Snorkel help and tech wanted

[Tonk]

yes, maybe i diverse slightly.

it has to be done to wot would look about right at the end of the day aswell, if optimum was at say a 6" tube then it would look silly (bit like its owner ) but if a 3" only robbed 10bhp or summat then it wouldn't be worth worrying about so much?

[dollythelw]

or negate the flow loss of having a snorkel by fitting a K&N filter ending up with the same flow as a stock car on a stock filter.... (just to play devils advocate)

Cheap snorks to be had by asking nice stainless exhaust man to mandrell up some 3" bore (good tree resistance) and then wedging a boy racer tailpipe trim on the end, all up for £75 and a packet of ciggies

[Turbocharger]

The length/diameter/bends will all affect the pressure drop along the snorkel - what's acceptable? I asked a thermofluids lecturer at Uni on this subject - he said it's difficult to estimate because the flow is turbulent, you'd need lots of CFD work or some qualitative data. I'm going to do before/after power curves with my GPS oojit but, for example, I'm running 2.5" plastic drainpipe on my Tdi and I do see a power drop before 4000rpm. I'd suggest you'll see no real reduction in power below 4000rpm WOT or 6000rpm part-throttle. As Mr Falklands said earlier, it's not about revs...

I looked at tuning a snorkel on my 2.25D, but for best results at peak torque it'd have to be about 20ft long - which probably negates the benefits somewhat.

[Astro_Al]

or negate the flow loss of having a snorkel by fitting a K&N filter ending up with the same flow as a stock car on a stock filter.... (just to play devils advocate)

Cheap snorks to be had by asking nice stainless exhaust man to mandrell up some 3" bore (good tree resistance) and then wedging a boy racer tailpipe trim on the end, all up for £75 and a packet of ciggies

Good point Jez, I was also just thinking about negating the bad effects of adding a snorkel by taking nice cold air from up top - away from the engine bay (which I guess is where you get it at the moment), so you get a better charge density (colder air).

This combined with a free-er flowing filter, fat tube and few bends could probably see you with close to zero losses.

For a little info on sizing (for example) a K&N filter, look here:

http://www.knfilters.com/filter_facts.htm

With a bit of thought and time we can probably bang together some theoretical losses without too much trouble (if you provide details of your proposed system), but frankly, if you just stick to the above, I guess that's about as good as it'll get, so who cares about the numbers...?

Nice thread. Though I still vote for the supercharger option...

Al.

[globalhead]

Steve's (@ Lund) restrictor was a very nice job (34mm diameter in case anyone cares), but it did knock 50 bhps off the engine (relative to running without) and about 7 lbft off the max torque (which also shifted 400 rpm down).

Hi,

Sorry to make this my first post on your forum, but one of my friends from ORRP alerted me to this discussion, and I'd like to set the record straight.

The restrictor for the Saluki Racer was not designed by Steve Lund, it was designed by me. I am a professional automotive engineer with many years experiance in race engine engineering (WRC and IRL being among the forulae I have worked in), and I designed that part - through Steve - as a favour for Team Saluki. The restrictor has since appeared on Steve's site being passed (in my view) as his own work. This view is reinforced by the comments above. If ever evidence was required of my intellectual ownership of the design, I have original drawings and emails etc from the time I did the work.

I have no interest in starting an arguement here, but frankly it makes my blood boil when I hear of "Steve's" restrictor - especially in light of other issues that have existed between Lund Engines and Team Saluki.

Dave.

[Daan]

Mine:

Just get a piece of straight 3 inch alu tube and Fit a Safari snorkeltop.

My airfilter sits under the rh wing and the Tube ataches straight onto this.

You can rotate the snorkeltop, so it is within the junglewires and therefore protected.

Simple, cheap and good flow.

[Astro_Al]

I have no interest in starting an arguement here, but frankly it makes my blood boil when I hear of "Steve's" restrictor - especially in light of other issues that have existed between Lund Engines and Team Saluki.

Dave.

Dave, my sincere apologees.

I had been led to believe, at least by omission of some facts, that Steve was the originator of the design.

I'm very sorry for my comments attributing the restrictor's success directly and solely to Steve.

I must confess I had wondered how he had managed to come up with such a successful restrictor with no formal training in the field (as far as I know) of fluid flow etc.

I have discussed the restrictor with him, following some research I have done, but your name was never mentioned.

You have a 'PM', I would very much appreciate a reply if you have time.

Once again, I'm very sorry for my misleading comments. Congratulations on a successful design.

Al.

[dollythelw]

Dave - nice to see you here, I dont think any offence was meant, I guess its a generic. Whats your input on the snorkel debate?

[Lara]

Forget all the p-----n about with calculations etc,

Have a look at mine, (details on the readers rides page) it is 90mm diameter 2mm stainless tube and flows 1058 CFM of air tested on my flow bench, If your engine needs more than this then I take my hat of to you sir.

Good luck,

Lara.

