question for the engine gurus

[mtruex]

i been working with a novarossi 12.trying to get more rpm out of it..right now the sleeve is raised .020 and it puts the timing at 125 178..pipe is at 6 3/4 on 65% nitro..i can put .010 more shim under the sleeve and get 130 182, or leave the transfers at 125 and cut the exhast port up .020 and get 186..what do you think would be better and why? also im wondering how much rpm im losing after raising the sleeve and having the ports in the case not match up to the sleeve perfectly..thanks Martin

 

[shoboat]

Martin,

Is that a DEI engine now? :lol:

Give me a call about that propeller,today or tomorrow.

Good race last week.

Thanks,

Mark Sholund

231-590-3023

 

[gooycheese]

I am very interested in this topic, I am running a NR .12 what version do you have? How does this engine compare to your others? I notice you mention 6 3/4 pipe length i know i am about 1 inch longer than that and i know some are 1 inch longer than what i run, how does 6 3/4 work for you do you lose torque like that?

Thank You,

Paul

 

[mtruex]

I am very interested in this topic, I am running a NR .12 what version do you have? How does this engine compare to your others? I notice you mention 6 3/4 pipe length i know i am about 1 inch longer than that and i know some are 1 inch longer than what i run, how does 6 3/4 work for you do you lose torque like that?

Thank You,

Paul

[/quote

mark ill call you tomorrow..

paul, its the engine that glenn quarles is selling, basicly the same as yours but the exhaust timing is a bit higher from the factory.wth the pipe that short it still has plenty of torque, turns x637 x438 and backcut 1440 done by mark..it is a different pipe than you are running though, ive ran the macs pipe also but only down to 7 1/2..it runs good but when i go to the smaller of the props it turns the same rpm just goes a little slower..it runs right there with my other .12s but they all have pretty close timing numbers right now, just looking for a little advise on which way to go from here..thanks Martin

 

[steve wood]

if you raise the sleeve,and it loses too much torque to reliably launch the boat, you can drop the sleeve back down. if you cut the exhaust higher and it loses to much torque, then you buy a new piston and liner. i'd probably try the shim first. sometimes the only way to know for shure is to try something. also, if you put too many shims under the liner, you can lose the fit,and torque. you can sometimes get the fit back by squeezing the liner or by re grooving the piston. another thing to rember is to maintain the head clearance at about .006. also check your head volume and compression ratio. the little motors need 10 to 1 or a little higher to make good torque. if your volume is too high, cut the head down to raise the compression ratio,then raise the sleeve, and i would grind the top of the case ports, if the're showing up in the port windows. use a hot plug, like a 1L, and don't over cool. sometimes running water will put the fire out. sometimes these things are as hard to set up as a cup car.

 

[TERMINATOR]

if you raise the sleeve,and it loses too much torque to reliably launch the boat, you can drop the sleeve back down. if you cut the exhaust higher and it loses to much torque, then you buy a new piston and liner. i'd probably try the shim first. sometimes the only way to know for shure is to try something. also, if you put too many shims under the liner, you can lose the fit,and torque. you can sometimes get the fit back by squeezing the liner or by re grooving the piston. another thing to rember is to maintain the head clearance at about .006. also check your head volume and compression ratio. the little motors need 10 to 1 or a little higher to make good torque. if your volume is too high, cut the head down to raise the compression ratio,then raise the sleeve, and i would grind the top of the case ports, if the're showing up in the port windows. use a hot plug, like a 1L, and don't over cool. sometimes running water will put the fire out. sometimes these things are as hard to set up as a cup car.

what pipe are you running on your 12 boat martin? i am using the mac 2.5 pipe and want to try something else to get some more speed outta it and maybe more torque? i am using a os 12 5 port tz.. thanks

terry

 

[mtruex]

if you raise the sleeve,and it loses too much torque to reliably launch the boat, you can drop the sleeve back down. if you cut the exhaust higher and it loses to much torque, then you buy a new piston and liner. i'd probably try the shim first. sometimes the only way to know for shure is to try something. also, if you put too many shims under the liner, you can lose the fit,and torque. you can sometimes get the fit back by squeezing the liner or by re grooving the piston. another thing to rember is to maintain the head clearance at about .006. also check your head volume and compression ratio. the little motors need 10 to 1 or a little higher to make good torque. if your volume is too high, cut the head down to raise the compression ratio,then raise the sleeve, and i would grind the top of the case ports, if the're showing up in the port windows. use a hot plug, like a 1L, and don't over cool. sometimes running water will put the fire out. sometimes these things are as hard to set up as a cup car.

what pipe are you running on your 12 boat martin? i am using the mac 2.5 pipe and want to try something else to get some more speed outta it and maybe more torque? i am using a os 12 5 port tz.. thanks

terry

terry,

i am running any browns 12 pipe right now, glenn quarles has a nice one also..

