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Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
My view is that at certain times, the engine can take in more fuel and
air. More power, yes. Better fuel mileage, I don't think so. bob Matthew Hunt wrote: > > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
My view is that at certain times, the engine can take in more fuel and
air. More power, yes. Better fuel mileage, I don't think so. bob Matthew Hunt wrote: > > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
One could argue that the biggest benefit of V-TEC (compared with a
standard 3 or 4 valve / cylinder engine) is when it is NOT engaged. At low RPM / light load (where you spend the most time) a single intake valve is better than two. With V-TEC both ends of the range can be optimized. "'Curly Q. Links'" wrote: > > When comparing a '96 Odyssey to a '98 Odyssey (which has V-Tec in > Canada), would you say that the '98 will get better mileage at all > engine speeds, or just when revving it up to the point where the V-tec > cuts in? > > I.E.: Is this statement true? > Mileage is mediocre in both of the first generation Odysseys, but you'll > waste less gas when passing (or speeding or climbing hills) with the > V-Tec model.... > > Reply to group, thanks. > > 'Curly' |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
One could argue that the biggest benefit of V-TEC (compared with a
standard 3 or 4 valve / cylinder engine) is when it is NOT engaged. At low RPM / light load (where you spend the most time) a single intake valve is better than two. With V-TEC both ends of the range can be optimized. "'Curly Q. Links'" wrote: > > When comparing a '96 Odyssey to a '98 Odyssey (which has V-Tec in > Canada), would you say that the '98 will get better mileage at all > engine speeds, or just when revving it up to the point where the V-tec > cuts in? > > I.E.: Is this statement true? > Mileage is mediocre in both of the first generation Odysseys, but you'll > waste less gas when passing (or speeding or climbing hills) with the > V-Tec model.... > > Reply to group, thanks. > > 'Curly' |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
One could argue that the biggest benefit of V-TEC (compared with a
standard 3 or 4 valve / cylinder engine) is when it is NOT engaged. At low RPM / light load (where you spend the most time) a single intake valve is better than two. With V-TEC both ends of the range can be optimized. "'Curly Q. Links'" wrote: > > When comparing a '96 Odyssey to a '98 Odyssey (which has V-Tec in > Canada), would you say that the '98 will get better mileage at all > engine speeds, or just when revving it up to the point where the V-tec > cuts in? > > I.E.: Is this statement true? > Mileage is mediocre in both of the first generation Odysseys, but you'll > waste less gas when passing (or speeding or climbing hills) with the > V-Tec model.... > > Reply to group, thanks. > > 'Curly' |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
One could argue that the biggest benefit of V-TEC (compared with a
standard 3 or 4 valve / cylinder engine) is when it is NOT engaged. At low RPM / light load (where you spend the most time) a single intake valve is better than two. With V-TEC both ends of the range can be optimized. "'Curly Q. Links'" wrote: > > When comparing a '96 Odyssey to a '98 Odyssey (which has V-Tec in > Canada), would you say that the '98 will get better mileage at all > engine speeds, or just when revving it up to the point where the V-tec > cuts in? > > I.E.: Is this statement true? > Mileage is mediocre in both of the first generation Odysseys, but you'll > waste less gas when passing (or speeding or climbing hills) with the > V-Tec model.... > > Reply to group, thanks. > > 'Curly' |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
"Matthew Hunt" <mph@wopr.caltech.edu> wrote in message news:c203vq$jkb$2@naig.caltech.edu... > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. Excuse me. You are correct. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
"Matthew Hunt" <mph@wopr.caltech.edu> wrote in message news:c203vq$jkb$2@naig.caltech.edu... > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. Excuse me. You are correct. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
"Matthew Hunt" <mph@wopr.caltech.edu> wrote in message news:c203vq$jkb$2@naig.caltech.edu... > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. Excuse me. You are correct. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
"Matthew Hunt" <mph@wopr.caltech.edu> wrote in message news:c203vq$jkb$2@naig.caltech.edu... > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > > V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. > > Each cam shaft is optimized for its own speed range. > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. Excuse me. You are correct. |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
