Intake, Header, HFC, CBE = Too Lean?

Zsteve

Not sure what the thickness of the piping has to do with anything at the MAF location. Its about the diameter of the piping, and that is how some intakes are making the gains they are, is that they make the MAF size a little bigger tricking the ECU on the actual amount of air coming in (more air coming in but the ECU thinks less is coming in cuz the larger pipe means less velocity, if I remember the explanation to me before about this) which then causes the ECU to adjust in a way to make more power.

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2010 LS3 C6 Silver coupe corvette

Daishi

Zsteve that's exactly what I meant your just being too literal on my word choice. I meant diameter instead of pipe thickness.

BalanBro

That's right. A larger pipe will have slower airflow than a smaller pipe at a given flow rate. Think of it like a garden hose: when the end is open, a large volume of water slowly pours out. Now you put your finger over it, and all of a sudden the water moves out much faster, but the amount of water coming out is pretty much the same. What you did was in effect make the hose act as if it were smaller.

This concept is important once you know how a maf sensor works. Basically, it's a wire that is heated to a target temperature by an applied voltage (aka "hotwire"). As faster air goes over the wire and cools it down, more voltage is applied to compensate. It is this voltage that the ecu uses to calculate the required amount of fuel.

In a nutshell, it's like this: larger pipe-->slower air-->less cooling of hotwire-->less MAF voltage from ECU-->less fuel injected-->leaner air/fuel mixture.

I think exhaust and HFC's alone have little effect on A/F ratios, as any additional airflow gained by these systems is still going to be metered by the MAF and more fuel will be injected accordingly.



Wow. Sorry, that was boring

neveucd

Ok I am pretty much understanding what goes on now from this thread. But looking at my numbers from a Uprev tune on a 7at w/ Injen CAI, FI CBE and HFC's I feel kind of jipped. I also didn't get any of the special valet or anti theft maps. The tuner told me only one map was needed/loaded for my application, and a second would only be necessary if I wanted to run a different fuel. Help me to understand, is this about normal? I understand Mustang Dynoes read lower then the rest. So I'm probably making around 300rwhp?
Also thinking about getting short headers, so I would need to retune it again correct?

Vehicle: 2009 370z
Mods: Exhaust
EMS: UpRev
Base HP/TQ: 272/215
Final HP/TQ: 280/221

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GTM Stg. 2 TT||F.I. CF 18" Res. CBE||GTM 3" Downpipe ||Injen Cold Water Intakes||UpRev||Work Gnosis GS2||Hankook||Tein Monoflex||Hawk||Seibon||Aero Jacket||

semtex

Your gains are actually better than what a lot of people, including myself, have been seeing (probably because you don't have that many mods yet, so there's more to be gained from a tune). Whether or not you'll need a re-tune with short headers depends on what they do to your AFR (which is absent from the sheet above). Honestly, I doubt you'll need a re-tune just due to headers. What you want to do ideally is finish getting all your bolt-on mods first, and then do the tune. That way you only pay once. I'm not sure why you think you're making 300whp when your final HP number is 280. You're making 280, not 300. Now, I have no idea which exhaust you have. Depending on which one you have, 280 could be good or mediocre. Which one do you have?

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"There are no small accidents on this circuit." -- Ayrton Senna
316.8whp & 248 ft/lbs (Dyno Dynamics) | 319whp & 256 ft/lbs (DynoJet) (04/23/10)
Stillen G3 CAI, CBE, Pulley / F.I. LTH / GTSpec Ladder Brace / Setrab Oil Cooler / UpRev-tuned by Forged Perf.