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Old 21 Aug 2007, 02:26 am
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Default What is the difference between i-vtec and vtec??

I am getting an RSX soon, and it has i-vtec, what does the "i" stand for?
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Old 21 Aug 2007, 02:34 am
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injected? intelligent? probably intelligent, as all v-tecs now are injected!
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Old 21 Aug 2007, 02:40 am
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intelligent
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Old 21 Aug 2007, 02:42 am
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probably fuel injected
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Old 21 Aug 2007, 02:46 am
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I think "i" stands for intelligent.(I don't know what those words stand for).V-TEC is probably for standard automobiles while i-VTEC is for the luxury models . I think an i-VTEC is better.
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Old 21 Aug 2007, 02:48 am
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intelligent
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Old 21 Aug 2007, 02:54 am
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I have an acura with vtec and if I understand correctly, the normal vtecs are V6s. The i-vtec has an inline 4 cylinder engine. I think that is what the I stands for. So a regular vtech would have more power. The i-vtec is just similar with 4 cylinders.
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Old 21 Aug 2007, 02:58 am
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VTEC itself stands for "valve timing is electronically controlled" this basically means, u get better gas mileage because you are not always using 'performnace' settings, however once you reach a certaiin RPM it will kick into 'performance mode' (if thats what you want to call it" usually this is between 4000-5500RPM and with certain engines you can actually feel it kick in,the I-VTEC is basically a more updated version getting you EVEN better gas mileage and everything good like that.
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Old 21 Aug 2007, 03:02 am
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VTEC - Variable valve Timing and lift Electronic Control. At low RPM, a VTEC engine uses a normal cam profile to retain a smooth idle, good fuel economy, and good low-end power delivery. The VTEC mechanism engages a high-lift, long-duration "race" cam profile at a set RPM value (i.e., ~5500RPM on the B16A) to increase high-end power delivery.VTEC-E - Variable valve Timing and lift Electronic Control for Efficiency. This system isn't really VTEC as we know it. At low RPM, the VTEC-E mechanism effectively forces the engine to operate as a 12-valve engine - one of the intake valves does not open fully, thus decreasing fuel consumption. At a set RPM value (i.e., ~2500RPM in the D16Y5), the VTEC-E mechanism engages the 2nd intake valve, effectively resuming operation as a normal 16-valve engine. Note: in a VTEC-E engine, there are no high-RPM performance cam profiles; this engine is supposed to be tuned for fuel economy, right?VTC - Variable Timing Control. This is a mechanism attached to the end of the intake camshaft only which acts as a continuously variable cam gear - it automatically adjusts the overlap between the intake and exhaust cams, effectively allowing the engine to have the most ideal amount of valve overlap in all RPM ranges. VTC is active at all RPMs.i-VTEC - intelligent Variable valve Timing and lift Electronic Control. This is a combination of both the VTEC and the VTC technologies - in other words, i-VTEC = VTEC + VTC. Currently, the only engines that use the i-VTEC system are the DOHC K-series engines.Now this is where things get tricky - Honda uses the term "DOHC i-VTEC" for two different systems: The first system is used in the K20A2 engine of the RSX Type-S. The second system is used in the K20A3 engine of the Civic Si.The First System (K20A2):This system is pretty close to the older DOHC VTEC engines. At low RPM, the K20A2 uses a normal cam profile to retain a smooth idle, good fuel economy, and good low-end power delivery. At 5800RPM, its VTEC mechanism engages a high-lift, long-duration "race" cam profile to increase high-end power delivery. The only difference between this i-VTEC engine and the older VTEC engines is the addition of the VTC system. The intake camshaft has the automatic self-adjusting cam gear which continuously optimizes valve overlap for all RPM ranges.Here we see an image of the intake cam lobes of the K20A2. Notice there are 3 lobes; the two side lobes are the low-RPM profiles, and the center lobe is the high-lift, long-duration profile which engages at 5800RPM. Basically the same setup as the old VTEC engines we are familiar with.Now here we see the VTC mechanism - the gear on the end of the intake cam that adjusts valve timing (overlap) automatically on the fly.This system is used in engines powering the JDM Honda Integra Type-R, Civic Type-R, Accord Euro-R, and the USDM Acura RSX Type-S and TSX.The Second System (K20A3):This system does not really conform to the "DOHC i-VTEC" nomenclature, as Honda would like us to believe. As I mentioned in my previous post, it actually should be called "i-VTEC-E," because it uses a VTEC-E mechanism rather than a standard VTEC mechanism. At low RPM, the VTEC-E system effectively forces the engine to operate as a 12-valve engine - one of the intake valves does not open fully, thus decreasing fuel consumption. At 2200RPM, the VTEC-E system engages the 2nd intake valve, effectively resuming operation as a normal 16-valve engine. There are no high-RPM performance cam profiles; this engine is tuned to balance fuel economy and power, rather than provide pure performance. On the intake cam, there is the VTC mechanism which basically is an automatic self-adjusting cam gear used to continuously optimize the valve overlap for all RPM ranges. This being a VTEC-E system - and not a true DOHC VTEC system - is the reason the K20A3 redlines at a measly 6800RPM, while the K20A2 is able to rev all the way to 7900RPM.Here we see an image of the intake cam lobes of the K20A3. Notice there are only 2 lobes - there is a nearly round one used only for the low-RPM disabled intake valve, and then there is the regular lobe used by the other valve at low-RPM and by both valves at high-RPM:This system is used in engines powering the USDM Acura RSX base, Honda Civic Si, Accord 4-cylinder, CRV, and Element.Special note: The K20A3 engine used in the Acura RSX base has a slightly different intake manifold design from the K20A3 engine used in the Civic Si. The RSX engine uses a dual-stage manifold, similar in concept to the manifold of the B18C1 in the old Integra GSR. It uses long intake runners at low-RPM to retain low end power, and switches at 4700RPM to a set of shorter intake runners to enhance high-end torque. This accounts for the extra 9 ft-lb of torque in the RSX (141 ft-lb, vs. 132 ft-lb in the Civic Si).Here is an image showing just how this dual-stage manifold works. On the top, you can see the low-RPM (long) runners are in use, and on the bottom, you can see the high-RPM (short) runners in use.Myths:1. The i-VTEC engine engages VTEC gradually, and not suddenly like in the old VTEC engines.Wrong. The i-VTEC engine "engages VTEC" at a single set RPM, like always. Whoever started this rumor is a ****tard. Read the definitions above.2. VTC engages at a set RPM.Wrong. VTC is always activated. Read under "VTC" above.3. The K20A3 engages VTEC at 5000+ RPM.Wrong. Technically, there is no "VTEC" (as we think of it) in the K20A3 engine - it uses a VTEC-E technology, which engages at 2200RPM. Read under "The Second Sytem" above.































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Old 21 Aug 2007, 03:04 am
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There is also a new engine that will be out within a few years, it is known as A-VTEC, and the A stands for Advanced. It features more power and burns even cleaner with better MPG. This new system permits optimum control over intake valve lift and phase in response to driving conditions, achieving improved charging efficiency for a significant increase in torque at all engine speeds. Under low to medium load levels, the valves are set for low lift and early closure to reduce pumping losses and improve fuel economy. In comparison to the 2.4 iVTEC these advancements claim to increase fuel efficiency by 13%
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