Outer Limits 4x4 Board

Hey guys im going to build my own snorkel for my SD33 and wondering what size pipe to use?? 3" or 4"? And what is the theory behind the size of the snorkel? My current air intake is equivalent of a 2 1/2 " pipe in area.. Also i will most likely put a turbo on my engine down the track and want the snorkel to be future proof.
Going to make something like this..


Cheers Craig

3inch would be plenty...

I put a 4inch snorkel on my 1hz 80 series. I chose 4inch because I figured that the further that the air has to travel and the more bends it has to travel through the more restrictions to clog up the air intake. So if I had a 3 inch snorkel the same amount of air has to travel faster and through tighter bends etc than a 4inch pipe. I also modified the air box to take the 4inch pipe so it doesn't step down to the original 3inch.

bogged wrote:3inch would be plenty...

agree 100%, even a turbo sd33 won't use a huge amount of air, i had a 4" on a 383 chev.
Some people have used 3" and some have used 4" have a good search mq & gq and just decide what you think looks better, then go for that, won't be any harm in using 4", might be a tad dearer, also look at what will be easier to adapt to you current piping.

3" looks funny on patrol i think, they need 4"

I agree 4inch does look better on the bigger fourbies like nissans and toyotas. After seeing some comp pics of what looked like 5 and 6inch snorkels I wished I had gone down that path and got an even bigger one

I have 3 inch and are bleeding I didn't go 4, for more air and wankfactor mainly more air but honesty it runns better than befor when it had no snorkel

This engine is a massive 3.3 powerhouse... WTF would it require a 4inch snorkel for? just easier to get damaged.

My brother has a VE Senator with 6.x litres/3xx kW - all breathing through a 90mm throttle body. I think a 4" would be ample for most 4wds.

This engine is a massive 3.3 powerhouse... WTF would it require a 4inch snorkel for? just easier to get damaged.

I disagree because the way I see it the bigger the pipe the easier and more air can flow through it and I'm pretty sure its impossible to go to big only possible to go to small.
Also the DIY stainless snorkels that a few rigs have don't have a ram head on them which would make them less easy to knock off/damage than the plastic over the counter types. I made up a 4 inch snorkel with a ramair type head on it and it doesn't stick out that much more than a standard plastic type snorkel.

My brother has a VE Senator with 6.x litres/3xx kW - all breathing through a 90mm throttle body. I think a 4" would be ample for most 4wds.

Aren't throttle bottles where the fuel etc is mixed? A snorkel is an extra restriction added to the air intake because of the extra bends and length of it all that the motor has to suck the air through so by rights it should be made the biggest it can be IMHO

Kitika wrote:

My brother has a VE Senator with 6.x litres/3xx kW - all breathing through a 90mm throttle body. I think a 4" would be ample for most 4wds.

Aren't throttle bottles where the fuel etc is mixed? A snorkel is an extra restriction added to the air intake because of the extra bends and length of it all that the motor has to suck the air through so by rights it should be made the biggest it can be IMHO

The throttle body is the mechanism which regulates the air flow into the motor (petrol motor - diesels are different.) A 6 litre engine which produces over 300kW passes all the air it needs through an orifice 90mm wide - with a throttle plate in the middle of it. I don't believe my 3 litre engine producing (nominally) 109kW requires anything larger than that - I have a commercial snorkle and have NFI what of its equivalent cross section.

On the subject of bigger is better, I really don't know. There is a concept that air velocity is important - a "ram" effect, which relies on the velocity of the incoming charge air to do beneficial things (it's a theory...) Too large a diameter will produce a lower air velocity, which may work against this effect - if it is really beneficial. Obviously, too small will be restrictive - but there is a possiblity that larger isn't always better.

Ok ive got some prices now on both 3" and 4".. looks like its going to be about $190 for 3" and $230 for 4" so a little bit of difference 3" to me just looks a bit small.. Might see if i can get 3.5"!! Found this in my searches tho look at the question that says can i put my snorkel head on backwards? they state that you can but you will damage your engine if you go over 25 km/h!! can anyone enlighten me on the theory behind that.. or is it just bs?

http://www.snorkels.com.au/g/33706/snorkel-faqs.html

Cheers Craig

I've been running the snorkel on my sierra backwards for about a year now and there doesn't seem to be any problems. As long as the motor can breathe there shouldn't be any problems, facing it backwards prevents mud and leaves etc getting sucked down the snorkel well that's my experience anyways.
Also your pricing seems a little high is that stainless and all mandrel bends?
I got mine 4inch made out of mild steel for $140

for the 4"
The stainless is $37 per metre plus GST need 2 metres
1 x 90 deg rubber bend $39 each
2 x 45 deg rubber bend $35 each
plus 6 stainless hose clamps and a bit of flexi hose to my air filter ~ $40
Total $230~

the stainless price was from tubesales and the rubber bends from total rubber if you have any idea where to get it cheaper id love to know!!

Cheers Craig

you might also want to get some V shaped rubber to run around the hole you cut in the guard to make it look neat and some flat steel and pop rivets to make your brackey from the snorkel to the A pillar

I did mine about 12 months ago and its going great
here is a few pics to give you an idea of what 4" looks like, 3" looks like a POS on a Patrol

Cheers mate.. very neat Job! You wouldn't happen to remember how much the bends and stainless cost would you??

Thanks Craig

have you priced going to an exhuast shop and just getting some 4 inch tube bent to your exact needs walk in walk out, rather than having rubber joiners etc?

i would think most exhaust places would charge the same or even less than those joins are costing.

just a thought.

That's where I got mine done bent up at an exhaust shop and then got a rubber bend through the guard.
With a ram head, rubber bend and a bit of flexy hose it cost me under $200 even after painting it all up

my snorkle

what do you guys do inside of the guard, do you run the pipework all the way up to the airbox or do you then just join it to the pre filter assembly (which leaks, so makes your snorkel pointless)?

i was going to run mine all the way through, but was unsure what happens when it rains and you start getting water going down it, is it not enough to worry about and it wont harm the motor, or do you need the factory pre filter with the hole in the bottom thats designed to spin water and dust out?

cheers, andrew

The only thing with the one piece snorkels is that if you dint or bend a section you have to replace the whole lot, with a 2 piece with the rubber bends you can just buy another 1m section and cut to size and fit, probably going to be cheaper.

I would definatly go the 4 inch snorkel. I run a 5 on my V8. Going to big is not bad! Going to small is!

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LudaCris