Induction piping minimum diameter?

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-Nemesis-

-Nemesis-

New Member
After nearly drowning my 1UZ (water soaked filter) in a comp recently I have been thinking about running a snorkel. Currently I use a VN Commodore airbox as it's the only thing that fits.
I'm thinking of blocking off the normal mouth of the box and plumbing the pipe straight into the bottom/side of the air box and too the snorkel.

Now i'd like to have this snorkel act as a cold air induction system as I don't think my current airflow is adequate (airbox feeds only from the gaps around the headlight.) This type of question is often asked on 4X4 forums but I thought i'd ask the experts.

How big a pipe diameter will I need to use in order to ensure the 1UZ gets too much air (stock engine, k&n, extractors and 3" exhaust), well at least not starved of air? 3" 3.5" 4" ?

The pipe will run from the the front corner of the engine bay, up to near the top of the drivers side door like usual....
 
I am also interested in this - will be keen to see some pics of your setup once you get it sorted out. I have just put a 1UZ into my 40 series Landcruiser and at the moment i just have a pod filter on there to get by, but before i go offroad I want to get an airbox and snorkel made up. My old motor (2F 6Cyl petrol) had a 3 inch stainless, but I was thinking this may be too small. I was leaning towards going about 4"... or what ever the intake size is to keep it the same all the way through.

Also, what material will you be using and will it be a one piece unit or have rubber bends?


Adam
 
I was thinking either stainless pipe with rubber bends for a bit more bling hehehe.. Or using black PVC pipe, the plus for the pvc is it breaks when crushed and can easily be replaced, unlike steel which will bend panels.

The only thing with 4" for me is I think it will look massive on the conservatively sized 4Runner.
 
Another idea I was toying with, because I like on road performance (stock suspension, this thing actually handles) was to run a short cold air type duct to get the most power, tucked under the front like a street car. But carry a length of flexi pipe that can quickly be attached, when I come to a water crossing (i avoid water) I can just temp plumb the piping to the back of the engine bay etc...
 
Yeah thats a good idea, you would need to make it easily accessible to hook up the extra pipe for when its wet. I noticed a number off trucks at Tuff Truck had their regular air intake system with no snorkle, but for the mud stage they were ducting the intake into the cab/ onto the roof/ tray with a pod filter on the end as a temp set up.
 
-Nemesis- said:
Another idea I was toying with, because I like on road performance (stock suspension, this thing actually handles) was to run a short cold air type duct to get the most power, tucked under the front like a street car. ...
Click to expand...

So I did this on the weekend and can happily say the VN airbox WAS restricting air flow. Seems to have heaps more top end now, goes hard! Plus the extractors gave it heaps more bottom and top end.

I wish I could switch between how it was with log headers and old airbox and now to feel the instant difference, there's a huge gain there.

I'm still interested in anyones opinion on my original question though.
 
Nem,

I wouldn't drop below 4" my standard UZ had a 4" system from the arifilter to the AFM (MAF).

My new set up will probably be 5 or more inches.

I don't run a snorkel as they rob a lot of power.

My inlet would be 4' above the ground as is so a snorkel is a little over the top.
 
How do they rob power? I thought if anything they would improve it, breathing direct fresh air. Even if the head is forward facing for a ram effect?
 
Flow area requirements increase with tract length and transitions. Where 3" is OK for relatively short distances it would probably restrict in a snorkel length at full power.

One consideration is using some sort of a check valve like a wet-dry shop vac has. The ball inside floats so if water fills the tank it will block the blower inlet. One or two shop vac check valves could resolve this issue and then a smaller diameter snorkel could be used and would be automatically selected in such conditions. Then again, you may be hesitant to run a check valve as the final defense against hydrolock!
 
-Nemesis- said:
So I did this on the weekend and can happily say the VN airbox WAS restricting air flow. Seems to have heaps more top end now, goes hard! Plus the extractors gave it heaps more bottom and top end.

I wish I could switch between how it was with log headers and old airbox and now to feel the instant difference, there's a huge gain there.

I'm still interested in anyones opinion on my original question though.
Click to expand...

Nem, It's interesting it was restricting the flow. The VN V8 would have similar induction to the 1UZ, so maybe it was just because it was getting hot air from the engine bay. I'm going to remove mine now temporarily just to see if it does make a diff. I've drilled a 4 inch hole in the base of my air cleaner and thru the right hand guard, just as Sideshow has on his ute, so it should be getting fresh air from the wheel well.

As for the snorkel, I've always suspected a long one of even four inch dia may restrict flow. Just as when using a real snorkel in the water, if you were to make it, say, double in length you would have difficulty breathing thru it, so too, surely, a car snorkel must be designed to allow for the losses in a long tube. Fitting a snorkel from a 4 cyl Surf would probably not allow enough air for the 1UZ. Try looking at what size snorkel the V8 Cruisers use as a guide.
 
-Nemesis- said:
Sorry I should have mentioned, i've used the boxy VN V6 filter box. Have you got a pic of your V8 box setup?
Click to expand...

Sorry, I don't seem to have any photos of that, but mine is actually the VN V6 air box. I think I got the idea from Twistys buildup from memory. The box is mounted exactly where the battery was originally, just behind the drivers side headlight and the hole I drilled thru the guard goes thru the guard and the old battery platform. I just used a 4 inch hole saw.
 
im also looking at this for water crossings. Im thinking of just making my own box up and i have limited room near the front drivers side and running the 4" pipe... but like u said nem, it might look to big on the surf. I got some small off cuts... i might hold it up and see how it looks.

Do u know if the landcruiser (80series) snorkels fit? as they are mounted on the drivers side? and just have a 4" intake pipe on it...
 
I haven't tried but I can't see it looking too factory. I doubt the body to pillar angles are the same.

My other thought was running a ram head on a 4" pip but have it only just popping out the side of the gaurd or down low, instead of a full 4" pipe to the roof. No way i'm taking on water crossings higher than the bottom of the windscreen in this thing anyway.
 
i had mine running thur the standard 3f snorkel/airbox on the middy for ages(was losing 30 odd hp) but going to the 4" s/s with rubber bends.

and it is the air box causing the loss which will be changes as well, i was told to put in a gen3 air box in then make an adaptor to the snorkel and have a plate that unbolts for street/no water crossing and just put it on for water crossings
 
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