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Old 01-21-2012, 07:41 AM   #21 (permalink)
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In November 1969 Nissan built the first 240 Z a car heralded by the automotive media as a revelation of economy reliability and performance. On the air filter of the early Z cars you will see a lever on the side of the intake snorkel. It was marked winter and summer.
A metallic hose ran from the air cleaner down to the exhaust manifold and the flap actuated by the lever closed off the intake snorkel in the front of the air cleaner and forced the air to be drawn from the exhaust manifold.

At the time emissions controls consisted of a PCV, EGR, and air injection.

Anyone here who has been around and driven cars of that era and actually worked on them and understood the operational principles, knows that almost all cars of the era had WAI to mitigate the effects of colder air, in particular air at just above and below freezing temperatures. The variable venturi carburetors of the era were particularly susceptible to "icing", a condition where the higher velocity of the air passing through a variable venturi carburetor would simply not atomize properly, the early Z car was undriveable unless you moved the flap to the winter position.

The same basic design carburetor is used on motorcycles to this day.

While fuel injection vastly improved atomization, it did not change the laws of physics. There is a freezing point of gasoline, and although it is very low temperature wise, you still have the "chill factor" of air at higher velocities making the actual temperature much lower than ambient.

Sentra spent a lot of time and found no benefit with his testing. This is more of a testament to modern fuel injection, than an attempt to defy the laws of physics. Every liquid has properties that change as temperature drop. His testing did not include temperatures that were low enough to freeze salt water, to the extent where you could drive a car across a 4 mile wide river.

I gets much more cold in places more north of here. I've seen 38 below F, some here see that every winter.

I have found that warmer intake air and warmer wintertime coolant exiting the radiator made a difference of about 10 MPG on my Insight and on my VX. I could feel the difference in power, power I didn't need was reduced while efficiency was increased.

regards
Mech

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Old 01-21-2012, 10:33 AM   #22 (permalink)
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This has been an interesting read for me. Even though I don't understand the specifics (pumping losses:throttle opening etc.) I get the main understanding. Warm air is less dense and means less fuel.

I am not a mechanic by any stretch of the imagination. Just a guy who likes to tinker with his truck and squeeze as much as I can get out of it. I do have two questions that I hope someone can explain for me without going into too much techspeak. (I ain't got much fer smarts)

1) Why does this not seem to work with a MAF but does with a MAP? And what is the difference in these two doo-hickeys anyhow?

2) I have heard of the ZX2's using a resistor to "trick" the computer into thinking the intake air is colder than it really is. I realize it is to help advance the timing (I know what that physically means but don't know why it works), but doesn't it use more fuel to compensate for what it thinks is colder/higher density air?

I'm sure these questions seem trivial for the most of you, but I'm always trying to learn something new.

p.s. I made a what I think is a "poor man's WAI" but I don't know how to re-size my pictures to get them posted here. They are about twice as big as the site allows. Any help there would be appreciated also.

Thanks.
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Old 01-21-2012, 11:09 AM   #23 (permalink)
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HOWTO - Images in Ecomodder

This may be of some help.. Post #10 deals with resizing images.

http://ecomodder.com/forum/showthrea...der-18279.html
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Old 01-21-2012, 11:36 AM   #24 (permalink)
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Thanks Nemo. I think I did it right. Going to try and start a new post on my idea. If you don't see it soon then I didn't re-size properly.
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Old 01-21-2012, 12:11 PM   #25 (permalink)
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Quote:
Originally Posted by Old Mechanic View Post
In November 1969 Nissan built the first 240 Z a car heralded by the automotive media as a revelation of economy reliability and performance. On the air filter of the early Z cars you will see a lever on the side of the intake snorkel. It was marked winter and summer.
A metallic hose ran from the air cleaner down to the exhaust manifold and the flap actuated by the lever closed off the intake snorkel in the front of the air cleaner and forced the air to be drawn from the exhaust manifold.

