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Old 03-06-2011, 09:00 AM   #1
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HATS (heat attenuation throttle system)

Many years ago, I devised a system I called HATS, though I never did build one. The concept was that as hot air was less dense than cold air, I could throttle the engine at least in part by feeding it hot air rather than by closing the throttle. The idea was that at full throttle, you would get full cold air, an as you backed the throttle off, the ratio of hot to cold air would increase until you were running full hot, and finally the throttle itself would back off. This daydream dates from about 1980. The idea was to reduce engine load resulting from having to pull a vacuum, as well as trying to increase the temps at TDC compression stroke to the point where they are as near constant as possible. I want that temp to be the same at 30% throttle as it is at full throttle. This should increase combustion efficiency.
Automotive engineers focus heavily on performance, and most people seem to have difficulty understanding that you are only using (producing) perhaps 20-30 HP at efficient cruise, and that this is where you "live", only rarely making excursions into the higher horsepower regions. In the single minded pursuit of power, not enough attention is being paid to the 25% - 30% throttle region. The volumetric efficiency of gas engines operating in this power zone is far below what it is at close to full throttle. That is the gap that needs to be closed.

Howard
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Old 03-06-2011, 10:17 AM   #2
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Re: HATS (heat attenuation throttle system)

Quote:
Originally Posted by Howard View Post
Many years ago, I devised a system I called HATS, though I never did build one. The concept was that as hot air was less dense than cold air, I could throttle the engine at least in part by feeding it hot air rather than by closing the throttle. The idea was that at full throttle, you would get full cold air, an as you backed the throttle off, the ratio of hot to cold air would increase until you were running full hot, and finally the throttle itself would back off. This daydream dates from about 1980. The idea was to reduce engine load resulting from having to pull a vacuum, as well as trying to increase the temps at TDC compression stroke to the point where they are as near constant as possible. I want that temp to be the same at 30% throttle as it is at full throttle. This should increase combustion efficiency.
Automotive engineers focus heavily on performance, and most people seem to have difficulty understanding that you are only using (producing) perhaps 20-30 HP at efficient cruise, and that this is where you "live", only rarely making excursions into the higher horsepower regions. In the single minded pursuit of power, not enough attention is being paid to the 25% - 30% throttle region. The volumetric efficiency of gas engines operating in this power zone is far below what it is at close to full throttle. That is the gap that needs to be closed.

Howard
Great Stuff!!!

This is the same idea I had and just started collecting data last Summer. As you can see in my AVATAR I made a crazy turbo manifold. Part of its design was to increase IAT temps at freeway speed during cruising speeds. I could run my IAT temps at 225* F(still not hot enough IMO) while driving 65mph. In combination with my turbo and lean burn I was able to run with very little pumping losses.

I ran out of time for testing and had to start on my 5th generation N/A Lean Burn Honda engine.

From my own calculations you would need to be over 300*F IAT to equal the same amount in air lbs/min. This should give you enough throttle angle to over come a lot of the pumping losses.

My other concerns would be at what point will the distillation fuel curve have to be changed?

Would you have to recalibrate the IAT sensor?

Would you have to build a delay from hot IAT's to normal IAT's to prevent knock?

Theses are just some concerns I have right off the top of my head.

The other thing is you have to have a engine management system to right your own tune. But this is not a really big deal.
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Old 03-07-2011, 05:35 PM   #3
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Re: HATS (heat attenuation throttle system)

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Originally Posted by pgfpro View Post
Great Stuff!!!

This is the same idea I had and just started collecting data last Summer. As you can see in my AVATAR I made a crazy turbo manifold. Part of its design was to increase IAT temps at freeway speed during cruising speeds. I could run my IAT temps at 225* F(still not hot enough IMO) while driving 65mph. In combination with my turbo and lean burn I was able to run with very little pumping losses.

I ran out of time for testing and had to start on my 5th generation N/A Lean Burn Honda engine.

From my own calculations you would need to be over 300*F IAT to equal the same amount in air lbs/min. This should give you enough throttle angle to over come a lot of the pumping losses.

My other concerns would be at what point will the distillation fuel curve have to be changed?

Would you have to recalibrate the IAT sensor?

Would you have to build a delay from hot IAT's to normal IAT's to prevent knock?

Theses are just some concerns I have right off the top of my head.

