Snorkels - are they as good as “they” say.?

aastek · Veteran Member

Snorkels - are they as good as “they” say.?

Whenarewethere · Guru

They reduce efficiency as the air has to go through more plumbing & bends.

Peter_n_Margaret · Guru

Fuel economy can be best improved by paying a lot of attention to the right foot.
Cheers,
Peter

Aus-Kiwi · Guru

Its more about have induction high so water doesnt get sucked into engine .When crossing any water . Another benefit ? It sucks fresh cold air in away from engine bay .Often cleaner air if dusty roads ??. The ductwork is much larger than std !!

KJB · Guru

Aus-Kiwi wrote:
Its more about have induction high so water doesnt get sucked into engine .When crossing any water . Another benefit ? It sucks fresh cold air in away from engine bay .Often cleaner air if dusty roads ??. The ductwork is much larger than std !!

Simple and practical - and they work! Not about economy......

Magnarc · Guru

Aus-Kiwi wrote:
Its more about have induction high so water doesnt get sucked into engine .When crossing any water . Another benefit ? It sucks fresh cold air in away from engine bay .Often cleaner air if dusty roads ??. The ductwork is much larger than std !!

Simple and practical - and they work! Not about economy......

Ditto.

Bicyclecamper · Guru

Formally an owner of an 2009 Pathfinder r51 series, and the fuel economy was crap. never got it to be better, and towing average 20 litres/100km, and it is only 2.5 lt 4 cylinder engine. Loved the vehicle, until 2019, then it became a lemon, just a money pit after that.. and .I don't think you will ever solve the fuel usage issues with it, as I spent a fair bit trying to and it never made a difference, so sold it, and went back to a Vitara, I have owned 4 of them before, so I trust them wholeheartedly.

-- Edited by Bicyclecamper on Wednesday 25th of May 2022 08:22:25 PM

yobarr · Guru

aastek wrote:
Looking for improved fuel economy
i have a 2012 Nissan Pathfinder and I am pulling a 2.5tonne caravan. I already run a diesel chip

Best to get a tune by someone who actually knows what they're doing. Mine increased power by 25% and torque by 45%, and I achieve 5.8km/litre at 6800kg GCM. Not bad for little V8! Beware of people who don't really know how to tune. Cheers

shakey55 · Senior Member

Different vehicle. I have 2005 patrol (4.2 td). Found it sluggish a few years ago, took it to a quality diesel mechanic (I used JC Diesel - Narellan). Had a long discussion which resulted in 3 exhaust, new injectors, quality tuning and its a different vehicle. Im told the checking/replacing of injectors about every 100,000 kms will keep fuel consumption in good order.

Not being critical, but you are making a 2.5 litre (possibly 3 litre), work hard all the time towing your heavy van.

Snorkels work - giving cool fresh air, rather than hot contaminated air from the engine bay.

-- Edited by shakey55 on Thursday 26th of May 2022 05:37:45 AM

Hewy54 · Senior Member

Whenarewethere wrote:
They reduce efficiency as the air has to go through more plumbing & bends.

I think you will find that the opposite is true.

They increase efficiency due to the ram effect as well as keeping the air taken in cleaner.

The main reason for fitting a snorkel is to give a lesser chance of water ingress during a water crossing.

There may be a marginal effect of improved fuel consumption, but I have not noticed this in either of the vehicles I have had with a snorkel.

Whenarewethere · Guru

Years ago I calculated the wind resistance and on the additional plumbing. A lot of air has to get through every minute. At least on my Land Rover it already gets air from outside on the passenger side.

Peter_n_Margaret · Guru

Snorkels work - giving cool fresh air, rather than hot contaminated air from the engine bay.

They increase efficiency due to the ram effect .

The above varies dramatically from vehicle to vehicle. In some cases it is true in many it is not.

The main reason for fitting a snorkel is to give a lesser chance of water ingress during a water crossing.

Mostly true, but unless the water is deeper than the original air intake, so what?

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Cheers,

Peter

PeterD · Guru

Hewy54 wrote:
They increase efficiency due to the ram effect

Fallacy. calculations and experiments were made way back when racing cars were much slower. These showed that using a funnel to increase the air flow actually had a negative effect. The overall drag caused by the supposed free supercharging produced a larger drop in performance than the gain from the increased induction pressure.

The only benefit I can see from the forward facing scoop would only negate the losses from the longer induction path the snorkel introduces.

yobarr · Guru

PeterD wrote:
Hewy54 wrote:
They increase efficiency due to the ram effect
Fallacy. calculations and experiments were made way back when racing cars were much slower. These showed that using a funnel to increase the air flow actually had a negative effect. The overall drag caused by the supposed free supercharging produced a larger drop in performance than the gain from the increased induction pressure.
The only benefit I can see from the forward facing scoop would only negate the losses from the longer induction path the snorkel introduces.

Might I suggest that the drag from a Ram air intake on a decent sized 4wd, towing a 'brick' (caravan) would be significantly less than that from a Ram sticking up above a racing car, albeit a 'much slower' racing car? Quite frankly, I believe that it would have such a small effect that it would be immeasurable when there is a far bigger air disturbance , in the form of a chunky car and a caravan directly behind. Cheers

PeterD · Guru

yobarr wrote:
Might I suggest that the drag from a Ram air intake on a decent sized 4wd, towing a 'brick' (caravan)

You are correct there, just the same as I said the effect it will have on the boost to the engines performance - SFA. The two effects are reciprocal.

Whenarewethere · Guru

& not to forget to raise the transmission breather.

Peter_n_Margaret · Guru

Whenarewethere wrote:
& not to forget to raise the transmission breather.

Yep.

