Nitrous Oxide for take off??

EdFred said:
Maybe with a working autopilot and a coffee can with kitty litter in it. :ihih:
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You just need more practice. Hand flying and a Dr. Pepper bottle are sufficient.

Or... you can just not drink so much liquid. ;)
 
Ted DuPuis said:
You just need more practice. Hand flying and a Dr. Pepper bottle are sufficient.

Or... you can just not drink so much liquid. ;)
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Dr. Pepper bottles aren't big enough. Noodle on that one for a while. :eek::D
 
EdFred said:
Dr. Pepper bottles aren't big enough. Noodle on that one for a while. :eek::D
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You either have greater than 2L capacity (impressive) or have poor directional control that would render you incapable of flying a mid-air refueling mission (not impressive).

I'm done. :D
 
Ted DuPuis said:
You either have greater than 2L capacity (impressive) or have poor directional control that would render you incapable of flying a mid-air refueling mission (not impressive).

I'm done. :D
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When I landed at SRQ, I may have been able to fill a 1-gallon milk jug. :eek:

Besides, you ever see what happens when you let go of a firehose at full operating pressure? :D
 
Ted DuPuis said:
In a 6-cylinder engine, an angle valve weighs 50 lbs more than a parallel valve. Not much else is different, so figure you'd be about 35 lbs heavier. That takes 70 lbs out of your 200 lb savings, so you'd only be saving 130 lbs.
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WOW! there has to be a big difference between the heads besides valve angles. 8.3 lbs per cylinder is a lot of extra Al.

Think about what you're asking for. A stock parallel valve 4-cylinder makes 180 hp. A stock angle valve 4-cylinder makes 200 hp. Even the 390 I think is rated at 210 hp (someone else might know this better than me). You're looking at trying to add about 25% more power to an engine. That's not exactly a small feat. Compression will gain you some, but ultimately it comes down to getting more air in the cylinders, which will require some porting work and/or more RPMs. Let's not forget that the induction systems weren't designed to flow that much air, so you'll have to design a new induction system.

Possible? Yes. Reliable? Probably not. Fuel efficient? Definitely not moreso, at best it'd be equal. Your SFCs are not going to be much different, and that is ultimately what impacts your economy.
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I figured that a stroker 390 would have a MUCH shorter engine life. After all, it would have to be built as a 2700 rpm maximum effort racing engine. The effective maximum volumetric efficiency for a naturally aspirated engine is 130%. If you apply the formula [c.i.d. x rpm/ 5600/ 1= volumetric efficiency] you can see that a ~400 c.i. engine running @ 2700 rpm, would be at the 130% maximum.

This is the thing that I'm not getting. With only a slight difference in rpm's, the stroker 4 cylinder should be more efficient. The overall weight of reciprocating mass would be less, less internal friction, higher volumetric efficiency, less combustion chamber surface area to lose heat to (247.5 sq. in. to 177.8 sq. in.), therefore more thermodynamically efficient. Everything in in the 4cyl seems more efficient, enough so to more than make up for the slight difference in rpm's. Did I miss something here?
 
Capt.Crash'n'Burn said:
WOW! there has to be a big difference between the heads besides valve angles. 8.3 lbs per cylinder is a lot of extra Al.
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Try picking up a parallel valve vs. an angle valve cylinder. There is a lot of extra metal there. The angle valve heads have much more fin area. Consequently, they also have better cooling.

I figured that a stroker 390 would have a MUCH shorter engine life. After all, it would have to be built as a 2700 rpm maximum effort racing engine. The effective maximum volumetric efficiency for a naturally aspirated engine is 130%. If you apply the formula [c.i.d. x rpm/ 5600/ 1= volumetric efficiency] you can see that a ~400 c.i. engine running @ 2700 rpm, would be at the 130% maximum.
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...and that will require a lot of work to make work.

This is the thing that I'm not getting. With only a slight difference in rpm's, the stroker 4 cylinder should be more efficient. The overall weight of reciprocating mass would be less, less internal friction, higher volumetric efficiency, less combustion chamber surface area to lose heat to (247.5 sq. in. to 177.8 sq. in.), therefore more thermodynamically efficient. Everything in in the 4cyl seems more efficient, enough so to more than make up for the slight difference in rpm's. Did I miss something here?
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You're assuming that all of that amounts to a significant efficiency difference, which it doesn't. I'd bet that at the end of the day you'd have about the same fuel burn.

In my experience, they're all pretty efficient engines, and all produce pretty similar SFCs.
 
