If anyone's seen my last post I've now got my engine running on an emerald I managed to pick up cheap!

My question is do after market velocity stacks really make a difference on a car engine?

I've got some '03 R1 TBs to put on my zetec e 2.0 with an st170 manifold. I've found DanST does a stack kit for this for £126 with proven gains over none. OR I could cut out some OEM rubber ones from a stock R1 airbox which can be had for £25.

Does anyone have any experience of OEM stacks Vs aftermarket on car engines? I need to get it booked in for mapping soon but would like to save £126 if OEM ones work just as well....

[Edited on 14/2/20 by Se500zetec]

OEM designed for a bike with an air box and (probably) ram air. Dan ST designed for after market fitment to a car engine.

Go figure :-)

The only way to tell for sure would be to carry out back to back tests on a dynamometer/rolling road

As above but as a starting point, zetec's are said to like the longest inlet tract you can fit.

But this will depends on lots of things.

Inlet tract length definitely has an effect or there wouldn't be loads of manufacturers using loads of different systems to utilise it. The table below probably (definitely) over-simplifies it but it is a starting point.
Aiming with 6-7K in mind it suggests that 20" would be best but probably not practical. Next best would be around 14" which is usually doable under the bonnet. I made mine 14" based on this diagram using home made stacks.
Maybe use whichever stacks give you the suggested length based on your idea of what rev band you would like to enhance (a bit)
As regards the flow capability I wouldn't write the Yamaha ones off just because they came off a bike. I doubt if the air knows what it's destiny is. Flow is flow.





Yes, I know it's " just something plucked from the internet" and won't "optimise" anything but it's a start. The correct method means lots of engine dyno time using various and varied stacks. I think Danst sell a set for this purpose. I toyed with the idea of a variable length setup like some late R1s use but settled on making full radius custom stacks to suit my 'Busa ITBs.