Engine Overview on the Zenith 701

[@bonza007]

Hi Matt, I feel uneasy about your promotion of the Chinese Knock off engine. You said at 2:03 that it is OK to copy the Rotax intellectual property, because it is no longer patented (you think). Why don't you call someone high up at Rotax and ask them about it? The guys selling the Knock Off engines tell you that Rotax are greedy for charging so much for their engines. The reason the Knock Off engine is 2/3 the price is that they don't have to pay for the design and research that it takes to develop. The Knock off engine sales will surely cost Rotax money, which they will not have to pay off the research. If your designs just get knocked off when you release them, you might not bother next time. This results in the de-industrialization of the industry, which ends up in the hands of the IP thieves. Not a good outcome.

[@mmatt]

Thank you for your well written comment. I just looked up the patent on the 912, it expired 5 years ago. I just didn't want to say that for fact in the video as I hadn't confirmed it yet. I don't think the inflated prices of the Rotax engines are paying off their design costs at this point as the 9 series engine has been around since 1989. Rotax is pretty much the only player in the light aviation engine game and so they can charge whatever they like. Competition helps the consumers and keeps monopolies from forming. I don't think Rotax will be going anywhere anytime soon just because someone copied their 25 year old design. Copies of things also allow less fortunate people to participate; we all can't afford a $40,000 engine. Think about how generic medication allows people to afford to stay alive when they can't afford the inflated price of the name brand stuff. If that's ok to do, why isn't this?

[@rc300xs]

The 912 has nearly doubled in price. It’s a money grab. Look up the price of a sprag clutch, now look up the price of a sprag clutch for a Honda 300 quad. It’s the same part. Radiator, ignition modules, I could go on and on. All over priced to the very max.

[@peterp696]

There are multiple copies of the Lycoming engine for the hombuit world. Builders that want Lycoming buy a Lycoming, people who want to pay less but a clone Lycoming. This is the same thing here.

[@kenfawcett4006]

I watched a documentary about Rotax filmed at their factory. They basically said that between shipping thousands of engines for military drones and even more for snowmobiles the GA side of their business model is tiny. Once a business starts selling a product to the US Military the general public consumers are going to get gouged. We need competition.

[@DougBow96]

Rotax also has to pay for lawyers since this is an aviation engine. That's why Rotax no longer uses NGK plugs in new engines. NGK was tired of the lawsuits. 😢

[@waynekimm.ngi.5696]

Very interesting matt please keep us updated on this project, there will always be a few negative comments, don’t let them dampen your enthusiasm!

[@mmatt]

I understand that this is a controversial subject and that's ok, everyone is entitled to their opinion. 🙂The nice thing about it though, is that if a person doesn't want a Chinese engine, they don't have to buy one!

[@waynekimm.ngi.5696]

exactly

[@portnuefflyer]

3000+ hrs + carbed 912S pilot here, who has used 85 degrees as my before launch temp the entire time, no gearbox issues. 3 hrs since intalling the EDGE EFI, you are going to love it! I use a cockpit controlled divertor for the rad fluid, plus I can control how much air my oil cooler gets, both help in less time wasted warming up. My strip is steep, so I don't use full power, around 4300 rpm, for take off, and only go to full power after it reaches 120+, one reason why that works for me. The Zonsen is new to me, interesting! There is no need to vent the header tank, you already have vents in the wing tanks, won't hurt, but for sure it's not needed.

[@mmatt]

Did you vent your header tank? If so, how? How was the installation process? Did you install it yourself or have Edge do it?

[@martinjmerritt]

If using Mogas you really should vent the header…for Avgas only you could get away with only wing tank vents. I’m a Rans S20 builder with 914 engine. Vapour build up in the header can prevent fuel from gravity draining to the header.

[@mmatt]

@@martinjmerritt That's true, mogas is more volatile than avgas. We're definitely venting the header tank.