Ted DuPuis said:
Try picking up a parallel valve vs. an angle valve cylinder. There is a lot of extra metal there. The angle valve heads have much more fin area. Consequently, they also have better cooling.
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That extra cooling is needed because the engines develop more power and as a result, more heat.


In my experience, they're all pretty efficient engines, and all produce pretty similar SFCs.
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Compression ratio does affect min BSFC somewhat so it's likely the angle valve engines are slightly more efficient if they also have a higher CR. I believe the valve arrangement is intended to improve volumetric efficiency (more airflow pre revolution) but that doesn't by itself correlate with better fuel efficiency, just more HP per cube.
 
gismo said:
That extra cooling is needed because the engines develop more power and as a result, more heat.
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While true, if you run both head types with the same differential pressure across the cylinders, the angle valves run significantly cooler. They just cool better.

Compression ratio does affect min BSFC somewhat so it's likely the angle valve engines are slightly more efficient if they also have a higher CR. I believe the valve arrangement is intended to improve volumetric efficiency (more airflow pre revolution) but that doesn't by itself correlate with better fuel efficiency, just more HP per cube.
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This is correct. Angle valves have 8.7 CR (naturally apsirated) vs. the 8.5 of the parallel valves. As I said, it really comes down to them both being pretty darn similar.
 
gismo said:
That extra cooling is needed because the engines develop more power and as a result, more heat.
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Do you know of anyone having success with ceramic combustion chamber coatings??


I believe the valve arrangement is intended to improve volumetric efficiency (more airflow pre revolution) but that doesn't by itself correlate with better fuel efficiency, just more HP per cube.
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No, it does mean that you will have lower fuel consumption because the engine doesn't have to work as hard to pump air. A higher V.E. at a lower rpm, means that you don't have to turn more rpms to move the same amount of air.
 
Ted DuPuis said:
While true, if you run both head types with the same differential pressure across the cylinders, the angle valves run significantly cooler. They just cool better.
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I wasn't disagreeing about that, just stating the likely reason the angle valve cylinders were designed to cool better. Then again, you should know the actual design criteria, I'm only guessing.
 
Capt.Crash'n'Burn said:
No, it does mean that you will have lower fuel consumption because the engine doesn't have to work as hard to pump air. A higher V.E. at a lower rpm, means that you don't have to turn more rpms to move the same amount of air.
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You're assuming that a small difference in efficiency will result in a noticeable difference in fuel consumption. The truth is it won't. The angle valves are a bit more efficient, but not by a huge amount.
 
gismo said:
I wasn't disagreeing about that, just stating the likely reason the angle valve cylinders were designed to cool better. Then again, you should know the actual design criteria, I'm only guessing.
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I don't know much about the design criteria (both were designed well before I was born), I just know what happens when you run them.
 
Capt.Crash'n'Burn said:
No, it does mean that you will have lower fuel consumption because the engine doesn't have to work as hard to pump air. A higher V.E. at a lower rpm, means that you don't have to turn more rpms to move the same amount of air.
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No, it means you will have higher fuel consumption because you are moving more air, and with that air comes more fuel, that is unless you close down the throttle or lean the mix until you are at equivalent HP, then there is no difference.
 
Henning said:
No, it means you will have higher fuel consumption because you are moving more air, and with that air comes more fuel, that is unless you close down the throttle or lean the mix until you are at equivalent HP, then there is no difference.
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Perhaps I should've quantifed that statement better.

In two engines where the displacement and horsepower are the same, the engine with higher V.E. will produce that horsepower at a lower RPM. I'll give an example.

Engine "A") 550 c.i.-117% v.e.= 310 HP @ 2700 rpm

Engine "B") 550 c.i.-100% v.e.= 310 hp @ 3156 rpm

Turning 456 more rpm is going to suck more gas I reckon. ;-)
 
Ted DuPuis said:
You're assuming that a small difference in efficiency will result in a noticeable difference in fuel consumption. The truth is it won't. The angle valves are a bit more efficient, but not by a huge amount.
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Obviously it would take a bit more than just a head swap to make a big difference in V.E. You'd need custom intake and exhaust systems along with dyno testing about a dozen different cams to see which one works best.
 
A lot of bucks for not much bang...

If you want to improve your fuel consumption, start advancing the ignition timing as you lean.

Consider masking the intake valve to improve swirl and push out the lean limit - you will lose a little power, but will get better fuel economy.
 
Capt. Geoffrey Thorpe said:
A lot of bucks for not much bang...

If you want to improve your fuel consumption, start advancing the ignition timing as you lean.

