2013 JK K&N Intake + Throttle body Spacer ? - JeepForum.com
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post #1 of 6 Old 09-01-2013, 04:13 PM Thread Starter
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2013 JK K&N Intake + Throttle body Spacer ?

My wife and I own a 2013 Jeep Sahara Unlimited that has been lifted 2.5 inches and is running 33s. My question is has anybody put an cold air intake on a Penstar 3.6 if so have you seen any benefit. I was considering also buying a Throttle body spacer as well to try to increase the MPGs.
Thanks for reading.
(She says its her jeep.)

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post #2 of 6 Old 09-01-2013, 06:03 PM
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You aren't going to increase fuel economy on a Wrangler. It just isn't going to happen.

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post #3 of 6 Old 09-01-2013, 08:12 PM
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CAI and TB spacer, the top two wasted money mods on the list....unless you got money to throw away and all you want is a different sound, go for it, otherwise, do some research and save your money for something useful. opcorn:

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post #4 of 6 Old 09-02-2013, 09:06 AM
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Maybe the naturally aspirated engine in the JK is different than the one in this car.
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post #5 of 6 Old 09-02-2013, 10:04 AM
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Originally Posted by PaXJ View Post
Maybe the naturally aspirated engine in the JK is different than the one in this car.
At best its a percentage thing. Say you get a 3% gain. On a 285 horse engine thats 8.5 hp at peak MAYBE (all engines are different in design of port shape, size and flow quality). On that 350HP camaro the same 3% is 10.3 HP. How sensitive is the seat of your pants. I know I cant feel 10HP at 4500 RPM in a race car where its over 3000 RPM 70% of the time! the stop watch would barely even show that (do all the math a dragster has to do and you will see).

AND if that gain is at RPM over 4000 - how often are you driving at that RPM? 1% of the time? So you gain 1% of 3% in real world comparison.

Please don't waste your money - I want to see you do things that you enjoy not disappoint yourself.. Spacers especially - they work by changing the distance from throttle to plenum floor (the first place the incoming air charge has to make a turn) and prevent fuel fall out during the turn... There is NO plenum floor on a JK engine and no fuel in the air charge TO fall out (air turns but the heavier fuel particles want to go straight) - fuel is delivered directly in front of the valve after all turns - ZERO fallout. There is a plenum on that Camaro... but still no fuel to fall out of the air charge as it is also injected at the valve...

Look at it this way. Gears multiply. If you have 260 ft lbs of torque at 4500 RPM with a 2.7 first gear and a 3.73 axle - you have 260X2.7X3.73 or 2618 at the axle (the tire/axle radius saps this downward so not all hits the ground - and also not considering parasitic losses from gear friction etc). Go to a 4.10 gear and the math looks like 260X2.7X4.11=2885 available! 13% increase in ALL rpm ranges not just the peak! (and since the tire is spinning slower than the engine the HP calc at the tire uses less time thus a lower HP rating - the gears do not reall multiply the HP as much do they)

Look at that dyno chart and see how much HP you have at the RPM you drive. At 2000 RPM the HP is a LOT lower than at 4500!. Since Horsepower is torque delivered over time - the ONLY way to increase performance and USE that torque gain an engine mod could make is to increase the TIME of the equation - which is RPM. gears and tire size effect performance way faster than HP gains - until the HP is REALLY cranked up - more than a CAI kit would. You want to feel more kick in the seat? Go to a smaller tire or bigger numerical gear! That is gain that is returned in power and economy at ALL RPMs not just the RPM up high in the range where PEAK occurs...

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post #6 of 6 Old 09-02-2013, 10:31 AM
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Like stated above increasing plenum size rarely has an affect on sfi engines, now throttle body and carbs. Its a huge deal. I would start with tuning exhaust NOTE : bigger pipe will not increase scavaging!!. You want velocity without restriction. Then tune the intake, go to an actual tuner and then youll see some differences. Btw chrysler spent a lot already doing this. But they probably went more economy.

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