Just talking about VWs

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,805
Location
Midwest
The way I see it is you need to cool the air going threw the fins and around the cylinder head faster or at the same amount to control the temp of the engine and oil mainly. If I was to experiment I'd put my thoughts on Freon or cold gas mix. in air stream and a gate to control amount passing by cylinders.
 

blane.c

Well-Known Member
HBA Supporter
Joined
Jun 27, 2015
Messages
3,906
Location
capital district NY
Matching the intake and exhaust ports to their respective manifolds at the connection is a simple thing that can provide dividends in better and more evenly matched flow. Misalignment of these connection points is common in mass produced engines. Even that alone would be a performance enhancer.
 

blane.c

Well-Known Member
HBA Supporter
Joined
Jun 27, 2015
Messages
3,906
Location
capital district NY
The way I see it is you need to cool the air going threw the fins and around the cylinder head faster or at the same amount to control the temp of the engine and oil mainly. If I was to experiment I'd put my thoughts on Freon or cold gas mix. in air stream and a gate to control amount passing by cylinders.
I would like to see at least a napkin sketch of that idea, the words ain't getting thru this thick skull.
 

don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,805
Location
Midwest
I would like to see at least a napkin sketch of that idea, the words ain't getting thru this thick skull.
Picture a fuel injector spraying a coolant in the air stream coming in at the cowling and with the right control you can adjust/regulate air temp passing over the heads and jugs. On take off you need more coolant for engine and at cruise possibly none. The best part I think it all can be controlled by a cable and a CHT gauge. I can see a 2 lb. O2 canister on firewall filled with liquid hydrogen or Argon/ CO2 and used for coolant with a simple on off valve.
 
Last edited:

Pops

Well-Known Member
Log Member
Joined
Jan 1, 2013
Messages
8,143
Location
USA.
Matching the intake and exhaust ports to their respective manifolds at the connection is a simple thing that can provide dividends in better and more evenly matched flow. Misalignment of these connection points is common in mass produced engines. Even that alone would be a performance enhancer.
Any engine I build I always use a Dremel tool and smooth the intakes and make sure everything is matching. The aluminum casting in the intake ports of the heads can be very rough on some heads.
 

blane.c

Well-Known Member
HBA Supporter
Joined
Jun 27, 2015
Messages
3,906
Location
capital district NY
As much time as is spent doing all the weight balancing and blue printing of the components and also of cc'ing the combustion chambers and cleaning off the excess flashing, simply flow "matching" the heads seems like it would be a worthwhile endeavor as long as it is not cost prohibitive. I am not suggesting making undue alterations just bring up the (3) weaker flow cylinders to match the cylinder with the strongest flow. The poor thing should really be happier that way, and will probably have side effects like better cooling.

It was over 40 years ago now but I spent time in a performance shop, one of the best port and polish shops in California, the setup to flow matching was bone crunching simple and made my boss good money and respect.
 

N8053H

Well-Known Member
Joined
Jan 31, 2013
Messages
2,523
Location
Right here in front of my computer
IMHO if you pay attention to heat, think in terms of keeping intake tubes cool, you will gain more in terms of power then trying to do all this porting and polishing. The same with exhaust. My engine has more of a tuned exhaust system and not straight pipes. Because of this these pipes come very close to the bottom of the engine and those push rod tubes. One side more so then the other. But I wrapped my exhaust pipes to again try and control some of this heat radiating into the engine and oil.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,521
Location
North Carolina
Picture a fuel injector spraying a coolant in the air stream coming in at the cowling and with the right control you can adjust/regulate air temp passing over the heads and jugs. On take off you need more coolant for engine and at cruise possibly none. The best part I think it all can be controlled by a cable and a CHT gauge. I can see a 2 lb. O2 canister on firewall filled with liquid hydrogen or Argon/ CO2 and used for coolant with a simple on off valve.
Water is good. Water injection into the engine has a lot going for it. Raises effective octane, raises permissible CR, cools things down. A system that just activates over, say, 3/4 would allow you to run a higher hp, more efficient engine. It's a definite maybe for me to play with.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,521
Location
North Carolina
As much time as is spent doing all the weight balancing and blue printing of the components and also of cc'ing the combustion chambers and cleaning off the excess flashing, simply flow "matching" the heads seems like it would be a worthwhile endeavor as long as it is not cost prohibitive. I am not suggesting making undue alterations just bring up the (3) weaker flow cylinders to match the cylinder with the strongest flow. The poor thing should really be happier that way, and will probably have side effects like better cooling.

It was over 40 years ago now but I spent time in a performance shop, one of the best port and polish shops in California, the setup to flow matching was bone crunching simple and made my boss good money and respect.
If they were polishing, they weren't the best.
 

wanttobuild

Well-Known Member
Joined
Jun 13, 2015
Messages
660
Location
kuttawa, ky
I am so glad to see a real advance in the cooling of the VW engine. HD cylinders and heads. The gentleman from Texas is to be commended.
Next year he is gonna have a redrive equipped, 4 cyl high flow screamer that is gonna leave everyone in his wake. Your fixed wing ac will be able to takeoff like a helicopter. So no wake turbulence for the rest of you guys! But nobody wants to discuss it. HaHa.
The redrive is gonna be tuff to pull off, I hope they don't copy Revmasters, but add a Procharger to the mix he is gonna need some belts.
 

blane.c

Well-Known Member
HBA Supporter
Joined
Jun 27, 2015
Messages
3,906
Location
capital district NY
Water is good. Water injection into the engine has a lot going for it. Raises effective octane, raises permissible CR, cools things down. A system that just activates over, say, 3/4 would allow you to run a higher hp, more efficient engine. It's a definite maybe for me to play with.
If you inject water, you de-enrich fuel. Stoichiometric is why you water inject. But on a VW? Maybe overkill?
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,521
Location
North Carolina
On a 60hp VW, water isn't needed. But get too ambitious, you have heat problems. Heat is the achilles heel of VWs. Ameliorate that, you can maybe find a new one at a higher power level.
 

