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After this worrysome discussion, I went back to the turbonetics site and checked the map for my turbo.
I'm running so close to the bottom of that map, in terms of both airflow and pressure ratio, I think I'm plenty safe for ground runs and initial flights. I'm expecting to run with a pressure ratio of less than 1.2 with a flow rate of less than 40 lbs. Does that seem right for a 13b at 200 HP 6500 RPM?
My exhaust manifold is fancy looking, but it's a basic log manifold. The main Y tube from the ports to the turbo flange are very big, 2.5".
I installed exhaust nozzle cones inside, to smooth out the transition from the port to the manifold interior, but mostly to keep the direct heat off from the turbo flange welds for the main Y pipe. The result is exhaust blasting into a log type volume, with a nice Y to collect it and guide it into the turbo. I imagine that quite a bit of the sonic pulse is attenuated compared to a Yaw Turbo header. Less pulse tune and more continuous flow...who knows? Its so short, not much accumulator volume.
My turbo manifold supports the weight of the turbo, similar to a stock Mazda cast iron mainfold. I've added support straps between flanges for additional support. Also, it's easy to remove and inspect, which I have done.
-----Original Message-----
From: Kelly Troyer <keltro@att.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, Feb 14, 2010 7:12 am
Subject: [FlyRotary] N.A. Renesis to turbo
Scott , Ed , et al ,
I will echo Ed's opinion about the TO4 turbine A/R ratio (fully admitting to having having
no turbo experience than that of others on the group)..............My junk yard mock-up TO4 has a
turbine housing with a 1.30 A/R ratio (not a "On Center" housing")..........If I built a turbo system
without wast-gate and/or inter-cooler I would probably start out with a housing this "Loose".........
IMHO & FWIW
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from "Ed Anderson" <eanderson@carolina.rr.com>: --------------
Well, youngster {:>), Gregg sounds like he has the right combination. IF you are going to fly without boost control (other than the throttle), then you want a turbo with a high a/r (area/radius) ratio, larger than 1.0 in my opinion.
The same turbo with a small a/r (< 1.0) will spin up faster with less exhaust/throttle and give you gobs of boost on the low rpm engine – the problem is you must have some sort of boost control or at WOT the boost will go high enough to damage the engine.
If you use a larger a/r, the turbo takes more exhaust gas (read more throttle) to produce the boost, this generally means low boost at low rpm (so not good for that sports car feel), but more most and HP at the higher rpm where we generally are interested. If you either have an example to follow (or can work with a turbo seller who will permit you to swap in/out different a/r turbine housings), you can experiment to find the best a/r for your installation and operating environment.
Another benefit of high a/r is that there is less exhaust back pressure due to the more open channel through the turbine housing.
But, if you are going to try that route, make certain you start out with an a/r that you are confident is perhaps a tad too large. You can always put on a smaller a/r to get more top end performance – provide you have not blown your engine {>)
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
IIRC the specs on the turbo is .71 A/R and P trim. I called Turbonetics and told them the application was a 13b used as a generator in a sound proof box that would have quite a pressure drop at the air filter to overcome.....and be used on top of a mountain...!?!
The sales guy assured me that a 60-1 .71 A/R and P trim was the ticket.
Later I emailed Greg Richter of blue mountain fame...he was running his Cozy with a 13b Turbo, and he was using the same exact turbo?
Anyway, he had some mamoth Warnke 3 blade that he could overspeed at will, and was looking for more bite.
I indicated that I planned to use (some specific) blow off valve and waste gate, Greg said why? do you need it? Don't put that stuff on your engine unless it needs it. That left me in a quandry. I left them out for lightness and simplicity. I'll add them if I have a demonstrated need. How ever that manifests it'self??
Remeber, I have a RD-1 with a 4 planet set, so I should endevor to keep HP at or below 200. I'm supposedly way over turbo'd. I don't have an intercooler for this reason. Self control will be required.
Scott
PS. I'm only a few months from turning 55!!
Sorry Scott............This was directed at you !!..................<:)
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from "Kelly Troyer" <keltro@att.net>: --------------
Curious what the A/R ratio of your "On Center" TO4 exhaust turbine housing is ?.............
Most of the recommendations from those of the group flying ahead or behind the TO4 range
from about .96 to 1.15 A/R ratio..............Will be interested in your rpm/mp numbers when
you get airborne................
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
I'm just a bit ahead of where you want to go, but way behind on the rest of the plane. I'm wingless in the garage at home, test running in the yard with the tail tied to a cedar tree.
I'm building an RV-8 with a turbo 13b. I welded up my own exhaust manifold mounting a Turbonetics 60-1 using an 'on center' TO-4 turbine housing. The compresor faces forward and a cone shaped K&N filter is direct mounted to the compressor housing. The exhaust is an S shaped 2.25" pipe that crosses in front of the firewall and exits out the center of the cooling air exit (cowl flap area) parrallel to the sheet metal ramp. The pipe is supported with a clevis to the engine mount plate (between the block and oil pan) so it all moves in harmony with the engine/turbo, yet can grow a bit from heat. So far the turbo muffles the engine fairly well.....but I have not gone to War Emergency Power.....yet.
I 'borrowed' David Leonards radiator advice, and mounted it under the chin, making a fairly generous scoop, which I tested today.
the oil cooler is mounted on the right side and uses the entire airflow from the right cowl cheek opening. Separate air paths for radiator and oil cooler helped solve my previous cooling failure.
I ground ran for 20 minutes today, building up RPM as it warmed up, and the temps are stable. I chickened out and held at 3850 RPM for the last 5 minutes, the highest I've gone yet. water temp stable @ 154F, Oil stable at 172F. Tracy's engine monitor gives direct HP readout based on fuel flow, so it varies as you adjust the mixture, but I ran up to about 50HP with firm temperature control. This was very exciting for me becuase it's enough power that the fuselage is starting to buck and shake like there might be some power there, and promises of more.
I have not done anything with the left cowl cheek opening yet. Air entering here goes right to the tubo air filter, and washes over the fuel injectors, turbo assembly, and spills out the bottom with the heated radiator air.
To keep from choking the heated radiator air, I'm thinking of making a duct to carry the left cheek air out the left side of the cowl, where I could mount an intercooler. I've trial fitted a stock Mazda intercooler here, I would need to remake the air tubes into/out of it. The important part of this is cooling the fuel system and isolating the turbo heat from anything it could damage. Dave warned me of this early on, and I have not forgotten it.
Constructive comments are always welcome!
PS, I'm working very hard to keep this simple and light. Weight adds up fast!
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