Snorkle intake backwards, better fuel economy....GU8

[WogsRus]

OK so the past three weeks i have had to drive 400km intrastate and i figured i would do a little test.

I figured i would see if turning the snorkel intake to point backwards made a difference and without a doubt, on the highway it has made a HUDGE difference.

I did two trips with snorkel forward, diesel from the same stattion, similar day conditions, managed 12.65 average at about 120 kph

Did two trips with snorkel backwards, diesel from same station as always, similar day conditions if not slightly cooler, managed 10.2 l/100 at about 120kph.

All runs were done with cruise control on the same road, under pretty similar conditions.

SO i have left the snorkel backwards around town, and i picked up about 100 kms out of both tanks.

Anyone else found this?

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[jack]

Hi WogRus,
Never tried it but the snorkel will be facing backwards tomorrow. Have a 400k trip to do so will be a good test, thanks for the tip.

[mudnut]

That's very interesting. I would have to guess, the computer would give extra fuel to burn with the extra air being forced in. I wonder what I'll find with my petrol, carby engine when I fit a snorkel.

[Teamdjbilo]

That's awesome and interesting.

Do you lose any power or so?

[BigRAWesty]

Yea I'm with mudnut. At a guess though..
Could be interesting for us mechanical guys..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[Malgreen]

well this is interesting... on thursday the 20th of june i will be doing my usual 1400k trip from Newman to Kalbarri via Coral Bay.
i normally get about 14 ltr per 100k and the last trip was after a service and the induction system cleaned out i average 15.5Lph ( mechanic said it should be better than before??? hmmm )
so i will turn the head around and do the trip and report on here my findings..

[WogsRus]

No loss in power that i noticed, but i do have an exhaust on the car and that helps i guess. It goes against what i would have thought, with the ram effect and so forth, but maybe, just maybe, the troll prefers it teh other way.

Added bonus, open the passenger window and the howl from the turbo and so forth is soooo addictive.

[threedogs]

You dont get ram air as it stops at the filter and can only suck what it needs.
Need a few more results first I think

[Parksy]

Might give this a go, very interesting. I suppose instead of ram air it would be collecting the vortices created by the snorkel head.

[kevin07]

I done this a while ago and got no change didn't do a trip though just around town bit up the m5 and my figures were the same as before. read this elsewhere as well some were reporting better others not. go figure cause I cant suppose its the same as some get 11kpl and others get 16kpl. but it does sound magnificent with the window down.kev

[BearGUST]

Being a turbo I wouldn't think it would make much difference. Ram effect shouldn't really override any turbo pressure.
But hey, if it works - go for it!

[Nvd323]

I agree with BearGUST that's a big difference in fuel savings over something so minor. Ill give it a go and see what I find...

[twisty]

Backwards for me as well. 4.5 lpg/petrol.

With the inlet forward the engine dies when slowing below 40kph (leaning out?). Economy 25l/100k either way. 4 different mechanics, thousands of k's and no one knows why! A mate with a TD42 swears forward facing gives better power and economy.

Give it a try.

[BigRAWesty]

May have been similar conditions, but even 10k/h head wind increases wind speed to $130, but a tail decreases it to $110.. that's a fair change itself and not really noticeable..

Kallen Westbrook
Owner of
Westy's Accessories (http://www.nissanpatrol.com.au/forums/showthread.php?15134-Westy-s-Accessories.-A-small-back-yard-builder.)

[MudRunnerTD]

Have you got a GU8 with a factory snorkel? can you post a pic of the factory snorkel head turned around? must look a little Odd?

[Irvs]

Maybe there is something in it, think of all the stainless snorkels that face backwards. Unless that was just for convenience of manufacturer?

Sent from my GT-I9300T using Tapatalk 2

[WogsRus]

Nope mine is a copy of a Safari, so you can turn the head around backwards

[mudnut]

I have seen many rigs, both turbo or not, with the snorkel either way. I have always wanted to know why. Maybe we can get mythbusters involved, or a one of our forum members has access to a wind tunnel...

