C & L intake kit

gera8712 · 10-23-2008, 10:07 AM

hi guys i was wondering if i will need a tuner for this kit?
is a c&l 85 maf system for a 2004 mustang gt my car is basicly stock, all ive done is changed mid pipe and catback but im planning to get a new plennum and throtle body as well with this intake kit, i just dont wanna buy a tuner chip yet? or is it better if i just get a k&n intake kit?

thanks!

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silverstang1996 · 10-23-2008, 10:09 AM

I believe c&l kits are the best power gain with aftermarket intakes, at least they back up their statements with cars they dynoed with the intake kit on (at least the cobra kit i got)

gera8712 · 10-23-2008, 10:23 AM

did u need a tuner to install it or can it work just fine in a stock engine?

cliffyk · 10-23-2008, 11:15 AM

This is long, today is one of my "off" days. I was intrigued by C&L's claims and wanted to run some "back of the napkin" numbers to see if their numvber were even feasible--they are, and are accomplished by tricking the OEM tune...

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The C&L 85 mm MAF is just an 85 mm housing into which you mount your stock MAF sensor. This bastardized combination will not have the same transfer function as the stock MAF. While this might make one believe you would need a tune, what it really does is trick your PCM into making the AFR in open loop mode leaner, read more below.

A MAF works by sampling a portion of the air flow passing through it and reporting that value to the PCM. The PCM infers from that sample value what the flow rate through the entire MAF is. This is because of the Transfer Function, a pre-defined relationship between the MAF output voltage and total air flow through the MAF in kg/s. Putting the OEM sensor in the larger housing will alter the transfer function.

With the OEM 80 mm MAF the sensor measures 1.60% of the total flow, so the total is 62.4x the sampled flow. By placing the OEM sensor in the C&L 85 mm housing the sensor will only be measuring 1.55% of the total flow, making the total flow 64.4x the sampled flow, or about 3% more air than being indicated by the MAF output. Because the MAF output hasn't changed the PCM will continue injecting as much fuel and it normally would, into 3% more air = slightly lean.

In closed loop mode the AFR is controlled based on feedback from the O2 sensors, and the PCM will add or remove fuel by changing the injector pulse width. The PCM will sense the lean mixture and increase the Short Term Fuel trim so as to add more fuel and keep the average AFR at 14.7:1.

However, in open loop mode (WOT) the PCM sets the injector pulse width (amount of fuel injected) from static (programmed) lookup tables based upon rpm, load, ECT, IAT, and other inputs--and air flow info from the MAF. Once again this will result in a lean mix, but guess what--the OEM tables tend toward rich, typically 11.25:1 to 11.5:1. This is done so that the 4.6L 2V can run on 87 octane fuel; even lousy 87 octane fuel. It has no effect on EPA mileage ratings as none of those are run at WOT, so why not...

By leaning out the mix a bit at WOT, to 12.0:1 to 12.5:1 you will make more power--with the OEM tune.

Fueling at higher loads and WOT is in part controlled by two setting known as the low and high injector slopes, which are the injector's capacity in lb/h at longer and normal pulse widths. The OEM tune on my '03 had these set to typical 19 lb/h values, even though the '03 and '04 model have 21 lb/h injectors. I was seeing AFR at WOT of 11.3:1 to 11.6:1 with these settings, by increasing the values to typical 20.5 lb/h values AFR at WOT went to 12.0:1 to 12.5:1 and there was a noticeable kick in the pants.

This is in effect exactly what C&L is doing with their larger MAF housing. Doing it in that manner is not an entirely proper way of doing it as there are other things that use the MAF transfer function and expect it to be accurate, however doing it a small way as they have is quite ingenious and should increase power at WOT without a tune. In fact if you were to tune a car with that MAF you would have to add 3% across the board to the transfer function as one of the first modifications.

silverstang1996 · 10-23-2008, 02:10 PM

^wow I'd read that like 2 more times to fully understand it but it's just too long for me to concentrate on

. I remember they put one on a 5.0 stock on HP tv, and it made around 9rwhp more, so it does add more than your run of thee mill CAI, but deffinetly not as cheap since you need to buy thee whole kit to get the best power from it.

gera8712 · 10-23-2008, 03:54 PM

lol ^+1, i know i red it 3 times actually, and if i understood this kit is just what 03 & 04 models need; right?

thanks for replaying!

cliffyk · 10-23-2008, 04:31 PM

It's not the way I'd do it, because the way it bastardises the MAF and tricks the PCM is a bit of a kludge. It's an somewhat ingenious kludge, but it's a kludge nonmetheless. Any gain it provides does could easily be accomplished with a tune, without even getting you hands dirty.

However if one is the sort that does not ever envision themselves getting a real tune and/or tuner it's kind of a neat way to actually get more power. Just be aware then when you want to do a real tune you will need some method of properly mapping the MAF transfer function, or at least understand that the t/f in the stock tune does not match the knickered up MAF...