Benny, thanks for the hands-on tuning input! Lovely engine bay! On the longer, upturned velocity stacks, if you're running in the rain and water gets into the intakes, does it swirl clockwise or counter clockwise?

I have tried a couple of differnent velocity stack lengths.

These short 50mm tapered full radius ones made for better peak power.




And these ones are much longer, resulting in a much fatter torque curve in the mid RPM range at the expense of peak power. The difference was about 4HP at the wheels difference. I went with the longer tubes with the aim of having better punch out of a corner.

The length mainly relates to RPM

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Some reason not adding the pic correctly but got them today was advised for the cfm of my intake head and carbs and for how ill be driving and events ill be wanting to do a 40-50mm length velocity stack is best so I went ahead and have got 43mm billet Bell end stacks being that I already have a uni filter backing plate and cage with foam filter the cage is just not long enough so ill have to space the cage a little from the backing plate and still be able to use the uni filter along with it

Most Modern cars use variable length runners in their intake manifolds.

Long runners promote more turbulence of the air going in giving more torque at low RPM.
Short Runners get the air in quicker and easier at high RPM as there is less restriction.

May have something to do with it.
Just my 2 cents.

when i added 3 inch velocity stacks to my SU's, i had to completely retune them. so yes, they make a difference.

Velocity stacks do,make a difference on most carbs. I can tell you from my motorcycle road racing days that proper stacks will see you changing main jets so obviously there is a power increase.

Tom

You might think about the curved intake runner stacks, something like inside the airbox of an M5 V-8 BMW. the radius of the curve would probably allow you to build a filer housing that would enclose them and then you would get the benefit of having a pretty long intake tract, if that is what you are after.

On my A14 I did not notice any noise difference between Velocity Stacks and open/no air filter. Both were extremely loud (like Harley loud)

Ram tubes have significant impact, especially in NA applications. Take a look at full radius tapered type. they are the business. As for the noise, fitting them under the air fiters will be a challenge. Pipercross make some rather cool longish pillow type filters complete with a backing plate etc.