Water crossings deeper than the axles need breathers on the transfer case, the gearbox, the clutch housing, and both diffs to stop them sucking in water as they suddenly cool. Even then, the wheel bearings are at risk of getting water in them and should be opened and checked at the first opportunity.

Cheers,

Peter

aastek · Veteran Member

Thanks for everyones contribution.
As seen from all the postings, there is such a wide variety of opinions
Google searching on this subject also has a broad perspective on the economic effectiveness/benefits of snorkels, apart from the obvious benefits during water crossings

Peter_n_Margaret · Guru

Vehicle manufacturers are keen to improve fuel economy. It sells cars.
If a snorkel improved economy or provider significant other real benefits, they would all have done it a long time ago.
Cheers,
Peter

Whenarewethere · Guru

I have done enough km with different tyres on my car that my current all terrain tyres use about 0.3L/100km more fuel than the previous road tyres.

I'm sure all the people who have stuck a snorkel on have done due diligence and will have collected enough data to say how many L/100km things have improved, or not.

yobarr · Guru

Whenarewethere wrote:
I have done enough km with different tyres on my car that my current all terrain tyres use about 0.3L/100km more fuel than the previous road tyres.

I'm sure all the people who have stuck a snorkel on have done due diligence and will have collected enough data to say how many L/100km things have improved, or not.

Can't help you there, Jonathan! My car came with a factory fitted snorkel but I did change the intake to a 'Ram' type when I fitted 3" exhausts and got the engine tuned for 25% more power and 45% more torque. Didn't do economy figures before the work, but now, loaded to my 6800kg GCM, I achieve 5.8km/litre, or 17 litres/100km. Not bad for the little V8. Happy with that, and, on paper,I can get 1000km between fills. However, I rarely exceed 900km, just because! Cheers

erad · Guru

Hewey54 wrote, in part "They increase efficiency due to the ram effect".

Years ago, the Snowy Mountains Authority used to have its own fleet of aircraft, and a qualified aero mechanic to maintain the fleet. Near the end, the SMA bought 2 Pilatus Porter aircraft - STOL (Short Take Off and Landing). From memory, the maximum speed of the beasts was 120 knots - they were not fast. The aero mechanic used to clean the engine by standing on the engine cowling and chucking a bucket of detergent and water into the air intake as the engine was running (propeller feathered). We commented that he would have his bum close to the propeller, but he said he was well back from it. The air intake faced backwards. We queried him about this and he replied that in order to get a decent ram effect, you needed to be doing at least 150 and preferably 200 knots (over 300 km/h). SO if Pilatus aircraft point their air intake backward, they must have a good reason.

iana · Guru

Out of curiosity did those Pilatus Porters have Turbo-Prop engines?

PeterD · Guru

Pilatus PC-6 Porter. The PC-6/340 Porter and PC-6/350 Porter had 6 cylinder Lycoming engines. The later ones had Turbomeca Astazou, Garrett Air Research TPE 331 or Pratt & Whitney Canada PT6A turbo prop engines.

"The air intake faced backwards." I would not call the intake as pointing that way but it certainly was no pointing forward.

iana · Guru

Pilatus Porter.jpg

The turbo Prop model certainly looks as though the air inlet is pointing forward to me.

Just doesn't seem to be anyway to reduce picture size. Sorry about that.

-- Edited by iana on Saturday 28th of May 2022 05:33:54 PM

-- Edited by iana on Saturday 28th of May 2022 06:35:01 PM

-- Edited by iana on Saturday 28th of May 2022 09:18:10 PM

erad · Guru

We never saw this guy cleaning the engine (probably a good idea at the time), but he did say that he stood on a ladder and threw a bucket of water/detergent into the air intake. When we asked what happened, he said it all came out as extra thrust. I gather he must have somehow got between the whirring propeller and the air intake - not much room. He did say that the engine was running at the time. Obviously it must have been with the propeller at neutral pitch. But his main pitch was that the ram effect was of little value unless you were travelling at much higher speeds than this aircraft could do.

iana · Guru

I think that he was bending the truth a little. These engine do have to have a controlled compressor wash, so not quite throwing a bucket of water into the air intake, there is a spray wand installed for the purpose, and a controlled flow. Its to clean the compressor blades, to reduce abrasion and restore efficiency.
These engines which are probably the most popular turbo-prop engines made, are a bit strange, in that they are made the wrong way around, the intake and compressor section is at the rear, and the hot end is at the front. Your friend probably meant that when doing this work, he was a safe distance from the prop.

iana · Guru

During my stay in Papa new Guinea, we did a bit of 4wd trekking about the place, this involved fording rivers using our Toyota land Cruisers and Nissan patrols. None fitted with snorkels, we had no trouble with the engines ingesting water, but heaps of trouble with ignition, probably caused by the fan picking up water and spraying it over the electrics.
I think the main purpose of a snorkel is so that its a blokey thing to do.

Whenarewethere · Guru

The additional air pressure calculations are quite complex starting with the inverse square of the volume of the air difference.

At the end of the day you might end up with 1 psi extra at 100kph but as most engines are turbo these days it make effectively no difference.

The only benifit you get is the extra insects you collect which you can BBQ each evening saving funds in bought protein.

yobarr · Guru

iana wrote:
During my stay in Papa new Guinea, we did a bit of 4wd trekking about the place, this involved fording rivers using our Toyota land Cruisers and Nissan patrols. None fitted with snorkels, we had no trouble with the engines ingesting water, but heaps of trouble with ignition, probably caused by the fan picking up water and spraying it over the electrics.
I think the main purpose of a snorkel is so that its a blokey thing to do.

Definitely a "Blokey thing". Why else would you fit a snorkel? Cheers