mhconley

I obtained a used SCT Xcal 2 from a friend and I'm now looking at CAI's.

I have several in mind, C&L Street, ProFab, and Steeda Carbon Fiber, and I know they all perform fairly equally with a good tune. (i.e., within a couple of HP/ft-lbs of one another) I have also read in several forums opinions that the tune produces the biggest performance gain and the choice of CAI seems almost inconsequential in comparison. This leads to my question...

Will using the stock intake with a drop in high flow filter and a custom tune produce a noticeable increase in performance? What would it add in terms of HP/ft-lb to the stock tune? How much more will adding a CAI to the equation add? I guess what I am getting at here is this: All things being equal, is a CAI worth $200-$400?

Martin

mhconley

Don't all chime in at once now... Let me start this discussion off with these numbers...

I read each and every post in the Your Dyno Numbers sticky and found a single entry that validates the point I was trying to make in my original post.

Stock: 255HP/269TQ
Stock w/Tune: 286HP/309TQ
JLT CAI w/Tune: 293HP/315TQ

The difference:
Tuned stock over stock: 31HP and 40TQ
CAI + tune over stock + tune: 6HP and 6TQ
CAI + tune over stock: 37HP and 46TQ

The difference between the stock airbox + tune and the CAI + tune is almost within the 5HP margin of error that 5.0 Mustang and Super Fords set in their CAI comparison.

That magazine's own numbers from that comparo for almost the same three data points:
Stock w/hydrocarbon trap removed: 261HP/282TQ
Stock w/"modest 91 octane tune": 271HP/289TQ
JLT CAI w/Tune: 290HP/304TQ

Their difference:
Tuned stock over stock: 10HP and 7TQ
CAI + tune over stock + tune: 19HP and 15TQ
CAI + tune over "stock": 29HP and 22TQ

The difference between what the magazine reported and what I found in the Your Dyno Numbers post is both significant and interesting. It is interesting because the magazine removed the hydrocarbon trap from the stock intake to set baseline which they admit added 6HP to the true stock baseline. They also purposely state the tune they used on the stock airbox was a "modest 91 octane tune."

I find these differences telling. 5.0 Mustang and Super Fords is supported by advertising, including CAI advertising. I would venture to guess that CAI's are by far the number one selling aftermarket performance mod.

What would the real difference had been had they started with true stock numbers and used an aggressive tune on the stock airbox? Would you ever satisfy yourself with a "modest tune"? I think not.

How much air does our N/A 3V 4.6L V8 need? Will it ever draw more than the 550CFM the stock airbox will pass?

What would the numbers be for a stock airbox with the hydrocarbon trap removed, a high flow drop-in air filter and an aggressive tune? It seems to me they would be very similar to what are being claimed for these CAI systems.

Comments anyone...

Martin

mister

mhconley,

I have a drop in K&N filter with stock intake, and XCal2 with Bamachips 91 Race tune. Let me say it is a huge difference in throttle response and acceleration. It can only get better with a CAI, but i am sticking with what I have. I noticed a big improvement and it is plenty of power for me as a daily driver.

mhconley

Thanks Mister!

I also found the answer to my other questions:
How much air does our N/A 3V 4.6L V8 need? Will it ever draw more than the 550CFM the stock airbox will pass?

CFM = (displacement in cubic inches/1728) x (RPM/2) x volumetric efficiency

displacement: 281.08 CI
RPM: let's use 7,000 RPM (6250 is stock redline)
volumetric efficiency: 0.8 for N/A

CFM = (281.08/1728) x (7000/2) x 0.8 = 455

So the stock airbox is perfectly capable of feeding sufficient quantities of air into the engine. It would take running the engine to 8453 RPM before it would hit the 550 CFM the stock airbox can provide.

Interesting numbers... I think I may just order tunes and do without the CAI, at least until I begin thinking about force feeding.

Martin

Martin

n8rfastback

interesting find....

another option would be the bullitt intake and box... just for thought

Five Oh Brian

mhconley,

I've never dyno'd my 07 GT automatic coupe, nor did I ever drag race it stock, but I think my info may help you none-the-less.