[@portnuefflyer]

@@mmatt OK guys, do what you feel you need to do, but I'm telling you that after first hand experience, not just conjecturing, a separate vent to the header is not needed, it's basic plumbing 101! It's already vented! The only reason I persist in explaining this, is others that may read this and go away with the impression that a separate/additional vent is needed, it's not. It can't hurt, other than the extra hose, fittings, weight, etc., but it's a belt and suspenders approach. I've been flying with a "unvented" header tank for well over 20 years, and never have had any issues whatsoever, EVEN when I transfer fuel in flight (from a ferry tank via a floor mounted transfer pump ) emptying it out and then pumping air into the header, a worse case scenario one would think. It immediately runs rough as heck, as you'd expect, but the second I shut the pump off and quit pumping air in (which I only do if I'm trying to get every last drop out of the ferry tank) the engine immediately resumes normal operation. Nothing about this has changed with the EFI install. BTW: I haven't burned a drop of avgas in all this time, strictly mogas, and when I have to, even E-10.

[@mmatt]

@@portnuefflyer I understand completely and if I wasn't already removing the wing covers to upgrade the fuel line, I probably wouldn't be venting the header tank. Since I'm already gonna be in there though, I figure I might as well. 🙂

[@martinjmerritt]

The CV carbs adjust for density automatically, that’s the magic of them. Yes, you need to dial in the jets to start with and the left and right sides will often require slightly different sizes. You are correct that there is a balancing process to get the two carbs sync’d so that both sides make similar power at every throttle setting. If you do this properly, once, they do not tend to drift. The Rotax maintenance manual describes the procedure well. I assume that the Chinese clone has also copied the manuals…if not the Rotax ones are on line and can be downloaded for free. If considering EFI be sure that you have enough spare power to run it…unlike carbs EFI requires electric power to operate, no electric power, an engine will go quiet. The Rotax 912 has only a 20A alternator and Rotax suggest you limit electrical load to 80% of that. Add up your lights, instruments, radio, CDI ignition etc and then ask your EFI vendor what their system requires. You may be ok if you don’t have too many electrically powered toys on board.

[@mmatt]

Thank you for your comments! We have indeed followed the manuals to set everything up properly but I didn't know that the carbs might need different settings. That's interesting info. We asked about upgrading the alternator; it's not needed but the option is there if we want it.

[@martinjmerritt]

@@mmatt I just realized I gave you bad info on the potential need for for different jetting left and right. This is an issue on the (turbocharged) 914 because of its asymmetric airbox design but not a factor on the 912 whose intake system is the same L & R. Sorry about that. Once set up though the CV carbs DO adjust mixture for air density. They are able to do this because the carb slides are not directly connected to a cable, like in say a Mikuni. The slide floats in its bore suspended by vacuum above that is modulated by both throttle position and automatically by air density. TA CV carb essentially meters fuel based on the air’s mass. I have operated my 914 from sea level to 13,500’ and from -20C to +30C and the CV carbs do a good job of mixture control throughout that range. All that said EFI can be a great efficient and fiddle-free thing if you have the $ to buy it, the electrical juice to run it and realize that it introduces different points of failure.

[@mmatt]

@@martinjmerritt Thanks for the clarification. I mentioned in another post that I set my carbs up in the summer. Maybe now that they're set for winter they will self correct in the warmer temperatures. I guess I'll find out in a few weeks when it warms up. :-)

[@Tryagain205]

Thanks for experimenting with your experimental aircraft. You are an inspiration to many. Keep going Matt!

[@mmatt]

Thanks for the kind words! :-)

[@LTDan-hu5fq]

Thanks Matt, i have a Rotax 912uls and i am going to install the edge efi system before i mount the engine to my ch-701 build that is still 2 years from completion, the efi system is expensive but i think it will be well worth it in the long run! Awesome Video

[@DougBow96]

Thanks for sharing your mods. 👍

[@cameronlapworth2284]

Great video Matt. Love to see a comparison overlayed on each other part transparent so you can really nail home the difference.