steve,

head clearance is .006, and running temps about 180, i tried it with water cooling it definently put the fire out..using odonnel 89 plugs in it now they sem to work well..i think first i will fix the case ports and see where that gets me..im not having any problems with torque right now and its been pretty hot out..compression ratio is 10.5 the fit is also still tight, i raised the liner before running it in..

basicly if i raise just the exhaust or the whole liner im going to lose some torque correct? but which do you think will get me more rpm ? or is the rpm tied mostly to just the exhaust timing?

what are considered high timing #s for these little motors..are they close to 21 numbers?

next question is the rotor timing on this motor, the duration is 201 with it closing at 57 , im sure this is hurting top end also..would it be a good idea to try a later closing like 65..

thanks Martin

 

[tnrcboatracer]

Martin, I made my first 12 pipe last week, but it had the NR header. The CNC shop has the drawing for the Associated Header insert. They're trying to work it in. They nalso have drawings of the 12 mandrel set as well. I can make one on the existing mandrel, but the transition is a bit wierd. Hopefully I'll get the 12 mandrels in the next month or so. I also need the mandrels for the 45 pipe soon for my boats (I have 3 ea 45 powered hulls).

I'll be in touch once I have a 12 Squarewave pipe for you.

 

[TERMINATOR]

Martin, I made my first 12 pipe last week, but it had the NR header. The CNC shop has the drawing for the Associated Header insert. They're trying to work it in. They nalso have drawings of the 12 mandrel set as well. I can make one on the existing mandrel, but the transition is a bit wierd. Hopefully I'll get the 12 mandrels in the next month or so. I also need the mandrels for the 45 pipe soon for my boats (I have 3 ea 45 powered hulls).
I'll be in touch once I have a 12 Squarewave pipe for you.

jon i hope you will be in touch with me as well, i really need choices in pipes for my 12 boat, thanks

terry

 

[tnrcboatracer]

Martin, I made my first 12 pipe last week, but it had the NR header. The CNC shop has the drawing for the Associated Header insert. They're trying to work it in. They nalso have drawings of the 12 mandrel set as well. I can make one on the existing mandrel, but the transition is a bit wierd. Hopefully I'll get the 12 mandrels in the next month or so. I also need the mandrels for the 45 pipe soon for my boats (I have 3 ea 45 powered hulls).
I'll be in touch once I have a 12 Squarewave pipe for you.

jon i hope you will be in touch with me as well, i really need choices in pipes for my 12 boat, thanks

terry

Yes, Terry, you are also on the list. Martin gets the first production pipe, you're second in line.

 

[steve wood]

if you raise the sleeve,and it loses too much torque to reliably launch the boat, you can drop the sleeve back down. if you cut the exhaust higher and it loses to much torque, then you buy a new piston and liner. i'd probably try the shim first. sometimes the only way to know for shure is to try something. also, if you put too many shims under the liner, you can lose the fit,and torque. you can sometimes get the fit back by squeezing the liner or by re grooving the piston. another thing to rember is to maintain the head clearance at about .006. also check your head volume and compression ratio. the little motors need 10 to 1 or a little higher to make good torque. if your volume is too high, cut the head down to raise the compression ratio,then raise the sleeve, and i would grind the top of the case ports, if the're showing up in the port windows. use a hot plug, like a 1L, and don't over cool. sometimes running water will put the fire out. sometimes these things are as hard to set up as a cup car.

what pipe are you running on your 12 boat martin? i am using the mac 2.5 pipe and want to try something else to get some more speed outta it and maybe more torque? i am using a os 12 5 port tz.. thanks

terry

terry,

i am running any browns 12 pipe right now, glenn quarles has a nice one also..

steve,

head clearance is .006, and running temps about 180, i tried it with water cooling it definently put the fire out..using odonnel 89 plugs in it now they sem to work well..i think first i will fix the case ports and see where that gets me..im not having any problems with torque right now and its been pretty hot out..compression ratio is 10.5 the fit is also still tight, i raised the liner before running it in..

basicly if i raise just the exhaust or the whole liner im going to lose some torque correct? but which do you think will get me more rpm ? or is the rpm tied mostly to just the exhaust timing?

what are considered high timing #s for these little motors..are they close to 21 numbers?

next question is the rotor timing on this motor, the duration is 201 with it closing at 57 , im sure this is hurting top end also..would it be a good idea to try a later closing like 65..

thanks Martin

about everything you do to these motors to turn more rpm loses torque. i think 190 exhaust would be max. if you still have a tight fit, raise the liner a little more. on the rotor, you can try to take off the closing side a little at a time. i try 60 first, before i went all the way to 65