used on my 91 for a year. no problem with the pin boss.

as far as more nitro this set up has burned 65% in the 101 no problem with a 1cc chamber as it is now and .02 for the plug.

It is not the mod to the piston or the high nitro that is the problem it is the rod bearings at 260000+ RPM.

I have talked with Jim Allen about this. but as my self there is only so much time in a day. I will try to find some on who can help making the right bearing.

this eng reves. will log it and post the results should have the new V4 this week.

I am out of town this week with the job so will see how it goes this weekend on the logger set up.

 

[dwilfong]

David, How Much Nitro & Oil? if you think it runs good with 60% try 65%. Both will require a larger head button.

For now 50% is working fine. I will bump it up when I land on a prop to get the last bit out of it and shorten the pipe if the bottom end holds up.

 

[dwilfong]

have you had any issues ripping out the wrist pin boss? i am suprised if you havn't been how close you are cutting it to the piston

Chirs

David has a catch22 there. If he increases RPM He will have a ripped Piston. But in order to turn the big ABC props he needs power....................But will not be as fast as turning the RPM.

There is a TON more to this Equation................Good luck with the Calculus...

Chuck

How many Rs you think its turning at 11 1/2" on a 13cc pipe?

Just make a estamate and when I log it will see how close you are.

David