powerflow exhaust surprise

[Dust]

i think it would cost you mph's it would be draggy from the pipes and from the air going out.

[Lynn Erickson]

The Exhaust system is a 4 into 1 type where the exit is in the open end of the boat tail cowling. This system is very low drag and and adds the thrust of the exhaust gas to the props thrust. The combination of the increased HP and low drag cowling have shown large increases in top speed and cruse perforance. A vari ez with a O-235 has increased top speed by 10 Knots. A vari ez with a IO -320 that raced in the Airventure race increased his speed by 15 Knots. The cozy IV with a IO-360 200 HP increased top speed by 7 Knots ( the box fuselage on the mark IV is not condusive to speeds above 200 MPH ) but the fuel consumption was lowered buy 1 GPH to 6.8 GPH in cruse. The system is made of 321 Stainless steel welded in an inert gas chamber and the flanges have welded doubler plates. There are none of the spring on the flanges that can break and go through your prop. The system is a lite 12 Lbs. only 1/2 lbs. more then the standard ez system with all its springs and slip joints. Eze's with down draft cooling can use a system where the exhaust is directed through a cooling augmentation tube to help cooling and reduce cooling system drag ( smaller inlets ). The last picture shows the straight airflow on this type of lower cowling.

[Don P-Factor]

This is really a sweet set up Lynn. Thanks for the pics and the results of these mods. Dust were you familiar with the Exhaust Augmentation tube Lynn identified? The tube is located at the exit of the system and uses the venturi effect to extract engine cooling air from the cowling area. The tube can be either attached to the collector or not. In Lynns middle pic the tube is touching the cowling. Its a tube larger than the collector that begins a few inches before the exit point and extends beyond the end. As the exhaust air exits it creates a low pressure zone in the tube which pulls out cowling air. Don.

[Dust]

Yes - am planning on augmentation - great stuffff lynn

[Dust]

LYNN - do you make and sell these types of units? 321 SS on an N/a engine should last forever.

[Lynn Erickson]

Yes. I do make the exhaust systems. I have jigs for all lycs. and have done some contis . Right now I doing a heat muff for a IO- 520 conti and a turbo outlet tubes for a TIO 550 lancair. On a turbo a lot of the exhaust energy is used up and and there is not much exhaust velocity to make the cooling augmentor work. if you nozzel down the turbo outlet to get velocity you may slow down the turbo ( not good ) and the turbo does not work good or it over heats because of slower flow rate of exhaust gas. This has been tried on some turbo twins. don't if any still use it. These are just some of my thoughts and I would like to someone make it work.

[John Slade]

What is the reason for having exhaust going out the back at the prop?

Drag. When you point the exhaust at an angle it interrupts the airflow and causes drag. Someone - I forget who - likened having a 90 degree exhaust to having a 3 foot 3 inch diameter pipe sticking out the side.

I had the pleasure of meeting Lynn and looking over his plane at Redlands, CA airport last week. The exhaust is very nicely done and, I think, bares emulation. I snapped the attached picture showing the insides.

The Berkut style retract gear is also very interesting. There are a lot of other innovations in the "EVOLUTION EZE" that the folks here would love to hear about, but I'll leave that to Lynn.

PS - Lynn - That late evening low pass was spectacular! I hate to think what speed you were doing. I took a video of the take-off and the fly-by, but the approach was so fast I couldn't keep the camera on you.

Unfortunately the sound wasnt working on my camera either, but here they are in case anyone would like to see them.

http://canardaviation.com/cozy/lynnez1.avi
http://canardaviation.com/cozy/lynnez2.avi

[DustinD]

You do not want back pressure in an exhaust system, you want velocity. Exhaust systems do not flow like most fluids through tubes due to the exhaust valves being open only a short time, the cylinders quickly running out of pressure, and the very high speeds that can develop.

The reason why you do not want an exhaust system that is too wide is because you want the exhaust to leave with a high enough speed that it forces a vacuum behind it which helps to suck out more air. At high fluid velocities you can create large pressure differences very easily.

The reason for equal lengths is so that the high/low pressure regions/waves do not interfear with each other in a bad way. You do not want two high pressure waves to meet at the same time and place.

Tuning for length tries to let the exhaust out at a time when the pressure in the pipe is at it's lowest due to sound waves bouncing back and forth.

[Dust]

Originally Posted by Lynn Erickson

On a turbo a lot of the exhaust energy is used up and and there is not much exhaust velocity to make the cooling augmenter work.

Well - i am basically just normalizing, 1 psi at sea level boost, and as i go up the amount of boost will slowly increase. i will only make the trek to 25000 on long cross countries.

I'm thinking that the augmentation may help at low boost, climb and higher OAT. As i go up the outside temp will decrease and if i keep the same IAS during the climb, the amount of cooling air will remain the same (but traveling faster), although it will be cooler, decreasing the need for augmentation.

Also the augmentation will be designed to cool the turbos.

just thoughts - am just working on the mount and exhaust right now

[MarbleTurtle]

I don't think you will have any augmentation due to the restriction of the turbo... I do however think equal length exhaust pipes will reduce stress on the turbo by giving even compression force and timing pulses from the cylinders.

[Riseguy]

John, a EZ expert told me the same thing about the 90 degree exhaust being like 4, 3 foot pipes sticking out of the cowling.
Well, My K B exhaust lasted around 10 hours then cracked. I Ordered a real nice H H system. It lasted around 50 hours then it too failed. It took a few weeks to get it back, and almost 50 hours later more cracks.
It was almost summer, and I was not going to wait for the repaired exhaust. I went to the shop, cut four straight pipes welded them to flanges bolted them to the engine. Cut four holes in the bottem cowling. Hack sawed off the exsess pipe. Then went flying.
What I found was quite interesting. No loss in airspeed. No more soot on the prop. Now 1100+ hours (15+ years) of flying later still no cracked pipes.
EX (one time) SPERT (drip under pressure)
P. S. People on the ground say it sounds way cool!

[neverquit]

Thanks DJ. Love those facts. A Mustang pilot once told me he'd get another 100 mph out of it if he could point those 12 pipes inside the cowl and out the back.

You do not want back pressure in an exhaust system, you want velocity.

Contrary to what a "collector" does. Vacuum in yo' pipes will toast yo' valves.

[neverquit]

Mike, I've been reading a lot about "turbosuperchargers". They're supposed to give you that extra oomph on takeoff and low altitude while giving you what you need at high altitude. Used very successfully on th P38 and 300+ "thin wing" aircraft.

[Dust]

"turbosuperchargers" = full name for what we call a turbo

[Dust]

DJ Rise

Well, one simple explanation for your success with the straight pipes and no speed loss - the area that you are exiting to is probably pretty turbulent already and the extra turbulence just blends in.

lynns tufted under cowling is a beautiful sight and what i am aiming for