[Astro_Al]

Sweet! Nice numbers. That saves me a job!

Course, that's 3.5" which is larger than he's looking to use...

Al.

[Hybrid_From_Hell]

Pah,

I go off to do a load of work "work", as opposed to LR "Work" and come back to this lot !

ta everso will have a read later, and digest

Guess the main reason for this post is..

1. I want to use as smaller tube as possible for ease of manufactuer.

2. If I do use too small then apart from the performance I run the risk of the engine running rich as low air available, and this can cause damage long term, ie fuelling can wipe the bores of oil etc etc etc..

3. If I can get it right I could leave it connected all the time, rather than the off for the road, and then have to connect off road mess ?

Keep the thoughts coming

Nige

[02GF74]

I agree with Bogbuster's analogy.

Increasing the wire thickness is the same as increasing tube diameter - i.e. minimising losses, and I suppose wire junctions equate nicely to tube bends in terms of resistance to flow.

So apart from minimising these by getting fatter tube and fewer bends, the only option you have as far as I see it, is to chuck a sodding great supercharger on the top. Which is analogous to increasing the potential difference.

Al.

well I don't.

I'm no expert in fluid dynamics but sure I've seen mentioned that the air flow through at tube is not linear - the air in the centre flows differently to that along the sides. And aren't there other effects related to the fluid molcule size and the tube diameter? Think capillary action with very tiny tubes. Ok, for snorkels these effects can be neglected.

With electricity, are we talking DC or AC? With AC there is apparently skin effect whereby the electical thingies prefer to trvel along the surface of the conductor rather than the centre. That is depending on application is is better to have many small multi strands as opposed to one strand of equivaltnet cross section.

... so the analogy is bad or good depending to what level you go.

.... err, what was the original question again?? (too lazy to go back and read all the posts!)

Edited December 21, 2005 by 02GF74

[Astro_Al]

Yay! I've found someone who over-analyses more than me!!!

Well, it is Christmas...

Ok, all I meant was that if you use a thicker cable your electrical resistance will be less (take DC if you really want to be specific, just think of voltage drop with distance or whatever makes you happy). This intuitively seems the same as increasing tube diameter for airflow. Yes, there are effects at the wall (eventually the flow velocity drops off to zero at the wall), so the more flow away from a wall, the better - therefore, a bigger tube.

It wasn't a highly technical analogy, just an intuitive one.

Obviously molecule dimensions with respect to tube size is irrelevent in this case.

It's really not that important, it's just an example.

Al.

[BogMonster]

Well poo to you with nobs on then 02 I call the skin on the outside of my wires, "insulation"

anyway this is all getting a bit tetchnickel for me

One way you could do a basic check would be to put a vacuum gauge on plumbed in immediately on the upstream side of the throttle plate. You could measure a stock engine's vacuum depression at high throttle openings (which will give the pressure loss through the intake system), and then easily measure the change with any particular design of snorkel, which would be a pretty good indication of how much air was being strangled from the engine I would think? You could easily F around with the design then until you minimised the pressure loss.

[ltwt1981]

Nige we deal with 4*3 inch rainwater pipe in ally or even cast iron ( adds to the weight ) commes PPC in black or a range of colours.

Nige T

[globalhead]

Whats your input on the snorkel debate?

Well, I've had a read through the thread, and generally speaking I think most things I can think of have been said already.

The airflow calculations are probably a bit high imho as the volumetric efficiency of each engine hasn't been considered (vol eff = how efficiently the engine pumps air into itself i.e. theoretical max airflow / actual airflow), I'd hazard a guess at 80% for the type of engines being discussed (and its a wild guess at that).

Basic theory would be to keep the pipes as large, as straight and as short as practical. A slighly rough internal surface on the pipes is better (as if rubbed with 180grit) as it trips the boundary layer flow in the pipe from semi laminar to turbulent. This means that the velocity profile across the duct is flatter - or to put it differently - the layer of slow moving air near to the pipe walls (the boundary layer) will be thinner; and hence there is a larger area of faster moving air. For this reason my restrictor drawing mentioned above carries a note stating something like...

"After final machining polish internal surfaces of component using grey scotchbrite or similar to produce a lightly burnished finish. Minimum material condition must not be exceeded by this operation".

Placing the inlet in a position where it will draw cool air is a big advantage (as mentioned).

I would think that ram air effects at off road speeds will be negligable - and probably not much better at road type speeds. Perhaps on a dyno you would notice a slight increase, but I would be quite surprised if the driver would feel any difference. On a racing car you would point the intake in the direction of oncoming air, but if it were my vehicle I would sacrifice that tiny (if any) power gain in order to avoid sucking rubbish into the snorkel.

When designing intake systems there is usually a reasonably large amount of analytical work done using simulation programs to size the pipe diameter. While large diameters are good for steady state airflow - they are bad for throttle response because you have a larger volume (and therefore greater mass)

of air to get moving when the throttle is slammed open. Given the long lengths being discussed it probably takes several engine cycles to consume the volume of air sitting in the pipe, so throttle response may be so sluggish (in the grand scheme) anyway that any change from one pipe size to another is negligable, but it is worth bearing in mind.

