I don't see any references to AFM in STU. Does that mean that they can be replaced with an aftermarket MAF?
TIA
I don't see any references to AFM in STU. Does that mean that they can be replaced with an aftermarket MAF?
TIA
Anthony
STU Porsche 944T
ITB Volvo 142 (in the making)
Since ECUs are free and there's no mention of it elsewhere, I don't see any reason why not.
the only stipulation is the STU rules state the engine must use it's factory supplied "air metering device, e.g. throttle body."
some tech people could construe air metering to be a MAF, some could consider it a throttle body/carb butterfly.
Yes, they can. Or even removed entirely. Or so I'm told.
Here's where the fun begins.
In IT parlance, "metering" means "measuring"; here's how the IT regs words it:
"All air must also pass through the stock air metering device, eg MAF, or AFM, etc. if so equipped."
So in that case the AFM has to be there, be stock, and air must pass through it.
However, the applicable STU rule states:
"All cars shall use the installed engine’s stock air metering device (e.g., throttle body) and intake manifold, unless noted otherwise."
In that context, "metering" means "restricting", as in a device intentional to meter - or restrict - the flow of air at the command of the driver. Now, it has always been my understanding that the word "meter" when used as a verb describes the process of measuring something; e.g., I am "metering" the cost of postage as the letters go through the system to see how much money we're spending. It's to that context that the IT rules refer. However, I am told that the STAC intends the word "metering" in the context of STx to mean what I describe above; e.g., I am "metering" (restricting) the volume of letters that are flowing through the system so that we do not exceed the available postage budget.
So, to my personal understanding as a competitor, AFMs can be replaced or removed in STx, but I suggest this might be a good letter for someone to submit to the STAC for discussion/verification/clarification.
GA
Wow, I would have assumed the answer would be 'no'. nearly identical rules with very different outcomes, or intents.
It's an odd 'place' they wind up with the STx rule....Half the intake passage is "free", but half is not. In some cars, you win, some you lose....
Seems to me that the formula classes car by displacement to weight, which is an assumed HP basis. Yet the rules leave in place HP restricting items like Airflow metering devices, intake manifolds, and heads. That eliminates a lot of cars from being competitive as the items that prevent the car from reaching the "theoretical golden number" are left in place oon many. Removing one aspect of that is good, I guess, because it might increase the number of cars that have a chance at hitting the "theoretical golden number". But it does make it important to have intimate knowledge of an engines limitations going in. (Not much different than picking a car for any class I guess)
Jake Gulick
CarriageHouse Motorsports
for sale: 2003 Audi A4 Quattro, clean, serviced, dark green, auto, sunroof, tan leather with 75K miles.
IT-7 #57 RX-7 race car
Porsche 1973 911E street/fun car
BMW 2003 M3 cab, sun car.
GMC Sierra Tow Vehicle
New England Region
lateapex911(at)gmail(dot)com
Actually, while you're inferentially correct ("displacement to weight, with assumed HP") I think you're off the mark in that while you are assuming it's based off of stock output/displacement, the category is actually assuming relatively-equal modified (resulting) output/displacement. Removing non-standard restrictions such as varying AFMs would tend to equalize that.
Get past that IT mindset and it "kinda" makes more sense...ain't sayin' you'll agree, just sayin'... - GA
On edit: Actually, in re-reading your response, I think you're saying the same thing. Were one to take that concept further, then the category could remove other reasonable non-standard restrictions, such as intake manifolds and equalizing throttle bodies...in the end, you'll never make different engines with equal output no matter how hard you try, but the variables are minimized.
Last edited by Greg Amy; 12-17-2010 at 04:02 PM.
Chris "The Cat Killer" Childs
Angry Sheep Motorsports
810 417 7777
angrysheepmotorsports.com
IT,SM,SS,Touring, and Super Touring
Bookmarks