Deck plate mod, worth it?

octanejunkie

Elite Member
Besides having to clean the air filter more often and stop to plug it during deep water crossings, are there any noticeable differences, like improved MPG?

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No, it's been shown to give 7 horsepower at the wheels but you aren't going to feel that. Another alternative is to remove the elbow on the fender. That is proven to give the same increase without cutting a giant hole. IMO it's not worth it unless you are forced induction where the motor can take advantage of smoother airflow. When the motor is naturally aspirated the intake really works about as good as you can get.
 
Besides having to clean the air filter more often and stop to plug it during deep water crossings, are there any noticeable differences, like improved MPG?

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I just recently did it.

It was cheap and easy, but worth it? I am not certain. I don't feel anything.
 
I did it to my Tacoma back in 2011....never really blown away by it. It made more noise, sounded throatier which was cool, but cleaning the air filter more was something I wasn't keeping up on, so I put the plug back in.
 
No, it's been shown to give 7 horsepower at the wheels but you aren't going to feel that. Another alternative is to remove the elbow on the fender. That is proven to give the same increase without cutting a giant hole. IMO it's not worth it unless you are forced induction where the motor can take advantage of smoother airflow. When the motor is naturally aspirated the intake really works about as good as you can get.

Agree with this. If you're SD'd or turbo'd, then the elbow of the intake can be pretty restrictive to the additional airflow. But under standard conditions, the difference is nominal.
 
Why does everybody think that moving the intake to the engine bay makes the filter dirtier faster?

The current air intake is in the FENDER WELL!!! Right above the tire! What happens there?!?! In the reverse - do you see dust, dirt, etc. build up between the airbox and headlight? Not so much. They are about equal with dirt on the filter. Just 'cause you can see the filter doesn't mean it will be getting dirtier faster.

And water crossings would have to be about even with the bottom of the headlight to get water in the airbox. So, for just about every situation but Aussie style river crossings, you have no worries.

I personally have done the mod and have it closed or not based on mood (daily driving, open... long trips, closed for less sound). It does get a bit loud on throttle with an ISR and the deck plate open.

-Charlie
 
Why does everybody think that moving the intake to the engine bay makes the filter dirtier faster?

I used mesh screen inside my deckplate mod to help catch bigger stuff...because to answer your question, the deckplate mod faces straight at whatever you are driving into, so while I agree that dust can get in through your fender, you are sending more in at 60 mph head on with the mod. I had so much debris caught in my mesh screen that without would have been in the filter...
 
For years I have heard apocryphal tales of horsepower gains from the "deckplate mod."

The story goes that a bigger hole on the airbox lets in more air. More air equals more hp, right?

First, the stock airy intake is more than large enough to supply all the air the 3.4 can consume.

Second, the air supply (no not the crappy band from the 80's) the air supply is regulated by the Throttle Body. You can cut a hole in the hood. You can install an airbox 10 times the size of the stock airbox; you can do ANYTHING you want anywhere along the air intake BUT and the entire air induction system is limited by the size of the Throttle Body and the Throttle Body alone.

The deckplate mod is bunk...nonsense...a myth in the minds of many.

Yes, I know I have committed heresy among the true believers.

.
 
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Besides having to clean the air filter more often and stop to plug it during deep water crossings, are there any noticeable differences, like improved MPG?

Sent from my Nexus 5X using Tapatalk

Will try and keep my comments concise, since I like to talk performance :)

I've learned the hard way the deckplate mod is not smog legal in CA. But seeing that I run a 99 box in a 98 with the smaller MAF and blah blah blah, I bought and extra unmodified 98 box and MAF to put in to pass smog, then take back out. If you are concerned about passing smog, remove the elbow in the fender instead.

For my overboosted S/C engine, it is a noticeable power loss when I switch boxes with no deckplate.

Why does everybody think that moving the intake to the engine bay makes the filter dirtier faster?

The current air intake is in the FENDER WELL!!! Right above the tire! What happens there?!?! In the reverse - do you see dust, dirt, etc. build up between the airbox and headlight? Not so much. They are about equal with dirt on the filter. Just 'cause you can see the filter doesn't mean it will be getting dirtier faster.

