jlwlynn

I know this question has been asked quite often, but after much searching, I haven't been able to find a definitive answer. Has anyone successfully done the deckplate mod on a 4th gen 4runner V8? On my 2003, there is a small (3in or so?) concave section on the front of the intake that looks like it might be a good place. I'm not sure though... I'm kind of new to all of this stuff. I have over 120k on my truck now and just want to cheaply (as possible) increase performance and mpg. I do mostly highway driving and towing a boat on occasion (less often than I would like . I was thinking about the deckplate mod and a high-flow air filter. If it's not worth it... just let me know. And if there's any other mods I should look at, I'd appreciate the insight!

Thanks!

William

I don't have any specific details about the deckplate mod, but there are misconceptions about airflow mods.

First off, if airflow is increased, the fuel injection system has to compensate by adding more fuel to maintain the same fuel mixture. So what this means is with more air comes more fuel.

Being that this is true, how can you have both a power increase and fuel economy increase?

Second, if the deckplate isn't where the greatest restriction is, there will be no airflow increase. Why? Air flow is the same at all places in the air intake at a given time.

And by the way, the greatest restriction may not be in the intake. It could be the heads, it could be the exhaust.

You won't have 450 CFM of airflow at one place and simultaneously have 500 CFM at another place. If you increase one part so that the flow capability increases from 550 CFM to 600 CFM and the flow is restricted elsewhere at 450 CFM, the total flow will still be 450 CFM.

Third, beware of high flow air filters. I have held 2 different K&N air filters up to sunlight and have seen light through pinholes in them. I have trouble believing that they can filter as good as the filter media of a replacement air filter, which has no holes that you can see light through.

After I bought my Tacoma, I went to do the 30k service. I bought a Purolater filter and then discovered the previous owner had installed a K&N. Not only did the Purolater have a much better filter media, but it looked to have about twice the filter surface area.

The increase in surface area over the K&N should mean more flow even if the K&N's holes help it to flow.

Fourth, any potential increase in flow would be at or near full throttle and when the engine is pumping air at the maximum or near maximum amount.

At part throttle, the throttle plate is the most restriction. And if the engine isn't pumping enough air to be restricted by the air filter, deckplate, etc., then any modifications to the filter or deckplate will do no good.

So any increase in flow or power will only be at or near full throttle and at or near redline. How often do you drive like that? Needless to say, not very often. So any mods you do wouldn't be likely to help you.

I'm sure others will post here disagreeing. It's a common disagreement on any forum I've seen this issue discussed, and mainly because there are misconceptions and hype.

Some people may do a mod that causes more intake or exhaust noise, and that, combined with them expecting more power, causes them to think they feel more power.

I figured I would let you know all of this so that you can make an informed decision.

jlwlynn

Thanks! That was definitely informative. It has me thinking twice about the mod and even the filter! I'd like to hear differing opinions (if any) as well. Thanks again!

jlwlynn

Also, I just saw a 'catback system' from Magnaflow I think. It seemed kind of pricey, but would that be worth it? Is it easy to install (for someone who pretty much only knows how to change the oil, antifreeze, etc.)? Is it TOO loud (in the cabin)?

Joe's Toy

Hey jlwlynn maybe check over at www.t4r.org, if you haven't already. There's a lot more 4th gen 4runners over there.

As far as the deckplate goes I was under the impression that the performance gains were because the stock air box restricts to much air therefore not letting the engine breath enough. When you cut a hole in the box (add a deckplate) you aren't giving the engine so much air it has to start throwing in more fuel. You are just making it not have to work so hard for the air it needs. The performance gains have been recorded by numerous people by dynoing before and after the deckplate mod.

jlwlynn

Thanks! And sorry.... my name is Jason... my username is a bit hard to follow.

Thanks,

jason

William

No problem. I like to inform.

I used to think that such mods improved performance. I belong to a forum called The Ranger Station. There's a guy there that works for NASA named Michael A. K. Gross. He is a literal rocket scientist. He knows everything about different types of engines right down to every last detail of what happens in a cumbustion chamber.

Sometimes he may talk above the average person's head, and he can seem like a jerk at times, but he does know what he's talking about. He convinced me (and I also learned on my own) that for the most part intake and exhaust mods are useless on an otherwise stock engine.

When I took the K&N out of my Tacoma and installed the Purolater, I noticed no power loss.

If the engine is modified where it pumps more air/exhaust, then you can modify the whole intake/exhaust and could see a significant gain. Otherwise, simple mods will have little or no gain.

That's not to say that this will be the case with every vehicle, because engines vary among brands. But this is typical.

As far as a cat back exhaust, I have installed 3 different Flowmaster 50 Series exhausts with no power gain. They sounded good, and yet were quiet in the vehicle and quieter outside the vehicle than most any catback. From what I have heard and seen discussed, Magnaflow tends to be louder than the Flowmaster 50 Series. Flowmaster is cheaper. I would choose Flowmaster.

You should find it pretty easy to install.

twilson

Generally when you do exhaust you will be lucky if you get a 5-15hp increase.
Intakes can vary, but are generally similiar. Thats not really a lot when you factor in how much a truck weights. But combined they can add some useable power. I reccomend a dyno run before and after you add mods for a true picture of reality.