Patrol 4x4 - Nissan Patrol Forum banner

1 - 20 of 68 Posts

·
Registered
nissan
Joined
·
173 Posts
Discussion Starter #1
gday all

im about to build a stainless snorkel and im trying to work out which way to have the snorkel head front or rear facing, if i go front facing ill get a ram head but if i go rear ill weld a 45 deg on top. what are the pro's and con's of either direction.

ive seen heaps of pics and searched the topic but nobody has really put an answer to it.
your thought and opinions please

kezz
 

·
mechanical necromancer
Joined
·
1,682 Posts
I have had forwards and backwards facing heads on a 4" snorkel it started out facing the rear and a mechanic I worked with said with it facing rear you get a vacuum effect from air passing by when you drive at highway speeds. It made sense, but it's only really going to cause an effect at 80/110 cruising speeds.

But if you play in dirt and mud lots then your intake is facing away from the crud you are driving into. With it facing forwards you do get a "ram" effect but you also get any crap you are driving into straight into the snorkel and possibly the airfilter.

Realistically they both have their pro's and con's..
 

·
Registered
Joined
·
1,502 Posts
If you are running a LPG petrol motor you generally have to run the head backwards as when facing forward it places positive pressure on the gas diaphram and will cause it to miss pop and backfire.
 

·
Registered
nissan
Joined
·
173 Posts
Discussion Starter #4
so im better putting a ram head on and turn it around when i play in the mud.

im running a sd33t
 

·
Registered
nissan patrol gq
Joined
·
1,045 Posts
How bout the stainless snorkels with just a bend back over roof. No snorkel head.like millweld.im on gas but I think having a ram head backwards looks ****.

Sent from my GT-I9000T using Tapatalk
 

·
Registered
nissan patrol
Joined
·
37 Posts
Hey mate,
I use a ram head, then just spin it around when it gets muddy.
Best of both designs IMO.
 

·
Registered
nissan patrol
Joined
·
1,364 Posts
i have always planned to get an air ram, but i dont have one at the moment so i have a 90 degree elbow facing backwards. Im on LPG so this is suppose to be ideal anyway, if you are on lpg and want it foward then you can put an equaliser pipe in which will stop the backfires.

to be honest my fuel usage has gone up slightly since i put the snorkel on, im putting this down to it being starved of air on the highway. I dont have any figures to back this up, but i know before the snorkel install id use just under half a tank to get to work and back, Now i use smack on half a tank.
 

·
Registered
nissan
Joined
·
555 Posts
Just finished mine facing towards rear drivers side and it makes no difference
Stress less do it the way it looks best for you
All the ram and vacuum IMO is dribble until someone proves it
 

·
KICKEN BACK IN THE BUSH
nissan gq
Joined
·
4,690 Posts
Interesting topic Bigkezz

I too am looking into a snorkel for the SD33T ute

Im still not convinced,
Snorkel yes/no
Rearward facing yes/no
Forward facing yes/no

Or wether the cost to make or buy a snorkel are worth the benefits at all

Or is it all a w*nk factor ???
 

·
Registered
nissan
Joined
·
173 Posts
Discussion Starter #13
its ended up costing me $108 for 2m of 76mm stainless 2x 90 deg mandrell bends and 1 x 45 deg and it works out that ill have a meter of tube left because the bends have about 100 to 150 long tails.
so for around $110 for a full stainless welded snorkel and around $40 to $50 for a ram head if i go that way, its about $150 cheaper than a plastic one..
 

·
Registered
nissan
Joined
·
11,121 Posts
Just finished mine facing towards rear drivers side and it makes no difference
Stress less do it the way it looks best for you
All the ram and vacuum IMO is dribble until someone proves it
i honestly reckon mine uses more fuel since i put the snorkel on with the head facing backwards. and it went better before the snorkel as well. but ive done a few creek crossings that wouldnt be nice without it.
i do plan on soon enough turning it forward but it isnt that simple haha.
 

