VTEC:Fact or Fiction
11-13-2004, 02:08 PM
#1
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VTEC:Fact or Fiction
I am trying to learn as much about the VTEC engine as possible. But I have one question. Do you guys agree with this statement: "VTEC only works in high RPMs, therefore a VTEC car is just like a non-VTEC car at low RPMs. And since most people drive at low RPMs most of the time, VTEC is a waste of money." I do not, but I wanted to get some other input. 
11-13-2004, 03:44 PM
#3
Not a Blowhole
I do not agree with that statement whatsoever! It is completely idiotic, and shows a fundamental misunderstanding of VTEC, and how cars work.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
11-13-2004, 04:50 PM
#4
Burning Brakes
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Originally Posted by dcarlinf1
It's true that it only kicks in at higher RPM's but it certainly isn't a waste of money. It starts at 4700 rpm and max RPM's is 6900.
11-13-2004, 09:55 PM
#5
Registered Member
Hey Road Rage;
The term "cammer" had another meaning in the mid-60's. Do you remember when Ford brought out the 427 "Cammer" (SOHC Hemi) that they put in a few select drag machines. LIke Connie Coletta's AA/FD? 'm trying to remember if this engine also saw the bays of a few (like maybe 1000) Galaxie's or Fairlanes.
Remember the Duntov cams from the late 50's.. small block Chevy's? The 30/30 model? Isky made a name for himself with some excellent cams at resonable prices. And Crowler (spelling?) made the first roller cams I can remember.
Remember in the mid-80's when Ford and Chevy started pulling roller lifters in their small blocks for the Mustangs and the Monte Carlos? They tried to sell the public on the idea of lower friction, which, of course, a roller cam/lifter offers. But the real reasons were the fact that roller lifters allow longer duration and faster ramp speeds which aids cylinder filling and inproves emissions.
Magic and snake oil. God, I love it.
The term "cammer" had another meaning in the mid-60's. Do you remember when Ford brought out the 427 "Cammer" (SOHC Hemi) that they put in a few select drag machines. LIke Connie Coletta's AA/FD? 'm trying to remember if this engine also saw the bays of a few (like maybe 1000) Galaxie's or Fairlanes.
Remember the Duntov cams from the late 50's.. small block Chevy's? The 30/30 model? Isky made a name for himself with some excellent cams at resonable prices. And Crowler (spelling?) made the first roller cams I can remember.
Remember in the mid-80's when Ford and Chevy started pulling roller lifters in their small blocks for the Mustangs and the Monte Carlos? They tried to sell the public on the idea of lower friction, which, of course, a roller cam/lifter offers. But the real reasons were the fact that roller lifters allow longer duration and faster ramp speeds which aids cylinder filling and inproves emissions.
Magic and snake oil. God, I love it.
11-13-2004, 10:11 PM
#6
Not a Blowhole
SB: Yeah, i remember some of them by history - i am not THAT old!
BTW, there is now a 5.0L DOHC "Cammer" crate engine from Ford - a great deal in a NA engine - with some of the SVT power adder trick parts used on the SVT Cobras, the extra displacement should make for hellacious torque specs.
For you Yankees, "hellacious" is a southern term for "eye popping".
BTW, there is now a 5.0L DOHC "Cammer" crate engine from Ford - a great deal in a NA engine - with some of the SVT power adder trick parts used on the SVT Cobras, the extra displacement should make for hellacious torque specs.
For you Yankees, "hellacious" is a southern term for "eye popping".
11-13-2004, 11:00 PM
#7
Mike
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Originally Posted by Road Rage
I do not agree with that statement whatsoever! It is completely idiotic, and shows a fundamental misunderstanding of VTEC, and how cars work.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
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11-14-2004, 09:00 AM
#8
Registered Member
Well, I'm not THAT old, either. Let's just say it was in the later 50's when I first started to become aware of cars, though I didn't have any real knowledge about them until the 60's. But I have vivid memories of a lot of cars from the 50's when I was growing up. I remember in the third grade, we studied the 4-stroke internal combustion engine and had a cutaway of a single cylinder "reo" lawnmower engine for an example so we could turn a crank and see the piston and valves operate. I already knew something by then because of my dad who liked cars and engines and my older cousin who was a mechanic and boat racer.
