Pe

I have always lived by two addages taught to me at my mothers knee:

If you can't say something nice, say nothing. and

You can't respect other people if you don't respect yourself.

Just in passing I am old enough to think that if I haven't already made the ranks of a gentleman then I have missed out, not enough time left.

Mike

Right, I am sure my engine will blow up to kingdom come, just because I am not using high octane gas.... I don't know if you are aware of that, but many manufacturers of gas RC motors recommend lower octane fuel, ie: Desert Aircraft..... any way, to each its own..... oh, an I did call Horizon and was also told by their product support person to use 87 octane gas.....

If I were you, I'd go with what Pe says over the Horizon Product support.

And based on what are you giving me this recommendation?

In addition, if you motor will run a higher octane, which will probably result in increased performance, I don't understand why you would want to bother running a lower octane fuel anyways?

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The simple reason for running lower octane in my engine is - I have DA50-R which runs on 87 and that is what Desert Aircraft tell you to use in the instructions, and I also verified with them via phone - with this in mind - when I go to the field and I have both planes with me I prefer to have only one gas can, and since I can run 40:1 mix in both motors, 87 octane works for me. Do you know Pa, and what makes him an expert?

A life of study and experience will make any man an expert in his field if he is dedicated. I have studied engines and engineering since day one, and spent a lifetime practicing what I studied. In the course of my own stupidities I wrecked more engines that most, just by pushing things beyond limits.
Low octane fuel in high performance engines will increase combustion pressure rise in time, and eventually cause knock and bearing damage. I found out in non graphite coated MVVS engines, that the compression ratio of these engines is right at the limit with our 95 octane gas (which is 90-91 US pump octane) If you run the engine well cooled, at light loads and high rpm, you may get away with it. You will however damage an engine by too low octane numbers. You will not damage the same engine by using too high octane. So if you want to use only one fuel mix, use the higher octane that MVVS requires. Fact: MVVS has a higher specific output than DA, which explains the higher requirements.

It's time to quit the arguing, product bashing, etc. I'll vouch for Pe's experience with these engines. Enuf said.......I hope.......

I thought this was a good explanation of the octane issue. It is from another thread. Needs spell check, but sounds like the guy has some knowledge of the subject.


quote:

ORIGINAL: octanehuffer

High octane fuel dosnt add power. It is used for those who have increased compression and the higher octane will not detonate as easy as low octane fuel.




He is right. Most race fuels and even alky when doubled up release about the same amount of energy when burned. Octane is the resistance to detonation or pre ignition and does not increase performance if the engine can run well on lower octane fuel. But race fuel is a different fuel, and it usualy is a better, cleaner, more consistant fuel. Some people sewar they get more power when running the high octane race fuel in their lawn mower (for example), and they may be right. They may be getting more power from things like higher evaporation rates (which could help the burn) because it is a better quality fuel (may be), but their not getting the gain from the Octane unless their lawn mower is making some big compression numgers, and we advance the timeing quit a bit (a couple of things that may require a higher octane fuel).

Adding Nito methane though---a whole different ball game. You could be the first to get it running good on a Nitro Methane/alky mix. . But if you just get rid of the stock exhaust and go with a big bore and big stroke top end, you will be spinning doughnuts at will.

I have always used regular gas and had several engine manufacturers recommend low octane when asked.

This conversation brings up a question I have been pondering. Just how do you advance the timing in an engine with electronic ignition? How do you know if it needs tweaking? The engine is an Evolution 26GT2 (newest generation electronic ignition).

Although this thread started to get ugly, sometimes arguments lead to knowledge instead of contempt. I hope it goes the way of the latter!

You set up a degree wheel and pointer with Zero at Top dead center. To do this, use a piston stop and split the difference from the approach to top dead center from each direction. With the ignition on, you slowly move the crank shaft in the direction of rotation until you hear the ignition fire. Note the location on the degree wheel. From my experience, 28 degrees BTC is my magic number.

The position of the sensor is adjusted to adjust the timing.

By trial and error, you try the timing in several different positions of advance until you find the maximum rpm obtained. You then retard a degree or two from peak for preignition safety.

A note from back up the way in an earlier post . . . . The C-H ignitions I own are not made in China but in Wyoming USA.