Consider masking the intake valve to improve swirl and push out the lean limit - you will lose a little power, but will get better fuel economy.
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I was a little curious about something almost related if you look at this real broadly. Since you're limited on your leaning in a carbureted due to the very uneven mixture going into the cylinders, would one of those little air swirly things they sell for cars help any with the mixing of the air and fuel to the point where you could get LOP and still have all cylinders firing?
 
bigred177 said:
I was a little curious about something almost related if you look at this real broadly. Since you're limited on your leaning in a carbureted due to the very uneven mixture going into the cylinders, would one of those little air swirly things they sell for cars help any with the mixing of the air and fuel to the point where you could get LOP and still have all cylinders firing?
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No. .
 
Capt.Crash'n'Burn said:
Obviously it would take a bit more than just a head swap to make a big difference in V.E. You'd need custom intake and exhaust systems along with dyno testing about a dozen different cams to see which one works best.
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Even then, you'd be surprised at how small the difference would be between what you started with and what you ended with, which is my point.
 
Ted DuPuis said:
Even then, you'd be surprised at how small the difference would be between what you started with and what you ended with, which is my point.
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You quickly reach the point of diminishing returns... this sort of tuning is good for racing.. or drag strip racing engines... but for long cross country stuff, the money would be better spent on an auto pilot.. or avionics.. or xtra range tanks...

(I'm agreeing with ya, Ted..)
 
bigred177 said:
I was a little curious about something almost related if you look at this real broadly. Since you're limited on your leaning in a carbureted due to the very uneven mixture going into the cylinders, would one of those little air swirly things they sell for cars help any with the mixing of the air and fuel to the point where you could get LOP and still have all cylinders firing?
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Not sure what "air swirly things" you're talking about, but according to some of John Deakin's excellent articles on the subject, there are people who are able to run carbureted engines lean of peak by pulling the throttle just a hair back from WOT so the throttle plates induce some turbulence in the air, which sounds like what you're talking about. However, this would be HIGHLY airplane and type dependent - I can't get it to work very well in the 182.
 
flyingcheesehead said:
Not sure what "air swirly things" you're talking about, but according to some of John Deakin's excellent articles on the subject, there are people who are able to run carbureted engines lean of peak by pulling the throttle just a hair back from WOT so the throttle plates induce some turbulence in the air, which sounds like what you're talking about. However, this would be HIGHLY airplane and type dependent - I can't get it to work very well in the 182.
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That's just crazy talk!!
 
Capt. Geoffrey Thorpe said:
Hmmmm. Can't find the "mini supercharger" thing that they used to sell but they now sell this:

http://www.jcwhitney.com/max-fueler-vortex-generator-fuel-economy-device/p2019655.jcwx?filterid=j1

And, of course, who could pass up on a magnet to strap to the fuel line:

http://www.jcwhitney.com/vehicle-fuel-saver/p2005685.jcwx?filterid=j1

:loco:
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That first one is what I'm thinking about. I know it doesn't do anything for a car, but I was thinking the swirling air might aid in mixing the fuel to get a more even burn across the cylinders.
 
flyingcheesehead said:
Not sure what "air swirly things" you're talking about, but according to some of John Deakin's excellent articles on the subject, there are people who are able to run carbureted engines lean of peak by pulling the throttle just a hair back from WOT so the throttle plates induce some turbulence in the air, which sounds like what you're talking about. However, this would be HIGHLY airplane and type dependent - I can't get it to work very well in the 182.
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And it sounds like it could if you were allowed to put one in. This seems easier and more simple though. I think I remember reading that article, thanks for bringing it back up. I'm going to have to try this Saturday.
 
flyingcheesehead said:
Not sure what "air swirly things" you're talking about, but according to some of John Deakin's excellent articles on the subject, there are people who are able to run carbureted engines lean of peak by pulling the throttle just a hair back from WOT so the throttle plates induce some turbulence in the air, which sounds like what you're talking about. However, this would be HIGHLY airplane and type dependent - I can't get it to work very well in the 182.
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I use a crack of carb heat until it smooths out.
 
EdFred said:
That's just crazy talk!!
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It's not. We used to have a 172 that would climb better, with an RPM increase of 40 or 50, if we pulled the throttle back just a bit. The throttle shaft and plate were OK, there was no overtravel, but in this particular carb full throttle did something to reduce power: maybe it was poor mixture distribution or the nozzle's spray was coarse and the slightly angled plate atomized it better. I don't think it was weak spark. Whatever it was, it was clearly unhappy at WOT. The engine that came after that one, with a new carb, didn't mind full throttle.