[@mmatt]

Overlaid and transparent didn't work out so good so I did a side-by-side comparison for you instead. kzbin.info/www/bejne/aoiVlZx6aqipn7s

[@cameronlapworth2284]

@@mmatt ah thanks. Its impressive difference

[@OldRX550Pilot]

Excellent attention to detail as usual Matt 👍 Very interested to see how the Edge Performance EFI Upgrade goes, when you get to that. I’m sure you know about the French-made LAD Aero EFI Kit as well. Lots of them flying on 912 Series in Europe. However, there’s also lots of Edge Performance upgrades flying in Europe and in the U.S.A. I’m not an expert, but the Edge Performance Kit looks like a more robust design. Be interesting to see an apples-to-apples comparison/review of these 2 kits. Also, use Decalin Fuel Additive if you’re forced to use 100LL Gas with Rotax 912 Series Engines. Most airfields out here in B.C. don’t carry MOGAS, so always have the Decalin onboard.

[@mmatt]

We considered the LAD kit as well but ultimately went with Edge. Thanks for the info on the Decalin. :-)

[@philipritson8821]

​@@mmattBelt and Braces Matt. If you are forced to use 100 low lead, use the additive and change the oil every 25 hours. Sadly too many airfields assume everyone flies behind a Lycocaurus and only offer leaded fuel.

[@rangefreewords]

This build up is going to be sick! Those wing panels should be easy to remove. Look forward to seeing the fuel lines swapped and mounting that header in the hell hole. Quite a plenum/ manifold going on up front. As always, I am excited to see your videos!

[@mmatt]

I'll try to document as much as I can! :-)

[@LTDan-hu5fq]

Matt i have been reading some of the replies to your new ZD Engine, most are negative and that bothers me because they are pissing and moaning about this new engine using a computer that was made in China and on their cell phone that was made in China on their way to work riding in their car that was made in China you can see my point the Chinese technology is so far past our own that we are the ones trying to play catch-up not them. I love my country but our country was based on competition in the market place so i say good for you!!!!!!

[@joeshmooo5327]

Hi Matt, found your channel after watching your video over on the experimental built channel.

[@mmatt]

Welcome! I hope you find some entertaining videos here. :)

[@MichelSchott]

very nice video

[@dieseldan5189]

When you install the fuel injection system I would recommend you replace the lithium battery with an AGM. Why, the BMS in the lithium battery will turn off your battery when the cells within the battery become uneven. This is to protect the battery from going thermal overload. The outage may only last a few minutes or a half hour. I am sure it has done it in your existing setup but you don’t notice unless you have an indicator just for your battery voltage. As long as the charging system can keep up you will not notice. That is just one reason why a lithium battery increases risk with a fuel injection system. There are a couple others. The weight savings do not out-weight (pun intended) the increase in risk. I have watched a lot of folks who live in their boats in Florida who use lithium batteries. Every now and then the lithium batteries fry the alternator due to the BMS. The technology just isn’t quite there yet but it is close.

[@FLY--wy2yi]

So glad the new engine is running well! I just did my first oil change on my new Rotax so that was a bit of a milestone! I’m using 100LL so unfortunately I’m stuck with the 25 hour oil change instead of 50. Are you running AVgas or auto gas? Like everyone else, been waiting out the crap weather…..hang in there everyone…….spring is coming!

[@mmatt]

We're running auto gas exclusively. We'll use 100LL if we have no other option but that hasn't happened yet. I thought I read somewhere that there's an additive you can use to help scavenge the lead if you have to use 100LL, if you did, would that let you go back to 50 hour oil changes?

[@rc300xs]

@@mmattDecalin is the additive. I used it lots and did the 25hr oil change.

[@FLY--wy2yi]

@@mmatt , yeah Matt, you are correct. I have used it in the past but you still have to go with 25 hours on the oil change. The big problem with the auto gas (in the US anyway) is the Ethenol is bad for the gas tanks. A friend of mine had to replace two wings on his Pipistrel because it ate up the tank.