At the time emissions controls consisted of a PCV, EGR, and air injection.

Anyone here who has been around and driven cars of that era and actually worked on them and understood the operational principles, knows that almost all cars of the era had WAI to mitigate the effects of colder air, in particular air at just above and below freezing temperatures. The variable venturi carburetors of the era were particularly susceptible to "icing", a condition where the higher velocity of the air passing through a variable venturi carburetor would simply not atomize properly, the early Z car was undriveable unless you moved the flap to the winter position.

The same basic design carburetor is used on motorcycles to this day.

While fuel injection vastly improved atomization, it did not change the laws of physics. There is a freezing point of gasoline, and although it is very low temperature wise, you still have the "chill factor" of air at higher velocities making the actual temperature much lower than ambient.

Sentra spent a lot of time and found no benefit with his testing. This is more of a testament to modern fuel injection, than an attempt to defy the laws of physics. Every liquid has properties that change as temperature drop. His testing did not include temperatures that were low enough to freeze salt water, to the extent where you could drive a car across a 4 mile wide river.

I gets much more cold in places more north of here. I've seen 38 below F, some here see that every winter.

I have found that warmer intake air and warmer wintertime coolant exiting the radiator made a difference of about 10 MPG on my Insight and on my VX. I could feel the difference in power, power I didn't need was reduced while efficiency was increased.

regards
Mech
That's a thought I had, because I don't like how hot the IAT is in the summer (140+). Thanks for this posting, one of the most welcomed I have seen in a while. Question: I looked for pics of the intake snorkel you mentioned and did not find one... do you know of any?
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Old 01-21-2012, 12:33 PM   #26 (permalink)
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http://i263.photobucket.com/albums/i...4_145140-1.jpg

Here you go. You can see the lever that shuts off the air flow through the snorkel in front of the housing, also the opening at the bottom that went to the tube to the exhaust manifold.

Incidentally, the same model Z car also had cooling lines running to the intake manifold itself to use engine coolant to warm up the manifold.

Heck even my 1937 Ford had a passageway through the intake manifold that used exhaust gas to heat the manifold right under the carburetor.

The latest developments in fuel injection combine superheated fuel with 200 bar pressure injectors to achieve truly homogeneous mixture of the fuel and air in the cylinders. The result is emissions clean enough to eliminate the catalytic converter altogether. In the end you will see fuel injection evolve into a system that ensures the air and fuel molecules are perfectly distributed in the combustion chamber just prior to ignition, without any necessity for a spark to ignite the mixture. Even diesels would benefit from the same technology, and Argonne labs is actually working right now on an engine that uses a combination of gas and diesel fuel.

We will see 60% thermal efficiency in IC engines. The problem is the great variations in load encountered in normal operational scenarios makes such an accomplishment extraordinarily difficult.

It's one of the most basic premises of my in wheel hydraulic design, which eliminates all but the most ideal engine operational parameters which makes true homogeneous combustion much easier to accomplish. They are already there today as I write this post.

regards
Mech
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Old 01-21-2012, 12:46 PM   #27 (permalink)
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Quote:
Originally Posted by hat_man View Post
This has been an interesting read for me. Even though I don't understand the specifics (pumping losses:throttle opening etc.) I get the main understanding. Warm air is less dense and means less fuel.

I am not a mechanic by any stretch of the imagination. Just a guy who likes to tinker with his truck and squeeze as much as I can get out of it. I do have two questions that I hope someone can explain for me without going into too much techspeak. (I ain't got much fer smarts)

1) Why does this not seem to work with a MAF but does with a MAP? And what is the difference in these two doo-hickeys anyhow?

2) I have heard of the ZX2's using a resistor to "trick" the computer into thinking the intake air is colder than it really is. I realize it is to help advance the timing (I know what that physically means but don't know why it works), but doesn't it use more fuel to compensate for what it thinks is colder/higher density air?

