Hey guys,

What is the best prop to use on the mvvs 26cc with pitts and with tuned pipe silencer? I want to mount the pipe if the plane allows it but i dont know what prop to use can anyone with this engine help me out?

with a pitts, go for 16x10 to 18x8, depending on what you want to do and your plane weight
with the tuned pipe, the range will be much the same, but you will see a substantial rpm increase.
When you shorten the header and remove the end section of the tuned pipe, a 16x8 or 16x10 will scream.

Sounds good =) my plane will be 5.5kg max. How can i remove the end section of the pipe?

Check out Mark Fues at
http://tech.flygsw.org/all_about_evolution_26_gt.htm

I have the engine and pipe now, i dont intend to cut it unless i can find someone that knows what they are doing because i dont have any good way of cutting the pipe like the picture. What prop should i go for with just the pipe?

18x6

Thanks!

I have a 18x6 MenZ S prop on my 26 IFS which is fitted with the MVVS tuned pipe.

I got 8640 rpm with the engine a little on the rich side. Is that good?

Helge.

you seem to be running too rich. With settings as they should be, rpm will be about 8800 - 9000 (conservative estimate)
I got 8200 rpm on APC 18x10, which is a slender blade design.

I get 8900 rpm on the very same prop, haven`t tried to lean it more, but I think there`s even more in it

8900 is fine, and allows the engine to unfold.
When using larger props, you are better off using an extra shim under the head. The engine then runs even "smoother".

Hi guys, what are all the differences between the new 26 IFS SP and the old 26 IFS other than the head and carb stack?

heavier crank/conrod
beefed up lower rod bearing
modified crankcase

Only is SP: narrower, deeper hemi head to allow side plug (resulted in wider squish zone)

Thankyou sir, I will wait until they become available at our Canadian dealer, Dave Moen in BC and buy the SP model instead of the old model that he has in stock.

Hi, the link you have provided for the pipe mod doesn't seem to work. I have the new 26 IFS SP and would like to mod my tuned pipe. Could you help with the picture please.

Thanks
Ed.

Mark's page seems to be down.
from google cache:
http://209.85.135.104/search?q=cache...lnk&cd=1&gl=nl

Thanks Pe the link works but the page won't load completely and I can't navigate on the page to other items, I always get a network time out error. There must be something wrong with my computer I guess. Will keep trying and thanks again.

The link if from the google cache. (saved web space by google)
When I try to go to mark's pages directly, the line is dead.

What is the mod he does to the pipe anyways?

He takes off the rear damper part

So he removes the end cap and leaves the pipe wide open? Is it ok to use Aviation 100 and 140 octane fuels in this engine?

no, he removes the silencer. That is not the same as leaving the pipe wide open.
No, the fuel must be leadfree. Avgas is not leadfree, so use premium leadfree gas 91 pump octane (95 RON) or better.
and no, do not use any old oil. use fully synthetic two stroke racing oil only.

Sounds good, Thanks.

Hi Pe. I`m now getting 9100 rpm on my engine after I fitted a 11.1 mm carb, prop is MenzS 18-6. How much more do you think/know that the pipe cutting mod will provide??

there are a few more things that need to be done at these rpm.
shorten the header
check the carb intake manifold. It should allow the air from the larger carb to pass
smooth the crankshaft inner gas passage.
set ignition slightly later. (undo one screw, and rotate the sensor

After these mods, you will have a few 100 rpm more.
The modified muffler will be a lot louder. Better is to reduce the inner flow resistance, which is quite high, and leave the muffler on. It then tends to act as a low pass filter, and make the engine sound much more pleasant than without the muffler.