The "Official" 1HZ/1HD-T/1HD-FT Airbox/Intake Mod Thread (2 Viewers)

[mudgudgeon]

If you don't cross rivers then a cold air intake is better than a snorkle. It's about 1.5 metres less pipe and 3 fewer bends. Which is a huge flow restriction gone.

But I'm well aware they aren't an option for many.

I'm going to put a snorkel on my 105 eventually. I've been thinking it would be good to do some manometer testing with snokel head facing forward, vs snorkel head facing rear ward, vs open ended pipe facing rearward.
People continually spruke the "ram effect" of a forward facing snorkel, which I'm pretty thoroughly convinced will be non-existant. But I have been wondering whether rearward facing open pipe could perhaps have the opposite effect with a slight vaccum/venturi effect at speed with air rushing passed the end of it.

 

[Wildnlost]

I personally don't like this concept at all.

Any details on the inline filter?

the air will primarily be drawn in via the path of least resistance. If the inline filter is less restrictive, majority of your intake air will be through it. If the filtration isn't up to par, you're potentially feeding your baby dirty air.

FWIW, the genuine toyota filters generally flow better and with better filtration than many aftermarket filters. You may get less pressure drop with a genuine filter.

I here what you are saying. As a motorcycle mechanic I am not a fan of K& N style filters in dirt applications although on road bikes I feel they are useable. Certainly I would like an XXi airbox but I am tapped out for cash. I had most of the component parts in my garage already and it was easy to fab. I will monitor the downstream side of the filter for excessive dirt and most of my driving is on road.
Regarding oem filters has anyone tested pressure drop of different filter brands.
Regarding the path of least resistance that is what I am hoping to create.

 

[Mcreight911]

I here what you are saying. As a motorcycle mechanic I am not a fan of K& N style filters in dirt applications although on road bikes I feel they are useable. Certainly I would like an XXi airbox but I am tapped out for cash. I had most of the component parts in my garage already and it was easy to fab. I will monitor the downstream side of the filter for excessive dirt and most of my driving is on road.
Regarding oem filters has anyone tested pressure drop of different filter brands.
Regarding the path of least resistance that is what I am hoping to create.

My opinion of the The k & N style is they have a bad rep from people putting them in air boxes that don't have proper clearance between the filter and airbox wall. Large volumes of air passing through the small space create to high an air speed Accross the filter depositing oil n dust on the inside of the pipe work after the filter . You don't notice it with the paper filter because it not oiled . Design your airbox around your desired filter . Give it at least 30mm clearance around the filter for round filters the same on the inlet side of a panel filter you'll get much less pressure drop too.

 

[gerg]

Sub sonic ram effect is a myth. Venturi effect is easy to create. Only reason I could see to face rearward would be to avoid large amounts of water or heavy debris like rocks or sticks or perhaps a locust swarm. Even snow can be a problem as I've heard of it clogging up intakes when they are outside of the engine bay.

 

[mudgudgeon]

Regarding oem filters has anyone tested pressure drop of different filter brands.

A member on another 4x4 forum (dougal will remember this from outerlimits4x4 I'm sure) tested of a whole bunch of aftermarket and OEM filters for flow characteristics and filtration.
He worked for a company designing air filtration products and had the right technical knowledge and equipment to test this.
His conclusion was to use OEM in most cases for superior filtration. he recommended OEM over the company he worked for, and said if you go anywhere near dirt, avoid K&N type filters like the plague.
it was done maybe 10yrs ago, but I would expect the results would be the same now.

 

[Dougal]

A member on another 4x4 forum (dougal will remember this from outerlimits4x4 I'm sure) tested of a whole bunch of aftermarket and OEM filters for flow characteristics and filtration.
He worked for a company designing air filtration products and had the right technical knowledge and equipment to test this.
His conclusion was to use OEM in most cases for superior filtration. he recommended OEM over the company he worked for, and said if you go anywhere near dirt, avoid K&N type filters like the plague.
it was done maybe 10yrs ago, but I would expect the results would be the same now.

That and the ISO filter tests show exactly the same thing: ISO 5011 Duramax Air Filter Test Report

If anyone is chasing pressure drop, it would be excellent to get readings inside the filter box. Showing pressure drop in the inlet piping leading to the box and again inside the filter. To see how much is housing and how much is filter.

 

[Wildnlost]

The motorcycle magazine Sport Rider had tested the ram air effect of a popular 900cc sport bike on a dyno that could simulate wind speeds to 150mph. The effect on pressure inside the airfilter housing was barely measurable until 60 mph but there was enough of a pressure increase to add 9hp at 150mph. Being that many of us travel around 60 mph there may be a small effect at the airbox from ram air induction or is it lost to the extra restriction caused by the 1.5 meters of pipe and 3 bends a snorkel adds to the intake piping as dougal mentioned. They did note the benefit of breathing cooler air which for us driving cruisers may be the only advantage for a snorkel. Crossing rivers aside.
Hmmm...how much additional drag does a snorkel add to wind resistance?

