3M Mintor 170 questions

[Dean Pappas]

Right-o! Though the 3M is the best I have seen opn a pipe. Really.
Dean

-----Original Message-----
From: Jeff Hughes [mailto:jhughes at hsonline.net]
Sent: Monday, May 05, 2003 4:18 PM
To: discussion at nsrca.org; discussion at nsrca.org
Subject: RE: 3M Mintor 170 questions


Another way to fix it is to put it on a muffler instead of a tuned 
pipe. The 3M is very linear on a muffler (bolly)

> Sorry for the incomplete response, before.
> Most 2-C setups require a lengthening of the pipe to cure the 
midrange richness or bog, and to eliminate the power versus throttle 
position hysteresis that can plague any piped 2-C.
>  
> The problem was that if you pushed to level from warmed-up WOT 
vertical and reduce to 1/2 throttle the engine may stay "on the pipe" 
and you get a different power setting than if you came from idle to 
the same stick position. Or (and this is a goodie) you may end up with 
a level flight cruise setting that changes with what thermal/load 
condition the engine was in a few seconds ago, or a lagged settling 
time at 1/2 throttle. How about rounding the top of the square loop, 
pulling the throttle back, getting a good setting, then 1/2 way across 
the top of the loop, the engine falls completely off the pipe, and 
gets soft.
>  
> The long pipes fixed that set of problems, and caused the airspeed 
dependant mixture problem. O.S. fixed it with a box that looked at RPM 
versus throttle position, and corrected the mid-range mixture to get 
rid of the hysteresis. One other way to fix ( or at least help ) this 
would be controlled spark timing; the other is to make the engine 
equilibrate thermally much more quickly. As you know, temp is ignition 
timing in a glow engine. 
>  
> Dean
> 
> -----Original Message-----
> From: Woodward James R Civ 412 TW/DRP/ACQ 
[mailto:James.Woodward2 at edwards.af.mil]
> Sent: Monday, May 05, 2003 3:44 PM
> To: discussion at nsrca.org
> Subject: RE: 3M Mintor 170 questions
> 
> 
> 
> Hi Dean,
> 
>  
> 
> I'm still sort of new.  Does W.O.T. = with out throttle?  On 45 
degree downlines of medium length like the reverse Cuban eight from 
the top (Masters sequence), I'd say the motor just unloads some.  If 
it were lean, it might cut-out for a second when throttling up.  If it 
were rich, it might gurgle or give signs of loading up.  The 140 or 
170 do neither.  They just increase in rpm as the throttle is 
increased.  
> 
>  
> 
> On the 140 setup (15% C.P., 2 OSA5), I needed to lean the low-end 
screw 1/8 turn during the 2nd tank on the ground.  This setting has 
held fine since, now with 1.5 gallons through it.  The engines will 
idle very low, however, I raise it to 2000 for takeoff and flight.  
> 
>  
> 
> Your technique is the first I've heard of like this.  So, once you 
get this one flight profile right, you find a prop that gets the 
torque you want?
> 
>  
> 
> Jim
> 
>  
> 
>  
> 
> Thanks for the response Jim,
> 
> That sounds right, though I just like more prop and more quiet.
> 
> When you dive W.O.T at about 15 degrees or so ( simulating using 
windup for extremely windy conditions) does the engine lean/richen/or 
just unload ? With the 17-13 on the 140, I shortened 'till the 
richening was gone. That was just under 1" gap from stock.
> 
> Dean
> 
>  
> 
> 

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