Chev V8 sweetness

maddog · #1 08-06-2007, 08:47 AM

Check this out... a Fly by of a V8 conversion by a company called Geared Drives.

http://www.youtube.com/watch?v=ln3BUn3rIQQ

doesn't that sound sweet!!!

It seems they are about the manufacture of a geared PSRU using spur gears combined with a centrifugal clutch to absorb resonance/torsional vibration. They mention a few engines the PSRU could be mated to only.

Here's the clutch in action.. http://www.youtube.com/watch?v=owTet...elated&search=

Like I said it PSRU only

However, on their site I did however find a vague reference there to the possibility of a Firewall FWD kit in the future.

The only other V8 Firewall FWD manufacturer I am aware of is Vesta V8, and unfortunately I have not seen any activity on their website for a long time. Nor am I aware of anything flying from them yet, waiting patiently however and looking forward to our very own Todd Swezey getting his Vesta V8 powered RV10 up and running.

Anyway, Geared Drives looks very interesting and if they did develop an engine/PSRU package that works, they might be onto something. Best of luck!

http://www.geareddrives.com/

rv6ejguy · #2 08-06-2007, 09:13 AM

I've talked to many people who have seen Bud's Wheeler fly and are impressed. He has 450 hours on it which bodes well. I like many features about his drives. Not sure how the clutch stuff will work out really long term or about the use of stainless shafts. Once he gets a few thousand hours cumulatively on the engines and drives, we'll know for sure. I'm impressed with what he has accomplished so far. Bravo. He could stand to reduce the photo res on his site. Very long to load over dialup.

EPI is the most experienced in the V8/ redrive field with the proper equipment and experience to do the job right. I really like their professional, no BS approach and their informative, up to date website. http://www.epi-eng.com/index.html

This is where I'd be putting my money for a reliable V8 conversion package at this time. Unfortunately no prices. I expect they are not cheap.

The LS engines seem to be the way to go. They are cheap, light and reliable with a fair number now flying especially in Oz. I was just reading an E-mail this morning from a fellow there using one of these in a glider tow plane. They get 3 more tows per hour over the Lycoming tug because they just cut the throttle completely, dump full flaps, and don't worry about shock cooling. Pilots love to fly it. Much smoother, quieter and burns less fuel in this mission than their IO-540s.

We are actually looking at getting into a new ECU for these engines as we have had many requests.

frankh · #3 08-06-2007, 12:20 PM

I think a modern auto conversion would be hard to beat. I mean while on a cross country cruise I would expect to be able to fine tune the LOP mixture on the IO540 to beat the auto conversion (less cooling drag and infinitly variable mixture) . But going up and down it would be virtually impossible to dial in the right mixture for altitude that is varying all the time.

Thats what the modern auto FI will do for you you, and as you say..Shock cooling...Whats that?

Frank 7a IO360...Now featuring mogas for 5 hours at 25DEG max timing

DanH · #4 08-06-2007, 02:16 PM

<<a geared PSRU using spur gears combined with a centrifugal clutch to absorb resonance/torsional vibration.>>

1. A centrifugal clutch does not "absorb" vibration. If the F1 natural frequency of the system is less than the exciting frequency at the lock-up RPM, then the system cannot resonate at F1. For example, this system has a stated clutch lockup speed of 1000 RPM. With an 8 cyl 4-stroke engine, the most powerful exciting frequency is (RPM x #cyls)/120 = hertz, thus 1000 RPM equals 66.66hz. The system will not resonate if F1 is 50hz or less (66 x 0.8). If this is the case with the GearedDrives system, then it is a nice solution to one possible problem.

However, that is true only of F1. F2 is somewhere further up the RPM range. It may lie within the operating range (bad) or it may be above the operating range (good). No modeling or telemetry equals no knowledge. Within the context of torsional vibration, total hours flown means nothing.

The only real downside to a well designed centrifugal clutch is loss of glide distance after an engine-out. Unless you also install a prop brake, you are stuck with a windmilling prop.

rv6ejguy · #5 08-06-2007, 02:28 PM

The V8 is starting to make a comeback for the higher powered 4 and 6 place experimentals after a bad rep for reliability the last few years. As some like Bud and Gary Spencer (LongEze Ford V8 direct drive), Robinson etc. are building some decent hours on their conversions and showing great speed and climb, more people are looking at the cost and performance available today. The turbine Lancairs are truly expensive to build and operate and I think many are looking at the LS-2, LS-6 and LS-7 type engines over the older Gen SBC. A properly turboed LS-7 would blow off a Walter turbine above 18,000 at a fraction of the fuel flow as Orenda demonstrated a few years back.

I'm very interested to see David Algie's LS powered Reno racer fly as well.

A good, proven redrive is part of the recipe for success.

The jury is still out on the cooling drag issue in my view. This is less of a point with 400-500 hp available from these engines and the easier integration of a slick radiator setup on the composite airframes.

rv6ejguy · #6 08-06-2007, 02:34 PM

Hey Dan, might find this interesting http://www.epi-eng.com/Pub-260003.htm

Looks like they use a double tubular torsion shaft to handle TV on their drive. Do you see merit in this type of design?

TSwezey · #7 08-06-2007, 03:08 PM

That sounds like my engine!

frankh · #8 08-06-2007, 04:17 PM

Quote:

Originally Posted by rv6ejguy

The jury is still out on the cooling drag issue in my view. This is less of a point with 400-500 hp available from these engines and the easier integration of a slick radiator setup on the composite airframes.

And it seems the pusher guys are better set up with longer intake plenums than the tractor airplanes.

Frank

rv6ejguy · #9 08-06-2007, 05:38 PM

Thread hijack. Ok Chevy sounds ok but how about this Subaru EJ25 turbo? Yeah baby, yeah! http://www.youtube.com/watch?v=sJiq1xsqUA4

DanH · #10 08-06-2007, 05:53 PM

Ross,
<<Looks like they use a double tubular torsion shaft to handle TV on their drive. Do you see merit in this type of design?>>

Sounds like a garden-variety nested quill shaft. Torsional stiffness is a function of material modulus, shaft diameter, and shaft length. A longer tube is torsionally less stiff. Let's suppose you really need a longer shaft in your design to lower it's F1 frequency, but you can't increase the overall length of the assembly. Well, you can consider a nested quill shaft, a shaft inside a shaft. It can be the same length as the original shaft but a lot less stiff. You input power at one end of the inner shaft. The other end couples to the far end of the outer shaft. The outer shaft drives a gear (or whatever) at the end near the inner shaft input. You have a long shaft in a very short space.

There are also ordinary single shaft quills. Generally, it is a shaft designed with the minimum possible diameter and maximum length. It functions as a torsional spring.

Reliable springs require careful control of material and manufacturing. Heat treat is critical, as is detail design at the connecting ends. If you damage the surface of a highly loaded quill you should consider it a mark that says "break here".

Old idea, and works fine with proper engineering. I think a RR Merlin has a quill shaft in the gearbox.