[TPC]

I have emailed Mythbusters but doubt I will get a response.

[taslucas]

Maybe there is something in it, think of all the stainless snorkels that face backwards. Unless that was just for convenience of manufacturer?

Sent from my GT-I9300T using Tapatalk 2


I have seen many rigs, both turbo or not, with the snorkel either way. I have always wanted to know why. Maybe we can get mythbusters involved, or a one of our forum members has access to a wind tunnel...

A lot have them facing backwards to stop water, mud, dust from going in there

Sig test. android, MC version 2.4.7.11

[nissannewby]

What sort of driving were you doing prior to your comparative trips? I know mine will be better if it gets to sit on a set speed day in and day out but driving around town I use more fuel.

Snorkel forwards helps a tiny bit but facing backwards doesn't make it any better. Factory snorkels are restrictive so spinning the head won't make a different. What I noted in my first paragraph will though.

[krbrooking]

I turn mine around when u remember and when I am in convoy on dirt/dusty tracks only to try and reduce how much dust enters but not sure of the fuel and power diff. Had it facing backwards for a couple of weeks and can't say I noticed any diff in either, the thing was like said before the turbo whistle did sound awesome but the misses didn't like it.


Sent from my iPhone using Motorculture mobile app

[WogsRus]

The driving was all compared on the highway, exactly the same route and so forth. The comparison has taken a whole month to do so far, now on tank 5 see how we go

[nissannewby]

That's what I mean. I can do the same in my 4.2 it will always be better over long distances. For eg I have moved house and the mrs drives my patrol to work. It uses less fuel while the distance is further simply because she can sit on a set speed all the way to work now instead of stop start traffic b

[WogsRus]

ok sorry you need to go back to page 1

All the test were done on the same bit of road under similar conditions, all were done on a highway run, ie, the comparison drop is for EXACTLY the same conditions, road and the like over 4 trips ie four full tanks.

I did two trips with snorkel forward, diesel from the same station, similar day conditions, managed 12.65 average at about 120 kph,

Did two trips with snorkel backwards, diesel from same station as always, similar day conditions if not slightly cooler, managed 10.2 l/100 at about 120kph.

[threedogs]

Air density/pressure may play a small part , cause we all know on cool crisp nights the Patrol flys
I'm not sold on this but you say its better ,Its better. but I just cant see how.

[mudski]

What ever your smoking. I want some. You sure you didn't fit Hi-Clones as well? :)

[WogsRus]

Come on guys, why would i be bothered to post if i didn;t find any differance.

[mudnut]

They're just jealous, that you get better mileage.:)

[happygu]

Come on guys, why would i be bothered to post if i didn;t find any differance.

Don't worry about them too much .... you know what us mainlanders are like

Mic

[mudski]

Placebo affect maybe.
I really can't see how turning the snorkel backwards gives you better eco. Theoretically, it would be worse. But having said that. If you have the numbers, who am I to argue...

[june]

you also say in your first thread that you had the cruise control on. I thought this would make it worse. I am still not a believer of your test.

[WogsRus]

Cruise control for all highway runs, forward facing intake and backwards, this way it was comparative.

Doing the test again this Friday run number 6, wait and see i guess

[pascal1]

awsome thread!
- has anyone get figure comparing stock vs shornkel economy (before/after instal)?
- is the length/diameter of the shnorkel having any influence vs the needed flow?
- would the shnorkel be recommended only for (slow) offroad drives?
- can you guys easily disconnect the shnorkel (without unmounting) and revert to stock (say when on highways)?

(- last but not least: what happens with shnorkel facing sideway (in addition to the blow sound)?)

[Winnie]

Why would you ever want to disconnect the snorkel? If anything the air you are getting is ever so slightly cooler which would effectively better your fuel consumption.

If you're happy and you know it tap a post!

[twisty]

- has anyone get figure comparing stock vs shornkel economy (before/after instal)?


Yep. No change for me. But I do have a cleaner air filter.