The other thing is you have to have a engine management system to right your own tune. But this is not a really big deal.
Presumably the IAT signal should result in the computer compensating correctly.

Your temp estimate reflects my own

My real question is what happens at TDC with that amount of preheat? Assuming that the engine is running at close to WOT, the vacuum will be virtually zero. The reduction in air density due to the higher temp should result in approximately the same temp at TDC, but the actual compression pressure should be the same as with throttled cool air. Thermodynamics tends to work that way. The result should be the same temps as you would have at WOT, when effectively running at 1/3 throttle or thereabouts.

It would be great to be able to set up a test rig to see what actually happens with induction temp increase. 300 deg F may be a bit more than some components of the induction system are able to deal with.

I frankly consider turbos a liability where economy is concerned. You have to throttle back your induction during cruise, so it is doing nothing at all for you. One rarely uses WOT, and that is the only time a turbo offers any benefit at all. Turbocharged engines also have a lower compression ratio to allow for the extra air being pushed into the cylinder at WOT without having per-ignition issues. This in itself results lower efficiency. This is observable in both gas and diesel engines. The higher the compression ratio (diesel) the greater the efficiency. Also the smaller the injector orifice, which results in smaller droplet size. I also do not like the additional system. Personally I do not have turbos on any of my diesels, and I refuse to own a turbo gas engine.

Howard

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Old 03-07-2011, 10:59 PM   #4
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Re: HATS (heat attenuation throttle system)

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Presumably the IAT signal should result in the computer compensating correctly.
My question of IAT is more about the scaling of the sensor (NCT type). From what I can gather on IAT sensors is the scaling stops around 250*F. It would be nice to adjust the scaling. One could change the scale to get a higher resolution for the ECU at the 250+*F mark.
Your temp estimate reflects my own

My real question is what happens at TDC with that amount of preheat? Assuming that the engine is running at close to WOT, the vacuum will be virtually zero. The reduction in air density due to the higher temp should result in approximately the same temp at TDC, but the actual compression pressure should be the same as with throttled cool air. Thermodynamics tends to work that way. The result should be the same temps as you would have at WOT, when effectively running at 1/3 throttle or thereabouts.

It would be great to be able to set up a test rig to see what actually happens with induction temp increase. 300 deg F may be a bit more than some components of the induction system are able to deal with.
It would be great to see what it would do on a real engine. Are you considering doing this?

I frankly consider turbos a liability where economy is concerned. You have to throttle back your induction during cruise, so it is doing nothing at all for you. One rarely uses WOT, and that is the only time a turbo offers any benefit at all. Turbocharged engines also have a lower compression ratio to allow for the extra air being pushed into the cylinder at WOT without having per-ignition issues. This in itself results lower efficiency. This is observable in both gas and diesel engines. The higher the compression ratio (diesel) the greater the efficiency. Also the smaller the injector orifice, which results in smaller droplet size. I also do not like the additional system. Personally I do not have turbos on any of my diesels, and I refuse to own a turbo gas engine.
I personally have had great success with petrol turbo charge engines for economy.But all four of my engines are running lean burn with a few other mods to get the higher results then OEM. At light load freeway driving I'm running around .5psi or around 103 abs/kpa. No more vacuum.

Howard

Howard
Great thread!!!
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Old 03-10-2011, 10:47 AM   #5
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Re: HATS (heat attenuation throttle system)

PGFPro wrote:

"I personally have had great success with petrol turbo charge engines for economy.But all four of my engines are running lean burn with a few other mods to get the higher results then OEM. At light load freeway driving I'm running around .5psi or around 103 abs/kpa. No more vacuum."

No vacuum = WOT ............. You have to have manifold vacuum or some other way to reduce the volume (by weight) of air you are taking in or you are running full throttle. Where are you measuring positive pressure? It has to be in the plenum, not the intake manifold below the throttle if you are showing positive pressure. It's useless to pressurize the air with a turbo and then throttle it. No lean burn system is capable of running an engine with a full charge + of air, and outputting 20-30% of the potential power at that RPM. Engines simply will not run that lean, nor would they run efficiently if they could. I think you need to re-examine your figures and the point at which you are taking your readings.

Howard
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Old 03-10-2011, 04:40 PM   #6
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Re: HATS (heat attenuation throttle system)

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Originally Posted by Howard View Post
PGFPro wrote:

"I personally have had great success with petrol turbo charge engines for economy.But all four of my engines are running lean burn with a few other mods to get the higher results then OEM. At light load freeway driving I'm running around .5psi or around 103 abs/kpa. No more vacuum."

