engine and drivetrain Velocity Stacks - should they have filters or not?

[visionaut]

IMHO, and I've run many combos over the years, the best set-up is stacks in an airbox with a remote filter. Next best are stacks in a large foam filter, with at least 1.5x stack bell mouth diam free space in front of the bell mouths. And multi-throat/multi-carb foam filters are much better than single foam socks. Last are paper or K&Ns over each carb.

I also think you should always run a stack on DCOEs, even if it's the stubby 'zero length' ones.

And I find my BBR stack screens to be less restrictive than individual foam socks in the seat tests I've done.

Tom

[LimeySteve]

Yes BBR's are the dogs bollocks , mine have been on for ages & still not fell apart or off , not cheap but you get what you pay for & no HP robbing, as tested on dynos.

 

http://www.bbrfilters.com/

[Stevenola]

Can you ellaborate on this regarding dyno results, flat screens appear to block at least a 1/3 of air based on the wire diameter in the mesh, I've also read that the mesh causes turbulence, essentially negating the smoothing effects of the trumpet.  I can see the domed screens maybe having enough surface area spread out to compensate for the mesh but not the flat ones.

 

What about small dirt etc that can get through the screens?  Are you only using these for occasional track use or on road trips etc?

 

I'd love to run screens, but need some proof here

 

 

Yes BBR's are the dogs bollocks , mine have been on for ages & still not fell apart or off , not cheap but you get what you pay for & no HP robbing, as tested on dynos.

 

http://www.bbrfilters.com/

[LimeySteve]

Go on their website & search it's interesting , here are 2 quotes I have no affiliation just a happy customer & my A/F didn't change at all upon using the filters.

 

On the last engine we did back to back comparison with and without covers from 4500 to 9200 RPM. The covers actually helped at the bottom end where air flow is minimal (probably organized and straightened airflow like a gas lens) and only lost 3-4 HP above 8000 and did not significantly alter fuel air mixture. Peak HP without was 359 hp and with was 355hp all from 183 ci.

Rick Bunkfeldt

Comparison

 

 

Hi, When we did the Dyno tuning on my car we tried one run without the air cleaners and immediately following a run with the air filters, the result was only a difference of 2 HP less, which could have been Dyno error reading of just difference in engine run. Based on this, I would say that your air cleaner screens do not have any negative effort on engine performance. Tom

Tom

Edited September 17, 2015 by LimeySteve

[zinz]

Now... where do we find the UNI filters or screens that fit these miniature stacks on this Maserati's Webers?  ...look closely at the float chamber intake

 

 

so fine...

 

 

Ed

 

(pic credit goes to Steve, though)

[Stevenola]

The ultimate carburetor porn pic!

 

 

Now... where do we find the UNI filters or screens that fit these miniature stacks on this Maserati's Webers?  ...look closely at the float chamber intake

 

 

so fine...

 

 

Ed

 

(pic credit goes to Steve, though)

[zinz]

oh... there are others...

 

Twin V12 Lambo engines in a Riva boat.... How'd you like to synch twelve Webers??

 

 

or maybe a paltry 6 on a '60 Testa Rossa

 

 

....sigh

 

 

Ed

[visionaut]

mo' sidedraught pron... 

 

[vinntagejoe]

if your looking for a set of angled sock uni filters to go over your 40mm webers; amazon has them right now at a sale price:

 

Uni 2 1/2in. ID Angled (63mm) Two-Stage Pod Filter - 6in. Length UP-6245AST

 

$15.12 each

[Tom P]

My E9 set up - many thanks to Stevenola for his input and advise!

Recently purchased siennabraun 74tii and will start to bring it back soon. Looking forward to the wealth of knowledge over here!

Sent from my iPhone using Tapatalk

[flybmw02]

Think of an engine is like a vacuum cleaner, an engine with out a filter will suck up sand and destroy the valve job and cylinder walls there are plenty  of filters available that you can run air horns do a search on EBay for  ITG filters.   http://www.ebay.com/itm/ITG-Megaflow-JC50-Universal-Large-Twin-Carburettor-Air-Filter-Race-Rally-/301086552818?var=&hash=item461a2832f2

[Emyers]

^{My system......}

[gracer]

Hugh McKinnes stated in his turbo book. "A boat that never docks or a plane that never lands

does not need a filter. All other engines need a filter. I use a ITL filter on my race car. G

[Justin99]

If you are worried about flow restriction try removing those pesky little metal butterflies in the throttle body. They are so restrictive that they force your engine to idle at a measly 800 or 900 RPM and rob your car of power at any setting other than WOT.

Seriously, the (designed) flow restriction of throttle butterflies vastly dwarf that of any air filter in all scenarios but WOT. So unless you are competing in a dyno shoot out in a clean room, or flying in an aircraft where the engine sits at WOT for hours on end you want air filters on your stacks.

But, those mesh covers on the trumpets do look retro race cool, even if they do little to save your engine.

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[AlanM]

Some years ago I was at dyno running a L20 Nissan motor with socks over the ram tubes.  I told the owner that they caused interference to the intake flow for the am tube and reduced Hp.  On a chassis dyno it picked up 10Hp at the wheels with them removed. Ideally you would have your ram tubes housed in an air box with a panel filter at the front of it, where the engine can take in the air from a relatively still air area.  I have found on the M10, it seems the longer the ram tubes the more power and torque are produced.  Do not use the mesh covers as they only stop rocks, and depending on the engine will reduce top end power.

 

200mm tubes produced the same top end hp just at 5700rpm instead of 6500 over 100 mm tubes.  At 3000 the long tubes were up 12hp, 4000 still up 12, 5000 up 20, 6000 up 8, on a chassis dyno. At that time it was topping out at 151Hp at the wheels on a Dyno Dynamics.  With some more work it now makes 165Hp at 6700 only dropping 3hp by 7200, still with the 200mm ram tubes. Comp ratio is only 10.6 on 98RON, and could be pushed to a little over 11 with some improvements in chamber squish, picking up a little more power.