Real Life Engine Comparisons

[CLS447]

Ok, this is what I'm trying to figure out maybe I'm off base, maybe not. Since alot of people are using the warp drive, including me, I will use that as the load for the engine.

Here is what I'm getting.........EA81 with 68" warp drive at 13 degrees of pitch with 2.28 to 1 Joe Souza redrive. Tied down. 5120 engine rpm's at max throttle. As everybody knows I can increase my engine rpm's by decreasing pitch.

I am interested in finding out what other engines are doing with their combinations. I am looking for engine weight, hp, rpm, redrive ratio, prop and pitch. This should be an easy answer for all.

The Hirth f-30 with 68" warp drive........a common application.
The Rotax 912 with warp............another one.
The EJ-22 with warp....
The SUB-4 with warp...

Any other combos I've missed?

If the 912 can get what I am getting, then the only thing would be less weight and more money. Please give me your figures, so I can see where I stand as far as my output is concerned.

[Caribean_gyro]

chris
have you flown it. becasue we were tuning a 582 at max RMP in the floor and whenin cruse we have to keep power a bit higher. Then we tune it down on the floor with more pitch and I took a bit more to take off but crusing wow RPM came down to the same airspeed.
ChuckP

[CLS447]

I'm not gonna let up on this subject!

[mceagle]

Subaru

Ea 81 carby - 72" warp @ 13 degrees = 5000rpm

EA 81 EFI - 76" warp @ 15 degrees = 4900rpm

EJ22 76" - warp @ 17 degrees = 5100rpm

Degrees measured at tip.

(76"warp = 72" with different hub = 30 lbs static thrust and extra 100 fpm climb)

Redrive = 2.62:1

In the last two cases props "cavitate" at very low airspeeds.

Prop speed at full power = 1900rpm

Prop speed at cruise = 1500rpm to 1600rpm (surprisingly efficient and quiet)

[CLS447]

Thanks Tim, Is this a stock EA81?(carby) Do you think the extra performance out of the EJ22 is worth the extra weight(100lbs?)? Those are good numbers though,Same machine or all different machines at the same time? I don't have room for a 72" ,do you think that it makes a big difference over a 68" ? Thanks alot, I hope for more of these #'s. What do you feel the FI did for the 81 in regards to HP ?

[ben]

chris
ea81 carb = 62in prop 4700 rpms 350lbs thrust full throttle 5400rpms at 14 degs pitch ben

[mceagle]

Chris,
Different machines. Difference between 68" and 72" is approx 20 lbs static thrust. Top speed the same.
Modifyied FI EA81, according to prop pitch, is between EA81 TC (100hp) and EA81 turbo (120hp) in horsepower - guessing approx 110hp.

EJ 22 certainly worth it on heavier machine where the engine weight makes up a smaller percentage of the overall weight. The ability to turn much higher pitch means less rpm at cruise and excellent economy (15 - 20 lph at cruise and up to 26 lph at full noise - using factory computer)

[CLS447]

Thanks Tim, I guess I'll have to live with my 68" due to clearances.What prop & pitch do most guys run on their RAF's w/EJ22's ?

Thank you very much Steve. I can thank Joe Souza of Bandit gyros for the engine build & that geogeous redrive.($7000 for both) So far she runs great & I'll let you know how she stays together. The block is painted silver & the supposed red powdercoating on the valve covers & oil pan is not up to snuff. I'm sure I will have to keep after the block( I'm not gonna tear it apart for powdercoating yet !) & I'll probably get those other parts redone. I'm not as worried about being pretty as I am about being safe right now! Thanks

[CLS447]

C'mon, Nobody's got a Hirth with a 68" Warp! Surely somebody knows a person using one!?!

[eruttan]

Carl Shnieder? Forgot the last name spelling. Own design with bicycle wheels.

It is a 72" blade but it is a hirth.

[GyroRon]

Chris those Hirths just don't stay running long enough to be worth the measurements! lol

[CLS447]

C'mon Ron, You mean to tell me that Maxie,Dan L., & Mike S. Are all having trouble with their Hirths?

[automan1223]

All these numbers are nice but could you update and post how many blades your are running ?

Jonathan

[Dean_Dolph]

Chris, when I talked to Dan L., at Bensen Days '03, about his Hirth he seemed to be okay with it.

Right or wrong, it seemed to me, from what Dan was saying, is that there is a learning curve with the Hirth. Apparently there are some idiosyncrasies that former Rotax owners are slow to pickup. No, don't anyone ask me what they are 'cause I don't know! And again, that was my impression of what Dan was saying.

Carl Schneider has been running a Hirth for some time now and Carl doesn't strike me as someone that would continue to use something that doesn't work. If Carl drops it then there is a problem!

[automan1223]

I came to look upon the hirth situation with an open mind. I was more inclined to believe that it was user error or neglect or something other than hirth. After watching Maxie toil with his machine I can honestly say that those that have a trouble free hirth experience are the very rare ones. Hirth must have HUGE problems in quality controls. There has not been a part of the engine, redrive, or engine managment control system that has not needed repair or attention. This is no way to have a product perform or service its customers.