Dan
 
Dan Thomas said:
It's not. We used to have a 172 that would climb better, with an RPM increase of 40 or 50, if we pulled the throttle back just a bit. The throttle shaft and plate were OK, there was no overtravel, but in this particular carb full throttle did something to reduce power: maybe it was poor mixture distribution or the nozzle's spray was coarse and the slightly angled plate atomized it better. I don't think it was weak spark. Whatever it was, it was clearly unhappy at WOT. The engine that came after that one, with a new carb, didn't mind full throttle.

Dan
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Perhaps a mis-adjusted WOT fuel enrichment circuit? /pure speculation off!

-Skip
 
Ted DuPuis said:
In a 6-cylinder engine, an angle valve weighs 50 lbs more than a parallel valve. Not much else is different, so figure you'd be about 35 lbs heavier. That takes 70 lbs out of your 200 lb savings, so you'd only be saving 130 lbs.



2575 RPM. Standard 4-cylinders are rated at 2700 RPM, helicopter ones have been higher (as R&W pointed out), but are then typically derated.



Think about what you're asking for. A stock parallel valve 4-cylinder makes 180 hp. A stock angle valve 4-cylinder makes 200 hp. Even the 390 I think is rated at 210 hp (someone else might know this better than me). You're looking at trying to add about 25% more power to an engine. That's not exactly a small feat. Compression will gain you some, but ultimately it comes down to getting more air in the cylinders, which will require some porting work and/or more RPMs. Let's not forget that the induction systems weren't designed to flow that much air, so you'll have to design a new induction system.

Possible? Yes. Reliable? Probably not. Fuel efficient? Definitely not moreso, at best it'd be equal. Your SFCs are not going to be much different, and that is ultimately what impacts your economy.
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Well, I figured that If I could dream of it, someone else probably already tried it, and I finally found the company that did it.

Placo XP-400SRE

It's an IO-390 with a 4.5" stroke crank, and it makes 250 HP and weighs 310 lbs. The one thing their site doesn't specify is the PRM that peak HP is obtained. It's theoretically possible to make 250 HP@ 2700 RPM in a 400 CID engine, so I'll just assume that for a second.

An Aztec that used this engine in place of the stock IO-540 should be able to fly aprx 275 miles more because you could exchange the engine weight for fuel weight. Obviously, cost and engine life would be a major issue.
 
Except that the W&B characteristics of the Aztec aren't such that you typically have to trade fuel for cargo or passengers as with some planes. You'll probably run out of bladder first.
 
True, but it seems to be important to a lot of people.
 
Skip Miller said:
Perhaps a mis-adjusted WOT fuel enrichment circuit? /pure speculation off!

-Skip
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No enrichment circuitry on an MA3 or MA4 carb. Dirt simple, those carbs. Some don't even have an accelerator pump. They are so crude that many of them won't idle worth a hoot, and there is no consistency between carbs of the same part number. When we buy Lyc remans we get new or overhauled carbs with them, and some will work OK and some will be rotten. Had to replace at least two in the last year or so. One leaked all around the bowl gasket and the other (an HA-6 used on the O-540) had such poor atomization that the cylinders feeding off the bottom of the intake plenum would not fire much at all at idle, being flooded with fuel, and in cruise they ran rich and cold. By the time they were lean enough to run right the other cylinders were cutting out. That carb was replaced on warranty but the interim bill that came with the new one was for $8800. For a carburetor. With maybe five moving parts. Could buy some whole airplanes for that.

And the 64-year-old Stromberg carb on my Jodel runs far smoother and with less trouble than the "modern," obscenely expensive, "aircraft-quality" carbs. What happened?

Dan
 
Dan Thomas said:
No enrichment circuitry on an MA3 or MA4 carb. Dirt simple, those carbs. Some don't even have an accelerator pump. They are so crude that many of them won't idle worth a hoot, and there is no consistency between carbs of the same part number. When we buy Lyc remans we get new or overhauled carbs with them, and some will work OK and some will be rotten. Had to replace at least two in the last year or so. One leaked all around the bowl gasket and the other (an HA-6 used on the O-540) had such poor atomization that the cylinders feeding off the bottom of the intake plenum would not fire much at all at idle, being flooded with fuel, and in cruise they ran rich and cold. By the time they were lean enough to run right the other cylinders were cutting out. That carb was replaced on warranty but the interim bill that came with the new one was for $8800. For a carburetor. With maybe five moving parts. Could buy some whole airplanes for that.

And the 64-year-old Stromberg carb on my Jodel runs far smoother and with less trouble than the "modern," obscenely expensive, "aircraft-quality" carbs. What happened?

Dan
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"Modern" aircraft carbs? The MS carbs make your Stromberg look space age. Those damn things haven't changed significantly since the 20s.
 
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