smap

And this....


Now is he saying that, for example.

One engine that is 2litres, and another engine that is also 2litres, but has VTEC, has less torque? How is that so?

If they are both 2litres, and one has VTEC, how does it have less torque, if they are both of 2litre variety, however one having VTEC and the other not?

Or is this guy just typing lost? I know that from a bigger displacement you will therefore have more torque. But somehow he is like mixing up words, which is sort of confusing me.



Someone help me out here.

Decode all this rubbish for me please!!!

smap

Oh and here, what do they mean by, "a VTEC engines displacement is the smallest of the three methods of increasing power output"

I realise that they are saying, that both FI and Bigger Displacement are BIGGER compared with VTEC, in getting more power. But why do they add in the "VTEC engines displacement" ...........if you get what I mean???

Shouldnt it be like this .......

Y'all following me on this?

Edr0e

Honda utilizes a technology that adjusts the amount that intake/exhaust valves are opened based on the current engine speed also known as Variable-Timing & Lift, Electronically Controlled
V. T. E. C. lol


So basically, its a higher revving motor with a higher compression ratio but less torque than a normal naturally aspirated motor.

On our J series, I believe only the intake (single cam) valves adjust based on the engine speed.

Edr0e

That guy is just confusing you bro.



3 methods of increasing power output - ( torque )? hp? ?? ?

1) Increasing Displacement
2) Forced Induction ie: Turbo, Nitrous, Supercharger
3) VTEC?

Edr0e

After the sucess of DOHC VTEC engines, Honda became increasingly confident with the use of VTEC technology. It has proven to be a reliable and economical alternative to increasing displacement or using forced induction. Honda decided to apply VTEC technology to a larger segment of the market with the introduction of the SOHC VTEC system. Like its DOHC counterpart, SOHC VTEC optimizes the flow of fuel/air mixture for high RPM operation while maintaining smooth and economical low RPM operation. But due to its simpler design and humbler performance intentions, its specific output is not as high DOHC VTEC engines.

In a SOHC engine, there is a single camshaft per bank of cylinders. So both the exhaust and intake cam lobes are on the same camshaft. The figure to the right illustrates this design. The three cam lobes in the middle are the intake cam lobes. The two low RPM lobes actuate two valve rockers, which in turn pushes the intake valves open. The high RPM lobe actuates a follower, which is shaped like a valve rocker, but doesn't actuate any valves. While there are different intake cam lobes for high and low RPM operation, the same two exhaust cam lobes are used for all RPMs. The lack of cam profile changing for exhaust valves is the primary difference between DOHC VTEC and SOHC VTEC engines. Since the exhaust valves in a SOHC VTEC engine behaves just like a non VTEC engine, only the intake valves will be discussed below.

During low RPM operations, the two outer intake cam lobes directly actuates the two valve rockers. These low PRM intake lobes are optimized for smooth operation and low fuel consumption. The high RPM intake lobe actuates the follower. But since the follower isn't connected to anything, it doesn't cause anything to happen. This procss is illustrated by the figure to the right.

At high RPMs, oil pressure pushes a metal pin through the valve rockers and the follower, effectively binding the three pieces into one. And since the high RPM lobe pushes out further than the low RPM lobes, the two valve rockers now follow the the profile of the high RPM lobe. The high RPM lobe's profile is designed to open the valves open wider, and for a longer duration of time, thus allowing more fuel/air mixture to enter the cylinder. The improved breathing allows the engine to sustain its torque output as RPM rises, thus resulting in higher power output

The SOHC VTEC is a system that achieves mild power gains. Usually, SOHC VTEC engines gives about as much power as DOHC non-VTEC engines of similar displacement. Whether or not the added complexity of the VTEC mechanism off-sets the simplicity of SOHC (versus DOHC) is up for debate. SOHC VTEC is currently found on the Civic EX, Accord LX/EX/V6, Odyssey LX/EX, Acura TL, CL, and CL Type-S.

Edr0e

Lets say the engine is running at 4,000 rpm, the valves are opening and closing 2,000 times every minute, or thirty to fourty times every second. When the intake valve opens right at the top of the intake stroke, it turns out that the piston has a lot of trouble getting the air moving into the cylinder in the short time available (a fraction of a second). Therefore, at higher rpm ranges you want the intake valve to open prior to the intake stroke -- actually back in the exhaust stroke -- so that by the time the piston starts moving downward in the intake stroke, the valve is open and air moves freely into the cylinder during the entire intake stroke. This is something of a simplification, but you get the idea. For maximum engine performance at low engine speeds, the valves need to open and close differently than they do at higher engine speeds.

