Snorkel heads.

[Portal Pat]

Hi,
Has anyone done any definitive flow tests on various snorkel heads? I am not so concerned with pipe diameters etc to the airbox, just the snorkel inlet. Thanks in advance.

[Tombie]

The inlet isn’t the restriction.

The diameter of the snorkel is, as is its length and transitions in direction etc.

It has been shown that the “Patrol style” pipe snorkels facing backwards perform worse than forward facing versions.

[mrb505]

Test Results: Donaldson Precleaner vs Safari RAM vs Toyota Head (https://www.aulro.com/afvb/technical-chatter/169594-test-results-donaldson-precleaner-vs-safari-ram-vs-toyota-head.html)
Recently I tried a Toyota mushroom head on my 130 300tdi egt raised from around 620 max with a ram head to 650 with the Toyota one on the same hills similar weather and load. Around here your either going up a hill or down a hill, seems to be more uphills though in the tdi.

[Baytown]

It’s interesting isn’t it.

I see on the replacement Defender, that the snorkel induction is rear facing, but vertical in its execution. I’m sure the team at JLR have a fair idea of what their up to, as do Safari. Chances are they have or have access to a pretty effective flow bench.

Obviously it’s a way safer/more efficient and cleaner looking option than a three inch piece of pipe bent backwards as a fashion statement.

[Tote]

The factory snorkel on my Puma also draws from the rear of the head.

Regards,
Tote

[Tombie]

Factory Puma and Disco 4 RAIs are very restrictive.
By comparison to forward facing offering from Safari.

Even with the Safari, Nuggets filter and pipe work we still generate vacuum on intake of the 90 under throttle.

[Portal Pat]

I took the plunge and changed out the cyclonic style head for a Safari type head. Whilst I can't quantify any difference as I don't have a flow bench, it HAS made a difference. The intake roar has increased, so am assuming less restriction and torque is marginally better.

[W&KO]

Even with the Safari, Nuggets filter and pipe work we still generate vacuum on intake of the 90 under throttle.

Is there a speed where is changes from neg to pos?

[trout1105]

The MAIN reason I like to fit a snorkel/raised air intake is to lessen the amount of dust getting sucked into the air cleaner..
Having the ram head facing forward to me makes sense as having it facing back would suck more dust due the the head creating cavitation..
A forward facing ram head would also assist with the airflow into the engine.

[scarry]

All snorkels have some sort of restriction, even the Safari Armax.

There have been many tests on the Ram effect, but it has been found to be negligible.

[trout1105]

If you have a boat with a water pick up fitted for your bait tank/deck wash have a look at where the inlet is facing and you will find that it is facing forward, The same principle applies to a ram head on a snorkel I would suggest.

[Tombie]

Is there a speed where is changes from neg to pos?

Not one I’d like to find in a Defender.

[rick130]

Not one I’d like to find in a Defender.[emoji23][emoji23][emoji23]

[W&KO]

Not one I’d like to find in a Defender.

Oh, so even at 100km/hr on full throttle it’s would still neg pressure

[Dorian]

If you do some ball park calcs of Dynamic head generated by the air at 100 km/hr, you get an increase in pressure of 0.07 psi.
Even if you quadrupled that due to body effect of the Defender and the change of area from the opening of the to the down tube (?), you still only get 0.24 psi and I reckon that would be generous compared to the reality.
Would that be enough to notice a performance change ?

Cheers Glen

[cjc_td5]

If you have a boat with a water pick up fitted for your bait tank/deck wash have a look at where the inlet is facing and you will find that it is facing forward, The same principle applies to a ram head on a snorkel I would suggest.

I think the density of water vs air is slightly different. With air being less dense, other factors such as friction at bends become more significant.

[Tombie]

Oh, so even at 100km/hr on full throttle it’s would still neg pressure

At WoT it is struggling to get the air it wants at any Speed.

The 90 is well mannered to about 150km/h it starts getting interesting above that, but it will go there (limiter is removed)

[trout1105]

I think the density of water vs air is slightly different. With air being less dense, other factors such as friction at bends become more significant.

Regardless of the density difference the same laws of physics apply.
IF rear facing air intakes were a better option then why are they forward facing on aircraft engines [bigwhistle]

[scarry]

Regardless of the density difference the same laws of physics apply.
IF rear facing air intakes were a better option then why are they forward facing on aircraft engines [bigwhistle]

Why do many rigid trucks have them facing rearwards, and are at the rear of the cab?[tonguewink]

And a plane goes a hell of a lot faster than any vehicle, therefore ram pressure would be a lot more.

[bemm52]

I had my air filter turn to mush and take out the airflow sensor in not overly rainy conditions
Mantec snorkel which from memory sucks from the back

Cheers Paul

[Rick Fischer]

Snorkel for wading, cooler air or less dust, more so with Donaldson.

A bit of physics and aerodynamics ...................with jet engines, "ram" pressure drops with forward speed. Hence the term "static thrust". (max thrust is developed while brakes are on) "Ram" recovery doesn't occur till around 300mph. EPR (engine pressure ratio) is another story [smilebigeye]

Flowing air exerts less pressure than static, hence static vent, and pitot pressure (airspeed indicators work pretty well from wheels rolling) airspeed = pressure difference between pitot and static pressures...................Oh! and airspeed drops as altitude increases. [bigwhistle]

Another wee consideration is overspeeding the turbo. Low tubo outlet pressure causes the controller (of many descriptions) to demand more air and hence more speed. (unless there is an overspeed control) Crook/clogged air filters or inlet tracts are able to cook a turbocharger or possibly fling many bits through many places they are not meant to be [bawl]

Cheers

RF

[ramblingboy42]

I do believe jet engines suck an aeroplane along.

May need a new thread to tackle this one.