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Discussion Starter #1
Ok, I'm still very new to the whole Honda thing. I'm a voracious reader and have been digesting large quantities of information on the R18 1.8 I-VTECH engine. The problem seems to be there is a LOT of contradicting information out there. So I need a hand knowing what is good, and what is bad.

What I've read would appear to indicate two different things. Which is true? Neither or either?

1) The 1.8 R18 I-VTEC engine only uses its VTEC for fuel economy. There is no 'performance' mode as may be the case on older and different models.

2) The 1.8 R18 I-VTEC engine uses its VTEC for both fuel economy and performance. The mode you are in will be influenced by a wide degree of factors, but this effectively gives your auto multiple driving modes.
 

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Good posting of that video, it's one of my favorites :giggle:

In summary, basically the R18 has 2 cam profiles, "econ and mild" instead of "mild and wild" cams like in the K20. When you're under 3500 rpm and you're cruising or any other low load condition, i-VTEC is on (economy cams). If you're under 3500 but you're accelerating or doing something that isn't keeping the throttle constant then i-VTEC isn't on even though you're in the range it could be operating in.

If you're over 3500, no matter what you're doing i-VTEC isn't on because you passed the threshold. It only comes on during low load conditions under 3500 rpm. Which is why they say "Fuel economy of a 1.5L when cruising."
 

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Discussion Starter #5
Excellent, thanks guys!

I'm off to laugh at the wife for saying that she could feel the VTEC kick in while accelerating. Or maybe I'll just wait until she says it again and I'm in the car.:dance:
 

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Discussion Starter #6
Oh, I guess that begs another question.

What kind of fuel economy difference does one see between I-VTEC and non?

Let's say, to keep this simple, one is driving on the freeway and your gently, slowly, ever to slowly picking up speed... the engine speed rises from just below 3,500 rpm to just above and I-VTEC kicks off.

Are we talking about 2-3 mpg difference or a 3-7? etc.
 

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The R18 makes peak torque near 4000 rpm, which is why there's a satisfying pull all the way from 2500 to 5000 rpm. It's an amazing little engine. That's what she was feeling, no need to rev it any higher!
 

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She actually was probably on low load, then hit the gas to accelerate, and the engine kicked into normal driving/accelerating mode. Even on a R18 that would be a noticeable difference, hence you can't laugh at her, because she was right...
 

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You can only be on low load when you're cruising.. this is where there's confusion.
VTEC is not on around town. When it goes out of VTEC there's no delay or mechanical notification, it's seamless.
 

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She might be feeling the car switch to a lower gear which gives a bit more push
 

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Cool info.
 

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Actual MPG figures are too subjective, but on average the R18 was created to fill these requirements:

1.) Low-end torque equal to an equivalent 2.0L
2.) 7-10% more power than the D-series 1.7L
3.) 6% less fuel burn than the D-series 1.7L
 

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Vtec function is only one part of the r18. The two stage intake provides proper torque throuhtout the rpms. No other 1.8 makes more power untill sky high rpms. Sure isn't a k20z3 but honda did a stellar job with the r18.
 

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^^^ yes haha finally people are starting to get it

also some people claim they feel a "vtec" kick or "vtec" sound change at around 5000 rpm on the r18 and this is somewhat true...around that point the variable length intake manifold shortens to provide the engine with quick flowing air at those high rpms to make some power up there...it is not performance vtec kicking in yo
 

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this is what vtec stands for in the R18

V.T.E.C. ..... Virtually Torqueless Economic Car

:sadbanana: sad, but somewhat true.
 

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By varying lift, they eliminate some pumping losses at lower RPM which makes the engine more efficient. BMW uses a slightly more complicated (read, 'not necessarily better' ; -) variable lift system known as Valvetronic.
 
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