Why the Deckplate Mod is Overrated*

[98OzarksRunner]

Originally Posted by Shibby!
Where do people come up with this stuff??

Oxygen doesn't burn?! What does the fuel require to burn using simple chemistry?

How does the combustion engine come up with X amount of POWER?!?!

Those factors of air intake temperature have correlations to air density at that temperature. People don't talk air density for more nitrogen, they talk more air density in relation to more oxygen. A requirement of any combustion.

I'm not trying to be a smartass but some of this stuff is blowing my mind.

Yeah, I caught that too. I also caught a number of other things across three pages of responses and didn't feel it was worth the time to address every one of them.

To more thoroughly address that particular point and to avoid further confusion, the less dense air means there's less available oxygen to burn the fuel (burning is, chemically speaking, rapid oxidation). By warming the air you are decreasing its density and thus decreasing the available oxygen. By decreasing the available oxygen, assume the engine continues to (at the split second the deck plat is removed) inject fuel at the "stock" rate. Once the available oxygen is decreased, the exhaust becomes rich. That rich condition is seen by the O2 sensors and a signal is sent to the fuel system to lean out to compensate. The decrease in available fuel for ignition leads to less power/response/etc.

My point was that, as anyone who's had junior high physical science knows, oxygen doesn't burn. It is an oxidizer (duh!) and combution is defined as the rapid oxidation of a fuel (the gasoline not the oxygen). Oxygen is required for combustion but it doesn't burn; the fuel burns (I don't remember if it was in junior high school physical science that I 'came up with this stuff' but I do remember that much, though I'm a little rusty on the oxidation/reduction equations).

To move a vehicle at a given speed, as spectre6000 noted, takes a given amount of horsepower. It does, as spectre6000 noted, take a relatively small amount of power to maintain a given speed even for a large vehicle like a 4Runner. That horsepower comes from the energy released by burning a fuel (gasoline). There are formulas for calculating exactly how much fuel is required to produce a given amount of horsepower, which take into account things like volumetric efficiency (how efficently the cylinders can be filled at any given RPM), temperature, load, etc. But the bottom line is to make X amount of horsepower it takes Y amount of fuel no matter what the air temperature or density is (except that if the ambient temperature is higher it might take slightly less horsepower [like a fraction of a percent] to move the vehicle in the thinner air).

As spectre6000 also noted, the ECM will correct the mixture (based on the mass of the air detected by the MAF [since it's measuring mass not volume it corrects for air temp - it knows the air is less dense], feedback from the O2 sensors, and a few other sensors, depending on the EFI system) to maintain optimal A/F ratio at a given load. Since warmer air will result in less oxygen at a given airflow the ECM will provide less gasoline to match the oxygen level. That SOUNDS like it will reduce fuel usage and raise economy. It would except that the power output also is reduced and to maintain a given speed you have to put the pedal down more, resulting in more airflow since it still takes Y amount of fuel to produce X amount of horsepower to propel the vehicle at a given speed.

 

[spectre6000]

My point was that, as anyone who's had junior high physical science knows, oxygen doesn't burn. It is an oxidizer (duh!) and combution is defined as the rapid oxidation of a fuel (the gasoline not the oxygen). Oxygen is required for combustion but it doesn't burn; the fuel burns (I don't remember if it was in junior high school physical science that I 'came up with this stuff' but I do remember that much, though I'm a little rusty on the oxidation/reduction equations).

Unfortunately, this represents a fundamental misunderstanding of what it means to "burn". To avoid getting off subject any further down this path,

Combustion - Chemistry .
a.
rapid oxidation accompanied by heat and, usually, light.
b.
chemical combination attended by production of heat and light.
c.
slow oxidation not accompanied by high temperature and light.

There are examples where a combustion reaction can take place utilizing elements other than oxygen (definition b.), but insofar as we are concerned with an internal combustion engine, "burn" means mixing of oxygen and hydrocarbon a la definition a. Fuel + oxygen + ignition = combustion. Without any of the three, you have no burn. Reduce an input, and you reduce the output. Oxygen is not a catalyst (what you're sort of hinting at) in this reaction. Research air fuel ratios if you want to get a better picture.

 

[98OzarksRunner]

Unfortunately, this represents a fundamental misunderstanding of what it means to "burn". To avoid getting off subject any further down this path,



There are examples where a combustion reaction can take place utilizing elements other than oxygen (definition b.), but insofar as we are concerned with an internal combustion engine, "burn" means mixing of oxygen and hydrocarbon a la definition a. Fuel + oxygen + ignition = combustion. Without any of the three, you have no burn. Reduce an input, and you reduce the output. Oxygen is not a catalyst (what you're sort of hinting at) in this reaction. Research air fuel ratios if you want to get a better picture.

Yes, I understand that. It is a chemical reaction in which both oxygen and fuel 'burn' and an energy source is required to initiate the process (as the fuel is oxidized and the oxygen, hydrogen, and carbon atoms form new molecules, mostly water and CO2).

My original point (in response to 4-Ripcord and then to shibby) was that higher temperatures and less oxygen do not increase fuel economy because the key factor in producing power is not the oxygen but the fuel (notwithstanding changes in A/F resulting in less power if the mixture is too rich or too lean) and it takes a given amount of power to move a vehicle at a given speed and a given amount of fuel to produce the necessary power. If one reduced the amount of fuel but maintained the same amount of oxygen, it would would result in less horsepower (not to mention detonation that would likely occur at some point) because the energy comes from the fuel not the oxygen (gasoline is the energy source, not the oxygen, and yes I understand that a certain amount of energy is released as the oxygen atoms are separated from the O2 molecule and join with the hyrdogen and carbon, but the major energy source is the fuel). (It is also true that at a certain point adding more gasoline will reduce power because there is not enough oxygen for the gas to 'burn' and an incomplete burn [or no burn at all] occurs.)

