Ok don't laugh .....BUT you can buy a BABY RING TOSS game for $3 and then cut one of the plastic rings in half and then use Grey Sealant to attach it to the K&N backing plate.
I run them on on my 240Z and have truned 12.804 @ 107.26 mph so I guess you could say that my ******* stub stacks work just fine!

Later,Norm

 

12.804 seconds...

Not bad "original Norm!" Norm K

 

i saw some testing done on different stacks commercially available for SU's, and the only ones that didn't DECREASE performance were the very shortest ones. The power increase from the very best was really very minor, maybe a couple horsepower was all. So certainly you wuldn't want to spend a lotta money on them; but certainly trying norm's ******* specials won't hurt anything.

 

In David Vizard's Carburetor book, he has a section which covers SU's
The short stub stack similar to what I have increased HP on his test engine by almost 5% although peak torque increase was negligible.
The longer air horns increased TORQUE but the shorter air horns increased HP.
The stock NON RADIUSED airhorns that are standard in the 240Z air filter housing DECREASED HP by about 4% on his test engine.

All the air horns/velocity stacks that David Vizard tested that were NOT fully radiused DECREASED HP!

Later,Norm



Post Edited (May 6, 11:35am)

 

Fully radiused? are those the ones with the rolled lip?

this guy http://www.jetlink.net/~okayfine/su/suexperiences.html says this style pictured below worked pretty well for him.

Also one other thing, what about driveablity and start up? any differences to be saw there?



Post Edited (May 6, 12:45pm)

 

Yes that is a good looking stub stack. It is smooth with no sharp edges at entry.
It's not really fully radiused though as only a taller airhorn can really be fully radisued.
Most of the airhorns that people run have sharp edges and actually hurt overall performance.

later,Norm

 

'This guy' is Julian Serles, and he knows SU's. Just sayin'.