A good read...

[turbobrat930]

I got this from a friend of mine Mr. Paul Yaw at Injector Dynamics... Definitely info that most of us usually don't think about.

Engine Basics: Detonation and Pre-Ignition by Allen W. Cline

[copbait73]

Contact, I wrote a couple articles on turbocharging for experimental aircraft engines. Mainly turbo normalizing. The early 2000 was a period of time many in the experimental aircraft movement were doing conversions of high power automotive engines for use in aircraft.

There were many like Cline who attempted to educate the masses that these engines were not designed for the duty cycle of typical aircraft engines. An engine failure while flying your plane can have much worse consequences than simply pulling your car to the side of the road and calling a wrecker.

[flightlead404]

Originally Posted by copbait73

Contact, I wrote a couple articles on turbocharging for experimental aircraft engines. Mainly turbo normalizing. The early 2000 was a period of time many in the experimental aircraft movement were doing conversions of high power automotive engines for use in aircraft.

There were many like Cline who attempted to educate the masses that these engines were not designed for the duty cycle of typical aircraft engines. An engine failure while flying your plane can have much worse consequences than simply pulling your car to the side of the road and calling a wrecker.

Care to share? Microsquirting and potentially turbo normalizing my RV-8 is something I've started to consider.

[copbait73]

Originally Posted by flightlead404

Care to share? Microsquirting and potentially turbo normalizing my RV-8 is something I've started to consider.

Been over 20 years ago, but let me see what I may have in my dusty old files.
I can say I'm not as comfortable with a system like Ms as you are. What is you engine O or IO? Fixed pitch prop or CS? If IO you are good to go. If O go pull-through. Would require a somewhat unique turbo build with either a carbon face seal on the compressor or a vented bearing housing or both.

As I recall the discussion was around a Continental O-200 which because of it's size lends itself to automotive type turbos having carb seals that were widely available then. Also I was building a W.A.R. FW-190 and collecting parts for it's motor. Two other members had Corsair builds.

[flightlead404]

Originally Posted by copbait73

Been over 20 years ago, but let me see what I may have in my dusty old files.
I can say I'm not as comfortable with a system like Ms as you are. What is you engine O or IO? Fixed pitch prop or CS? If IO you are good to go. If O go pull-through. Would require a somewhat unique turbo build with either a carbon face seal on the compressor or a vented bearing housing or both.

As I recall the discussion was around a Continental O-200 which because of it's size lends itself to automotive type turbos having carb seals that were widely available then. Also I was building a W.A.R. FW-190 and collecting parts for it's motor. Two other members had Corsair builds.

Superior/Lycoming IO-360 parallel valve engine, slightly higher compression than normal, I think 9.5:1, constant speed

Good article above, easy read with lots of good info.

[copbait73]

Originally Posted by flightlead404

Superior/Lycoming IO-360 parallel valve engine, slightly higher compression than normal, I think 9.5:1, fixed pitch.

Good article above, easy read with lots of good info.

Too good of an engine to risk reliability with any of these mods. Does it have header?

[flightlead404]

Originally Posted by copbait73

Too good of an engine to risk reliability with any of these mods. Does it have header?

sorry, its constant speed not fixed pitch, no idea why I mixed that up.

header? intake? exhaust?

Its the cheesy Bendix fuel injection. I'm thinking a speed-density Microsquirt, maybe with two MAP sensors with one plumbed into the static system and the other the intake manifold to allow MS to adjust based on changes due to altitude.

I think if I can figure out the mapping between AFR and EGT I can have two tunes, one for best power at 100*f on the rich side of peak EGT and an economy cruise at 30*f on the lean side of peak EGT.

[copbait73]

Originally Posted by flightlead404

sorry, its constant speed not fixed pitch, no idea why I mixed that up.

header? intake? exhaust?

Its the cheesy Bendix fuel injection. I'm thinking a speed-density Microsquirt, maybe with two MAP sensors with one plumbed into the static system and the other the intake manifold to allow MS to adjust based on changes due to altitude.

I think if I can figure out the mapping between AFR and EGT I can have two tunes, one for best power at 100*f on the rich side of peak EGT and an economy cruise at 30*f on the lean side of peak EGT.

Yes, but what happens when something, anything stops? Not convinced automotive EFI components would live in that environment.


I once talked with a guy at Oshkosh who flew an RV????(think -4) with homegrown 2 rotor Mazda with belt drive lash up. Had EFI also. Said he had already made 3 engine out off airport landings. Often wonder if he is still alive? Nice young man but as he so casually related his experiences I wanted to ask him how may more of these he expected to survive?

I have two dead friends and a third in a wheelchair. Three separate experimentals.
Don't take me wrong, I think RVs with certified engines are golden.

All I would add is a header if designed and available for bolt on.

[flightlead404]

Originally Posted by copbait73

Yes, but what happens when something, anything stops? Not convinced automotive EFI components would live in that environment.