I think those of use who cut our teeth on the engines of the 50's and 60's may be in a little better position to understand the finer points of engine breathing and fuel delivery. I say this because many of us (myself included) did full exhaust installs with headers, swapped carburetors, did ignition mods, and some engine rebuilding. You just get a feel and understanding about the whole thing when you do this. It's much harder now with modern cars to do these things because of the complexity of the bolt-on and wired equipment.
I think those of use who cut our teeth on the engines of the 50's and 60's may be in a little better position to understand the finer points of engine breathing and fuel delivery. I say this because many of us (myself included) did full exhaust installs with headers, swapped carburetors, did ignition mods, and some engine rebuilding. You just get a feel and understanding about the whole thing when you do this. It's much harder now with modern cars to do these things because of the complexity of the bolt-on and wired equipment.
11-14-2004, 11:11 AM
#9
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Normal cams are tuned for either high or low rpm power. You loose some low rpm power to get high rpm power and vice-versa. VTEC allows more low rpm power than normal since it has a separate cam profile for high rpm power.
11-14-2004, 12:33 PM
#10
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when VTEC kicks in this allows you to take avantage of (Dynamic Compression).So basically at higher RPM's when your piston reaches (Dead bottom center) and starts making it way back up your intake valve is still open.The force of your stroke when pulling in air is so powerful that your still pulling air and fuel in when the piston is making its way up and then the valve closes just before the air stops and changes direction.So more air and fuel= more power.Thats why the VTEC lobe is huge so you can have a longer valve duration(Valve opening).Thats why if you set the VTEC engagement to low of a rpm with a VTEC controller you will bog your engine because the during the intake stroke period your not pulling in the air strong enough so when the piston hit (Dead bottom center)and starts making its way up the air just goes back out into the intake.So thats the intake side the exhaust side VTEC helps get that extra exhaust out more quikly,effeciently.But there are several diffrent setups Honda uses and diffrent engagement points.So VTEC is da sh_t and only Honda has mastered it for they still only have the highest HP NA 4 bangers in the world.Thats a FACT.
11-15-2004, 01:07 AM
#14
Moderator Alumnus
Originally Posted by rxman4453
I am trying to learn as much about the VTEC engine as possible. But I have one question. Do you guys agree with this statement: "VTEC only works in high RPMs, therefore a VTEC car is just like a non-VTEC car at low RPMs. And since most people drive at low RPMs most of the time, VTEC is a waste of money." I do not, but I wanted to get some other input.
No.
I do enjoy VTEC by using SS mode even though often driving in the city. Without SS mode, I prolly would say YES.
Besides, so far it seems no one ever complains VTEC is a waste yet. Some ppl may dislike the quality or audio or features, but I havn't heard someone is vocally complaining VTEC "useless".
Our VTEC would make sure the current TL's engine would efficiently generate the most power when we need.
11-15-2004, 11:20 AM
#15
Burning Brakes
Originally Posted by Road Rage
I do not agree with that statement whatsoever! It is completely idiotic, and shows a fundamental misunderstanding of VTEC, and how cars work.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
Cams are always a compromise - too much lift and duration, and you lose smooth idle, and the car has peaky power, weighted towards the upper RPM range. It also will be hard to reach emissions/economy targets.
Too "soft", and the car goes flat at the top end, losing top speed capability, and delivering bad 1/4 mile performance.
The VTEC system essentially performs like a car with two camshafts - while still compromised (infinitely variable would be best), each cam profile is far better than can be achieved than one cam.
Combined with the intake plenum flap, VTEC delivers better low-end (RPM) power/torque, for good performance off the line, and excellent fuel economy and emissions performance. And when VTEC is enabled, a good performing engine becomes a terrific one! And VTEC does all this without the complexity and cost of a DOHC in the case of the TL.
The S2000 would be dead without VTEC - it would need a 10-speed tranny and constant rowing of the gears if it were a "cammer" engine - a "old" term which in the car crowd I run in means a car with a hot cam, designed for high RPM launches and power shifts to get max performance.