I hope this helps

Edr0e

Usually, SOHC VTEC engines gives about as much power as DOHC non-VTEC engines of similar displacement.


Thats what broski meant.

smap

ahahhahaha
thanks for your trouble, but you didnt really answer my question.

The main point is, why will an engine of 2litre capacity equipped with VTEC, have less torque compared with another engine that does not have VTEC and of the same capacity????

Edr0e

The DOHC (non-VTEC) engine camshafts have one cam lobe (the oval shaped part that opens the valves) per valve. The cam lobe is above a short rocker arm, which is fixed at one end and sits on top of the valve at the other end. Some engines have the cam lobe directly in contact with the valve head, but Honda did not do it this way so that they could get more valve lift, and open the valve quicker. Using a rocker made the valve train heavier, which uses more power and limits engine speed, so Honda hollowed out the cam lobes (as well as the camshaft) to save weight.

Ken1997TL

VTEC or non-VTEC, the torque is generally the same. What matters is when is the powered delivered and how broad the torque band is/how high can the engine rev.

VTEC (in theory) allows and engine to have decent low end torque (usually a mid range punch instead though) AND high rev power.

Edr0e

Ken is correct, there is not much difference in torque VTEC or Non - VTEC. Many companies have their own variations ie: toyota and VVTI

smap

ah Okay.

thanks for the replies guys.

Either I was just lost, because of the confusing info and how it was typed up, or what that person was saying was just wrong.

ahahhaha.....ill go with both.

Water-S

or in common terms
NO V-TEC I DON'T WANT IT.

Water-S

I know I'm gonna get flamed for this.
don't get me wrong I love Hondas(I have 3) but Hondas have no torque. I pull a box trailer with my 00 Odysee and if you stop at a light or railroad tracks and start again it doesn't like to get it rolling again.(grant it the trailer weight and load like 2 ton but still). If you look at almighty Integra Type R B18C5 motor . Yes you could rev the shit out of it but it didn't produce that much torque IMO. every Honda I've owned is almost like a 2 stroke dirt bike it produces it power on the top end and has very little bottom end.

Pure Adrenaline

iTrader: (2)

That is just the way Honda likes their engines. What are you gonna do, you know? Personally, I like having more RPMs to play with. I loved the torquey 5.7L V8 in my Tahoe. It had torque everywhere. But it wasn't fun to wind it out. I know, I know, I'm comparing to a truck engine. But you know what I mean. It's kind of like the LS1. I love their monstrous torque, but it's not as smooth or fun or high-revving as Honda engines. In the end, it's all personal preference.

I'm hoping for a day when Honda comes out with a V8 with DOHC VTEC. That would be a sick motor.

Water-S

yeah I rode in a new GTO the other day he'd bearly get into the gas and it would rip the tires off(and this is at a slow roll). the Torque nice to have from "dead stop" races. if your at a stoplight or stop sign (i'm not saying street racing right). now RPMs are great if lets say on interstate and someone flips out off and being a dick downshift and give it hell.
If you guys ever or still race dirt bikes i used to:
it's like this 2 strokers(like CR250,RM250, or YZ250): you peg the gas and their what you call a "clutch bike." if you had doubles or triples or long strights you'd get the 4 stroke guys but in the corners or starts no matter how good you tuned the bike you couldn't catch the 4-stroke guys unless you gave the bike gas through the corner(even while your brake) and hold in the clutch and as you come out of the corner let out on the clutch. the reason why myself and a lot of guys i rode with did this with our CR250s and 125s is due to the high powerband. if you had it down low end that 4 stroke guy would blow by you.

this is the same type of thing with RL 3.5 V-TEC vs Z-28 last gen camero(not the SS).
only sad thing is you can't a clutch in a RL so therefore its pointless in my opion to put that big of a motor in it with V-TEC=high revving engine without a clutch.

to me V-TEC without a clutch is like ordering a Porshe 911 in white or some bland color. don't get me wrong it's still a nice car but it's 100 times better in fire engine red.

Now about Honda DOHC V-8: I agree that would be great. but since OPEC is screwing us at 2.25 a gallon for regular gas.(and i know out in L.A.it's higher) unless gas drops majorly i'm saying like 75 cents a gallon) I don't see that happening anytime soon. sorry to be a spoiler of dreams but it's the truth dude.

Ken1997TL

Honda engines are designed for mid range punch to top end scream.

You're correct about a lack of low end but that goes for almost all SOHC/DOHC motors. Want low end? Buy a Buick with a pushrod design, no power past 3000 rpms.

Honda diesel engines... they have SICK torque curves and make a LOT of power off the line. Mmm.. diesel..

Edr0e

What about the Legend Max ? isnt it V8 DOHC VTEC? lol