I once talked with a guy at Oshkosh who flew an RV????(think -4) with homegrown 2 rotor Mazda with belt drive lash up. Had EFI also. Said he had already made 3 engine out off airport landings. Often wonder if he is still alive? Nice young man but as he so casually related his experiences I wanted to ask him how may more of these he expected to survive?

I have two dead friends and a third in a wheelchair. Three separate experimentals.
Don't take me wrong, I think RVs with certified engines are golden.

All I would add is a header if designed and available for bolt on.

Yea, because he was flying a Mazda rotary engine. I know a guy who is considered probably top mazda conversion guy he's had a half dozen and replaces his engine every year or two.

As far as fault tolerance I can easily put in two microsquirts and a switch to shunt between them in the unlikely event one fails. I already have a fully redundant electrical system, with shunting ability and dual alternators.

You mean exhaust header? To fit the turbo? I'm sure all the intake an exhaust would be custom work.

[copbait73]

Originally Posted by flightlead404

Yea, because he was flying a Mazda rotary engine. I know a guy who is considered probably top mazda conversion guy he's had a half dozen and replaces his engine every year or two.

As far as fault tolerance I can easily put in two microsquirts and a switch to shunt between them in the unlikely event one fails. I already have a fully redundant electrical system, with shunting ability and dual alternators.

You mean exhaust header? To fit the turbo? I'm sure all the intake an exhaust would be custom work.

No I mean keep everything as is and add a performance header system.

[boosted79]

Good article but I question this statement in reference to LPP, location of peak cylinder pressure with respect to piston location:

" There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center."

Seems to me it depends on ratio of rod length to stroke? A short rod ratio (rod c to c / stroke) would have a smaller rod to crank throw angle at 14 ATDC then a long rod ratio. These 3.3 930's have rod ratio of 1.7, LS1 392 aluminum has like just under 1.5 ratio. Can't believe they both would want peak cyl pressure at 14 ATDC?

[Speedy Squirrel]

Originally Posted by boosted79

Good article but I question this statement in reference to LPP, location of peak cylinder pressure with respect to piston location:

" There is another factor that engineers look for to quantify combustion. It is called "location of peak pressure (LPP)." It is measured by an in-cylinder pressure transducer. Ideally, the LPP should occur at 14 degrees after top dead center."

Seems to me it depends on ratio of rod length to stroke? A short rod ratio (rod c to c / stroke) would have a smaller rod to crank throw angle at 14 ATDC then a long rod ratio. These 3.3 930's have rod ratio of 1.7, LS1 392 aluminum has like just under 1.5 ratio. Can't believe they both would want peak cyl pressure at 14 ATDC?

That is a very astute observation. In LPP is no longer used, and 14 is really only a rough rule of thumb. We now are able to use CA50 to define where we would like 50% of the fuel mass fraction to be burned. That said, 14 is still a pretty good guess for the slow burning Porsche hemi chamber.

[flightlead404]

Originally Posted by copbait73

No I mean keep everything as is and add a performance header system.

What fun is that? Anyway I have a 4-into-1 basically straight pipe.

Getting waaaay of the Porsche topic here, but ECUs and sensors will work just fine in an aviation environment. Its auto ENGINES that are designed for a different mission and don't work well in the auto environment. I'm looking to take advantage of modern electronic ignition and fuel injection while maintaining the solid, proven, workhorse of the Lycon IO360.

The focus on "single point of failure" is likewise silly. I have many single points of failure. I have one crank, one cam, one prop, one oil pump, and on and one. The focus should be on MTBF of the system.

[turbobrat930]

Another "off topic" comment in reference to the actual article... But, I remember looking at a VW type 1 engine for a small single place experimental. And I remember even though numerous others have used this and had success. But the various air cooled aircraft engines have a HUGE thrust bearing on the crank nose. The vw engines obviously, do not. And all other auto engines fall into this same problem. That alone has steered me away from using an auto engine in an experimental acft.

[flightlead404]

Originally Posted by turbobrat930

Another "off topic" comment in reference to the actual article... But, I remember looking at a VW type 1 engine for a small single place experimental. And I remember even though numerous others have used this and had success. But the various air cooled aircraft engines have a HUGE thrust bearing on the crank nose. The vw engines obviously, do not. And all other auto engines fall into this same problem. That alone has steered me away from using an auto engine in an experimental acft.

Yes, many issues with engine design like crank shaft bearing, journal counts, size of bearings and how prop related harmonics and bending forces come into play as well as choice of materials, cooling, frequent requirements for reduction drives, the fact that an aero engine is working hard, all the time, but an auto engine is not designed to do that.....by the time you redesign the engine, rebuild it, add reduction drives, do the necessary cooling mods, its IMHO futile. My airplane is experimental enough without having some rube goldberg contraption up front that sooner or later is gonna have me in the "316 Club" (route 316 is the major road by my airport where people with auto conversion engines like to land shortly after takeoff).