[macca]

Interesting experiment Wogs, I can not turn mine so have no idea if it makes a change with my 4.2.
Thinking facing forward would have some positive pressure at the filter box and rear would be a little negative pressure. If car was doing 100kph with engine off I feel confident that is what you would see.
Does that mean your cars air to fuel mix is a little lean when the top is forward, that is slightly more air in the mix.
When turned the other way it runs a bit richer, higher concentration of fuel getting to the engine and it likes it.
The difference would be minimal, could it make a difference?
Like said before its one for Jamie & Adam on Mythbusters.

[riotpatrol]

Sideway would create vac like a chimney effect, maybe there is more positive pressure from behind, maybe you have hit a sweet spot in your air fuel ratio?

[riotpatrol]

Maybe air pressure coming off the windscreen surrounds? The A9X Torana scope faces backwards at the high pressure area at the base of the screen.

[Drew]

Could the ram air effect be messing with the MAF (giving it a slightly different figure) than what would be without the snorkle ?

[threedogs]

One of the mags did a comparo on general performance mods the average bloke would do to his 4x4.
they used 3 commonly used and popular 4x4s. First they fitted larger exhaust to all and good gains in
performance and economy acheived, They then fitted a snorkle to all the 4x4. Now the engine was
getting cooler air instead of under bonnet temps again small gain in eceonomy.
It maybe in archives of 4wd Action/monthly, made interesting reading

[Wizard52]

I have noticed my air filter has a lot more crap in it after fitting snorkel and needs cleaning far more often so perhaps there is more restriction from filter.
By turning snorkel head backwards, perhaps and I'm only grasping at straws here, filter stays cleaner for longer. As someone else mentioned, a better fuel/air ratio
to suit the individual vehicle may be obtained. This seems to be the most logical answer

[mudnut]

I remember that the Mythbusters had two Identical vehicles for one fuel economy myth. The two vehicles fuel usage was quite different, even before their testing. There is a chance fuel economy that Wogsrus experienced might be unique to his Trol.

[taslucas]

I remember that the Mythbusters had two Identical vehicles for one fuel economy myth. The two vehicles fuel usage was quite different, even before their testing. There is a chance fuel economy that Wogsrus experienced might be unique to his Trol.

I quite often think that mythbusters miss some obvious factors in their "tests"

Sig test. android, MC version 2.4.7.11

[mudnut]

I quite often think that mythbusters miss some obvious factors in their "tests"

Sig test. android, MC version 2.4.7.11

Yeah, Tas , but they blow stuff up!!!!

[taslucas]

Yeah, Tas , but they blow stuff up!!!!

Haha, I didnt say that I don't like it lol

Sig test. android, MC version 2.4.7.11

[macca]

Mythbusters, , big shed, DIY, science, maths, money to buy stuff, explosions, crashes, good mate Busta who has a go at anything, and get paid for it..... perfect job

[Winnie]

Don't forget the hot redhead girl.

If you're happy and you know it tap a post!

[macca]

And she can weld... perfect woman.
Didn't mention her cause I don't want to be a missoggeahman

[happygu]

I have noticed that the air filter does seem to get dirtier with a snorkel in general everyday driving. :SNruQWn369624407:

I am not as convinced with turning the snorkel head around for better economy as others have done tests and they have then concluded that it was better at 45 degrees from the windscreen. Most say that it does nothing. Whatever the result, the air filter would probably end up a fraction cleaner....

I have the same car as Wogs, so it would make sense to do the same tests, but i can't at the moment as i have just changed my exhaust and i need to reestablish the base line economy again.

Mic

[WogsRus]

Well ok just to convince myself, turned the snorkle facing forwards, cold morning like 2 deg C including Black ice, fuel economy according to Ultra Gauge was 12.8, n the way back, turned it back and got to 11.2.

I have not idea WTF is going on ut it works for meeeeeeeeeeeeee

[Robo]

lots of ways to look at this one,
forward facing = lean mixture and the foot goes down to achieve speed, as noted 120kph
backwards = factory settings for mixture,
(assuming factory tune is minus the snorkel).
less right foot for same speed 120kph and improve economy.
engine conditions and tune!!
driving habits from each individual.
then a tail wind can also make a big difference.
lots to get ya thinking, this forum is soooo usefull.