And water crossings would have to be about even with the bottom of the headlight to get water in the airbox. So, for just about every situation but Aussie style river crossings, you have no worries.

Well said. I personally have never covered up the deck plate. And if you are worried about water crossings, put the plate back in and it's back to stock.

For years I have heard apocryphal tales of horsepower gains from the "deckplate mod."

The story goes that a bigger hole on the airbox lets in more air. More air equals more hp, right?

First, the stock airy intake is more than large enough to supply all the air the 3.4 can consume.

Second, the air supply (no not the crappy band from the 80's) the air supply is regulated by the Throttle Body. You can cut a hole in the hood. You can install an airbox 10 times the size of the stock airbox; you can do ANYTHING you want anywhere along the air intake BUT and the entire air induction system is limited by the size of the Throttle Body and the Throttle Body alone.

The deckplate mod is bunk...nonsense...a myth in the minds of many.

Yes, I know I have committed heresy among the true believers.

.

He's the hard data showing the deckplate does increase power:

On a supercharged engine: Air Induction - The founder and owner of URD.

On a stock engine: Project SportRunner - Deck Plate Mod - A resident forum member and performance enthusiast.

Enjoy.
 
Just the sound is worth it. I can actually hear my motor when wheeling. Its nice to actually beable to hear and feel the revs instead of hearing nothing and needing to look at the tach.
 
Sounds cool for sure. I did it on my '96 and after I installed the s/c it would throw a lean code whenever I had it open. I've decided to leave the air box as is on the '00.
 
Im up to about 16.5mpg, which is a 1.5/10% improv3ment in fuel economy. At hihway speeds for long drives, In pushing 18mpg with a full trunk of luggage and passengers.

Best $30 ive spent so far.
 
I've learned the hard way the deckplate mod is not smog legal in CA. But seeing that I run a 99 box in a 98 with the smaller MAF and blah blah blah, I bought and extra unmodified 98 box and MAF to put in to pass smog, then take back out. If you are concerned about passing smog, remove the elbow in the fender instead.
I was always under the impression that modifications to the 'dirty' side of the air intake system were legal. I did some searching and couldn't find a good link/explanation one way or the other though.

I did just pass with a deck plate (closed) at a pretty thorough smog place...

-Charlie
 
Seems the deckplate and ISR mods are both heralded and scorned, depending on the audience
http://www.toyota-4runner.org/3rd-gen-t4rs/145264-isr-mod-new-info-must-read.html

If I find a decent airbox in a junkyard one day I might try the deckplate mod, but I like the idea of screening it to keep birds and boulders out, regardless.

A friend of mine had a dual headlamp goat that he converted to single hi/lo bulbs and ran intake scoops to the second headlight hole from a closed air filter housing.
865-728_2.jpg

The idea was MPH forced induction and lower intake air temp rather than breathing "hot" air from inside the engine bay. My seat of the pants dyno didn't register much difference.
 
With that picture, depending on the CFM of the carb used, it wouldn't make much of a difference, if any. The carb would be the bottleneck

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With that picture, depending on the CFM of the carb used, it wouldn't make much of a difference, if any. The carb would be the bottleneck

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Carb and throttle body are bottleneck #1

Cam timing is bottleneck #2

Cylinder volume is bottleneck #3

Chamber volume is bottleneck #4

Chamber swirl and quench is bottleneck #5

Unless the engine's components/characteristics are designed to operate under certain conditions, changing a single parameter after the fact usually creates negligible results, or introduces new problems. In my experience.
 
Carb and throttle body are bottleneck #1

Cam timing is bottleneck #2

Cylinder volume is bottleneck #3

Chamber volume is bottleneck #4

Chamber swirl and quench is bottleneck #5

Unless the engine's components/characteristics are designed to operate under certain conditions, changing a single parameter after the fact usually creates negligible results, or introduces new problems. In my experience.
Haha well, sure, if you wanted the long, more in depth, more accurate version.


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