Optimal CAI and Cat-Back Combination for Power

[Deinonychus]

The CAI and Cat-back are just two of the variables in the flow through the motor. These two areas are the least expensive to address. But to truly address motor flow we should identify all the variables to restrict flow.
I see the following (add to what I have over-looked):

• Intake Air filter and tube
• Throttle Body
• Intake Manifold
• Heads
• Valves
• Exhaust Ports
• Exhaust Manifold (or Headers)
• Cats
• Mid-Pipes
• Muffler
• Exhaust Pipes
• Resonator
• Exhaust Tips

This doesn 't consider forced induction, nitrous, cam, displacement increases, etc.

It is my opinion that most manufacturers do the least optimal work in performance at the intake air filter. It seems that most manufacturers optimize around motor noise. There is more pressure drop through the stock intake system that is easily possible to improve with a filter with larger cross sectional area/better filter material.

 

[dew.man]

On a slightly different note, do you guys think that the "typical" cai/canned tune combo sacrifices any low-rpm torque for high-rpm gain?

I think that SVT did a very nice job of tuning the truck for a wide range of uses. I'd like to go with a cai/catback/5star tune, but am concerned about giving up some streetability for good dyno numbers!?

 

[Deinonychus]

On a slightly different note, do you guys think that the "typical" cai/canned tune combo sacrifices any low-rpm torque for high-rpm gain?

I think that SVT did a very nice job of tuning the truck for a wide range of uses. I'd like to go with a cai/catback/5star tune, but am concerned about giving up some streetability for good dyno numbers!?

I could be off the mark, but I don't believe that there is any reduced pressure drop prior to the exhaust will sacrifice torque or horsepower.

The bigger concern develops in the exhaust, where exhaust velocity needs to be maximized.
Theoretically, optimal exhaust velocity would have tube diameter vary proportional to motor rpm.
Or more simply, exhaust velocity in a large tube at low rpm's might fall below the optimal velocity for power, yielding reduced torque at low and mid rpm's. But the same large tube would yield higher horsepower at the high rpm's.
And, velocity in a small tube might allow the optimal exhaust velocity at low rpm's, but at higher rpm's the the exhaust would be too restrictive, yielding lower horsepower numbers.

We would like to have a relatively small exhaust tube at low rpm's that increased to a relatively large tube at high rpm's. Extremely impractical.

Considering the weight of the Raptor, we would be very concerned of any modification that sacrifices low and mid rpm torque.
We would like to maximize the area under the torque curve, especially in the low and mid rpm range.

 

[mblgjr]

On a slightly different note, do you guys think that the "typical" cai/canned tune combo sacrifices any low-rpm torque for high-rpm gain?

I think that SVT did a very nice job of tuning the truck for a wide range of uses. I'd like to go with a cai/catback/5star tune, but am concerned about giving up some streetability for good dyno numbers!?

In short; no.

With any *good* tune, you will gain all the way through the curve.

A good catback by itself will not sacrifice any bottom end. Most typical catbacks for the Raptor will gain approx. 10rwhp at best. Not worth arguing. The cork in the system is the stock converters. Simply going to high-flows is the best bang for your buck; but will also add significant volume. You will also notice a slight, but distinct loss of bottom end below 2k RPM; but power gains will show up from about 25-2800rpm onward.

Going to LT's and a proper catback will gain around 40rwhp post-tuning, but gain most power under the curve compared to the 40rwhp gained by tuning alone. However, for the midrange gain, you also gain a fair amount of noise and for most people this isn't the greatest for a daily driver. Some love it, some don't. LT's on my car don't bother me because I don't spend a lot of time in it every day and it's "fun" for short bursts. Wouldn't really want them on the the truck though. Unless you plan on doing a Whipple/other forced induction, I don't think headers are necessarily worth it. But, once you get into boosted setups...yeah, I'd prob run headers and add sound dampening throughout the cab.

After living with it for a little while, I was averaging 13.8mpg in stock form and with the Magnaflow catback (no change in mpg; just a touch more midrange power and sound).

Added a tune from Dennis @ Tasca; gained feelable power from 1600 RPM+, and gained a minimum of 2.2mpg (16.0) but have already gotten my average as high as 16.8 with *ease* but then I started enjoying the new horsepower

 

[Maxx2893]

Just installed the volant intake with the power core filter. Has been raining tonight so could mash the peddle without breaking loose the tires. i did get on it pretty good once after the streets started drying (still pretty damp) and broke em loose at 45-50 mph. (yeah i would throw the bs flag too) but like i said the streets were still a little wet.

But the sound is MEAN. At times the sound from the engine was louder than the dumped magnapack but in a good throaty way.. I had a K&N CAI on my last truck without a lid on it and it still didn't have this big of a difference in sound.