No vacuum = WOT .............Not in a turbo engine!!!You have to have manifold vacuum or some other way to reduce the volume (by weight) of air you are taking in or you are running full throttle.Heat. Where are you measuring positive pressure? It has to be in the plenum, not the intake manifold below the throttle if you are showing positive pressure.Measured in the plenum area with an map manifold with signal from each intake runner. It's useless to pressurize the air with a turbo and then throttle it. I disagree. No lean burn system is capable of running an engine with a full charge + of air, and outputting 20-30% of the potential power at that RPM. Engines simply will not run that lean, nor would they run efficiently if they could. I think you need to re-examine your figures and the point at which you are taking your readings. OK……

Howard
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Old 03-10-2011, 06:13 PM   #7
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Re: HATS (heat attenuation throttle system)

Howard,

Sorry to Jack your thread.

I will start a new thread pertaining to my "ultra lean-burn turbo-charged system"

I just wanted to mention that what you describe as your HATS system is what I'm using to achieve some of the efficiency in my own design.
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Old 03-11-2011, 08:11 AM   #8
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Re: HATS (heat attenuation throttle system)

Don't worry about "my thread"..... I find the discussion interesting. I strongly disagree about the turbo thing.... It goes against all my years of experience. You mention measuring your pressure in the plenum, with a map signal from each runner. So is your pressure measurement that you quoted from the runners or from the plenum? What is the actual pressure/vacuum in the runners. Frankly the pressure in the plenum is meaningless as it is invisible to the engine which sees only the pressure/vacuum in the manifold. A turbo simulates running in heavier, denser air such as lower altitude, which means that the throttle must be closed more tightly for a given power output. My experience is that gas engines run at a lower efficiency at sea level than they do up here where I live (5000'). They have more power at WOT, but burn more fuel at cruise. I have observed this many times, and documented it in the past during trips to the coast. Temperature of the air is also significant.........I get observably higher efficiency in hot weather. I get more full throttle power with cold air, or at sea level, but greater efficiency at cruise with hot air and high altitude.
I am entirely unconvinced of any benefit of the turbo aside from heating the air. The lowered compression ratio of an engine designed for a turbo should offset this.

Howard
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Old 03-11-2011, 08:53 AM   #9
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Re: HATS (heat attenuation throttle system)

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Don't worry about "my thread"..... I find the discussion interesting. I strongly disagree about the turbo thing.... It goes against all my years of experience. You mention measuring your pressure in the plenum, with a map signal from each runner. So is your pressure measurement that you quoted from the runners or from the plenum? What is the actual pressure/vacuum in the runners. Frankly the pressure in the plenum is meaningless as it is invisible to the engine which sees only the pressure/vacuum in the manifold. A turbo simulates running in heavier, denser air such as lower altitude, which means that the throttle must be closed more tightly for a given power output. My experience is that gas engines run at a lower efficiency at sea level than they do up here where I live (5000'). They have more power at WOT, but burn more fuel at cruise. I have observed this many times, and documented it in the past during trips to the coast. Temperature of the air is also significant.........I get observably higher efficiency in hot weather. I get more full throttle power with cold air, or at sea level, but greater efficiency at cruise with hot air and high altitude.
I am entirely unconvinced of any benefit of the turbo aside from heating the air. The lowered compression ratio of an engine designed for a turbo should offset this.

Howard
In this pic its the second vacuum line from the drivers side, not the one going to the boost controller.

It also shares all four signals from the runners about 2" from the head. These are on the underside of the manifold. This is the Honda on my Talon its located between number 2 and 3 cylinder on the bottom of the intake plenum.

Also when I say plenum I'm referring to the intake plenum.
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Old 03-12-2011, 12:39 PM   #10
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Re: HATS (heat attenuation throttle system)

I hate to be rude, but frankly this goes entirely 100% against my 30 years of experience with internal combustion gas engines........ To put it bluntly, I honestly I find it absurd that one could claim to be running boost (below the throttle) and put out less than 100% of the horsepower available at that RPM. It is completely illogical, and irrational. Pressure in the manifold is proportional to power output at a given RPM range. I'm not trying to be insulting, but I simply cannot accept what you are claiming.

Howard
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