How do you tune a Hatori JK pipe to an OS-50 hyper...

[blue_collar2]

I only know 3 ways to tune an engine / exhaust...

1) Use a run-up stand (as described in Ray's Authoritative Helicopter Manual, 3rd edition p162-169) and adjusting the mix slightly richer than when the heli produces max rpm as read from a Futaba gv-1 (not connected to the frame, of course).

2) Do a loop at full throttle, if the engine slows then richen it up, otherwise try a little leaner

3) Do a bunch of consecutive loops and rolls, land, bring engine to an idle and touch the backplate. If it is too hot to touch for 4 seconds then richen it up. If it's cool, lean it out.

Using these methods, I tuned the same heli (caliber-5) with either the stock muffler or the Hatorri JK pipe. With the stock muffler I can get another degree of pitch and consistently longer run times (about 4 minutes more) compared to the Hatorri.

I'm running the engine around 16,000 rpm (maximum torque range per OS documentation), OS#8 plug, 30% nitro fuel.

I'm so frustrated :arggg: with this pipe that I'm either going to get a YS-50st to see if it likes the pipe or drive over the pipe with my car.

Any constructive comments welcome...

[Gscott]

If it's a Hyper you need to be in the 17k range for max power.

[Jafa]

I tend to use a temp gauge on the back plate,
you can run the OS50 at 50 to 55 C
Hard to judge with a finger

(Recently I found I was running my 90's too cool due to finger technique)

[blue_collar2]

Thanks for the info!

I have a digital temp guage that I'll try. I'll also bump the headspeed. Do you think the hatori pipe will do better at the higher rpms?

[Gscott]

The Hatori has a broader power range than the MP2 but still produces it's best power when the engine is running 17k+.

[BarracudaHockey]

The hyper is rated at 17K not 16, let er rip.

[G MAN]

The hypers power band flattens out at 16000,if you run it at 17000 it will let i stay in the band when it boggs down because you are using 8.5 gear ratio.DOUG

[Jafa]

Hmm, if you are using a Raptor with standard gearing
it would be a good idea to get the upgrade gearing (8.7?),
the OS50 works well on that gearing...

[BarracudaHockey]

Yep, I put those gears in my Titan when I built it, only about 6 flights so far but I really like them.

[blue_collar2]

Thanks to all for the helpful suggestions! I'm flying a Caliber 5 which I think has a 10:1 gear ratio (but I'll check). I think the heli will like the higher headspeed...

Thanks again.

[rcnut2]

I'm not having any luck with this muffler either. I tried it on my OS50 Hyper and tuned it for optimal, the engine starves when I go vertical with the tank below the engine. I have to richen it a lot in order for this not to happen and then see a drop in performance. :( I am assuming that I'm not getting enougn back-pressure as the stock Thunder Tiger works fine. :arggg: I'm using 15% Morgan Cool Power fuel. Any thoughts or suggestions?

Thanks in advance. :D