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Discussion Starter · #1 ·
Hey I just installed my TK CAI a couple nights ago and for SOME reason I get ridiculously good numbers for the highway but i get down to 20s just cruising in 45mph zones, im thinking its because of the cold, if so then Ill probably go to an SRI setup for the winter... I dont rev either lol
 

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The cooler the air and the easier an engine can breathe the better it's efficiency. 20s while cruising at 45. What gear? The 2.4L is torquey so you can be in 5th or 6th at 45 cruising and should be in the 30s... Did you reset your ECU after the install to allow it to learn the new air flow characteristics?

Hey I just installed my TK CAI a couple nights ago and for SOME reason I get ridiculously good numbers for the highway but i get down to 20s just cruising in 45mph zones, im thinking its because of the cold, if so then Ill probably go to an SRI setup for the winter... I dont rev either lol
 

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I think you should decide you dont like it, face it and consider your losses.......now send it to me and I'll
be sure to discard of it in a respectable manner. it will be my service to you :D
 

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Hey I just installed my TK CAI a couple nights ago and for SOME reason I get ridiculously good numbers for the highway but i get down to 20s just cruising in 45mph zones, im thinking its because of the cold, if so then Ill probably go to an SRI setup for the winter... I dont rev either lol
I usually get around 20-21 cruising. Never really ever took it far on the highway to get those kinda numbers. And when I'm cruising I barley rev it.
 

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Discussion Starter · #5 ·
I cruise in 6th at 45 and I'm down in the 20-22 range and yes I believe the ECU reset considering I left the battery disconnected throughout the whole installation.
 

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with the 6spd i find that the money mpg rpm is about 2000.... i'm in 4th at 45mph and get 24-26. its all about throttle.... i use 6th as exclusively a cruising gear at 70+ mph
 

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I agree w/ Bigbullldogg. Sounds like you are in 6th gear way too soon. I never use 6th below around 60 mph (unless it's downhill).

Higher gear does not necessarily mean higher efficiency. You have to "choose the right tool for the job" as they say.

While driving for efficiency I try to pick the gear that allows my gas pedal to travel the least amount. I cannot say this is the best method; but if you spend a week or so really paying attention to how far your foot has to travel at each gear to accelerate or stay at speed I think you will find that you are pushing the pedal further in higher gears if you enter them too soon than you would have if you waited.

I get fairly good gas mileage and driving this way my forte still has a good omph! to it. Every so often it is nice to hang in third gear till about 60 mph though ;) haha
 

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Discussion Starter · #8 ·
haha well ill have to try cruising in 4th then.. just to see what happens, I almost wanna think thats too low of a gear for 45 but then again i dont really pay attn to how fast im going when i shift lol i know i probably should but i dont lol i go by the sound and my tach, i usually shift at 2500-3500 unless im havin a little fun, in which case I usually tap redline then shift
 

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An engine has something called BSFC, or Brake Specific Fuel Consumption. It determines how much fuel is required to turn a engine at a specific RPM and a specific Load. Every engine has a different BSFC map curve. Here is a generic 4-cylinder BSFC map:



As you can see, the higher the load, the more fuel efficient your engine becomes. You will also see that, the closer to the engine's torque band you get it also becomes more fuel efficient.

Conclusion: Anything that allows you to keep the throttle open wider and the revs lower (like changing up to a tall gear and then holding it) will reduce fuel consumption because BSFC will be improved. However, lugging an engine will give you the opposite results. I would recommend keeping your RPMs over 1400 at all times in order to prevent lugging.



High load (high gear) + low RPM = good MPG
 

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Discussion Starter · #10 ·
I hardly EVER lug the engine, like once in a blue moon Ill lug and thats like if i forget im in a higher gear lol. So where do you SX 6spd owners usually shift? Im curious! I usually shift at about 2500 or 3000
 

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I'm 41 and I have been driving a manual since I was 16 in cars and motorcycles as well....and I have always been told and firmly believe it is better to "rev" you engine/RPM rather than letting it "lug"....typically "lugging" and engine is not good for it.
 

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The problem is that 90% of drivers have no idea what lugging is, most will tell you "anything under 2000 rpm" which is just not true. It is highly dependant on the load, the engine, and many other factors. You can tell when you're lugging an engine by pressing the gas pedal down and the speed of the car does not increase as expected. You may hear noises, pinging/knocking, this is an indicator of lugging. The solution would be to downshift and get up to speed, then to shift back into high gear.
 
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