Why the Deckplate Mod is Overrated*

[spectre6000]

*The asterisk is for naturally aspirated engines; only because I've not yet seen (and can't find) evidence for forced induction (supercharged) intakes either way.

The intake on these engines are setup from the factory to handle a bolt on supercharger from the factory; meaning the available air flow for a naturally aspirated engine is far greater than it can actually use; meaning all you're doing is letting hot engine compartment air into your intake; meaning less air density; meaning less oxygen per cubic foot; meaning less available oxygen to burn fuel; meaning the O2 sensors pick up a rich condition (compared to what they expect at startup) and lean out the charge at the injectors; meaning less available power.

Show me a before/after dyno chart where the only delta is a deck plate and I'll change my tune, but that increase in power people keep swearing they "feel" is the same increase in power you get with the TRD stickers save it probably cost more, took longer, and potentially compromised a perfectly good air box... Sorry to step on any toes, but it's a silly trend and I'm hoping a little common sense from an engineering perspective might make a few more clean uncompromised air boxes available 20 years down the road when people are scrounging for parts to keep their 4Runners alive...

I imagine the same is true for forced induction, but they at least have a leg to stand on at the surface level. I can't say anything one way or the other without a dyno chart or any flow specs. Regardless whether or not the additional airflow helps with the heavy breathers, the pre-heated charge isn't helping. You'd be better off opening it up through the fender and on the intake tube in the fender.

$.02 :nerd:

FYI, ISR has very similar connotations, but the technical side is a bit more complicated. Coming soon.

 

[Shibby!]

The intake on these engines are setup from the factory to handle a bolt on supercharger from the factory; meaning the available air flow for a naturally aspirated engine is far greater than it can actually use;

I'm curious where you found this info, or why you think so?

 

[Dark Lord]

Hmmm... very interesting. I haven't done either, but I'm curious to see what some other people have to say about this post.

 

[spectre6000]

I'm curious where you found this info, or why you think so?

What comes in a TRD supercharger kit? Not a complete intake, just the supercharger, some pulleys, tensioners, a belt, some bolts... Not an intake. Ergo, the intake handles enough airflow for the heavier breathing forced induction engines and no additional flow is being had to NA engines. I refer you from here back to the OP.

Hmmm... very interesting. I haven't done either, but I'm curious to see what some other people have to say about this post.

Me too... Probably a lot of flaming. People seem to take a lot of pride in that particular mod, and it's often the first one people do/are advised to do. There's a lot of cultural investment in this particular mod, so waves won't likely be encouraged... See: any disruptive cultural movement; i.e. jazz, rock n' roll, folk music, disco, industrialization, racial integration, etc. Obviously not as noteworthy as any of those examples, but you get the point.

 

[CanadianTRD]

What comes in a TRD supercharger kit? Not a complete intake, just the supercharger, some pulleys, tensioners, a belt, some bolts... Not an intake. Ergo, the intake handles enough airflow for the heavier breathing forced induction engines and no additional flow is being had to NA engines. I refer you from here back to the OP.

You think that decision from Toyota was for optimal engineering? Or cost savings on a global production scale? I would say that the VAST majority of Taco/T4R owners with SC complete the upgrade with a high flow exhaust and a straight shot intake. It only makes logical engineering sense, mechanically forcing so much more air into the combustion chamber and have so much more going out the exhaust ports. All this being said, are the factory components sufficient? Of course, all OEM components are engineered for total sufficiency, but what guy on this forum or any car modifier in history doesnt want MORE than "sufficient"?

Moral? Our intakes for a NA engine are more than adequate. I would say that seems to be the consensus around here as well. So you are correct in your OP, however, i cant imagine the mod being overly detrimental

 

[spectre6000]

You think that decision from Toyota was for optimal engineering? Or cost savings on a global production scale? I would say that the VAST majority of Taco/T4R owners with SC complete the upgrade with a high flow exhaust and a straight shot intake. It only makes logical engineering sense, mechanically forcing so much more air into the combustion chamber and have so much more going out the exhaust ports. All this being said, are the factory components sufficient? Of course, all OEM components are engineered for total sufficiency, but what guy on this forum or any car modifier in history doesnt want MORE than "sufficient"?

