ACE AX50 removable sleeve design

[Relentless]

One of the most asked questions about our new cylinders is concerning the sleeve. The sleeve is made of aluminum not steel and is coated with a very hard Nykasil Carbide coating. We could have just coated the cylinder bore itself but felt that for a few extra bucks a removable sleeve would be give us more flexibility for design changes and maintenance. If the bore ever gets damaged it is quite easy to remove the sleeve and insert a new or reconditioned one. Why aluminum? Now everything in the cylinder is one material which means we can close down tolerances to levels consistent with modern engine design. Less blow-by, lower oil consumption, better heat dispersion, and increased efficiency of chamber.

Here is sleeve by itself:


Installed:


Note the edge of sleeve, allows a mechanical lock when bolted to case:


Simple drawing how the rings actually ride on the carbide particles held in place by Nickel coating:

[Relentless]

Just had this question, here is my responds.

Our cylinders can direct replace any parallel or angle valve Lycoming cylinder for wide deck 320, 360, or 540 experimental engine. Economical? The AX50 or AX40 cylinder and valve train are $2850 ea. With new rods, pins, pistons, and ring packs the assembly is $3500 ea. This is about the same price as a comparable performing Lycoming Angle Valve cylinder that weights 8.5 lbs more.

BUT, I run 91 unleaded fuel in my R409 at a California price of $3.78 gallon, about $1.00 less per gallon than the local self serve. In 500 ours of operation that is a savings of $4000! (8gph x $1.00 x 500= $4000) I would say that is pretty economical? What does your local premium unleaded fuel cost?


Over 2000 hours of operation my AX50 cylinders are a better ROI than my savings account!

[hgerhardt]

Question about quench height or clearance (piston-to combustion chamber clearance): Since one of the features of your design is to minimize the quench height and maximize quench area, how do you go about setting that up? Do you make custom pistons for each cylinder-crankcase assembly? Or do you use custom shims to go under the cylinder base flanges? Or just machine all crankcases to some specified deck height?

From previous experience with other types of high-performance engines, I know that quench height and area is one of the critical factors in how much octane a given engine requires. Tight quench (and large quench area) can get away with significantly lower octane, all other factors remaining constant.

Heinrich

[Relentless]

Originally Posted by hgerhardt

Question about quench height or clearance (piston-to combustion chamber clearance): Since one of the features of your design is to minimize the quench height and maximize quench area, how do you go about setting that up? Do you make custom pistons for each cylinder-crankcase assembly? Or do you use custom shims to go under the cylinder base flanges? Or just machine all crankcases to some specified deck height?

From previous experience with other types of high-performance engines, I know that quench height and area is one of the critical factors in how much octane a given engine requires. Tight quench (and large quench area) can get away with significantly lower octane, all other factors remaining constant.

Heinrich

Great question, but we are not publisizing this information as of yet. It is in fact very critical and if your case is within new tolerances then our piston height will be correct.

We do require every piston be checked for this clearance with cylinder torqued during build using clay.

[BillL]

So - with the Nykasil coatings, do you recommend plasma faced top rings or are they too hot (and get soft) and scuff?

If so that will be a huge benefit for ring/bore wear and TBO.

Which brings the question, what is the typical bore wear compared to conventional materials?

[M McGraw]

Kevin,
I understand your preference is for unleaded fuel with the AX50 cylinders. This is very easy for me on local flights. For extended cross country flights I will have no choice but to use 100LL. Are there any hour restriction on leaded fuel to minimize carbon/lead build up in the squish area? Is this perhaps covered with a recommended periodic maintenance procedure? Possibly covered by LOP operations?

Thanks,

[AC Aero]

I recommend running AX50 engines LOP
I am not concerned with the potential build up when compared to a traditional Lycoming type engine.

Andrew

[AC Aero]

Our rings are specifically designed to run with our AX50 cylinders

Andrew

[AC Aero]

AX50 squish band relief, (quench height) has nothing to do with octane. The octane is a function of the fuel rating released from the manufacture.

Andrew

[Relentless]

A Lead scavenging compound is added to Avgas 100LL - this compound is Ethylene Dibromide. This scavenger is designed to react with the Lead oxide to form Lead Bromide which is more volatile - becoming a gas at around 200 - 250 oC. This is a low enough temperature to ensure that the Lead is removed from the engine as a gas end it subsequently goes back to the solid phase as the exhaust gas cools in the atmosphere.

What is important, more so than Avgas is the oil blowby and contamination, this will quickly build deposits and cause engine harm. We have worked hard to minimize the amount of oil blow-by in our products