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Which CAI to buy?

2615 Views 14 Replies 9 Participants Last post by  Colleton
I am looking for the "best" CAI on the market. By "best" I dont necessarily mean, the biggest HP gain. Im also looking for how effective/efficient and lasting it will be, ease of cleaning and looks too.

I have looked at K&N and their claimed 53.xx HP gain. It looks like they do not conform to the SAE J1349 dyno standard that Ford uses to compute the factory numbers for the GT500. The temperature and barametric pressure(s) are different, and it appears there was no retune done after adding the K&N, therefore making the engine run leaner, producing more power.

The FRPP grabbs 40HP with the SAE J1349 dyno standard test (plus a retune to correct the F/A ratio). I dont know the correction factors neede to accuratly compare these two filters, but it seems as if the k&N would do about the same as the FRPP when done at the same standard.

I have also tried to get info on the 2010 GT500 CAI or the KR CAI(which I guess are one in the same). That appears to be the FRPP CAI but with an added ram air that runs to the grill. It however, produces the same 40HP as the standard FRPP CAI. First, does anyone know why this is, and second, does anyone have a P/N for it and a price. It not in the latest FRPP (summer 2008) Brochure.

This is a quote from the FRPP summer 2008 brochure reguarding how dynos are done differently and how aftermarket companies forge their high numbers.

"There are two main types of chassis dynamometers (dynos) in widespread use today.
• An inertia dyno uses a large spinning drum that is accelerated by the drive wheels of the test vehicle. Power is then computed by
knowing the inertia of the drum and how quickly it was accelerated. Torque can then be calculated by knowing the speed of the drum.
• An eddy-current dyno absorbs and measures power by rotating a metallic disc through a magnetic field.

Without getting into which dyno is more “correct” under what conditions, and why, we will simply say that these two types of dynos typically
do not always give the same result even with all else being equal. It is generally not possible to accurately compare numbers from one type
of dyno with those from the other type of dyno. Each type of dyno has its own advantages and disadvantages, but as long as all the tuning
work is done on the same type of dyno, it doesn’t really matter which one is used.

With any dyno testing there is a need for correction factors that are applied to the raw numbers the dyno actually measures. These
correction factors are an attempt to correct for varying atmospheric conditions such as humidity, barometric pressure and air temperature.
The two most common standards are SAE J1349 and SAE J607 (sometimes known as “STD” on some dynos). How correction factors are
calculated is given in the “Crate Engine” section of this catalog. For this article understand that these correction factors will give results that
are different from each other, with SAE J1349 typically about 4% lower than SAE J607. OEMs will almost always quote J1349 corrected
numbers when advertising horsepower and torque. Some “tuning” shops will report STD numbers because they are always higher than SAE.
Be sure to ask which correction factor is being used when comparing dyno numbers!

Whenever comparing dyno results, always be sure that the numbers are corrected to the same standard. Despite these correction
factors, atmospheric conditions can play an additional role in terms of ignition timing. The correction factors account only for the change
in the density of the air due to atmospheric conditions and cannot account for things like engine borderline spark sensitivity. As inlet
air temperature increases, the PCM will generally retard spark to prevent detonation using the particular octane of fuel for which it was
calibrated. Correction factors cannot account for this because different engine designs can have different spark sensitivity and different sensitivity of torque relative to ignition timing. Basically this means that the closer the actual conditions are to the SAE J1349 standard
(77 deg F inlet air, 29.31 inHg barometric pressure), the more comparable the results are to those quoted by the manufacturer. Unless
otherwise explicitly stated, all horsepower numbers in the Ford Racing catalog have been determined by using the
SAE J1349 standard." :bigthumbsup
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Mustang dynos have information inputted that has a direct affect on horsepower and torque numbers based upon weight. You can "tune" a Mustang Dyno in order to achieve whatever numbers you want. In any situation, the Eddy Current ONLY Mustang Dyno should produce slightly lower numbers than a Dynojet. It's proportional, but alot of guys rate it between 5-10% depending on vehicle weight, etc.

A dynojet cannot inflate numbers at all, the only thing they can do is change correction factors (which only have a window of about 5% change).

Dynojet SAE corrected numbers are the industry standard and the only numbers that I would trust. But numbers are just numbers, and it's the tuning that is the important part. For more info on Muistang Dyno / Dynojet numbers, here's a link:

Tillman Speed, Inc. Forums • View topic - I Hear That Dynojet Dynos Inflate Numbers, Is That True?

Anyway...

FOR MY GT500 AIR INTAKE RECCOMENDATION I reccomend the C&L Cold Air Induction kit. I sell this system all the time, and do alot of custom tuning in-house on our Dynojet 224xLC with this system. We have a few different staged performance packages that we sell here in-house, but this intake will absolutely make every bit of 60-70RWHP and we have dyno'd back to back to prove it.

With the right pulley, etc... you'll have no problem making 100's of RWHP over stock. You can even use the system with a Whipple 2.9 down the road! :gringreen

You're only in VA Beach, call me and lets get her on the dyno!

Chris Rose
Tillman Speed Inc.
610-497-5776
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