Since at least one person may have expressed interest in hearing more about the engine I built for my 66 Chevy Corvair, and I don't see another, more appropriate forum on this board for this topic I'm posting it here.

DISCLAIMER: This is not an instructional how to. I am not an expert on Brayton cycle engines. I don't recommend building this engine. While it sounds awesome, its really no more impressive than a Wankel, and far more complicated.

The brayton cycle was invented by John Barber and patented in 1791. It was later developed into a working engine by George Brayton (from whom it gained its common name) in the later half of the 19th century, which he patented in 1871.

The brayton cycle explains the thermodynamic cycle which governs the operation of the gas turbine engine. Typically this consists of one or more compressor turbines which feed air into a fire chamber where fuel is added and ignited, and the expanding superheated gases escape through a drive turbine which draws energy out of the gases as the push through it. An overly simplified description I know, but its enough for you to get the point.

Brayton cycle engines are nothing new in cars. Most notable of the jet cars is the Chrysler Turbine car designed by Elwood Engel, and bodied by Ghia. This car is actually what inspired me to build my engine.

I'm sure there is a better way to build a turbine powered car than how I went about it. But here's a description of my rendition of the engine. Its basically a turbine engine with a 6 cylinder boxer engine shoved in the middle.

How it works: Air is drawn in by the turbochargers and compressed. The compressed air is then passed through a pair of intercooler. From the intercoolers it is drawn into the compression pistons and then forced into the central fire chamber. Fuel is injected into the chamber and ignited. As the fuel burns, the air is heated to extremely high temperatures, causing it to expand. The hot gases are then vented to the expansion cylinders. As the hot gas expands inside the cylinder it forces the piston down (con rod, crankshaft, powerglide, transaxle, tires road, smiles). The hot gases then exhausted out of the cylinder to the headers, and though a turbocharger.

Why I built it this way: Chrysler's turbine car used a second turbine driven by the exhaust from the turbine. This worked exactly like a torque converter. But it has its issues. Fuel economy on the freeway was just about as good as any passenger car of the day, but in stop and go traffic you were still burning fuel at the same rate, so it really put a dent in your wallet to drive it anywhere you couldn't cruise along at 60.

I came up with my engine idea while reading about the brayton engine. It was a piston engine, not a turbine engine. I thought, if it works as a piston engine, then maybe I can make my engine work that way.

So I spec'd out a cam that would change the cylinder timing so that the right hand cylinders would act as a compressor and the left as an expandor. Colt was shaking their heads at my specs. I had to go round and round with them before they finally realised "Yes I know thats what it will do, and thats exactly what I want it to do." They did a great job by the way.

The first manifold I built blew up; so did my wife when she came running outside and saw me putting out the fire. I continued experimenting, against my wife's objections. Eventually I built a manifold that has held up. Its made of haynes 230 that's been plasma coated with a ceramic heat shield (got the idea after watching a video on Jay's Garage about his Doble). This one has held up for two years now, and we've put about 15000 miles on the engine. I periodically remove it and inspect it, I then run a 2500 PSI test on it to make sure its not leaking. So far so good.

The first engine was built from the 2.7 corvair engine that came in the car. I had pulled it out and replaced it with an engine and trans from a '96 Porsche 911. Originally the corvair engine had 140 hp, but at some point about 50 of those horses escaped. This ended badly as the heads on the expantionside of the motor started to melt. Apparently Aluminum melts at 1,221 degrees F, and the egt of the fire chamber was about 1800. Needless to say, I was putting out another fire.

Taking the time to think about a suitable material (and let my wife cool down), I again looked to the exotics and found a company that could make ceramic cylinder barrels, heads, and pistons for the hot side, and another to make steel cylinder barrels, pistons, and heads for the compression side. The base block was milled from a piece of 4130 steel billet, same for the con rods and crankshaft.

I upped the engine capacity while I was at it to 2.8L by giving it a 3.5" bore and 3.0" stroke. The engine is currently fed by two Garrett GT32 turbocharger that feed air into a banks intercooler. I get a little more cooling by a water vapor injector, the water also provides a little extra umph once it reaches the fire chamber.

Fuel: The engine starts on gasoline, but once the glow rod comes up to temp it switches over to diesel oil.

Power output: 318 lbft (+/-10) @ 200 - 12,800 rpms, 775 hp @ 12,800.

Important notes: This is a constant torque engine. Its will to produce nearly full torque as soon as fuel is ignited in the fire chamber. The torque is there as soon as I hit the accelerator. Drives like an electric car, but much louder, with a much higher rev band.