That procedure works for engine using an ignition which RETARDS electronically
the ignitions on some designs do not work that way
if the setup has no provision for moving th pickup -leave it alone - these ignitions typically start at a low advance then- as design dictates -the rpm will determine advance .

on the mvvs/evolution gas engines it is easy to adjust. A degree wheel is handy, but I often use a calibrated piston stop and time the initial spark at 0.1mm BTDC.
Adjustment can be made by removing one of the M2.5 screws that hold the sensor. Now the sensor can be rotated +- 5 degrees either side. It is not needed but for the experiments. I found a slightly earlier ignition timing reduced the tendency to rotate backward at very low idle speeds.

Once a casual observer does readjust the timing - how do they really know if they have helped or hindered the engine .
My own observation on these is that the timing is fine - use the best pump gas and 32-1 synthetic - ad a free flowing exhaust preferrably tuned and do not over prop it .
fiddlin with the timing will produce no useful results
but if one just likes to fiddle----
I am speaking of the 26 -not some other setup On the otherhand if one adds a sharply tuned exhaust and is on a determined quest to extract every last bit of power - I have found on some other brand engines - the spark needs a bit of retarding if the cylinder pressures get very high (just like running a blower )
.

Indeed. My fixed ignition 50cc racer needed to have the timing retarded from 1.2mm to 0.9mm BTDC for best broadband performance.
Not much difference, but just noticeable. It made the engine sweeter to set up as well.

Can any one tell me the differents between Evo 26GT and 26GT2?

I talked to Horizon a while back and had the same question, and from what they told me the engine is the same, but they changed the ignition module - the GT2 module needs at least 6.4v up to 8.4v to operate, while the GT one works with 4.8v to 6.0v battery.... also you can "program" the module for the type of the muffler you are using, ie. tune pipe.....

Did you read post #16...you probably want to stay away from version 1.

Evolution version 2 is an improvement insofar that it can detect sense of rotation, runs on unregulated lipo cells, and can have added choke servo and ignition timing features. Furthermore, when the engine runs backward, the ignition just stops until it is reset.
If in version 1 the engine will not run right because of ignition issues, that is a warranty question and should be addressed as such. There will be no power difference between the two versions. So far, I have seen no reason to convert my engines under test to the new ignitions. The Vlach items served me quite well so far.
The very first MVVS engine with graphite plated piston had the same power on the same carb as the current engines. Nothing has been changed in engine construction and/or timing. As technology became available, ignitions were updated as well.
The new ignitions come in three flavors. The manual(s) can be downloaded from my website.

Pe,
I know from reading the posts you are very technical and an asset to this forum. I think the stark admission by you on the ignition system on the first version shows that Evolution should have recalled these engines.

Okay, it looks like it's time to step in and say a few things regarding the MVVS 26GT engine with the early generation ignition system. I really hate having to do this too!!!

1. The point that there were problems with this ignition system has been made, made again, and again, and again. Enough already. This has been beaten to death in 3 or 4 threads in Gas Engines. I will strongly consider deleting any more messages that are posted with the intent of just complaining about it. This is too close to manufacturer bashing and it will stop one way or another.

2. Plenty of advice has been given about contacting Horizon for warranty service.

3. Members are openly becoming tired of hearing the complaining. So, if anyone has information or solutions about fixes or workarounds, please post freely.

4. Lastly, the first generation ignition worked but had problems. I've seen the engines run myself. Most importers/distributors will not start a recall on an engine if a better subcomponent version is implemented. They may offer a replacement either for free, or some amount of reimbursement on the part of the owner. How you approach them, and how you present yourself with dealing with the support crew will probably play a large part in motivating them to help you with your problem. Angry comments may just motivate these people to not help you. If you call the support staff and start yelling, threatening, cussing, or vent any other similar feelings you are on your own and the problem is all yours. I can't count the times that a company has helped me freely when they weren't supposed to. I was always courteous and I listened to what they had to say even if it wasn't what I wanted to hear. This really works!

It seems that it is high time to move on.......please........

Thanks blw!!! Appropriate measure and appreciated by all, I'm sure.

Pe, How can I tell which ignition I own (2 and appear to be the same)? No problems, but education can be helpful to a dolt such as I!

Just picked up my second 26GT and I'm very satisfied with the original one (version 1?)....so I guess I have to go out an get a different battery for the latest and greatest....any recommendations as to which one to purchase? I'd like to stay away from Lipo's as I would have to get 'another' charger, charging box, etc.

PS My original 26GT wouldn't start until I plugged up that choke hole Now it runs like a champ - and it even starts

I haven't cussed anyone and am offended by your insinuation. As a moderator i expect better behavior and at least honor the rules you claim to inforce. I have issues with Horizon service and was lied to. Yes i took them to task over it, it was my right. You can take your advice and give it to Tubby.He will soon need it.