[@CrayonboxAviationAdventures]

Gidday Matt from Oz. Im very interested to see the efi installation and resultant outcome. Thanks for the updates!

[@mmatt]

I will be sure to document the installation process. :-)

[@eclipso104]

You don’t have to adjust those carbs because they have compensating fuel metering built in. Set the e clip on the high speed needle to match your usual operating airstrip altitude and leave it.

[@1972challenger]

As long as the risks are known for any given component you're using thats all you can ask for. Then make your own risk assessment based on that. And the comments about slave labor are laughable considering it was likely made from an iPhone.

[@walterrawdanik8077]

I live in Chicago where temperature swings are pretty extreme and i never mess with the carb needle setting and works just fine but on the other hand i don’t fly when it is colder than 20F ..

[@mmatt]

I found my EGTs were creeping up towards the redline during the colder weather so I went a jet size bigger and moved the needle clip down to the bottom and it brought the temps back into the green. That said, I set them up in the summer. If I had set them up during some colder weather maybe they would have been good all year.

[@trevorfurlotte]

Ha! Like zero snow here. Raining like it's Saint John

[@mmatt]

It's been raining here for two days now but it switched back to snow last night! Hopefully it doesn't last long.

[@superbill9066]

When you get to the streamlined struts, don't trust the measurements zenith provides for the jury strut holes. I made that mistake!

[@mmatt]

Good to know! Thank you!

[@dowkipling4859]

Hey Matt, good luck with the fuel injection conversion. The only issue I have with some systems is if they are fully FADC. I still like having the option of controlling things myself if things start going south rather than the computer just going into limp mode. Yes I might damage the engine but I might make be able to stay in the air longer to find a better landing option. Cheers

[@mmatt]

Yes, this is always a concern, but EFI tech has come a long way and is very reliable these days. We picked a system with a very good reputation so we're quite confident in its success. :-)

[@philipritson8821]

I think Edge Performance's EFI kit allows the user to tweek the ECU. The Rotax 912iS doesn't let you in to have a play, but Edge Performance do.

[@mmatt]

@@philipritson8821 This is one of the reasons that we're going with EP. :-)

[@frankhuber9912]

Just stumbled across your channel, interesting stuff. I'm sort of agnostic on the issue of clones. After all, once a patent expires, ANYBODY can copy it. But what's in the patent? The engine might LOOK exactly the same, but what about the metallurgy? That's hugely important... not saying that this clone is necessarily crap, it may even be better. The issue is, as far as I could see, how do we know for sure?

[@ParadiseHG]

Matt, I'm wondering if you have any fresh commentary about how well the engine is holding up. I've been seriously considering using one to re-power my Kitfox. I talked with the reps at Sun N Fun and it sounds like they have excellent service and support, has that been your experience so far?

[@mmatt]

Yes it has been. I have had no issues with the engine whatsoever.

[@philryder966]

Hey, Matt, how is the Great White North doing up there? Looks like you still got some Great White stuff!😂😂 Seriously, your explanation about the engine fascinated me!!! The only thing i fly is a drone, but i got my licks in many years ago! I wanted to comment on that gentleman that wrote about the knock off situation. And i agree with him. Yall get what you pay for sometimes. Ive never had to many Chinese knock offs that were good! Youare better qua.ified to pass judgement on the mechanics off this then i am ,but check cylinder wall thickness and welds. If this sounds like i dont trust their engineering, its because i dont. Anyway, on a lighter note you are gonna get so e warm air from here in SC! All my Canadian geese buddies are packing their bags and testing their direction finders!!!😂😂😂 Take care!😎👍

[@mmatt]

You are right, sometimes you do get what what you pay for. I feel like we got what we paid for without overpaying for it. This engine is slowly developing a solid reputation unless people are hiding their problems with it. I can say that we've had no trouble with it so far and others with the engine have reported the same. The true test comes with time though so we will have to wait and see.

