what prop?

[airbusmech]

Hey fellas,

I know this question has been asked before but I am too lazy too search.

Need a 3 blade for my eighty. I almost had a 24 x 10 Mezlik but my LHS let me down this week.What size should I go with?I may go two blade but ground clearence maybe an issue.

Thanks in Advance

[Billa]

Have you broken in the engine yet ? I have a ZDZ80 RV (blue head) and would like to settle on a running-in prop among the following choices - Bolly (carbon) 24 x 10 / Top flite (wood) 24 x 10 / Master Airscrew ( wood) 24 x 12/ MSC (wood) 26 x 10. Ground clearance is not an issue. What are minimum top end RPMs that one should be looking for. For example, the DA 50 instructions say use a prop which will give you a minimum top end of 6500 ? Is there a similar thumb rule for the 80.

[dick hanson]

what is the exhaust system to be used ?
for all practical purposes -on that engine - any 24x10 -25x10 26x10 prop can be bolted on - fill the fuel tank with 32-1 synthetic racing two stroke oil an auto grade premium gasoline --set the needles and go fly-
the rpm will be a direct result of exhaust system YOU selected and will run as low as 5500 on some worthless in cowl types on 26x10 - or as much as 7000 on a good open pipe/can setup - in either case learning to set the needles is your task -to get the engine running it's best . keep it slightly rich -this is a learned thing and if you have no experience with this - the engine should never slow down upon reach full power once warmed up ---rpm will read lower ALWAYS- by a 100-300 margin, when warm

[Billa]

I am using a 75cc PEFA cannister. Open Exhaust (header only) top end RPM with the Bolly 24 x 10 hit 7000 - header is around 7 inches long. Will try to tach with the can and post tomorrow. Thanks.

[airbusmech]

You guys quoting two or thre blade props?

[dick hanson]

you MAY need bigger can and more header - you should see some easy power increase when header length is correct.
also the exhaust system should not cause tempermental transition from lower to full rpm.
The ZDZ80 needs to be in the 6000rpm range to take advantage of it's flow abilities
It responds very well to tuned systems -done correctly and tuned cannisters typicaly use 10-13" of header
muffler ONLY cannisters about 5-6" long
The exhaust system can make hp vary 30% --easily.
on full pipe 26x10 at 7000rpm is not unusual on Mejzlic 26x10-as an example on this blue head model 80.

[Billa]

Airbusmech, I am quoting two blade props. Dick can probabaly best tell you which three blade prop to use - again you need to specify which 80 cc engine and the exhaust system in use.

Dick, the transition on the test stand is flawless at this header length but I must admit that I have not played around with the length as yet. Instead of cutting the header I thought I would extend it first (easier to do) and see if this enhances or mars performance. I think I have got the needles in the ball park for test flying and running in. In your experience, is the PEFA 75 cc can a 'muffler' only or a tuned cannister?

What I can understand from your explanation on prop selection is that a minimum top end of 6400 to 6500 should be achieved so that the 6000 mark is visited more often than not and running it up to 7000 is not unusual or detrimental. I wanted to select a break in prop so that the engine does not see heavy loads for the first five or six gallons. The plane albeit is a bit heavy at 25 lbs. Thanks.

[airbusmech]

	Quote: Originally Posted by Billa
	Airbusmech, I am quoting two blade props. Dick can probabaly best tell you which three blade prop to use - again you need to specify which 80 cc engine and the exhaust system in use. Dick, the transition on the test stand is flawless at this header length but I must admit that I have not played around with the length as yet. Instead of cutting the header I thought I would extend it first (easier to do) and see if this enhances or mars performance. I think I have got the needles in the ball park for test flying and running in. In your experience, is the PEFA 75 cc can a 'muffler' only or a tuned cannister? What I can understand from your explanation on prop selection is that a minimum top end of 6400 to 6500 should be achieved so that the 6000 mark is visited more often than not and running it up to 7000 is not unusual or detrimental. I wanted to select a break in prop so that the engine does not see heavy loads for the first five or six gallons. The plane albeit is a bit heavy at 25 lbs. Thanks.

I think I will choose a Mezlik 24X10 3 blade for my EVO 80.The exhauust is a standard JTEC pitts muffler.

[Billa]

Discovered that the Bolly was not balanced yet so used (the balanced) Topflite 24 x 10 ( 2 blade wood) and got 6200 on the can. Transition was pretty smooth. Do you think it is alright for break in purposes ?