Matthew Hunt wrote: > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > >>V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. >>Each cam shaft is optimized for its own speed range. > > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. First of all (not for Mr Hunt) - it's VTEC. All caps - no dash. Second - it's a pretty interesting configuration. For the DOHC configuration, there are 6 lobes (3 intake and 3 exhaust) per cylinder. The 3 intake lobes are divided into two small low RPM lobes, and a single high RPM lobe between the two low RPM lobes. At lower RPMs, each valve is actuated by its own rocker arm riding off the two outer lobes. The high-RPM lobe is used by locking a hydraulically-actuate flap (apparently called the "follower" by some) that both, rides off the high RPM lobe, and locks both rocker arms together so that the valves are operated with the more aggressive cam. The VTEC lobe is a few mm wider at the fully open end, but the same width at the fully closed end. The following has a decent diagram: <http://www.quickhonda.net/howVtecWorks.htm> |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
Matthew Hunt wrote: > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > >>V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. >>Each cam shaft is optimized for its own speed range. > > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. First of all (not for Mr Hunt) - it's VTEC. All caps - no dash. Second - it's a pretty interesting configuration. For the DOHC configuration, there are 6 lobes (3 intake and 3 exhaust) per cylinder. The 3 intake lobes are divided into two small low RPM lobes, and a single high RPM lobe between the two low RPM lobes. At lower RPMs, each valve is actuated by its own rocker arm riding off the two outer lobes. The high-RPM lobe is used by locking a hydraulically-actuate flap (apparently called the "follower" by some) that both, rides off the high RPM lobe, and locks both rocker arms together so that the valves are operated with the more aggressive cam. The VTEC lobe is a few mm wider at the fully open end, but the same width at the fully closed end. The following has a decent diagram: <http://www.quickhonda.net/howVtecWorks.htm> |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
Matthew Hunt wrote: > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > >>V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. >>Each cam shaft is optimized for its own speed range. > > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. First of all (not for Mr Hunt) - it's VTEC. All caps - no dash. Second - it's a pretty interesting configuration. For the DOHC configuration, there are 6 lobes (3 intake and 3 exhaust) per cylinder. The 3 intake lobes are divided into two small low RPM lobes, and a single high RPM lobe between the two low RPM lobes. At lower RPMs, each valve is actuated by its own rocker arm riding off the two outer lobes. The high-RPM lobe is used by locking a hydraulically-actuate flap (apparently called the "follower" by some) that both, rides off the high RPM lobe, and locks both rocker arms together so that the valves are operated with the more aggressive cam. The VTEC lobe is a few mm wider at the fully open end, but the same width at the fully closed end. The following has a decent diagram: <http://www.quickhonda.net/howVtecWorks.htm> |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
Matthew Hunt wrote: > In article <10474lehgvh649b@corp.supernews.com>, > Al Smith <ecarecar@yahoo.com> wrote: > > >>V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. >>Each cam shaft is optimized for its own speed range. > > > No, it gives the engine additional cam *lobes* for high engine speeds. > There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, > there's one shaft for the intake valves, and one for the exhaust valves, > like a normal DOHC engine. There are low-speed and high-speed lobes on > each camshaft. First of all (not for Mr Hunt) - it's VTEC. All caps - no dash. Second - it's a pretty interesting configuration. For the DOHC configuration, there are 6 lobes (3 intake and 3 exhaust) per cylinder. The 3 intake lobes are divided into two small low RPM lobes, and a single high RPM lobe between the two low RPM lobes. At lower RPMs, each valve is actuated by its own rocker arm riding off the two outer lobes. The high-RPM lobe is used by locking a hydraulically-actuate flap (apparently called the "follower" by some) that both, rides off the high RPM lobe, and locks both rocker arms together so that the valves are operated with the more aggressive cam. The VTEC lobe is a few mm wider at the fully open end, but the same width at the fully closed end. The following has a decent diagram: <http://www.quickhonda.net/howVtecWorks.htm> |
Re: ___ Does V-Tec get better mileage at ALL speeds ? ?
On Mon, 1 Mar 2004 19:47:06 +0000 (UTC), mph@wopr.caltech.edu (Matthew
Hunt) wrote: >In article <10474lehgvh649b@corp.supernews.com>, >Al Smith <ecarecar@yahoo.com> wrote: > >> V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft. >> Each cam shaft is optimized for its own speed range. > >No, it gives the engine additional cam *lobes* for high engine speeds. >There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety, >there's one shaft for the intake valves, and one for the exhaust valves, >like a normal DOHC engine. There are low-speed and high-speed lobes on >each camshaft. There are now so many variations on Honda's VTEC, it's getting difficult to give a single characterization - everything from the economy-minded VTEC-E to performance oriented and everything in between. Until the K-Series engines, AFAIK the DOHCs did have variable lift on both inlet and exhaust but now we have variations where, e.g. the RSX engine (K20A ?) has variable lift on only the intake and the RSX-S(K20C or is it K20A2?) has it on both cams. Rgds, George Macdonald "Just because they're paranoid doesn't mean you're not psychotic" - Who, me?? |
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