[@waynebailie6425]

Great video. Will we see you at Sun n Fun?

[@mmatt]

Currently working out those details. I'd say currently we're at better than a 50% chance. 🙂

[@waynebailie6425]

@@mmatt Hope to see (meet) you there.

[@fly-bc]

..course steel wool works well to slow the airflow in the heater box.

[@i.r.wayright1457]

Steel wool is great for starting fires too.

[@Skyrobscell]

Hey Matt Rob here. I would like to know where to get or a link to the coolent and oil thermostats if you have them. I was at sun n fun and they did not have them. Thanks in advance. Rob

[@Superturbo701]

Hi Matt I have been following you for a long time and I appreciate all the time you put into you videos. Currently I’m building a ch701 and I just purchased my firewall forward packages from Viking Aircraft Engines in Florida. I will be putting the Viking 140hp direct fuel injected turbocharged engine in my 701, AKA baby turbo. I have a KZbin channel, Maple Ridge @Superturbo701. Check it out sometime let me know what you think.

[@rccanuck4473]

When you fly you’re in the air. You need to get an AIR horn ( I know. Sad one ). Zapper

[@mmatt]

Hahahaha!

[@portnuefflyer]

I had a Subaru car horn on my first RANS S-7, but that's because it also had a Soob EA-81 conversion, just seemed right.

[@forsecurity1privacy]

Get a second set of carbs and a pair of vacuum gauges...

[@ikechukwuchiejina7631]

Who is the manufacturer of the copy 512 engine.

[@blinkybagger8342]

Are there any implications on engine response from the proposed, pressurised fuel system? That some diesel (seemingly unlike many gas) engines have a fuel return line, meaning (as I understand) that max fuel is continuously pumped during operation, with the unused portion being returned to the fuel tank. I'd figure that is about eliminating throttle lag and stress on the fuel pump in dealing with dynamic fuel requirements by simply pumping max fuel continuously (and possibly adding some warmth to diesel fuel that may otherwise be less prone to optimal ignition if excessively cold). Know the risks and fly the appropriate class of aircraft to one's own needs...where applicable.

[@mmatt]

You're talking way above my pay-grade... but what you said sounds about right. lol

[@kenfawcett4006]

It would have to have a return line IMO.

[@blinkybagger8342]

@@kenfawcett4006 I hope Matt unpacks the implications of pressurised fuel system on his way through the upgrade, possibly advised by new-MitchFox...whathisname-Brent.

[@ricardom959]

in our local club, there’s one pilot that put a ZD on his skyranger. he had several issues with the carb sync as well as a huge difference ou fuel consumption. I guess this might relate to the carb sync issue inf first place. Regarding that, did you noticed a significant increase in fuel consumption, when compared to a 912uls?

[@mmatt]

We are burning on average 4.25 gallons per hour at 5000 rpm. This is seems to line up with the other 701s based at the airport with the 912ULS. We're excited to not have to worry about carb synching and the lower fuel burn that the EFI will give us. :-)

[@ricardom959]

@@mmatt is that EFI kit compatible with the 912UL, the 80hp version, not the ULS?

[@mmatt]

@@ricardom959 I think it is.

[@blinkybagger8342]

Did you ever consider re-powering with twin-hairdryers? This reminds me of those Cri-Cri's and coincidentally seems to have some overlap with (cough) high efficiency powered aircraft. Going electric might improve the audibility of your horns. kzbin.info/www/bejne/il6vlpqFmZ19rtE

[@paulhilliard3774]

Also, this manufacturer only gives a 30 day warranty??? Rotax gives 24 months new, and 18 months on recondition or 400 hours!!! End of the day, you pay for what you get......

[@mmatt]

The warranty for this engine is 18 months or 200 hours, whichever comes first. Each dealer offers their own warranty I think so it depends on where you get it. I've seen some offering 2 years or 500 hours.