The reason a cooler mixture results in more horsepower is because more oxgyen (in the denser air) allows more fuel to be added. A hotter mixture doesn't contain enough oxygen to burn the same amount of gas as a cooler one, so combustion produces less energy (less fuel can be burned releasing its energy). The ECM will detect the rich burn and reduce the amount of fuel, but this also reduces the amount of power produced. Thus, if the air is hotter, it takes more airflow (but theorically the same amount of fuel) to produce the power to maintain a given speed. The bottom line is that hot engine air will reduce horsepower and will probably not (in an EFI engine) raise fuel economy because it still takes Y amount of gasoline to produce X amount of power (at least in discussion that ignores other minor factors).

 

[Shibby!]

I started skimming through your response because you weren't bringing anything new to the table. Everything you said was already mentioned.

What's your point?

We all know how engines work. From the sounds of it we're all mechanical engineers. Everybody and their dog's are engineers these days.

I don't even know what we're talking about now.

Somebody who has time should get reasonable measurements of the intake tube (at it's smallest point) so we can determine intake air speed. I think that would make some interesting discussion on what's relatively slow...

 

[SCHUNTER1969]

If you are not first you are last

Its all about making the most out of the car and engine. If you haven't done the mod I would suggest do a quick trial. Take the lid off the box for the air filter and take a quick drive. You will notice a difference. I have a 45min drive to work threw some back roads and pass people left and right, nothing like passing people faster!

 

[D Farms]

Its all about making the most out of the car and engine. If you haven't done the mod I would suggest do a quick trial. Take the lid off the box for the air filter and take a quick drive. You will notice a difference. I have a 45min drive to work threw some back roads and pass people left and right, nothing like passing people faster!

yeah you f***ing tell them!!!:gun5:

 

[SpidermanGeek]

You will notice a difference. I have a 45min drive to work threw some back roads and pass people left and right, nothing like passing people faster!

 

[s20004runner]

love it when someone revives old threads... haha

 

[1985taylor1925]

love it when someone revives old threads... haha

Since this thread has been revived, I think I should chime in with some objective info.

Before doing my "hole-in-the-air-box-mod", my 4runner was hella slow. But now I find myself passing people on the highway at 100mph all day long. Heck, the other day I blew past Jay Lenno in a Lambo. After that I retracted my wings I flew off into the stratosphere. shot down a meteorite, and then landed on an aircraft carrier and met the president. All of this because of the deckplate mod.

Holla for the deck plate mod :thumb3:

 

[JohnMc]

After my deckplate mod I'm slowly working my way up through the NHRA Top Fuel rankings.

 

[I_bRAD]

Since this thread has been revived, I think I should chime in with some objective info.

Before doing my "hole-in-the-air-box-mod", my 4runner was hella slow. But now I find myself passing people on the highway at 100mph all day long. Heck, the other day I blew past Jay Lenno in a Lambo. After that I retracted my wings I flew off into the stratosphere. shot down a meteorite, and then landed on an aircraft carrier and met the president. All of this because of the deckplate mod.

Holla for the deck plate mod :thumb3:

Not bad for a start. I took one of those 4" computer fans and put it over the hole for an extra 10hp. Well first it took away 10hp but I realized I had it wired backwards. Now I burn through a set of 4 tires at every stop light.

This weekend I'm working on getting some HIDs in the airbox. I figure I can fit about 30 of em in. The light from the HIDs actually excites the air molecules and causes them to flow faster. Its called convectioncharging and it's the next level, man.

 

[1985taylor1925]

Not bad for a start. I took one of those 4" computer fans and put it over the hole for an extra 10hp. Well first it took away 10hp but I realized I had it wired backwards. Now I burn through a set of 4 tires at every stop light.

This weekend I'm working on getting some HIDs in the airbox. I figure I can fit about 30 of em in. The light from the HIDs actually excites the air molecules and causes them to flow faster. Its called convectioncharging and it's the next level, man.

Nice. You're going for the bling version.

To be honest, I did do the deckplate mod several years ago, and still have it open. I was skeptical that it would actually make any difference in any way. And objectively, the only difference I ever noticed was the sound when under hard acceleration (if such a thing is possible for the 3rd gen).

 

[dirteater4]

Not bad for a start. I took one of those 4" computer fans and put it over the hole for an extra 10hp. Well first it took away 10hp but I realized I had it wired backwards. Now I burn through a set of 4 tires at every stop light.

This weekend I'm working on getting some HIDs in the airbox. I figure I can fit about 30 of em in. The light from the HIDs actually excites the air molecules and causes them to flow faster. Its called convectioncharging and it's the next level, man.

Super pleased with this mod. I also added the "tornado" in the tube just before the MAF for an added 15hp. Considering adding an additional "Tornado" in the exhaust pipe for the turbo sound. Correct me if I'm wrong, doesn't that add another 15hp and win a trophy for rice truck of the year?:thumb3:

 

[I_bRAD]

Be careful with that extra tornado. I've heard you can actually flip your truck from the vortex action.

It's recommended you go with stiffer springs on the passenger side to counteract it.

 

[JayRolla]

Nice. You're going for the bling version.

To be honest, I did do the deckplate mod several years ago, and still have it open. I was skeptical that it would actually make any difference in any way. And objectively, the only difference I ever noticed was the sound when under hard acceleration (if such a thing is possible for the 3rd gen).

Im in hard acceleration light to light just to make it to speed limit. LOL.