blane.c

Well-Known Member
HBA Supporter
Joined
Jun 27, 2015
Messages
3,906
Location
capital district NY
Getting lots of hp may be counterintuitive to the main draw of the VW engine, inexpensive, getting enough hp and keeping it tight and simple seems more of a draw to me, some sweat equity into making it right and safe. Sure you can get better hp to weight ratios but the cost keeps going up in many ways. A nice simple reasonably big cube slow turner around 65hp and keep the cost down.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,521
Location
North Carolina
They are inexpensive 60hp engines. go much over that, the price starts to spiral upwards, the reliability downwards. There are numerous tweaks, which is what this thread is about. some are cheap, some aren't. Some have yet to be tried on VWs.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,953
Location
US
Picture a fuel injector spraying a coolant in the air stream coming in at the cowling and with the right control you can adjust/regulate air temp passing over the heads and jugs. On take off you need more coolant for engine and at cruise possibly none. The best part I think it all can be controlled by a cable and a CHT gauge. I can see a 2 lb. O2 canister on firewall filled with liquid hydrogen or Argon/ CO2 and used for coolant with a simple on off valve.
The simplest way to do something like this is with plain (distilled) water. Water doesn't need to be kept at cryogenic temperatures and it will take away much more heat from the engine for every pound that is used. It could be sprayed into the intake (like the anti-detonation injection (ADI) used by the racers). Or, if we want to keep it simpler, water could be sprayed onto the cylinder heads. Obviously, some work would be needed to avoid cracking a head due to differential cooling.

But, generally it is not practical to do this, it takes too much water.

The math: In these engines, about 30% of the energy in the gasoline burned is lost as waste heat to the coolant (in our case--to the air). If we burn a gallon of gasoline (say that takes 10 minutes), that is 10.5 KWH of heat. If we want our water spray to remove just 25% of that (to give some assistance to the main cooling that is still being done by the passing air) then we need the water spray to remove 2.6 KWH in that 10 minutes.
If we start with a pound of water at 80 F, it takes .04 KWH to heat it to boiling temp, and another .3 KWH to turn it to steam. So, to get rid of that 2.6 KWH of extra heat in the engine head, we'd have to spray it with 2.6/(.04 + .30) = 7.6 lbs of water, or about a gallon. At this rate, we'd need to carry one gallon of water for every gallon of fuel, at least as long as we needed this cooling.
It could work for racers or others who just need a few minutes of extra cooling, but in a plane for normal use, it is a lot more practical to just find a way to get slightly better air cooling by opening up the clogged air passages, making sure the baffling is done right, maybe attaching some bigger fins, etc. No pumps, works all the time, less extra weight, etc, etc

BTW: It would take over 8 times as much R-22 refrigerant as water to get this done. And the EPA would NOT be happy.
 
Last edited:

12notes

Well-Known Member
Lifetime Supporter
Log Member
Joined
Aug 27, 2014
Messages
1,057
Location
Louisville, KY
Or, instead of an open ended system that sprayed water and evaporated it to the atmosphere, you could build a closed system that kept the water below the boiling point and ran the heater water through a series of finned tubes ok the airstream to cool the water before reusing...

Nah, that's too crazy to work.
 

Vigilant1

Well-Known Member
Lifetime Supporter
Joined
Jan 24, 2011
Messages
4,953
Location
US
Sheash Limbach is using water cooled heads which for my two cents would be better than steaming up the windscreen on takeoff with some spray-bar thingy, could get difficult to see forward on a cold day.

http://limflug.de/downloads/datasheets/L2400-DF_EF-datasheet-en.pdf
You'd better be ready to spend a lot more than 2 cents. :) For a liquid-cooled head for a certified aircraft engine (based on the VW, which is what the Limbach is), expect to pay a chunk-o-change. There have been liquid-cooled heads offered for homebuilders making VW aero engines, Great Plains sold them for awhile in their catalog. If I recall correctly, they said a 2180cc engine could make about 100 reliable HP using these heads (by going with a high compression ratio, or maybe it also required a reduction drive to allow higher RPMs). There are some threads here where we talked about 'em. The real-world results were not very good, and as far as I know these heads aren't available anymore.
If we could easily whip the cooling limitation, there would be other issues at higher HPs (maybe the longevity of the bearing saddles in magnesium cases, maybe the cracking of the cases themselves as Wayne Clagg had, etc). So, we'd need to add 17 lbs for an aluminum case, spend more money, etc.

A stock Lycoming or Continental, purpose-built for airplane use, puts out about .5 HP per cubic inch. A 2180 cc VW is 133 cu inches, so that would be 67 HP at the same HP/cu inch. A big 2387cc engine would be 146 cu in, for 73 HP. We generally turn the little VWs faster, which lets us make more HP per cu inch, but the heat issues and other stresses on the engines don't go away when we do that.

A nice simple reasonably big cube slow turner around 65hp and keep the cost down.
The great thing, if this is your objective, is that you don't need to worry about liquid-cooled heads, about polishing/porting, about spray bars, or even fat fins. The road to a reliable 65HP VW-based aero engine is a well-traveled one, and requires nothing more than standard parts (brands and styles proven to work in airplanes), standard assembly methods, good workmanship, and attention to the cooling airflow (nothing fancy, but very few leaks, good pressure drop from intake to exit, and keeping the air tight and flowing well over the hottest parts of the engine). Folks who do all those things and don't ask for more than 65HP (a MP gauge is your friend), seldom have cooling issues with VW-based aero engines.
 
Last edited:
Top