Cheers,

Dave.

Edited December 21, 2005 by globalhead

[FridgeFreezer]

Firstly - Dave, didn't realise it wasn't Steve's own design. As you said, the website (where I saw it) gives the impression it was.

I'm no expert in fluid dynamics but sure I've seen mentioned that the air flow through at tube is not linear - the air in the centre flows differently to that along the sides. And aren't there other effects related to the fluid molcule size and the tube diameter? Think capillary action with very tiny tubes. Ok, for snorkels these effects can be neglected.

With electricity, are we talking DC or AC? With AC there is apparently skin effect whereby the electical thingies prefer to trvel along the surface of the conductor rather than the centre. That is depending on application is is better to have many small multi strands as opposed to one strand of equivaltnet cross section.

... so the analogy is bad or good depending to what level you go.

I'd hate to see you and Al meet in a pub, it would be the longest most painstakingly detailed conversation ever!

It works pretty much the same for DC and AC until you get into RF where the skin effect is so great that hollow waveguides are used instead of wires. It has a startling similarity to airflow and general fluid dynamics really - sharp bends are bad, resonance of a specific length of guide can be beneficial or very bad, and strange effects can be had by adding funny shapes / convolutions to the inside path.

Multi-strand wires are used in electronics for their flexibility not their RF characteristics, rigid single strand wire does not like vibration or movement and fatigues over time. HF & RF cables tend to have single solid cores not multi-stranded.

As for intake trumpet length, short = better top end / better response, longer = better bottom end / more torque as I understand it.

I love the amount of effort Nige is going to to decide he can't use the right size of tube anyway because it's too big anyone would think this was rocket science not Land Rover maintenance!

[white90]

Keep it as as straight as possible and try to avoid 90 degree bends.

old style difficult to seal

Sothdown variant easy to seal and proved water tight in water up the windscreen

SEE HERE

Edited December 22, 2005 by white90

[Bush65]

With fluid dynamics, Reynolds number is an important term, particularly relavent to turbulent flow. From memory I don't think there is anything equivalent in electrical theory.

Reynolds number increases with distance.

A fly or bee is small and operates at low Reynolds numbers. Nature has given them near ideal aerodynamics - they have stubby bodies (to reduce surface area) covered with hairs to proLook at the aerodynamicswhich act as turbulance stimulators. And their wings are thin.

A large aircraft on the otherhand operates at much higher Reynolds numbers and the shape of the body and thickness of the wings has to be totally different to the insect.

As others have said, keep the length of snorkle and duct to the filter as short as practical. Friction losses also depend upon length.

Nige, why have you gone to the trouble and expense of the engine you have, if you are now going to restrict it with an inadequate snorkle?

If you are set on using a small long snorkle, sell your engine and get smaller one. Then will have some pounds left over to spend on something else.

[Daan]

Guys, this is just great!

We had one simple question with 43 replys, in which one is trying to outdo the other with expensive terms such as:

-volumetric efficiency

-Reynolds number

-Fluid dynamics

-drain pipes (cast iron or plastic)

-electric powercables (AC or DC)

Anyway, lets cut the carp shall we?

A good snorkel has a big diameter, few bends and is as as short as possible. Oh and it also stops water entering the engine.

Now go back to your workshops and knock one up. Show us the piccys when youre done.

Happy christmas, Daan

[Lara]

Thought that's what I said

Just don't fit one of those stupid Cyclone things, If you read all the tech stuff again you will see what I have been saying for years, Straight air flow is best.

Happy everything,

Lara.

[BogMonster]

Anyway, lets cut the carp shall we?

Good idea. You could start with that 2.5MB avatar so that those of us on dialup don't have to F download it!!!!!!

[Daan]

Ok than Bogbuster, lets have a peacefull 2006 with lowresolution avatar pics.

What do you think of this one?

Daan

[BogMonster]

Ok than Bogbuster, lets have a peacefull 2006 with lowresolution avatar pics.

What do you think of this one?

Daan

First class - thank you

And happy Christmas too

[globalhead]

Guys, this is just great!

We had one simple question with 43 replys, in which one is trying to outdo the other with expensive terms such as:

-volumetric efficiency

-Reynolds number

-Fluid dynamics

-drain pipes (cast iron or plastic)

-electric powercables (AC or DC)

Anyway, lets cut the carp shall we?

A good snorkel has a big diameter, few bends and is as as short as possible. Oh and it also stops water entering the engine.

Now go back to your workshops and knock one up. Show us the piccys when youre done.

Happy christmas, Daan

Fair comment!

Thing is though - us techy types have to spout our carp - how else can we compensate for our lack of friends, white complection (from sitting at our 'puters day and night), and genetic inabilities with women!

Obviously I'm the exception that proves the rule I should add (no - really....).