It does not require a starter motor. As soon as fuel is injected and ignited the engine will begins turning. I do not idle the engine because of this. If I have to stop, the engine does too. When I need to go, the fire is relit and I start moving.

My transmission is a two speed powerglide, but the torque converter has been removed. Neutral is achieved by disengaging both the clutch pack and band, allowing the transmission internals to freely spin.

Wifes take on the engine; now that I've got it sorted: Won't go near the thing (yes, my comment in the other thread was a snorky poke at her).

I'm with the Mrs on this.

How many miles have you put on it? Its hard to imagine 775 hp through a corvair bottom end without grenading it.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

pictures and video?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I get the impression it is more a silhouette of a corvair motor than anything else.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

PICTURES!!!!!!

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Um, yeah. Second THAT.

Sounds really crazy .

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

As I said, I've put about 15,000 on the odometer. As far as "grenading" the trans, not really. The powerglide trans is a very popular unit, with a huge aftermarket. Including a complete set of internals in 4340 Chromoly steel. As for pressure overload, that was fixed when I bypassed the torque converter, by including a flow regulator that routs excess fluid back to the pan. So when i'm ready to try pushing the engine passed 5 digits in the car, I'm fairly certain the trans will hold together.

That all has to wait until after Alaska. I'm praying for a really good catch this year.

Pretty much. If the catch is a good one this year I'll be starting in on a new version of the engine. I've been thinking that a tri-rotor wankel with a few modifications will work even better.

Be patent. I'll eventually get around to getting a new camera, though it is kinda low on my list of priorities.

I was really thinking of the crank, rods bearings and block of the engine, not the tranny.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

If it produces full torque on startup what purpose do the turbochargers serve? They have to spool up. Where does the oxygen come from to support combustion on startup?

It's a fun story but not sure I'm buying it. Have you posted this on the Internet before?

I'll bet that you don't need a heater on cold days.

Very interesting, I'm also in for pics/video.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Pics or it didn't happen

As i said, the con rods, crank, and crank housing are all milled from 4130 chromoly. Many sport bikes rev as high or higher, and they use sinister cast 1020 steel. So why would you think my engine would "grenade" if its made out of metal that is stronger and lighter?

Granted, if I was using this engine in a race car, and ran it at top rev most of the time it would impact the longevity of the engine, but due to the materials used, far less than it would most engines. Even the steel cylinder barrels are plated with the nickel ceramic carbide that the hot side cylinder barrels are made from.

Nikasil coating is pretty much standard issue for performance engines. It reduces cylinder wear and friction, while improving thermal conductivity.

Granted, you are right. It is somewhat inaccurate to say the engine has "full" torque at 0 rpms. At low rpms, the fuel rate is low, to prevent the air fuel ratio from getting below 30:1, which would spike my combustion temps.

But, If I stomp on it from a stand still (engine is at rest), the AFR will be below 30:1 for a moment, casing combustion temps to spike for a moment, causing over expansion of the working air, producing approximately 90% of full engine torque. This in turn generates a surge in exhaust manifold pressure, which in turn causes the turbo to surge. The GT32 turbo is a variable geometry turbo, its also what Honeywell calls a single sequential turbocharger; Garrett just calls it "Dual Boost", as it as a single compressor turbine that's double sided. This gives you the spool up time of a small turbo with the volume of a large turbo.

By the time I actually start moving the turbo has spooled up to begin pushing a high volume of air though the intercooler and into the intake piston. This in turn returns the AFR to within safe operation and maintains a AFR between 50-60:1 during most driving conditions.

Driving though town at 35 mph I'm running at right around 4000 rpm in low gear. On the freeway I'm also running at 4000 rpm in high gear. Both give me good fuel economy, as the fuel rates are optimized for the driving conditions. If I drive conservatively, taking my time to accelerate, holding steady speeds, the ecu will keep fueling rates low, and I'll get some ware north of 30 mpg. But if I put my foot in it, you can see the fuel gauge move.

I'm not Almighty God, so believing me is not required.

If you had told me, at this time last year, an indirectly injected, naturally aspirated, diesel engine from a 40 year old passenger car could rev upwards of 5 grand on the tach, I'd have thought you were a crank too (pun intended).

Nope. But I doubt I'm the first guy to think of this. After all, I got the idea after reading about George Brayton's engine online.

I see I did miss the part about milling block crank and cylinders out of 4130 Moly. I guess I was confused by the title calling it a corvair engine. I'd love to see some pictures of it please.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.