[@mindfulmunchkin1215]

Matt do you miss flying without an engine in the front?

[@mmatt]

Not at all, I have and fly the Beaver. There will likely be more videos of me flying that this summer. 🙂

[@peterp696]

For cabin heat, can you not reroute coolant lines and have car like heater in the cockpit?

[@mmatt]

Yes, this is an option too. It's a bit heavier and more complicated than this system though.

[@martinjmerritt]

Maybe slightly heavier as you will have a small radiator in the cabin and a fan to blow air over it BUT it’s no more complex AND you will have completely eliminated the prospect of bringing carbon monoxide into the cabin. With a coolant based heater you have access to substantially more heat than you can get from the muffler…really limited only by the size of heater core and fan you are prepared to install. My Rans S20 with 914 and coolant based heater keeps the cabin comfortable down to about -15C wearing a light winter jacket and fingerless gloves.

[@mmatt]

@@martinjmerritt Good to know! I was under the impression that the coolant based heaters were less effective than the muffler ones. I'm not sure how I feel about a potential coolant leak in the cabin though... although that's probably exactly what you're thinking regarding the carbon monoxide! lol!

[@martinjmerritt]

@@mmatt Exhaust muff heaters are in common use only because on air cooled engines that’s your only source of cabin heat. How many cars do you see using this method? How warm can you keep your car on a cold winter day? A coolant leak, like a carbon monoxide leak would not be good for sure. Unlike the CO leak a coolant leak announces itself and is easily stopped. A coolant based system will have 2 hoses passing thru the firewall. One in and one out. On the firewall side of the “in” hose you have a shutoff valve controlled by a cable in the cabin. On the firewall side of the “out” hose you have a check valve that prevents reverse flow. In the event of a leak in the cabin’s heater core (easily detected!) you simply close the valve on the input side.

[@BruceWyder-xw9ir]

So the header tank is sealed

[@portnuefflyer]

It should be, the existing wing tank vents are all he needs, proven by myself and a boatload of RANS pilots with headers.

[@mmatt]

Headers on a carbed engine are different than headers on an EFI engine. From what I understand, the return fuel flow from the engine can cavitate and vaporize creating air bubbles. Those bubbles need to go somewhere hence the vent.

[@portnuefflyer]

@@mmatt Mine is running perfect, without venting the header, the EFI didn't change anything. Why not get it all installed, but try running and flying first is all I'm saying. You are going to like having ONE throttle cable and NO choke cable cluttering up the engine bay, the only issues I had installing mine were the usual ones: figuring out how to get at stuff and where to lay out the lines etc., pretty simply in retrospect.

[@mmatt]

@@portnuefflyer That's great to hear! We have to get at the fuel tanks to change out the fuel line anyway so we're just gonna go ahead and vent the header at the same time. As others have pointed out, whether we need it or not, it certainly won't hurt anything. 🙂

[@akflyer7689]

Don’t sell yourself short about being a Zenith salesman. I bet Trent Palmer has sold dozens of Kit Foxes.

[@mmatt]

Hahaha! Probably! I don't think I'll be getting any commission checks anytime soon though... lol!

[@jimohanian48]

It's never as good as the Rotax, Please stop promoting cheap inferior Chinese slave labor made knockoffs. They did the same thing with Honda motors and I've had a ton of problems with them. Bing carbs are amazing I've used them for decade's but again too many little hidden flaw, shortcuts and cheats. Don't walk away from Chinese engines......Run!!!!!!!!

[@kenfawcett4006]

I've had darn good luck with Chinese engines and aftermarket parts for bikes and ATV's. I've actually been impressed with some of the design improvements they use on Briggs & Stratton and Honda clones.

[@portnuefflyer]

Times are changing...., I'm old enough to remember when Japanese products were thought to be cheap junk, and look at the Kia and other Korean cars and their high ratings.