2.8 air cleaner/mfi question

MST0118 · MST0118's Garage

Hello Everyone,

I'm finally getting ready to assemble my 2.8 MFI engine. I still have an outstanding question as to whether it makes sense to use air horns in conjunction with the K&N air filter and MFI magnesium stacks.

The magnesium stacks open at 46 on top and they fit perfectly on the K&N filter. The parts are in the photo below. The air horns also fit on the stacks and the top of the horn is about half way up the K&N filter. It seems that the air horns are really not necessary in that I could simply attach the air filters to the stacks so that the use of the air horns would be optional.

So, my question is whether I will get more air flow by using the K&N filter without the air horns or with them. This is a RSR type motor with DC80 cams so looking for good flow on top. Does anyone have experience as to whether the air horns will restrict air flow in any way and if either set up (with or without air horns) is superior?

Thanks,

Mike

abisel · 06:37 PM

Although I may not be able to prove it, maybe someone on the forum can, but this article does explain that the overall length of the intake does make a difference with airflow and torque. Unrestricted air flow is important, but so is the length of the intake runner. So I would say install the air horn.

Blog - Emerald Adjustable Length Intake Trumpet Development

HawgRyder · HawgRyder's Garage

Longer length = more torque in lower RPMs.
This is not absolute but a good starting point.
Eg: with high butterflys the torque curve is higher (for racing).
The overall length is slightly longer...but the distance from the intake valve to the throttle plate is much longer.
In your case...leaving the cones off...will result in a rough transistion inside the aircleaner (90deg turn for air to get into the stack).
Is is important to smooth out the flow down the stack...and this is what the cones do.
Bob

MST0118 · MST0118's Garage

Thanks guys! I'm starting to lean that way about using the air horns I noticed supertec uses those filters on some of their mfi builds so will check in with them as well.