·
Registered
nissan
Joined
·
555 Posts
how much fuel economy are we talking? like noticeable without doing the math?

you think it went better? as in more power? mine is completely opposite to that if yours was the case..
 

·
Registered
nissan
Joined
·
11,121 Posts
probs round 30 or so kms round town but probs 100 less on the highway.
and na goes slower since fitment. and thats with a 4" snorkel into zd30 air box with disco spud turbo.
 

·
Registered
nissan
Joined
·
555 Posts
it goes slower!
did you fit larger tyres at the same time?
ill figure out my fuel economy when i get back after easter then and that will tell the story

but with the snorkel it goes quicker for me, more responsive
 

·
Registered
nissan gu patrol
Joined
·
292 Posts
from the donaldson website - should answer any queries regarding ram facing direction....

Installation Note
All Air Ram inlet hoods MUST be installed with the screen facing forward to ensure best performance.
Airflow restriction will not be reduced if the Air Ram faces sideways; but if it faces backwards,
restriction does increase and adversely affects engine performance.

Again from Donaldson regarding the water seperation function of an air ram. There is a drawing that goes with the description but i couldn't copt it. Water seperation will not work if the ram is facing backward...

How Air Ram™ Works
1- Moisture-filled air enters Air Ram.
2- Air is naturally forced against rear
wall. Moisture sticks to the wall,
separating from the air.
3- Moisture collects on the Air Ram
wall and drains down to and out
of the drain hole.
4- Virtually moisture-free air passes
into air cleaner.

 

·
Registered
nissan
Joined
·
92 Posts
With the ram facing backwards a localised negative pressure will be created in the inlet of the snorkel, so at speeds it will be trying to suck the air out of the air box instead of providing air. At slow speeds it wont have any effect as the air flowing past the inlet is not fast enough to create the low pressure in the snorkel. So if a lot of slow speed driving is done backwards is ok, but if you are driving at speeds at any more than about 80kmh a forwards facing ram head is required.
 

·
Sydoforumsuperfan :)
nissan gu patrol
Joined
·
8,929 Posts
This is from XXi Industries so don't bust my balls

Busting myths time again...
Unfortunately, more people continuously get dooped into sales hype and unsubstantiated claims. Many companies don't do ANY research or development on their own products, just chuck it together and sell it. Its upto you to sort out fiction from fact and results!
So lets start busting them ..again..
BACKWARDS FACING SNORKELS.
In the early 90's we too used to turn our ram head around for mud events. But we turned it straight back after it was over. Basic fluid dynamics...
On a dyno or low speed = fine. As soon as your moving with any decent speed it is trying to cause a vacuum for your air flow. 1 argument is its tucked close to the pillar/body. Stick your hand out the window and see for yourself. This greatly retards air velocity (AND AIR SPEED IS KEY TO PERFORMANCE). When not moving it can reach its maximum velocity over a much shorter distance. At speed the actual intake air diameter is choked down - rendering your new 4" mandrel snorkel as useless (performance wise). Starving a turbo of flow by any means increases turbine backpressure and makes the turbo work harder = hotter discharge temps, and more load on the turbo causing reduced maximum boost and excessive wear over long durations.
Water Ingress... Backwards facing ram heads are only detrimental to performance. Open faced 4" backwards facing snorkels (possum traps) are incredibly problematic. Guaranteed to ingest water (parked or moving). Forward facing Ram heads have previsions in place for water ingress already. Ontop of this, plastic airtec/safari etc etc have a 20mm lip at the point the snorkel enters the guard.
80 Series snorkels
Safair/airtec snorkels - good for 25/26psi
4" mandrel with 4" forward ram head - good for 35psi (perfect)
Most owners are far better off sticking with their factory/safari/airtec snorkels. We do not condone to use of a 4" backwards facing snorkel with any of our products.
 
1 - 20 of 68 Posts
Top