jim52519

My Feedback: (3)

Hi all,
I am using a Zenoah G62 to power an 87" Ziroli Stearman. It seems uuder powered. It will not do a loop from level flight. Today I test ran the engine without the muffler. I picked up 500 RPM. I went from 6700 to7200 using an Xoar 22x8. Is this a typical loss for a muffler? Would 500 Rpm make the power difference to make the Stearman more aerobatic?

Jim

mrbigg

My Feedback: (21)

500 RPM is a big gain. I would recommend that you try a 21x8 or 10 on the 62 also and let it rev. You'll be shocked at the difference. I know people like using a 22" prop on this engine and that's what Zenoah recommends, but put a 21" on there and you'll see what I mean. That bipe you have is compounding the rev problem because of all the drag it has. The 62 makes it's power up higher in the rpm range.

rcdude7

My Feedback: (264)

If you are using a stock muffler then yes, it will be down on power, by a good bit. Anything else will be better with a header and tuned pipe being the best for top power.

pe reivers

The stock muffler comes to life at elevated rpm. A 20x10 prop will have plenty of pull and speed

Gray Beard

My Feedback: (-1)

Iuse the G-62 in a 30% Extra and the 22X8 worked pretty good but I started using a number of different pitches and found a lot more torque with the 22X6 and 22X4. I'm also using XOAR props.

soarrich

My Feedback: (98)

I have a MT62 which is a clone of the G62. I'm using a Xoar 23x8 with good result. I think the rpms where 6800rpm, the Vess 22A didn't pull as well, other than right out of hover, and was much louder.

RTK

My Feedback: (1)

Dump the stock muffler, or any muffler that knocks 500 rpm off of open stack, let the 62 spin up, they are not happy at lower rpms or with restrictive exhausts.. Try for a static of 7000
Yes, 500 rpm makes a big difference in performance on any plane.

soarrich

My Feedback: (98)

What is PS?

RTK

My Feedback: (1)

Horse Power in their measure

arobatx

A really good alternative in-cowl muffler, that is inexpensive and readily available...is the DL50 muffler. Last time I checked they are $35, and any of the DL engine distributors can mail you one. Buy yourself two 10-32 square nuts from the local hardware store, and you are set. The nuts will go into the exhaust flange on the cylinder, to accept the DL50 muffler bolts. This setup is INCREDIBLY lightweight, and a pretty easy breathing option if you must use an in cowl setup. Use red locktite on the muffler bolts/nuts, and permatex ultra copper (or equivalent) as a gasket. Only a very thin amount is needed at the mating surface between cylinder and muffler, but you can literally fill the void in the exhaust flange on the cylinder around the nuts for the mounting bolts, once attached, and it is completely leak free.

soarrich

My Feedback: (98)

I'm not breaking chops, but who are "they"? Is PS and HP 1 to 1. Pe's HPspreadsheetshows the 62 making about 5HPat 7000 rpm.

RTK

My Feedback: (1)

That comes directly from Zenoah.net All of their engines have HP/Torque curves

frieshoo

My Feedback: (20)

I agree with Chad. The DL muffler works great on a G62.

Like others have said: Always prop your G62 at 7000-7400 rpms.

Rcpilot

My Feedback: (78)

Did you tune the needles properly? If you haven't tuned it yet, then thats the problem. The stock muffler will cost you 500RPM easily. That engine should swing a 22-10 over 7000RPM. All mine do and I have more than a handful of them with pitts mufflers.

Lean the high speed needle to max RPM and then richen about 200RPM. Use a tach.

Now throttle back to idle and tune the low speed needle leaner about 1/8 turn. Check transition. Will it transition without bogging or skipping? If yes then lean the low speed needle again and again until it won't transition cleanly. After each adjustment run to full throttle and back down slowly. When it won't transition, richen a little less than 1/8 turn.

Now check high speed needle again. Lean to peak and then richen 200RPM. Use a tach.

BTerry

My Feedback: (8)

"PS" stands for "pferdestarke" = "horse strength". One BHP = ~1.013 PS. Apparently British horses are slightly stronger than German horses...(actually it is just a metric conversion from British units)

One BHP = 745.7 watts, one ps = 735.5 watts.

Mein Duff

PS comes from German meaning:  "Pferde Staerke"  or transalated as "horse power".....one PS ( horse power) is required to pull 10 pounds as a rule of thumb when calculating engine needs in model aircraft.
Don'  know why we didn't use an american acronysm for this......

Skratchbilt

My Feedback: (6)

Would you happen to have a direct link to these DL50 exhausts? I too am using a G-62, and would like to avoid all the hangups others are having before firing it up. So fa, this thread has been very useful!

Jonas Bergström

Hi
I have build a Stearman from Fliarand it was very heavy.
I also used a ZG62 but i used a REAL silencer and I have over 6500 rpm with a Menz 22x10.
Se the pics.
It sounds lovely also, not like a moped.
Look at www.toni-clark.com

Good luck
Jonas

arobatx

Call Bob at DLUSA: http://www.dlusa.net/Parts.html
Or Jody/Tom at: http://www.valleyviewrc.com/