Let's assume that my car probably would have run high 13's to low 14's at 99-100 mph bone stock in the 1/4 mile, as that's pretty average from magazine tests and reports at online forums from other members with similar cars.

I had 4.10 gears installed when my car 2 weeks old, and bought a DiabloSport Predator tuner to correct the speedo for those gears. Of course, I installed the 93 octane tune (firm shifting settings) that came with the Predator while I was at it (not any kind of custom tune from a popular vendor). Went to the track and ran 13.50's and 13.60's at 102-103 mph consistently. That translates to about 1/3 to 1/2 second improvement, along with a few mph through the traps. Very respectable given the cost of gears & tuner. This kind of performance gain works out to about a 25 rwhp improvement from my calculations. Worth noting, this was through the stock airbox/filter and stock exhaust.

I then installed a Fuddle Racing converter to increase flash/stall speed in my automatic transmission. Lost a little mph through the traps (101-102 mph), but ET's improved to 13.20's and 13.30's - about two or three tenths. Again, great improvement for a small investment. Still using the stock airbox/filter and stock exhaust.

I recently installed a JLT II CAI and tune, but haven't been back to the track yet (winter time), but can feel a noticable difference. The tune is more aggressive (as more airflow is available?) and I've owned and raced enough cars over the last 26 years to have a decent butt-o-meter. I'd say that there's enough extra oomph to get the car through the 1/4 mile in the 13.0's or 13.1's at about 103+ mph now. If that turns out to be true, then 1 or 2 tenths of a second improvement was $199 well spent on the JLT II CAI. I'm looking forward to being able to report real world numbers from a day at the track soon, but I am pleasantly surprised with how the JLT II CAI affects the car's performance.

I - like you - was skeptical at first about whether a CAI would add anything to the stock airbox + tune. If you search any of my posts from last summer & fall, you'll read how anti CAI I was then. But, having the CAI on the car has made a believer out of me!

mhconley

Thanks Brian.

I want it understood that I am by no means anti-CAI. I'm just a cheap bastard. I don't beleive in spending money just to spend money. I am also a strong believer in scientific method and statistical data analysis.

I don't know one person on these boards that would add a Turbonator or a throttle body spacer to their 2005+ Mustang GT despite the many claims of improved mileage and performance.

I'd love to see an unbiased dyno analysis of the various CAI's vs. the stock airbox. I don't have the money to do one myself so I've resorted to research availing myself of existing data.

I love the looks of many of the CAI's and I know they make a sweet sound. I'll probably add one someday just because. Right now I'm just looking to save some dough. I picked up used SCT Xcal 2 from a friend for $100 and can get 3 tunes for another $125. So for a total outlay of $225 I think I can get pretty darn close to the same performance boost as I'd get spending $550 to $800 for a tuner and CAI.

Martin

WaltM

Great stuff Martin. I am a believer in numbers and those really prove the point. But CAIs look cool and they sound mean when they suck in all that air !

Five Oh Brian

Martin, I'm cheap, too, so I know right where you're coming from. And why I fought the urge to buy a CAI for so long. With the 93 octane tune in my Diablo tuner advertised to add 27hp, and the CAI/tunes advertised to add 28-32hp, it sure sounds like the tune is much more important than the CAI.

It sure was priceless running 13.20's and 13.30's and have people look over the car afterwards, see the automatic shifter & no mods under the hood & factory exhaust! Sure made them ask a lot of questions. The tune is invisible, as are the gears & converter, keeping my stealth mode intact!

mhconley

I love the stealth look. Wish I could find someone, anyone, to take my trunk lid and GT spoiler. I hate the thing.

I think it's cool you took yours to the next level with the V6 look. The ultimate sleeper.

I may just use the savings from not buying a CAI for gears.

Martin

Five Oh Brian

Martin, gears are certainly one of the best performance values for our cars! Parts & labor for a gear swap are in the $500-$800 range. And with our steep overdrives, fuel economy doesn't suffer at all. I get 27 mpg highway if it's flat terrain, or about 24 mpg highway if it is rolling hills - either of which is better than the EPA rating. And that's with 4.10 gears.