cfv007

My Feedback: (5)

I bought a GT-80 ... About a year old. Its in a H9 Extra 330L. I use Amziol 50:1 and regular unleaded gas. I am using an NX 24x10 prop. I am getting 6000 -6100 rpms. This is my question. Shouldnt the GT-80 turn the 24x10 at a higher rpm? Anyone using the NX prop from Airwild hobbies? Im using stock mufflers. Maybe I should alter the mufflers?

Thanks for any help.

Charles

bhall01

My Feedback: (4)

Last time I ran my GT-80 was with Pennzoil 32:1 air cooled engine oil and 'regular' unleaded gas. Had a Mejzlik 24x10 prop and standard mufflers (unmodified). Turning the prop at 7100rpm.

Running the standard ignition. I removed the spring starter an was using a CH Ignitions Jump Start for starting.

At that time the engine had maybe 2 gallons of fuel through it. Horizon claims 7400rpm on a Bolly 24x10 with unmodified mufflers...... get a little more fuel through mine and I feel I'm on track for getting pretty close to that. They also claim 7700rpm with a bunch of holes drilled in the muffler's internal baffle, with an increase in loudness as well.

Haven't run mine in about a year. Currently building a Hostetler 33% Gee Bee Model "Z" that's going to house the GT-80.

BJH

cfv007

My Feedback: (5)

Hmmm ... Might be the prop Im using. Might be that the engine might need fresh rings. I know the spring starter does put some drag on the crank but in my G-62, removing it only made at best a 100 rpm difference.

Thanks for the response!

STUKA BARRY

MY GT-80 WITH A MEZJLIK 24X10 IS TURNING 6700. ITS STILL PRETTY NEW SO ITS A LITTLE RICH. I'M RUNNING BOLD MUFFLERS ON IT. ITS VERY QUIET, THE MUFFLERS LOOK AWESOME AND ITS RIGHT ON TRACK WITH THE RPMS. DONT WASTE YOUR TIME WITH STOCK HEAVY AND LOUD MUFFLERS. MELLOW IT WTHOUT A PERFORMANCE LOSS WITH BOLD MUFFLERS. (561)344-8785 MENTION THE "HARDEE'S AIRSHOW TEAM".

yojedi

My Feedback: (31)

cfv007,

Don't get stuck on static RPM. The real difference is when the prop is full under load ... meaning in flight. If the prop pulls the plane around the way you like it, then that's the right prop.

But here is a few personal observations on props;
1. Heavier props such as Mejzlik and Bolly tend to swing 200~300 RPM faster than wood prop due to its flywheel effect.
2. Many European wood props (ie. Menz) are shorter than they are advertised. If you have a Menz 24x10 prop and measure its diameter, you may find it's only 23.5" +/-. AirWild NX props (from my experience) is true diameter (I have a few that's actually 1/8" longer).
3. Shape of prop blade certainly affect engine RPM also.

In your case, sounds like many possible engine issues. Did you buy it used? Do you have good compression? Is timing properly set? Needle setting correct?

Yojedi

cfv007

My Feedback: (5)

Yojedi ... yes .. the engine is used. Has been flown for a year. Timing is set. I dont think I can change it ... Its CDI with magneto. How crucial is the gap though? The magento gap that is. Not plug gap. I worked with the high end needle. The best I could eek out of it was about 6000 rpm. I didnt mess with the low end cuz it seems to idle just fine. Compression seems good to however thats very subjective. I would like to check the compression. Maybe put in fresh plugs. I have heard too that the stock mufflers really dont allow the engine to breath as well as it could. Maybe some better mufflers are in order.

Thanks for feedback!
Charles

Russman

My Feedback: (12)

ya gotta loose those stock mufflers. I get 7100 rpm on a Menz 24x10 and 7110 on an Apc 24x10. The muffler change makes a world of difference in this engine.
Rusty

ChinookPilot

OK, Rusty. What mufflers are you using on your GT-80?

Russman

My Feedback: (12)

I can't remember the brand but they are very similar to the Slimline can type muffler.Check out this link.
http://www.chiefaircraft.com/cgi-bin...ne.html#Zenoah

Flyboyzel56

Hey Charles try playing with different pitches on your props and try switching to a carbon fiber prop. my GT80 is about 2 years old and i turn 7500 rpm with a meslich 24/10. but i dont run synthitic oils. i run AMSOIL at a mix of 80/1 ratio and this sucker screams. it pulls my 330L extra vertical with no problems. and that is with the stock mufflers drilled out only with a half dozen holes. Allan

cfv007

My Feedback: (5)

Allan ... how did you drill out the mufflers? What size are the holes? You just went in with a drill bit through the exhaust port opening?

Charles

tkg

My Feedback: (1)

Flyboy, Dude Amsoil IS a full snythitic

branded

My Feedback: (9)

hehehe...Ahhh, advice on the internet..........

Yep, AMSOIL IS synthetic.....