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Old 02-21-2013, 09:25 AM   #30 (permalink)
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Originally Posted by razor02097 View Post
I don't know that much about warm air intakes but I have read a lot about them...

from all the things I have read the 2 major benefits are introducing heat into the engine for a faster warm up to get to closed loop faster which saves fuel.

Then the other benefit is to potentially reduce pumping losses. Cooler air is more dense and contains more oxygen. More fuel can be added for the given volume which produces more horsepower. This is useful if you want to get every bit of power from an engine while running down a drag strip. However idling at a light or cruising around town you don't need power. Yes you may use less throttle but your pumping losses will increase. It takes fuel to turn the engine, with cooler air it takes more fuel to reach stoichiometric combustion....since you aren't using the power the engine is making most of the power is being used to turn the engine.... ergo pumping losses... you are paying money to move cold air through the engine.

In theory warmer air = less fuel for given volume = throttle open a little more = less pumping losses = more efficient engine = ???more mpg???....
This is what I'm trying to make the point on to you, 13B_88FC, a.k.a. Fart-Knocker-Ricer-Boi, about Warm Air Intakes v.s. Cold Air Intakes. Plus I'm not looking to build a racing machine. Instead I am looking to improve what I currently have for my daily commute. Since I don't go driving around at near-WOT-to-WOT like SOME people seem to think they should for MAX-Performance, I'm hoping to maximize fuel efficiency by driving conservatively, while using the Warm Air Intake idea I have to ensure a more complete mixing of air and fuel droplets from EACH of the SIX injectors on my 4.0L I-6's Intake Manifold.

My thinking is, if the Intake Air Stream is 30-50 degrees above Engine Compartment Ambient, the fuel droplets from each injector's pulse would be more likely to evaporate quickly enough to compensate for the lowered oxygen density of the warmer/hotter air, than if I were to drop the intake air charge temperature to BELOW Engine Compartment Ambient Temperature, which is what CAIs are supposed to do.

The use of a CAI would be more likely to cause the droplets to clump together more as they entered the Cold Air Stream into each of the intake ports on the head(s), requiring more fuel overall to be used per cylinder, whether on post-cold-start-warm-up, or once at operational temperature. By heating up the intake air charge to well above Ambient Engine Compartment Air Temperature, I'm hoping to avoid this, or at least reduce its likelihood, especially if it improves overall MPG, like I think it will.

Btw, the 4.0L Jeep engine NEVER had Throttle Body Injection since Day One. Even during the Renix years, it was a Multi-Port FI system. The earlier 4.2L Jeep I-6 WAS carb'd with a Carter "Chug-and-Glug", which was not as fuel efficient, or powerful as its younger 4.0L sibling, but not the 4.0L itself.

Last edited by Davinator61; 02-21-2013 at 09:36 AM..
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