Sub sonic ram effect is a myth. Venturi effect is easy to create. Only reason I could see to face rearward would be to avoid large amounts of water or heavy debris like rocks or sticks or perhaps a locust swarm. Even snow can be a problem as I've heard of it clogging up intakes when they are outside of the engine bay.

 

[gerg]

Did they raise the post filter pressure above ambient? I could see lessening negative pressure but stacking pressure waves doesn't happen until you reach the speed of sound.

edit. Very sorry, apparently I dont know as much as I think I do. I shouldn't say ram effect is a myth, but for the average vehicle it is not a useful tool. After reading on a formula one site doing the tests you described it can have a beneficial effect but the design of the intake has to be a very specific shape and placed strategically on the vehicle and, as you stated, doesn't have a statistically significant effect until much higher speeds than I drive.

 

[Wildnlost]

Did they raise the post filter pressure above ambient? I could see lessening negative pressure but stacking pressure waves doesn't happen until you reach the speed of sound.

edit. Very sorry, apparently I dont know as much as I think I do. I shouldn't say ram effect is a myth, but for the average vehicle it is not a useful tool. After reading on a formula one site doing the tests you described it can have a beneficial effect but the design of the intake has to be a very specific shape and placed strategically on the vehicle and, as you stated, doesn't have a statistically significant effect until much higher speeds than I drive.

I think we all know less than we think we do, that,s human nature. I appreciate a place to sound out our ideas and share knowledge. At the end of the day we all love our 3 tons of metal and just want the best for it.
Is my extra filter the best idea....NO but it is what I can build with my current skills and money. I will retest pressure drop after I install it and see if it improves it.

I do like your post regarding 100f drop in egt temps with snorkel fitted. Guessing cooler air not better flow unless the OEM resonator is horribly restrictive. Has anyone ran without the resonator on a 1HDT? Is there a simple way to get cool outside air to the factory air cleaner without a snorkel?
Great feedback ...thanks again for everyones input.
Whiskey time.

Some reading about intake air in general...
Air Induction Basics to Increase Horsepower • Muscle Car DIY

 

[Mcreight911]

When you test pressure drop make sure you test it through the whole rpm/boost range not just full boost . It may sound strange but as the turbo spools is a critical area that's often overlooked by both backyarders and professionals . It's hard to simulate, I guess that's why most tests are just done at a constant air speed and flow rate .

 

[Wildnlost]

When you test pressure drop make sure you test it through the whole rpm/boost range not just full boost . It may sound strange but as the turbo spools is a critical area that's often overlooked by both backyarders and professionals . It's hard to simulate, I guess that's why most tests are just done at a constant air speed and flow rate .

I have an automatic transmission which adds to the fun of testing as well. I tried a couple 2nd gear runs from idle as it stays in second and wont up or down shift. The trouble is it accelerates fast enough that it goes thru the rev range very quickly. it is hard to get a good reading. The manometer I have has a slow refresh rate which complicates things too. I will pay more attention and retest. Thanks

 

[J2P]

I'm putting in a 2094 Duramax stock airbox that I bought for $35 with tubes. I bought a 3" elbow and a 4" to 3" reducer in heavy gauge from the hard ware store and taped up with aluminum tape. The stock elbow from the intake was cut down and fits into the reducer. I did gave to shave a bit off the box bottom.

 

[BDA130]

Hey gang,

My 1991 HDJ81 fianlly made it over on the boat! The PO installed an IC and cold air intake. I'd like to go back to an airbox and 4" snorkel and will likely look at Gturbo down the line. Is XXI still in business? I can't find much of an online presence. I also sent Moonlight a message. Also, I've done some poking around online but can't find a good justification for the cold air intake on these engines...anyone have a quick explanation for me?

 

[gerg]

Cold air is more dense and it's free.

 

[mudgudgeon]

Is XXI still in business? I can't find much of an online presence.

And what an online presence he did have! He had quite a flair for burning people IMO.


Got any pics of the intake that's on it?

 

[AussieHJCruza]

XXi was always OK for me, but some had bad experiences with him. IMHO, Moonlight does a nice airbox, I had one on my 80

 

[SeaJay]

removed the xxi airbox, and replaced it with one from Moonlight Fabrications

 

[arnott1t]

I'm putting in a 2094 Duramax stock airbox that I bought for $35 with tubes. I bought a 3" elbow and a 4" to 3" reducer in heavy gauge from the hard ware store and taped up with aluminum tape. The stock elbow from the intake was cut down and fits into the reducer. I did gave to shave a bit off the box bottom.

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Really like this mod. What year of duramax was it? Notice any difference?

 

[remy]

What is the difference and why throwing the Xxi away?

 

[BDA130]

And what an online presence he did have! He had quite a flair for burning people IMO.


Got any pics of the intake that's on it?

Finally got around to taking some pictures. I feel like this is just sucking up hot engine air. Just noticed too that the PO drilled a nickel sized hole into the backside of the filter....

I'm thinking custom air box and snorkel...any inputs?