I'm sure these questions seem trivial for the most of you, but I'm always trying to learn something new.

p.s. I made a what I think is a "poor man's WAI" but I don't know how to re-size my pictures to get them posted here. They are about twice as big as the site allows. Any help there would be appreciated also.

Thanks.
MAF (MASS AIR FLOW) sensors are mostly fine wire that is heated by an electrical current. As the air flows past the wire the voltage differential, across that wire, is measured by the computer and this voltage signal is used to control injector cycling duration.

MAP (MANIFOLD ABSOLUTE PRESSURE) sensors read the amount of atmospheric pressure that is actually available to the cylinders. This pressure is equal to the atmospheric pressure minus the negative pressure created by flow restrictions. Otherwise know as manifold vacuum. MAP is the opposite of manifold vacuum. Take atmospheric pressure subtract MAP and you have manifold vacuum, the reverse is true.

Both MAP and MAF give the ECU a load signal and the ECU can calculate the amount of fuel to deliver to the cylinders knowing either MAP or MAF. This, combined with RPM, provides a amount of fuel which is then adjusted further by the feedback from the oxygen sensor which measures the content of the oxygen in the exhaust after combustion is complete.

MAP and MAF tell the ECU to deliver X amount of fuel. The oxygen sensor tells the ECU to trim the delivery of fuel slightly to achieve the ideal amount of residual oxygen in the exhaust when it leaves the combustion chamber.

Hope this helps and I hope the explanation is understandable. If not let me know what is still fuzzy and I will try to explain it further.

regards
Mech
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Old 01-21-2012, 01:03 PM   #28 (permalink)
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So I guess it works with a MAP because with different air temps the same cubic volume of air can have more or less pressure because of it's density. The MAP would register this and the MAF wouldn't (based on design?). Am i in the ball park?

If this is the case would/could it be possible to physically heat the air "downstream" of the MAF (if it works with a MAP then why bother) and ahead of the combustion chambers and would it make any difference?

p.s. I posted pics of my "Poor man's WAI" but they don't look very good. Any comments would be appreciated from anyone. Even if they are just to laugh at me. I'm a big boy, I can take it.
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Old 01-21-2012, 01:46 PM   #29 (permalink)
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I would say "probably" about one sensor working better than the other with a WAI. I would also say in my opinion WAI would make a difference with either as long as you are working with "severe cold temperature" as they are both using basically the same fuel.

Also consider the radiator block as a means of increasing the temperature of the coolant leaving the radiator and entering the engine. Since a cooling system is a "worst case scenario" design. it's capacity is far in excess of anything needed in very cold temperatures. In fact for some here, they could probably drive their car using hypermiling techniques with just the heater core for cooling, since their technique reduces waste heat significantly which exacerbates the excess cooling capacity of the stock radiator.

The colder coolant exiting the radiator and entering the engine will absorb more heat from the cylinder walls. Some manufacturers are using this knowledge to restrict air flow over the radiator in cold conditions to increase the temperature of the coolant entering the engine. That temperature can vary by as much as 100 degrees in the extremes of winter and summer conditions. Hotter coolant entering the engine means less heat loss through the cylinder head and walls, as long as it does not create an overheating condition in the engine.

regards
Mech
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Old 01-21-2012, 03:46 PM   #30 (permalink)
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Quote:
Originally Posted by California98Civic View Post
That's a thought I had, because I don't like how hot the IAT is in the summer (140+). Thanks for this posting, one of the most welcomed I have seen in a while. Question: I looked for pics of the intake snorkel you mentioned and did not find one... do you know of any?
Many cars with carburetors or TBI injection had some form of hot-air intake to help with driveability while the engine was cold. They would typically have some form of temperature-based control which would shut off the hot air intake when the engine warms up.

If you try a Google search for "Thermac" or "thermostatic air cleaner", you should get plenty of results.

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