Homebrew FIPK, K&N Drop-in Filter, Deckplate, and cleaned MAF/TB = HP! (1 Viewer)

[bamachem]

Just installed a homebrew FIPK type air intake, a K&N Drop-in Filter into the OEM box, added a 4" deckplate (hole w/ cover) to the bottom side of the airbox, and cleaned the MAF and Throttle Body.

HOLY CRAP!

I just unleashed some ponies and some much wanted GROWL!

I was reading about the Tundra airbox pressure drop issues (creates heavy vacuum at WOT) over on Tundra Solutions and I applied what some people used to do to the 3rd gen 4Runners to the UZJ. So far, I'm very pleased with the results.

Here's the basics of what is discussed on the TS thread:

First of all I wanted to know just how well the stock airbox supplied air to my engine. My truck has JBA headers and a custom dual in single outlet 2 1/2" cat back system, K&N drop in filter. For the tests I had a nice stretch of country road I could repeat the tests on all day long. I mounted 2 hose nipples into my stock airbox, one below the filter and one above. I also located a vacuum port right behind the throttle body. The first test was conducted with my K&N drop in filter installed. I placed a vacuum gauge on the lower nipple which would measure any restriction of flow from the inlet tube ( from the fender ). I ran at WOT to 4000 RPM and monitored the vacuum gauge (any vacuum reading would indicate a restriction). Next I did the same on the upper nipple which would measure air filter/inlet tube restriction. I finally used the engine vaccum port, this would give me throttlebody, air filter, inlet tube restriction. I did the same test with a stock toyota filter as well. I repeated the test a few times and got consistant results. To determine WOT I used the lowest spike in the vaccum readings. O.K. Here are the results:

K&N Filter

Intake 0.75" vacuum
Air Filter 0.75" vacuum
Engine 0.75" vacuum

Stock Filter
Intake 0.25" vacuum
Air Filter 1" Vacuum
Engine 1 " Vacuum

To understand what these numbers mean we must look at the differences in vacuum along the way: No difference between the air intake and filter numbers tells us that the K&N filter flows adequately for the engine. As well, no difference between the filter and engine vacuum tells us the throttle body size is adequate for the engine. The restriction is in the air box inlet !

Now if we look at the stock filter numbers we see something a little different. We can see the throttlebody is still fine ( no restriction ) as it should be. But the stock filter has 0.75" of vacuum over the inlet tube vacuum (restriction). The reason for the inlet tube's number to be lower is that the air filter's restriction causes less draw from the airbox and the inlet tube can keep up better during the reduced flow.

These results showed that there was indeed room for improvement so I did a similar mod as described by Tundraholic. From that post I understand that the air box mod is yet someone else's idea, however I am sorry I don't know who, but hats off, good job !

I crunched some numbers and calculated that an 1 1/2" ID second inlet should be sufficient (preferred instead of trying to modify the OE inlet). I used 1 1\4 " PVC fittings which are 1.7" ID. I used a Gates # 20523 2" rad hose ( cut a section) to connect the airbox to supplemental inlet tube. I have posted some pictures to show the installation. I chose to place the inlet behind the right headlight as it is protected yet gets air. The back of the headlight was very clean after 200,000 mi so it is a good place for clean air. All the parts cost $23.00 and took me a couple of hours to do.

After the install I re-ran all the tests, here are the results:

K&N Filter

Intake 0" vacuum
Air Filter 0" vacuum
Engine 0" vacuum

Stock Filter
Intake 0" vacuum
Air Filter 0.75" Vacuum
Engine 0.75 " Vacuum

As you can see, the K&N combination is just what we want to see, the stock filter, while better, only gives some improvement. The numbers show the quantitaive results, as far as my qualitative results... YES there is a noticeable improvement on my truck. Even at lower speeds it helps, here is why, when watching the vacuum gauge during a quick hit of the throttle, there is a vacuum drop to almost zero at 2400 RPM which indicates WOT as commanded by the ECU. CAI's should do the same thing, however the issue is how the intake runners affect the MAF. With this mod, the stock MAF characteristics are maintained as we are only modifying before the air filter. Well worth the $23.00 ! I may just abandon my CAI research from what I have just seen and felt.

We have the same exact airbox (same filter, etc)...