Moral? Our intakes for a NA engine are more than adequate. I would say that seems to be the consensus around here as well. So you are correct in your OP

Touché. I'll not begin to pretend that a manufacturer on the scale of Toyota would make an engineering choice to optimize anything that didn't optimize some financial goal first. What do the heads flow from the factory? Has anyone ever done any bench testing on these things outside of Toyota's engineering department? It's hard to say for sure without the numbers to be honest. That's hardly any sort of definitive answer worth taking a stand on, but that's why I left it open for the forced induction. I did say, and will continue to stand by the assertion, that a deck plate mod is hardly ideal for allowing more air into a supercharged intake due to the air density discrepancy. To accomplish the goal people THINK they're accomplishing (only in the case of supercharged engines) you'd have to increase the diameter of the hole in the fender and the associated plumbing AFTER the air box to allow more flow from the relatively thermally isolated air source (i.e. where the stock intake draws air).

 

[fish0281]

the simple fact that this 'mod' draws warmer air from the engine bay (vs the ambient air at the fender) would far outweigh any restriction in the flow path way; not to say there really is much restriction any way, it's relatively low speed flow.

needless to say, i don't think it's worth the time/effort.

as for engineering & cost, they obviously invested in optimizations or they never would have designed it to go through the fender in the first place. if Toyota engineered their vehicles based on cost first, they would not have the reliability record they do.

 

[Greg_Canada]

The proper mod is to do the elbow mod, pull out the tube in the fender, cut off the 90 deg elbow and re-install.
There you go, cold air intake with no restriction. Seriously, that tube in the fender necks down to half the intake pipe size... i was shocked.
It makes a little difference... doesn't struggle as much.

Agreed, i wouldn't do the deckplate mod....

 

[rm2fast]

I am pretty sure I saw somewhere online the deck plate mod and the silencer mod actually decreased the power on dyno i may be wrong but im almost certain i saw this

 

[4-Ripcord]

You are missing a big part of why the deckplate mod is so popular.

It's not that we want more air, clearly the engine is getting enough already. Its that we are getting a more unrestricted and effecient route for the intake. With the stock setup, the intake goes through the fender wall and through another foot and a half of piping with a nozzle, a diffuser, and an elbow. Any engineer will tell you there are losses associated with that. Try breathing through a straw, its harder the longer the straw is. While those losses are small, its still something.

But yes, the elbow mod is also a good solution to this.


On your argument of drawing in hotter air. At low speeds, I completely agree with that. But there is a decent gap around the headlights which are directly in front of the intake box. At higher speeds (35+), the deckplate is actually drawing in cool outside air.

There is an upside to having hot air though. Being less dense, there is less oxygen to burn, so there is less fuel needed; ie better MPGs. Cool air being more dense requires more fuel. Its one of the reasons you experience such drastic fuel economy differences between summer and winter. Its also why you have more power in the winter..

I am interested to see what you have to say about the ISR mod. Replacing a resonating chamber with a strait pipe is less efficient? Since when?

 

[CanadianTRD]

I am pretty sure I saw somewhere online the deck plate mod and the silencer mod actually decreased the power on dyno i may be wrong but im almost certain i saw this

It would have to. We are talking about 3 things here, Air Temperature, Air Mass and Air Flow. The deckplate mod essentially increases the available air mass...hot engine air to boot...thus making your engine work harder to pull the same amount of preset air mass through the throttle body. (based on throttle position, computer chosen ratio). The other mods ie: "cold" air straight shot, enhance air flow efficiency, but not air temperature. The elbow mod slightly enhances both key components, cool and easier flowing air available to your engine, but not much.

