Thread: Fitted Snokel drop in Performance

thanks ron, i did think mr lr had spent a lot of time researching this as it is really a small opening at the throat of the venturi.
err, mines hacked off to fit a battery, after long hours thinking about it, also i temp tested intake air in the box and in the inlet to sort the venturi differences, not much, but the engine does get very hot air, which probably has something to do with emissions - a snorkle would improve the intake temps, and therefore improve economy 'perhaps' by allowing more air in. but this is also flawed thinking, as the colder the air, the more the oxygen content, so the more fuel we can mix with it - all good so far, until that air gets sensed by the 'mass air flow meter' which has been set to give predetermined values at the factory.
so no gain.
as for those thinking about the ram effect of snorkels - forget it!
170 mph impact air [ram] has the potential to increase the manifold pressure by 1 inch of mercury.
or to make it a bit simpler -
still air, 60 mph [you work out the kph, i'm not doing it all for you]
pressure increase of air - psi - .065
in hg - .128
in h2o - 1.774
and then you have to factor in the air temp and humidity,
ram air in a truck is not an issue, it doesn't do diddly sqat!!!!!!!!!!!

Originally Posted by harry

thanks ron, i did think mr lr had spent a lot of time researching this as it is really a small opening at the throat of the venturi.
err, mines hacked off to fit a battery, after long hours thinking about it, also i temp tested intake air in the box and in the inlet to sort the venturi differences, not much, but the engine does get very hot air, which probably has something to do with emissions - a snorkle would improve the intake temps, and therefore improve economy 'perhaps' by allowing more air in. but this is also flawed thinking, as the colder the air, the more the oxygen content, so the more fuel we can mix with it - all good so far, until that air gets sensed by the 'mass air flow meter' which has been set to give predetermined values at the factory.
so no gain.
as for those thinking about the ram effect of snorkels - forget it!
170 mph impact air [ram] has the potential to increase the manifold pressure by 1 inch of mercury.
or to make it a bit simpler -
still air, 60 mph [you work out the kph, i'm not doing it all for you]
pressure increase of air - psi - .065
in hg - .128
in h2o - 1.774
and then you have to factor in the air temp and humidity,
ram air in a truck is not an issue, it doesn't do diddly sqat!!!!!!!!!!!

And I would guess that the obverse would be true:

A snorkel will not degrade the engines breathing either.

The Venturi effect is an interesting factor in the defender's case as the intake is on the side of the guard and the air moving over the intake at speed should and probably does induce a negative pressure which if these things are so sensitive the standard setup should result in a decrease in performance.

I think the snorkel performance improvement thing is a furphy as is the dust/cool air thing. It's a spin applied in 4wd magazines to seduce the unsure who think it looks cool.

I will install a snorkel to do what a properly installed snorkel should do on a diesel engine and that is to keep water out of the motor on the odd occasion that I exceed the wading depth.

Originally Posted by one_iota

And I would guess that the obverse would be true:

A snorkel will not degrade the engines breathing either.

The Venturi effect is an interesting factor in the defender's case as the intake is on the side of the guard and the air moving over the intake at speed should and probably does induce a negative pressure which if these things are so sensitive the standard setup should result in a decrease in performance.

I think the snorkel performance improvement thing is a furphy as is the dust/cool air thing. It's a spin applied in 4wd magazines to seduce the unsure who think it looks cool.

I will install a snorkel to do what a properly installed snorkel should do on a diesel engine and that is to keep water out of the motor on the odd occasion that I exceed the wading depth.

BINGO!
and if you arnt gonna use it as such why fit one

cheers phil

Originally Posted by discowhite

BINGO!
and if you arnt gonna use it as such why fit one

cheers phil

bingo 2


if ram air increased a vehicles fuel economy or performance,they would be fitted to them from new.

doesnt the d3,RR & RRS,all suck air from the side guard ,similar to the defender?

just my 2 cents worth

yep they sure do, even the freeloader.

cheers phil

Originally Posted by scarry

bingo 2


if ram air increased a vehicles fuel economy or performance,they would be fitted to them from new.

doesnt the d3,RR & RRS,all suck air from the side guard ,similar to the defender?

just my 2 cents worth

Just my 2 cents - but a lot of performance vehicles do have "ram air" fitted from new - just have a look at the aggressive looking vents on the bonnets on most sports cars and you'll see what I mean. They already come tuned to take advantage of it.

Before I got my LR I used to be one of the japanese 4-pot brigade. A ram air set up is a valuable modification for performance, but only when complemented with other modifications such as an optimised exhaust system and a reprogrammed ECU. Any one in isolation will offer minimal performance enhancement - in combination with the above can offer quite a bit.

I even put my Nissan Exa over a dyno to prove the point - 107kw from the stock CA18DE, 115kw with 2 1/4 inch maxiflo exhaust added, then 119kw with cold air intake & pod filter added, and 143kw once the ECU was replaced and the breathing mods were able to do their job! Without the ECU I had developed a huge flat spot at about 3000rpm - almost undrivable.

how do you get the ram air effect on a dyno?
cheers phil

Originally Posted by discowhite

how do you get the ram air effect on a dyno?
cheers phil

Stand a sheep in front of it and make it fart a lot...