Of course I can't quantify how much difference it made, but I can say that it's very noticable at higher RPM, and even made some improvements at initial light-footed take-offs from a stop. I'll post up some pics tomorrow, but it's basically the stock airbox w/ a re-sealable hole in the front which feeds to the throttle body via a custom intake tube.

The tube is a 3" rubber coupling, a 10" piece of 304L SS Sanitary Process Tubing, and a 3" 90* Rubber Elbow.

Idle sound is pretty much unchanged w/ the hood shut. Get on the throttle a little (1800-2000 RPM) and you can just start to hear it. Open it up and it's a NICE deep V8 sound with a MUCH improved throttle response. While I'm taking pics tomorrow, I'll get a vid clip at WOT as well.

 

[Skolfoppa]

I did that mod on my Tacoma. It was nice to gain a little power, but the drop in mpg was immediately noticeable. Skol.

 

[bamachem]

I did that mod on my Tacoma. It was nice to gain a little power, but the drop in mpg was immediately noticeable. Skol.

LOL - that's a problem with it called "leadous foot-itis". It goes away after the "newness" wears off... Same thing happened after I did it to my old 4Runner. After a couple weeks, I backed off on the heavy foot, and the MPG's went back up and were a little better than before.

Vids: **Right-Click, Save-As: Vid-1** **Right-Click, Save-As: Vid-2**

Pics shortly...

 

[bamachem]

There's actually an open spot between the radiator and the headlight bucket that will allow some airflow into this area at higher speeds. If I'm going to cross some water or in a dusty area, just pop the deckplate back in and it's sealed (o-ring) and back to OEM.

Deckplate was white, so it had to get the obilgatory rattle-can finish...

 

[yoter100]

What did you do with the lines that originally connected to the stock intake??


And what is the cut size of the hole for the deckplate??

 

[Skolfoppa]

I would highly recommend putting a wire mesh screen on the inside of the airbox. Its amazing what debris gets sucked into the engine compartment. Not to mention what can creep in...mice, birds, possums, etc.. Skol.

 

[1loudLX]

This is a nice idea for me since I used to have a real FIPK, but lost it for the snorkel. If I know I'm not going in the water....why not?

 

[hoser]

Why remove the resonator? I was under the impression it was better for performance and not just noise reduction.

 

[1loudLX]

Why remove the resonator? I was under the impression it was better for performance and not just noise reduction.

well i've got a large open box that increases throttle response greatly compared to the resonator. Didnt just put a tube across.

I was talking about the airbox mod.

 

[hoser]

Sorry, meant to direct that question to bamachem since he removed the resonator.

 

[bamachem]

What did you do with the lines that originally connected to the stock intake??


And what is the cut size of the hole for the deckplate??

To try it out, I just blanked them off. No issues. I'm going to either put some nipples on the SS tube or just install some on the top half of the airbox - eventually. There aren't any vacuum leaks since they are all connected to end-user points (Charcoal Canister, Crankcase Vent, etc). I'm going to check mileage first to see if I want to keep this setup. I may end up w/ the Resonator back in, but obviously keeping the K&N and deckplate.

The deckplate is a 4" ID opening, with a ~6" OD. Hole is probably 4.5" diameter. I sat the deckplate flush on the exterior of the box and marked the ID and OD with a pencil. I used a dremel with a router/cutting bit to make the hole just larger than the ID by 1/4" on all sides. Used the dremel to knock down the little ribs in the way on the exterior as well. Installed with Black Silicone RTV, some SS screws, then painted black (was white).

I would highly recommend putting a wire mesh screen on the inside of the airbox. Its amazing what debris gets sucked into the engine compartment. Not to mention what can creep in...mice, birds, possums, etc.. Skol.

Funny you say that - I plan on it. What started this whole thing was the fact that I had a harrowing moment w/ the Hundy a couple weeks back.

I was pulling out into traffic @ 3/4 throttle and it just died. Flat-out-DIED. Could not restart. I was a 1/4-mile from work, so I had a co-worker come tow me to the office. Would turn over and fire off - almost - and then spit, sputter, and die.