 

[rm2fast]

...You can change intakes to cold air, short ram, put polished/ported throttle body's, pulleys, and so on but without a hand held tuner to change factory settings changing these little things are not going to increase hardly any hp all your changing with deck-plate mod or silencer mod is intake sound. But then again everyone has there opinions

 

[fish0281]

I am pretty sure I saw somewhere online the deck plate mod and the silencer mod actually decreased the power on dyno i may be wrong but im almost certain i saw this

wouldn't surprise me. the intake geometry is engineered on purpose - to meet both volume and velocity needs of the engine. one to satisfy the stoichiometry & the other to ensure proper fuel-air delivery to the cylinder (e.g., it's better to have the air "burst into"the chamber rather than seep in... think about shooting a spit ball with a big straw vs a smaller one)

 

[BigFishAllDay]

You asked for a dyno test, here's your dyno test....

Project SportRunner - Deck Plate Mod

 

[Shibby!]

What comes in a TRD supercharger kit? Not a complete intake, just the supercharger, some pulleys, tensioners, a belt, some bolts... Not an intake. Ergo, the intake handles enough airflow for the heavier breathing forced induction engines and no additional flow is being had to NA engines. I refer you from here back to the OP.

The intake was not designed for FI. It works, but wasn't designed that for it.

Superchargers are positive pressure pumps. As they spin they WILL take in air no matter the restriction. There is no, or very little losses.

There is a lot more to vehicle intakes then most aftermarket parts companies know and understand. Simply placing a big pipe on a TB isn't suffice. You want laminar flow to reduce friction. OEM want it to be quiet and pass standards. You want it to be turbulent in other areas to increase fuel atomization, etc.

Exhaust is a similar situation. Changes can increase certain performance while decreasing others. I'm not saying OEM is best, but I am saying they are often a certain level of performance with fit, finish, and cost in mind. Specifically designing an intake for .005% of supercharged 3.4's is simply irrelevant. It's a price per performance for the SC. They could probably have included an intake for 500-800$ but only gain minimum HP.

I'm not saying the deck mod is or is not worth it. I'm simply stating that the intake was not designed for FI.

 

[fish0281]

my point is, the amount of restriction in the stock tube is most likely negligible for all intents & purposes. it'd be like folding the antenna down to cut down on drag.

also, the cold air thing is more related to the thermodynamics of the system than it is the density. the density change of air is very small, but the energy relative to the temp is more considerable.

 

[rm2fast]

Hmm, I bet i got 15hp from my snorkel then:guitar3:

 

[A.Wilson013]

I retract my post.

Read BFAD's post.

 

[rm2fast]

But in all seriousness my 4runner runs super cold sense the snorkel was put on Its a crazy difference when the air sucker is outside the engine compartment i guess

 

[Shibby!]

also, the cold air thing is more related to the thermodynamics of the system than it is the density. the density change of air is very small, but the energy relative to the temp is more considerable.

The thermodynamics IS the air density and the energy. The engine isn't affected by the temperature of the incoming air, but affected about how much oxygen is in that air.

The engine only starts to become affected about air temperature once it can't cool the combustion process. IE, turbo chargers and superchargers pushing high boost and no intercoolers. Both of these devices create and transfer a lot of heat into the air. Turbochargers will glow red absorbing heat from the exhaust and any mechanical moving parts in a blower at that speed will create large amounts of friction and therefore heat. It simply cannot keep up with displacing the heat produced by more fuel and overheated air hence the requirement to cool that intake charge prior to entering the head via intercoolers.

Also somebody mentioned the velocity of air in the intake being relatively low. I'm not sure what you consider it relative to, but if you want, you can calculate the velocity of the air if you take some basic measurements of the intake area. You know the engine is 3.4 liters. You can calculate the consumption of air based on RPM. I bet you'd be surprised at the speed with which the air comes into the engine.