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Triumph TR6 - K&N Stub Stacks

Does anyone know where I can get a pair of 1 3/4 in. K&N stub stacks for SU HS6 carbs. The supply seems to be drying up. I've read that these gizmos will help straighten out the air flow into the carb throat and therefore increase its efficiency. I'm using K&N filters in my original air box. Comments? For or against? Steve
Steve C. (member)

Stacks don't really straighten flow. They eliminate boundary layer separation and pressure drop by providing a smooth entrance transition to the carb. This is opposed to an abrupt direction change from a square 90 deg. bend.

That said, I don't really like the "stubs" I've seen because the entrance radius is WAY too small for much help. What I did was buy some cheap bicycle horns, then cut the bell off to the right throat diameter, and epoxied them into the filter housing. Sure, some touch-up & polishing is necessary to blend in the throat, and a small packing piece was used between the filter and plates to be sure there was not now a restriction caused by the protrusion of the horns, but hey - it's a hobby. What? I'm MAD? MAD you say?

Brent B

Brent--Now that is very creative! Does it honk like a goose upon acceleration?

Rick O.
Rick Orthen

Nice, Brent.

The problem I tried to solve was the intake of HOT air. In got an old air-cleaner box (with the 2 pipes at the front)and putted 2 hoses through the airduct. Now I get air BLOWN into the airbox and its also colder driving air instead of hot engine compartment air, which must be sucked into the airbox. Carbs (175cd) adjusted. Topspeed + 7 miles !

Eric de Lange

That's it, I'm calling the Goose Abuse Hotline.


Jim (protecting our Original Ornithoptic Mascot)
Jim Deatsch

It only sounds like a goose if it back-fires. Which is infrequent.

There is also a 4" duct line from the radiator shroud to the carbs for summertime relief from heat. Of course it's of minimal benefit when standing in traffic. It's not ducted directly to the carbs, but will provide cooler air in that region when at speed.

Brent B

Back on track...
So nobody knows where these can be had?
Steve C

Steve, I have these on my car, I think from Triumphtune by the way of Moss.
Mine are alloy castings, quite rough but can be smoothed out with wet and dry, and are really just a roll for the lip of the carb. They look like half of a bagel, so not a trumpet at all. They fit right inside the K&N filter, cost was maybe $50 for the pair. Can't tell if it makes a dfifference but simple and not too expensive. I have read in Grassroots Motorsports that they added about 1bhp to an MGB, this is not enough to feel when you drive the car.

Have you tried APT? Their catalog number SS52 K&N stub stack or for the offset SD24 K&N filter assemblies, use the SS24 stub stack (suggest you discuss fit with them if you consider these).

URL is:

or e-mail orders to:

They also have a WATS line for orders:

800-278-3278 or 909-686-0260

I have always had "above and beyond the call" dealings with them on "special" stuff. They're on the Left coast, so you still have time to order today if you wish.

Thanks Steve. I've sent off an e-mail to see if those stacks are still available. Hope to hear back soon.
Stay tuned...
Steve C

This thread was discussed between 05/03/2004 and 08/03/2004

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