Effects of snorkelling an LPG engine Q.

[sudso]

I want to put a snorkel on my dual fuel EFI V6 Rodeo.
I've heard reports that positive air pressure can occur in some circumstances and stuff the mixtures up.

I would have thought that even at idle the engine would suck in more air than can be rammed through the intake even at highway speeds into a headwind.
Correct me if I'm wrong.

I know some guys rig up a balance pipe but before I blow my doe on a snorkel I want to find out the con's of fitting one to my engine which runs predominantly on LPG.

Any "mathematicians" out there who can work out the air flows?
My engine is a 3.2 lt.
Here are the 2 sizes, I dont know which is for mine yet:

· Surface Area Intake = 7225mm sq ( 3" Diam )
· Snorkel Body Intake = 4419mm sq ( 3.5" Diam )

· Surface Area Intake = 8429mm sq ( 3" Diam )
· Snorkel Body Intake = 5155mm sq ( 3.5" Diam )

I know there's a few variables involved but it might tell me if I'll get positive pressure or not.


cheers
sudso

[Beastmavster]

snorkel air intake pointed forward has a certain ram air effect. If you point it backwards this would reduce the impact, so that the engine only sucks as much air as it wants, rather than how much it's fed.

Int he end though the "ram air" intake effect is only worth a small amount of impact to the total airflow, and only at higher speeds.

Kawasaki ran their ram air intake motorcycles a little rich at top end to cope with 180mph top end - if you think your 4wd will do that please show us pics

Generally speaking the amount of leaning out caused by it shouldnt have much of an impact to you fuel mixture ratio.

[Loanrangie]

Use a donaldson type pre cleaner on your snorkle instead of the ram - they look dicky when reversed.

[sudso]

Use a donaldson type pre cleaner on your snorkle instead of the ram - they look dicky when reversed.

You mean the big ugly ones that look like an oversized circumcised knob?

[Beastmavster]

well not everyone has the phallic thing going but yes, i see your POINT.

[sudso]

snorkel air intake pointed forward has a certain ram air effect. If you point it backwards this would reduce the impact, so that the engine only sucks as much air as it wants, rather than how much it's fed.

Int he end though the "ram air" intake effect is only worth a small amount of impact to the total airflow, and only at higher speeds.

Kawasaki ran their ram air intake motorcycles a little rich at top end to cope with 180mph top end - if you think your 4wd will do that please show us pics

Generally speaking the amount of leaning out caused by it shouldnt have much of an impact to you fuel mixture ratio.

Maybe 180kmh

Still waiting for someone to work out the air flows for me

[sudso]

well not everyone has the phallic thing going but yes, i see your POINT.

[Beastmavster]

snorkel air intake pointed forward has a certain ram air effect. If you point it backwards this would reduce the impact, so that the engine only sucks as much air as it wants, rather than how much it's fed.

Int he end though the "ram air" intake effect is only worth a small amount of impact to the total airflow, and only at higher speeds.

Kawasaki ran their ram air intake motorcycles a little rich at top end to cope with 180mph top end - if you think your 4wd will do that please show us pics

Generally speaking the amount of leaning out caused by it shouldnt have much of an impact to you fuel mixture ratio.

Maybe 180kmh

Still waiting for someone to work out the air flows for me

Well actually with kawasaki we were talking about 270kph + so 180mph is closer than 180 kph.

The flow loss due to drag between the 3 1/2" snorkel intake and the 3" throttle intake (EFI or carb you didnt specify) would easily be more than the difference in flow rate on cross-sectional area. After all you do a couple of direction changes and all, go through a primary and secondary filter......

As such I can't see you will actually face an issue.


Mathematics wise, does anyone know the flow restriction/resistance of te snorkel itself, or the flexi hose? I doubt it - too many variables based on path, filter, leaks et al. Too complex and brain intensive for me - I think you'd either need some airflow software or have to measure it (with all the requisit ehole drilling).


If you wanna grab a manometer that would be your only chance of measuring it (in pressure drop of mercury).


Still put my money 99% on the ram air/snorkle being a restriction rather than a hp booster that leans out your mixture..

[Vulcanised]

it shouldn't make any difference...... unless you run more than one..... a mate that had an MQ with a 327 in it had 2 snorkels.... but at highway speed, it played merry hell with his gas system.... he used to turn one backwards when travelling, and it had no problems. The safari snorkel on a Rodeo point down over the top of your passenger window and are as noisey as hell in a diesel...... would be better in a petty i suspect

[zookjedi]

i was told as long as you run a balance tube it should be fine ? (efi 45ltr gu)

[Loanrangie]

Use a donaldson type pre cleaner on your snorkle instead of the ram - they look dicky when reversed.

You mean the big ugly ones that look like an oversized circumcised knob?

If thats what turns you on , you are thinking of the toyo version,more like a round glass bowl.

[Zute]

The air filter would kill any positive pressure from the ram effect. The snorkel on my Pajero has made no difference to fuel or performance, but my filter gets more bugs.

[DamTriton]

I want to put a snorkel on my dual fuel EFI V6 Rodeo.
I've heard reports that positive air pressure can occur in some circumstances and stuff the mixtures up.

I would have thought that even at idle the engine would suck in more air than can be rammed through the intake even at highway speeds into a headwind.
Correct me if I'm wrong.

I know some guys rig up a balance pipe but before I blow my doe on a snorkel I want to find out the con's of fitting one to my engine which runs predominantly on LPG.

