Snorkel, Hiclone and Restrictor.

Submitted: Sunday, Mar 13, 2005 at 13:23
ThreadID: 21183 Views:5321 Replies:5 FollowUps:4
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Ok I posted last week that I was taking out my Hiclones and that I would report on any difference to induction noise from the safari snorkel on my 3.0L TD motor. No more noise than previously so I'd say at least on my motor/vehicle the hiclones were doing absolutally squat.

I did however pull the air ram off the safari to see about these so called restrictors that some of the Jack owners had reported about.
Yup, it had one, 7.5cm diameter of the ring with a 3.7cm hole in it!
Apart from perhaps lowering induction noise I was wondering if it had anything to do with the slits in the Air Ram for disposing of water in heavy rain etc. It would make more sense to me that the water would run down the back of the snorkel hit this ring and then get forced out the slits.
Who knows, but for whatever reason its there it's not now! LOL
You'd have to drive through a heck of a lot of rain to fill up my air box and if I'm doing a long run in heavy rain I normally reverse the air ram anyway, so it can stay out.

I'll let you all know if I get much more noise or better power/economy in a few days...
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Reply By: Rosco - Bris. - Sunday, Mar 13, 2005 at 19:03

Sunday, Mar 13, 2005 at 19:03
G'day Jeff

These restrictor thingees seem to be vehicle specific. I've had a bow-peep down my Safari and it's just a bloody big hole.

Check their web site re rain ... I don't bother reversing it in heavy weather.

AnswerID: 102252

Reply By: Member - Banjo (SA) - Sunday, Mar 13, 2005 at 19:51

Sunday, Mar 13, 2005 at 19:51
Re my post a week or two back - I rang Safari and got short treatment (they don't welcome client interaction - IMO, they should seek counselling for their attitude problems!). Despite obvious irritation toward this client, they did manage to offer that the restrictor is there to fix a "harmonics" issue. No mention of rain control. Seeing they extoll the "ram air effect" as a result of having a snorkel, why not say anything about a 60% loss of inflow pipe area, plus the turbulence created by the flat restrictor flange ? IMO, you should notice some improved breathing overall, in the form of "oomph" at the pedal - the little bit of "hum" coming from the Jack at 3-3500 rpm is of no consequence to me.
AnswerID: 102260

Follow Up By: pjchris - Sunday, Mar 13, 2005 at 23:22

Sunday, Mar 13, 2005 at 23:22
The issue with harmonics is a little more complex. Certain harmonics that can occur in air intake systems set up harmonic waves that actually impede air flow and can cause less air to reach the engine while they happen. So you may notice an improvement at high revs but may develope a flat spot elsewhere in the rev range (ie at 3-3500 rpm in the middle of the torque band!).

Only a dyno could tell for sure, and I don't think they would put these in only on certain vehicles if they didn't have some benefit.

FollowupID: 360049

Follow Up By: Member - Jeff M (WA) - Monday, Mar 14, 2005 at 16:18

Monday, Mar 14, 2005 at 16:18
pjchris if that is the case, how can they tell if it will make an improvment in my car vs a 2.8L 3L Hilux which is a totally different engine, air intake etc etc etc. How can they tell if the vehicle is turbo'd or naturally aspirated. Sounds like hogwash to me as this same snorkel kit is fitted to many differnt engine models and configurations all with different air inakt pathways, air boxs and filters...
FollowupID: 360127

Follow Up By: pjchris - Monday, Mar 14, 2005 at 16:46

Monday, Mar 14, 2005 at 16:46
My bet is they use the same basic snorkel set up, install their first one, take it for a drive and if it seems to have a flat spot or a harmonic then they fit a restricter plate (and I'm sure they don't call them that) or alter tubing sizes/shape etc and try again. It seems to be a bit hit and miss as some vehicles have them and some don't.

If they had the equipment they would set the vehicle up on the dyno and graph air flow and pressure across the rev range and compare power and torque figures before and after snorkel fitment. Analysing the after figures would show up harmonic problems as rate of air flow would not increase in line with engine rpm or air pressure at the air filter would drop and a 'flat' spot would be apparent on the power or torque graph.

