The Misunderstood Velocity Stack

Do you like to go fast? Well get out of that stocker and build a hipo motor for your VW. Come here to talk with others who like to drive fast.

Moderator: Tom Notch

User avatar
Piledriver
Moderator
Posts: 21720
Joined: Sat Feb 16, 2002 3:01 am
Location: Van Alstyne, Texas

Re: The Misunderstood Velocity Stack

Post by Piledriver » Wed Jul 08, 2015 10:41 pm

Only tangentallly related to the OP, has anyone tried building "offset" log manifolds for Kads?

Heres the logic: GM did it for Corvairs with single and dual single carbs.

Basically this puts a log on top of the runners with the carb heavily offset front or rear (depends on firing order)
This is done to even out the A/F distribution from the immediate suck/suck (wait/wait) cycle of the std firing order on dual single carbs. (1432=4321 as the sequence, so LL/RR induction cycles)

Is A) apparently quite effective, and B) provides a tunable plenum, which can make more power where you want it.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

datrod
Posts: 1
Joined: Wed Jun 01, 2016 5:49 pm

Re: The Misunderstood Velocity Stack

Post by datrod » Wed Jun 01, 2016 6:07 pm

I really enjoyed this write up. Thank you for posting it. I make velocity stacks for Mikuni & Weber carbs. I do any size and length needed for your set up. I'm not a VW guy currently, But have owned a few in my day. And love them.

I started making velocity stacks for Mikuni carbs for the simple reason that you can't get them anymore. I run triple 44 Mikuni's on a Datsun 240Z.
You can see some of my stacks on facebook and Instagram. IG @williams_machine_inc facebook John Williams
If this post violates any rules of your forum please delete it. I'm not trying to push anything on this forum just giving another option for you Guys & Gals.
Thank you.

User avatar
Piledriver
Moderator
Posts: 21720
Joined: Sat Feb 16, 2002 3:01 am
Location: Van Alstyne, Texas

Re: The Misunderstood Velocity Stack

Post by Piledriver » Thu Apr 13, 2017 2:24 am

No hard and fast rules like that here, as long as its not abused.
If you were to cross the line, you'll hear about it.

Thread has been quoted on Jalopnik :twisted:
http://thegarage.jalopnik.com/what-are- ... 1792235442

One of the guys there is an aircooled VW nut too!
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

SC3283
Posts: 25
Joined: Thu Nov 19, 2015 9:10 am

Re: VW Oil Bath Air Cleaner Vel Stack?

Post by SC3283 » Sat Apr 15, 2017 11:27 pm

FJCamper wrote:
Sat Nov 08, 2008 4:51 pm
Followup-



There is a trick velocity stack question that many VW guys never think about, even though they know the answer.

Did the VW Bug come equipped with a velocity stack as standard equipment?

Well, yes. The VW oil bath air cleaner had one inside. It was approx four inches tall, and it wasn't there just to keep the oil out of the carb. It was a real velocity stack.

The oil bath air cleaner stack acted to contain fuel fog stand-off at high RPM's. The old single barrel Solexes had too-small a small plenum under the carb, and at "high" (4500) RPM's fuel standoff was a real problem.

Tuners that swapped the oil bath for a racy-looking flat air cleaner got reduced intake restriction, but lost the VS effect. This caused engines to go lean at 4000+ RPM's.

A few of the aftermarket air cleaners had a short tapered stack on the lower half, but not many.

Savvy tuners made VS out of tin cans and hose-clamped them to the carb, and mounted the air cleaner to the top of the can.

FJC
So the bus, Ghia, thing air intake systems we're all made incorrectly?
70, 74 beetle, 81 Chenowth, 66 Fastback, 83GTI, 85GTI, 02 GTI, 72 Std Beetle

User avatar
Piledriver
Moderator
Posts: 21720
Joined: Sat Feb 16, 2002 3:01 am
Location: Van Alstyne, Texas

Re: VW Oil Bath Air Cleaner Vel Stack?

Post by Piledriver » Sun Apr 16, 2017 2:59 am

SC3283 wrote:
Sat Apr 15, 2017 11:27 pm

So the bus, Ghia, thing air intake systems we're all made incorrectly?
They lacked a velocity stack, but had a long feed tube in its place, that works to contain the fuel charge as well.
The direct on carb air cleaners from the factory, including the later plastic ones, had a built in velocity stack.
The plastic ones may have been tuned airboxes (plenums)
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

Post Reply