ZDZ USA Is Bringing ZDZ Brand Back to the US! Whoo Hoo!

[ghoffman]

Hopefully this post doesn't get way off track but a rotary valve engine does need a high quality oil to keep the rotary valve damage free. Seadoo had some of the strongest running engines because of the rotary valve design. But you needed to run their oil for best service life. in the late 90s my 800cc was killing skis in the 1200cc range.

Another thing about rotary valve engines is that there are no restrictions for the intake charge to enter when the valve is open. Reeds only open so far and can be fairly restrictive. I'd love to see the inside of this!

 

[jamesrxx951]

Another thing about rotary valve engines is that there are no restrictions for the intake charge to enter when the valve is open. Reeds only open so far and can be fairly restrictive. I'd love to see the inside of this!

I'm sure it would depend on actual valve timing but you can more easily hold the valve closed a little longer to create a negative pressure in the case to cause a larger pull of fuel air mixture when the port does open. They are cool designs with power benifits. A slight negative would be more weight and more moving parts that require lubrication. At least in the world of jetskis you can get carbon fiber rotary valves.

 

[Notorious B.E.N.]

If avgas was hard to come by, what other fuels would work?

What about SEF from VP or their other racing fuels assuming you could get them in 5 gallon containers?

 

[ghoffman]

I use that when I cannot get the 93 octane, no alcohol, no lead "mogas" at the small FBO nearby. It works great, with the oil of your choice but is expensive. I called the VP guys, and they said the oil they mix in the 50:1, 2 cycle version is Motul. Some say that the Stihl HP Ultra is Motul, but I cannot confirm that. At least the RV is the first thing to get lubricated on it's way in.

 

[Notorious B.E.N.]

Well, here's another question related to high octane fuel sources. There is a small airfield in Hereford, TX where I work and I just looked up what services they have. Their fuel is self-serve. So does that mean they have a pump with a long hose attached and you just swipe plastic?

Also, is buying 1 or 2 gallons possible or 5 gallons or is a quantity that small going to be hard to get in avgas?

 

[ghoffman]

DA told me specifically not to use AVGAS. What I buy is basically auto gas without the alcohol. Some small planes like Ultralights and Light Sport Aircraft do not use AVGAS, since they are essentially snow machine engines.

 

[Notorious B.E.N.]

Ah, good point.

 

[ThePledge]

Av gas has a much higher octane than they recommend. I'd use 93ish pump gas.

I also wouldn't want to be standing behind a plane running avgas of any octane (warming it up). There's no good way to avoid breathing several fairly toxic compounds relative to pump gas.

 

[Notorious B.E.N.]

Where I am, the highest octane you can get at the pump is 91. So if I needed 93 or above, I'd have to buy SEF or racing fuel.

 

[ThePledge]

91 should be perfectly fine. They list n95 which is the lower of the two grades they sell over there and their measurement system is typically 4-6 more than what we see at the pump for the same gas.

It looks like I was wrong to recommend 93 as that would be roughly equivalent to their n98 and they recommend n95 which is our 91.