Then you would alter the volume/size/shape of the tubing that comprises the snorkel to tune it differently to eliminate the problem.
Remember every tubular system has a resonant frequency be it intake, exhaust, manifolds etc. Any engine tuner will tell you that if the resonant frequency of the exhaust or inlet manifold is wrong the resultant standing wave (or harmonic) can spike the backpressure on the exhaust side or increase resistance on the inlet side resulting in a momentary loss of power that can vary from almost un-noticeable to a very noticeable flat spot.

That's what all those computer modelling programs are for. Comparatively, Snorkel design is fairly crude. fit it to the car and see how it goes. Of course they all follow certain rules relating to size of piping, sharpness of bends and inlet area, but without access to the engine design data they are a bit behind the eight ball so to speak.

In many, if not most cases, the fitting of a snorkel does not cause a harmonic or noise issue. But sometimes it would. Given the sheer number of vehicle variations, as you alluded to, Turbo, non, engine size and different air intake systems when the same engine is fitted to different vehicles it would prove to be very expensive to undertake a full computerised design process, followed by rigourous real world testing given the relatively small number of snorkels they sell.

Safari, who also design and manufacture the dtronic, have obviously done just this with the dtronic which partly explains the high price. Given the developmen costs, it took 6-12 months to design and test the unit for the DiD Pajero, the research cost per unit sold would be significant. And they have to recoup that.
Naturally they will sell more snorkels for a particular model than Dtronic's but people are not going to want to spend $1000 for a few pieces of plastic tube and a ram, which could well be the all up cost for a computer designed/modelled and tested unit.

FollowupID: 360131

Reply By: Member - Banjo (SA) - Monday, Mar 14, 2005 at 09:34

Monday, Mar 14, 2005 at 09:34
Well - I'm no scientist, so I make no authoritative comment on harmonics or anything else, but my main point is that Safarai claim improved air flow to the engine intake when their snorkel is fitted. This "might" be the case ... but there is drag associated with the snorkel's tubing - twist/turns/junctions etc. - and to add a restricting washer without advising the client, seemingly to fix a noise issue, may, in my view, find the engine breathing with less efficiency than the stock system. If that is the case, clients should know that !
AnswerID: 102338

Follow Up By: pjchris - Monday, Mar 14, 2005 at 11:33

Monday, Mar 14, 2005 at 11:33
As I said above the snorkel shape may actually hinder airflow with the resricter removed.

To install such a device which WILL restrict airflow at higher revs witout telling the client to help solve a potential flat spot issue is just plain stupid.

there are far better ways to solve harmonic/noise issues than restricters. Witness those plastic boxes that go nowhere that hang of the side of the intake (between air filter and inlet manifold) on many vehicles. By changing the volume of the intake tube here they change the harmonics of the system as a whole. This is a far better way to do it. I suspect most Snorkel manufacturers don't have the equipment to design this solution thogh, so they build one, drive it, see they've got a problem and fit a restricter. Problem solved as far as they're concerned.

Lazy, just plain lazy. And cheap too. A bit like certain car makers that fit restricters to exhausts to improve Cat warm up time on ULP vehicles, or to avoid exhaust manifold resonance. Again the cheap, quick way out.

FollowupID: 360093

Reply By: Member - Banjo (SA) - Monday, Mar 14, 2005 at 12:35

Monday, Mar 14, 2005 at 12:35
Indeed !
AnswerID: 102351

Reply By: Member - Jeff M (WA) - Monday, Mar 14, 2005 at 17:05

Monday, Mar 14, 2005 at 17:05
Ok I took the car for a drive yesterday and found that my Lukey exaust actually sounded slightly quieter under load at low revs, however when accelerating through the revs it actually was quite nice sounding instead of sounding all vacume cleaner like. You could actually here the burble.

As far as snorkel noise goes, the resonence is exactly the same at low revs, however I am getting a kind of sucking wind noise at higher revs (I can only here it with the window down) and you can actually here the turbo whistling a little bit if you listern carfuly when it's reving, which you could not here before.

Bascially the overall sound is more even instead of being loud at low revs and quieter at high revs, it's kind of evened out.

The responsivness at lower revs has increased quite a bit, being an auto it always drops back down to idle when you back off in city traffic, now when you put your foot back down it seems to get back up in the revs with less effort and quicker.

Of course this all may be phycological as I have no actual proof and of course my mind is thinking:Turbo Diesel - more air = more power. But hey, well see when the fuel figures start flowing in what difference it has really made, but for me I'm more than happy with the initial results of removing this peice o' crap and we'll see what happens next...
AnswerID: 102379

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