Wojo7

Does anyone have first hand experience with the HP limitations of the stock air box and AFM?

Willard Bridgham 3

I watched Jon Milledge get 400hp on an engine dyno with stock airbox and AFM.

reno808

BOOM facts

raleighBahn

I don't think the limitation of HP is the problem, per se, but rather once the door is physically open all the way you can't measure any more. Meaning your ability to match fuel to air and keep AFRs in control becomes guesswork.

Tom M'Guinn

Agreed! Once the barn door is open, it will read ~5 volts whether the engine is sucking in 300hp worth of air or 400hp worth. Assuming 15% driveline loss, 400 on an engine dyno is 340 at the wheels, which is more than most have gotten from the stock AFR. Hard to know what magic or sensors JME had up its sleeve to measure that much air.

Paulyy

There would have been some unique stuff done to the tune to accomplish 400

Dave W.

While it may be possible to reach high power levels with the stock AFM, it's much easier to free up extra power by upgrading to one of the popular MAF kits. Is there a reason you need to keep the stock AFM and airbox?

V2Rocket

In coming weeks I will have my NA running on VEMS with MAP input.
I will be doing back-to-back dyno testing with and without the AFM installed in the intact tract - no other changes (tune, airbox, etc will all be the same), but the AFM will be removed and a simple adapter pipe bolted between J-boot and air box.

This will tell us how much of a restriction the AFM really is.

That said, in the past while experimenting with the Rogue MAF kit, my car gained 14 ft/lbs at the wheels at 2400rpm with the MAF vs the stock AFM setup, and the ignition timing tables are pretty similar. At every other RPM, the minimum gain was +5wtq and whp as well,

I am certain that the AFM is a choke-point at all RPM ranges, it just depends on how severe.

Wojo7

How about if the AFM was out of the picture? Such as the Vitesse stealth MAF, then the limits would be based on the stock air box and snorkel. Has anyone tried to use the M Tune in this configuration? It looks like the tube could be made the same length as the AFM and just inserted in its place.