Would not idle or anything above. It was starving. People at work said it was starving for fuel. 138K and original filter, so it *had* to be the issue. I was skeptical because it was instant, no signs or symptoms previously. I thought fuel pump. Fuse checked out fine. I pulled the fuel supply line to the filter and turned it over - plenty of pressure - fuel pump was fine. Black crap drained out of the filter, so it needed replacing anyway, so we went to the local Lexus dealer and got one to R&R. Still didn't help.

Couldn't figure it out, so I knew it was either air or fuel, and I was hoping it wasn't the MAF. Opened the air box and just kinda stared at the OEM paper filter. It had a HOLE in it. WTF? ... Pulled the lid of the box up and peeked at the MAF to find a tiny piece of filter paper lodged on the sensor wire. CAREFULLY plucked it off, closed the box, and turned the key .... Needless to say, that was the problem. The hole was weird, all the little scraps were in the bottom of the box. I park outside. Apparently a little mouse got up in there and was looking around and chewed a hole in the filter and then crawled out. Luckily, he wasn't in the TB/Intake when I cranked up!

I got a paper filter to get me by, but I knew I wanted to either go FIPK or non-paper filter along with some mesh. I've been waiting to see which way I was going to go before getting the mesh installed. It's on my short-list for this weekend.

Why remove the resonator? I was under the impression it was better for performance and not just noise reduction.

HuH? De-resonator for performance? Not that I know of.... It silences the intake. It makes it quiet so you don't care if you put your foot down on accelerations or not - that's about the only MPG or performance gain that I know of form them. What have you read?

well i've got a large open box that increases throttle response greatly compared to the resonator. Didnt just put a tube across.

I was talking about the airbox mod.

PIC???? What box?

 

[96r50]

What does FIPK stand for?

 

[bamachem]

What does FIPK stand for?

It's K&N's "Fuel Injection Performance Kit", which is nothing more than a cone filter and a new roto-molded intake tube. The kit elimates the deresonation chambers that the factory one employs as well as the factory airbox (which is the real issue with airflow.

 

[LCHardriver_02]

What does FIPK stand for?

Thank you! Been wondering the same thing.

 

[bkgee]

i'd be interested to test each of the components separately. for instance, on my former tacoma, i removed the elbow inside of the wheel well (it connects fresh air to the air filter box, and has a very restrictive curve). that 'mod' alone made most of the perceived air flow difference. this was after i had used a K&N drop in, and it did much more than the K&N alone, and i ended up replacing the K&N with Napa paper filter (i have my own nits with the K&N).

following all that 'logic' i bet the deck plate alone does most of the improvement. after that, i bet the straighter pipe adds the next highest degree of flow, and the K&N contributes the least. just my guess

 

[bamachem]

According to the Vacuum Gauge tests on a Tundra (same intake and 4.7L engine) that I read on tundrasolutions, the largest pressure drop point was the intake to the box - 0.75" vacuum - the deckplate fixed that. The second thing that caused pressure drop was the OEM paper filter at 0.25" vacuum. When the airbox was opened up and a K&N was used, there was 0" vacuum before the filter, after the filter, and after the intake @ the throttle body.

The straight intake is for noise and does nothing for performance... However, so does the deckplate.

 

[hoser]

HuH? De-resonator for performance? Not that I know of.... It silences the intake. It makes it quiet so you don't care if you put your foot down on accelerations or not - that's about the only MPG or performance gain that I know of form them. What have you read??

I'm saying removing the resonator, though it may sound throatier, it reduces performance and can make your MAF sensor go haywire. Here's a good post:

Air induction systems primer. - Bimmerforums - The Ultimate BMW Forum

 

[bamachem]

hmmmm, interesting read. I'm not opposed to putting the stock tubing back on. The deckplate is going to be the most beneficial, with the filter being behind it...

 

[NMuzj100]

I'd be interested to see what the comparative air intake temps are. Seems to me you will be pulling in hot underhood air.

Maybe a dual filter and intake system or a big diesel airbox would reduce restriction.

 

[vxlc80]

I'm saying removing the resonator, though it may sound throatier, it reduces performance and can make your MAF sensor go haywire. Here's a good post:

Air induction systems primer. - Bimmerforums - The Ultimate BMW Forum

+1 i removed my k&n fipk due to poor performance but it sounds i think it has something got to do with the resonator just my opinion