O320 with IO580 cylinders?

Michael Gannaway · #1 08-14-2013, 01:48 PM

Has anyone ever done this to create their own 344 ci engine? With the 135mm bore and 98mm stroke it would be a screamer up top. Thoughts?

Mike S · #2 08-14-2013, 02:01 PM

Michael, welcome to VAF

Your idea may not work, due to piston availability issues------also bore size to crankcase hole size may come into play???

Dont really know if it is possible, just thinking of the possible pitfalls.

As to the high RPM potential, dont forget to consider the prop realities involved.

Anyway, good mental exercise

Good to have you aboard.

Michael Gannaway · #3 08-14-2013, 02:06 PM

Quote:

Originally Posted by Mike S

Michael, welcome to VAF

Your idea may not work, due to piston availability issues------also bore size to crankcase hole size may come into play???

Dont really know if it is possible, just thinking of the possible pitfalls.

As to the high RPM potential, dont forget to consider the prop realities involved.

Anyway, good mental exercise

Good to have you aboard.

From all the searching ive done the io-390 is just a 360 case using io-580 cylinders. The only real difference in the 320/360 is the crank stroke and rod length.

As far as the prop goes. Guys turn o-200s to 4000+ rpm and they find props somewhere. So why wouldnt you be able to find a prop ?

Neal@F14 · #4 08-14-2013, 04:31 PM

Quote:

Originally Posted by Michael Gannaway

As far as the prop goes. Guys turn o-200s to 4000+ rpm and they find props somewhere. So why wouldnt you be able to find a prop ?

A metal prop would be the biggest potential problem, since you'd be dealing with completely unknown harmonics... which have been known to crack blades in flight. A wood or composite prop wouldn't have any such issues, and since you're starting off with an O-320 as the base engine, the new Sensenich composite ground adjustable prop might be a choice too.

Mike S · #5 08-14-2013, 04:46 PM

Quote:

Originally Posted by Michael Gannaway

As far as the prop goes. Guys turn o-200s to 4000+ rpm and they find props somewhere. So why wouldnt you be able to find a prop ?

I did not say you would not be able to find a prop, just said not to forget the realities of the prop.

The prop must absorb a certain amount of HP. And it must keep the tip linear velocity under control.

Your proposed parts combination should be capable of overspeeding a prop designed for a 320, and the prop designed for a 4000 RPM O-200 will most likely not absorb the HP your engine should create.

All a balancing act.........................

Toobuilder · #6 08-14-2013, 05:00 PM

The F-1 guys turning their props to 4000 RPM is a need for horsepower, not because they work well. Yes, the 4000 RPM O-200 makes 150+ HP, but the 2700 RPM 150 HP Lyc would provide a bunch more practical thrust.

aerhed · #7 08-14-2013, 05:38 PM

Although the 320 and 360 jugs have the same bore, they are different length. So, you would need way taller pistons or longer rods. Don't know if either of those would work, or are available. Nice thought though.

Michael Gannaway · #8 08-14-2013, 05:58 PM

Quote:

Originally Posted by aerhed

Although the 320 and 360 jugs have the same bore, they are different length. So, you would need way taller pistons or longer rods. Don't know if either of those would work, or are available. Nice thought though.

well if you used a 360 case and eci 4.5" stroke crank with 580 cylinders. you would just need to use the same rods as the eci 370, but with a larger bore piston having the right compression height from the piston face to the wrist pin. I am sure there is a company that could produce a set of pistons for it if none are available currently.

Michael Gannaway · #9 08-14-2013, 06:00 PM

Quote:

Originally Posted by Mike S

I did not say you would not be able to find a prop, just said not to forget the realities of the prop.

The prop must absorb a certain amount of HP. And it must keep the tip linear velocity under control.

Your proposed parts combination should be capable of overspeeding a prop designed for a 320, and the prop designed for a 4000 RPM O-200 will most likely not absorb the HP your engine should create.

All a balancing act.........................

Quote:

Originally Posted by Toobuilder

The F-1 guys turning their props to 4000 RPM is a need for horsepower, not because they work well. Yes, the 4000 RPM O-200 makes 150+ HP, but the 2700 RPM 150 HP Lyc would provide a bunch more practical thrust.

I was never saying that it made more thrust just stating that if there are props out there for that type of combination then I would assume something could be found for a 3100-3200 rpm lycoming io-400 if you managed to get the right parts to build the engine.

Toobuilder · #10 08-14-2013, 06:26 PM

Yes, BUT...

You are quickly going to run into critical tip speeds for faster aircraft. Not such a big deal on a C185, but an RV at high speed cruise may be a problem.

Quick story found on the Web: guy is cruising along at altitude in his Glassair 3 on the way to a meeting. Decides he's going to be late, so he cranks the prop up from 2400 to 2700RPM...

...and losses 15 knots.

Since tip speed is a function of cruise speed of the aircraft as well as RPM, the tips went transonic and the thrust fell off big time.