The insult here is that hirth is selling its products as AIRCRAFT engines. These engines should be well designed and able to take the heat and abuse of turning a prop at full rpm. Sadly that is not the case. Even propped down 400-600 rpm below hirths stated max rpm most of the engines out there just do not hold up. I have been following the hirth story for a very long time.

My finely tuned ear heard and detected problems before they were evident. However every time you hear something are you going to tear down the whole thing to see what is on its way to failing now ? Over the operation of 120 hours Maxie had at least 4 or 5 major failures. Maxie is no idiot or dummy. He knows how to turn a wrench and I cannot imagine how he could be responsible or anyone be responsible for some of the metalurgy and engineering problems that are built into these boat anchors. Some of the problems were POOR ASSEMBLY AT THE FACTORY. Hirth should sell its engines as a kit.

I dont want to pull any punches here but hirth, in my professional opinion should recall all its products go back to the drawing board and fix all the problems before someone ends up in the trees or worse. As soon as your 1 year warranty is up look out because they are going to put a hurtin on your wallet and your fun time. In total seriousness, you could not sell me a hirth engine to put on a lawnmower.

In support of maxie, his engine now sounds the best it ever has. It sounds smooth, balanced, powerfull without sounding strained. I guess he has had it apart so many times he has worked out all the problems

AT this point I would not hessisitate to fly with him AT ALL ! it really did sound sweet.I know with 100% certainty that he broke in the engine as per instructions, has only run required oil and fuel mix, and has flown the craft with the utmost care and consideration for its continued service. Thats the truth.


Jonathan Weis
ASE Master Technician

[CLS447]

Oops forgot that! It's a 3 blade 68" WARP DRIVE. Thanks Jonathan.

[Brad_King]

Solano's Hirth puked a sparkplug at SnF. A witness said the other plug in the same cylinder was heli coiled and there was a crack between the spark plug holes. Matt Pearson's Hirth puked a plug on him and the second set of heads on his engine developed the same cracks between the plugs as the first set.

[GyroRon]

Two others with 2706 Hirths puked plugs at Bensen Days.

[Chuck Roberg]

Mike Solano also had a cracked cylinder on his Hirth. He's had a few other problems as well. But the last time I spoke with him he said overall he was satisified with the Hirths performance.

I also had a cylinder crack on my F-30. Factory said it was due to poor maintenance on my part????

[Brad_King]

That's the Hirth Company's motto "Blame the owner!"

Brad King

[Dean_Dolph]

I don't have either one at the moment so I don't have an axe to grind but...... I did a Google search using Hirth engine problems and Rotax engine problems as the search criteria in any language.

The results of the search were 1510 pages for Hirth problems and 5650 for Rotax. Is this relevent, gee, I don't know but why are the hits for the Rotax much larger? It could very well be that there are that many more in use. However one thing it does show is that the Rotax isn't problem free. Oh yeah, I did look at a few of the Rotax pages and it seems that the owner gets a lot of the blame there also!

The thing is, if any of us, or an acquaintance, have a problem with anything, it has a tendency to make us shy away from it and not only not reccomend it but in some cases bad mouth it. I'm sure that there are Toyota and Honda owners that despite the reputation for reliability have had problems and will never own another one.

[MikeBoyette]

Hey Ron,
You failed to mention that Tom's engine puked the spark plug with you at the controls. I have called the Hirth a German Mac for years. 1000 hr tbo my butt. I'd like to see one with 300 hrs. on it. At least that has not had a major rebuild. Knock on wood David Seace has not had a bit of trouble with his. By the way Carl is running a new type of hirth it is a in-line three cylinder water cooled engine. I am not sure of H.P. but he was very happy with it last I saw him.

[CLS447]

YEAH RON!

Quit beating everybody's machine! You gyro bully! LOL

Rotax rules! Who owns them now? But you just can't beat a 4-stroke!

[GyroRon]

Yes I was flying Toms machine when it shot out a plug. Made a beautiful landing engine out on the grass cross wind Runway at Wauchula. Didn't hurt a thing - unlike my first landing in his machine where I let the anti servo tab tap the ground, Sorry Tom!!! -

Dean, There is Countless many more Rotaxs being used compaired to Hirths. I would have to take a wild guess and say 20-30 Rotaxs per one Hirth. That is a low guess, I wouldn't be surprised to see 50-70 per Hirth. More complaints yes, but WAY more engines out there too. and the Rotax is pretty good right out of the box where it seems Hirths come with problems right out of the box that have to be fixed over the first 100-200 hours, only then can you have a fairly trustworthy Hirth.

Chris, I wanted to Beat up on your machine at ROC last year. Sorry I never got to experience the Climb King AC you got! lol

[Neil Hintz]

I think you will find that the new design WATER COOLED Hirth engines will be MUCH more reliable! Air cooling has had its day, in saying that the Rotax 503 still suprises me with it's duability.

Neil

[Neil Hintz]

Waiting to get it certified to fly. New guy doing the checks and it would seem he does not like the smaller registration numbers, no gyro can fit the standard letter sizes. So we have been waiting for a dispensation to go through. I'm not sure how this would affect saftey? I'll post as soon as we get information.

Neil