409 ACE Crank vs Lycoming

Here is a little perspective. Here you can see clearly why the fully counter-weighted 409 crank can handle so much torque. My R409 on my RV8 makes 234hp and 460lbs torque. That is about 100lbs more than a stock 360.



Tight fit

Why it can handle increased torque is not clear at all. I'm sure there are many other interesting, but equally obscure details. Could you or Andy offer a serious design analysis please?

Counterweights?

My guesss would be the pendulum conterweights, tho I did not stay in a Holiday Inn Express lately.. That sort of weight seems like it would dampen the torque pulses, and allow the crank nose and prop blades to survive.

Didja know the prop blades on an R2600 have a pendulum weight in their shank area? How the heck did the engineers figure that one out?

What is amazing is the R-series piston weight - about 1/2 of normal Lyc/TCM parts. My 550 pistons weigh 3lbs 6oz ea! That adds up to a weight loss of around 9lbs just in the pistons on a 540!

Carry on!
Mark

Yes, I'm with Dan on this one. I don't fully get this design either, nor can I see any pendulum dampers.

I can see that an attempt is made to fully internally balance the crank - i.e. each crank pin has, in effect, its own pair of counterweights. This is a good thing. Is this a 50% balance design or more?

The curious thing to me is the circular discs in the webs. The only thing I can imagine is that it improves the bending stiffness (2nd moment of area) of the crank at the web and since the torsional stiffness is a function of the sum of the stiffnesses in the two bending axes, then this improved bending stiffness would also add up to increased torsional stiffness. It seems like a lot of metal to achieve this though. I'd love to see an FEA on the design.

The only other thing that really bothers me is that the heavy metal inserts are too close to the pins and therefore could probably be easily eliminated with little weight gain by fattening up the counterbalance masses at the far end.

Will this crank fit my engine as an upgrade? How much does it cost?
Better yet, could you provide a part fit guide for engine combinations?
Some of us old time hot rodders could afford to put this crank in our O-360 with special pistons? But can't afford those cool new cylinders yet.
What compression ratio and build combinations are available and what power output is estimated for each?
I know that's a big question, but it's also a chance to showcase your product.
Many of us builders are engine guys too.
Or can you link us to such an info page on your site?
While everyone is speculating about the look of your crank:
I think I see an effort to reduce windage drag with the knife edged disc shaped cheeks?
And a final question: Can this crank be used in IAC competition aerobatics? (3 blade Hartzell constant speed, or 2 blade wood only?) If strong enough it would really help the 4 cylinder acro ships!!

SHIPCHIEF said:

Will this crank fit my engine as an upgrade? How much does it cost?
Better yet, could you provide a part fit guide for engine combinations?
Some of us old time hot rodders could afford to put this crank in our O-360 with special pistons? But can't afford those cool new cylinders yet.
What compression ratio and build combinations are available and what power output is estimated for each?
I know that's a big question, but it's also a chance to showcase your product.
Many of us builders are engine guys too.
Or can you link us to such an info page on your site?
While everyone is speculating about the look of your crank:
I think I see an effort to reduce windage drag with the knife edged disc shaped cheeks?
And a final question: Can this crank be used in IAC competition aerobatics? (3 blade Hartzell constant speed, or 2 blade wood only?) If strong enough it would really help the 4 cylinder acro ships!!

Click to expand...

This 409 kit can install in any wide deck case. It can go in traditional parallel or angle valve no problem. The add ax50 cylinders later.

All our pistons for all thee options will be at 10.5:1 static compression, 8.7:1 dynamic with stock lyc cam timing.

As for design, I am not going to get into a discussion on "why" the design is as you see it. The design is Andrews, it works and that is that.

Acro, you won't break the crank....