Any "mathematicians" out there who can work out the air flows?
My engine is a 3.2 lt.
Here are the 2 sizes, I dont know which is for mine yet:

· Surface Area Intake = 7225mm sq ( 3" Diam )
· Snorkel Body Intake = 4419mm sq ( 3.5" Diam )

· Surface Area Intake = 8429mm sq ( 3" Diam )
· Snorkel Body Intake = 5155mm sq ( 3.5" Diam )

I know there's a few variables involved but it might tell me if I'll get positive pressure or not.


cheers
sudso

Would also need to know the length of the intake, how many/what angle/what radius the bends are, any corrugated rubber, x-section of inlet horn, airflow speed, etc, etc. In esscence, too many variables to even make a ballpark figure.

As noted above, a minor positive pressure up to the airfilter with it facing fwd, and a minor negative pressre with it facing backwards. Both would be inconsequential when compared to the manifold vaccum past the throttlebody.

[xenith]

any ramed air will efict gas mixtures as the pressure under the bonet is diffrent to intake pressure all u need do is fit a pipe of 5\8 diy from intake before filter to back of converter all good pressure same every buy the way i am a gas fitter

[sudso]

Well actually with kawasaki we were talking about 270kph + so 180mph is closer than 180 kph.

sorry I meant my Rodeo might do 180kph

any ramed air will efict gas mixtures as the pressure under the bonet is diffrent to intake pressure all u need do is fit a pipe of 5\8 diy from intake before filter to back of converter all good pressure same every buy the way i am a gas fitter

Zenith, the threaded hole on the side of the convertor where you put the balance pipe in, whats it actually do?

[bazzle]

i was told as long as you run a balance tube it should be fine ? (efi 45ltr gu)

This is correct as mixture will be in proportion to air pressure.


Bazzle

[zookjedi]

any ramed air will efict gas mixtures as the pressure under the bonet is diffrent to intake pressure all u need do is fit a pipe of 5\8 diy from intake before filter to back of converter all good pressure same every buy the way i am a gas fitter

this is the balance tube we have on ours , with out it it dies in the a$$

[xenith]

THE HOLE IS TO ALOW ATNESPHEREC PRESHERE TO GET TO BACK OF DIEAFRAM TO GIVE THE CONVERTER SOMETHING TO COMPER ENG USEAGE TO. HERES A PIC MATE HAS WORKED EVERY TIME I HAVE TRYED IT AND A COPULE OF THE CARS HAD BEEN EVERY WERE TO FIX PROBLEM ( NOTE HOSE AND FITTINGS HAVE TO B 5\8 -16MM ) AND JUST A WARNING CONVERTERS SHOULD B MOUNTED WITH DIEAFRAM LONGATUDAL NOT ACROSS THE CAR

[sudso]

THE HOLE IS TO ALOW ATNESPHEREC PRESHERE TO GET TO BACK OF DIEAFRAM TO GIVE THE CONVERTER SOMETHING TO COMPER ENG USEAGE TO. HERES A PIC MATE HAS WORKED EVERY TIME I HAVE TRYED IT AND A COPULE OF THE CARS HAD BEEN EVERY WERE TO FIX PROBLEM ( NOTE HOSE AND FITTINGS HAVE TO B 5\8 -16MM ) AND JUST A WARNING CONVERTERS SHOULD B MOUNTED WITH DIEAFRAM LONGATUDAL NOT ACROSS THE CAR

Thanks Zenith, Good pic. Exactly how you described it should be.

So the atmospheric pressure is now coming from the snorkel obviously?

Another question though, would the same issue exist if the vehicle was just run on petrol only?

Oh, and my convertor is longditudal as you say it should be.
I suppose this is so the diaphram isn't accidently activating due to acceleration or braking forces?
Or is there some other reason?

cheers
sudso

[jimbo jones]

I have a 80 on gas/fuel with a snorkel no problems

[xenith]

no the prob should only b on gas. if it is same on petrol then i would look at desell diapharm on carby or carbon build up in the air bypass vavle (idle motor) carbon can b removed with carby clean
and yes converter is fitted longatudal for those extct resions
o and it's xenith with a X

[dinos4x4]

I just done the mod with the balance pipe that Xenith sugested and it worked like a charm


These forums are a wealth of knowlage

[sudso]

no the prob should only b on gas. if it is same on petrol then i would look at desell diapharm on carby or carbon build up in the air bypass vavle (idle motor) carbon can b removed with carby clean
and yes converter is fitted longatudal for those extct resions
o and it's xenith with a X

Sorry I should have been more specific:
On an EFI engine, like mine, would there be the same issue while running on petrol or not so because the fuel and air is mixing differently and not in the air intake between the air filter and throttle body like gas does?

[xenith]

it will not effict the mixtures as the ecu knows the dencaty of the air and the volume of air so it can compersat for altude change

[trh80]

My gas man has advised against fitting a snorkel to both my 80 and 100 series on gas. He said it was not worth the worry cause it played hell with air mixture. Up to you thought, he did indicate that you can muck around with balance pipes etc, but sometimes they don't work?

[dinos4x4]

the dudes that installed my gas said the exact same thing , and after trying Xeniths trick it is working fine

[wanna]

when i talked to Gas Reasearch about it they said for street use disconect snorkale as pulses from passing trucks will play hell with the mixture the balance pipe fixs most problems but a fast pulse can cause the gas to get upset

[sudso]

Yikes, the trucks that pass me on the highway nearly pulse me off the road sometimes!
My missus magna is on gas with the cold air induction right at the front, I think they would have a similar principal of a snorkel but no problems when trucks pulse past us on the highway.

I'm still going to get one

I'll deal with any issues after

[dinos4x4]

just because these poeple fit gas systems does not mean thay no everything there is to know about gas system .

my runs sweet on gas with the snorkel now .

The dude i have tuning my gas now used to lecture gas fitting at tafe , he picked heaps of things on my gas setup that they did not do right

for example they mounted the coverter flat on the wheel well under the bonnet which made it hard to get the the adjustment screws, also coverters should be mounted length ways with the car.