[Rustyboner81]

Wouldnt this be due to the MAF sensors (mass air flow sensor)? It calculates the air flow and corrects the fuel mixtures.. turning the snorkel backwsrds creates negative pressure which reduces the air going into the engine and then adjusts the fuel accordingly.

Be interesting to see how the carbys go. Probably starve of fuel

[threedogs]

Melbourne to the Murray river say 250 Ks What ppl don't know its up hill all the way.
Big fuel difference if you fill at the Murray and drive south, usually with a howling tail wind
and down hill, Just had snorkel fitted and has made no difference so far to economy.
Maybe summer I'll be sourcing cooler air, cant see how it makes a difference as it stops at
the filter. I'm getting about 330k to half tank and 560k when light comes on.

[Wizard52]

Just to see for myself, I turned my genuine Nissan snorkel head sideways as it won't do a full 180 without hitting windscreen.
I was sceptical but last full tank returned 12.8lt per 100k instead of usual 13.25 to 13.75. No change to driving conditions.
Going over to the Island early September so sand driving will distort figures but will check again when I return to normal driving.
It doesn't make sense but appears right.

[Sir Roofy]

melbourne to the murray river say 250 ks what ppl don't know its up hill all the way.
Big fuel difference if you fill at the murray and drive south, usually with a howling tail wind
and down hill, just had snorkel fitted and has made no difference so far to economy.
Maybe summer i'll be sourcing cooler air, cant see how it makes a difference as it stops at
the filter. I'm getting about 330k to half tank and 560k when light comes on.

thats about the same as mine it would vary as driving style is different

[threedogs]

Well my snorkel has improved my economy I now get 360 to
half tank and 12.6 /100 k around town on 305 muddies,
snorkel will remain facing forward

[janderson]

A turbo vehicle will only use the air that is needed, any more and it is expelled out the wast gate. So I would think forced in air is a small factor. As a turbo will suck the air that it needs, so then facing the snorkel to the back should not matter other than supplying cleaner air. Threedogs is also right, coming up to the Murray is all up hill.

[nipagu7]

hi guys , interesting thread .
wogsrus I just had an idea , if you set your ultra gauge to read the MAF sensor then get the patrol upto 100kpa on the highway and see what the maf reading is . do this with the snorkel facing forward , then try it backwards . this would let us know weather or not changing the snorkel direction changes the maf sensor reading , which I assume would change the fuel mixture . over the years I've heard people mention that they get better mileage with a snorkel , but can't remember anyone saying they had better mileage with the head turned backwards until common rail motors came along . ray

[Enthree]

very interesting read.
did anhyone tryt it with a carb yet?

[Throbbinhood]

A turbo vehicle will only use the air that is needed, any more and it is expelled out the wast gate. So I would think forced in air is a small factor. As a turbo will suck the air that it needs, so then facing the snorkel to the back should not matter other than supplying cleaner air. Threedogs is also right, coming up to the Murray is all up hill.

Not quite. Waste gate gets rid of exhaust gases which in turn controls turbine speed and boost. In a diesel with no throttle body, the motor will take all the air it can.

[Throbbinhood]

Backwards for me as well. 4.5 lpg/petrol.

With the inlet forward the engine dies when slowing below 40kph (leaning out?). Economy 25l/100k either way. 4 different mechanics, thousands of k's and no one knows why! A mate with a TD42 swears forward facing gives better power and economy.

Give it a try.

Pretty common on gas motors. Pretty sure there was an equalization pipe or similar that once installed would resolve the issue. Otherwise, turning the snorkel backwards works too.

[Throbbinhood]

And sorry, didn't realize previous poster have gravedug so far back :p

[GQtdauto]

Came across this thread by mistake but had me intrigued, has anyone else tried ?
I turned mine round and seem to be getting more power , not sure about fuel consumption just yet .