gearbox

iTrader: (95)

When I had mine dynoed, they said 2800rpm was the best setting that kept the most power. I just left it on stock passive mode tho cause it seems to feel smoother when the ecu controls it vs the vafcII.

Jrfish007

iTrader: (3)

How does this Vtec light thing work, I know there is a DYi on it (but I am to lazy to look for it, sorry), but I am assuming it read the oil pressure and activates the light from that. If this is correct, where does it read the oil pressure from. My other idea is that you some how tap in to the solenoid adn read a voltage from it, assuming it is electronically controlled. Could some one clear up for me just where this VTEC light is taking it's information.

gearbox

iTrader: (95)

I'm not sure, but my vafcII does the same thing and it's just hooked to ecu wires. Maybe it's the vtec vtm wire? It says the vtec wire, whatever that is.

http://www.7thgencivic.com/forums/sh...ad.php?t=88650

Jrfish007

iTrader: (3)

Hummm... so it looks like to me it's an actual electrical signal. Reason I ask is because if it was taking a reading from the oil pressure, the oil pressure could be off making the light come on falsely, but sense it is electrical signal, it is far more accurate than I thought.

That being said, I will say that I have go with the VTEC light and say that I was wrong about a 4,500 engagement point. I too thought it had a variable engagement point. So you say it will come on around 3k if WOT. Say you are at 70 mph, which I guess around 3,200-3,500 rpm, is it on then? I’m just curious.

gearbox

iTrader: (95)

The readout says engagement around 3200rpms, but that may vary with driving. If you're on the highway with an auto going around 65, the rpms are just under 3k and the light stays off. As soon as I push it to 68-70, the rpms are just above 3k (3090k or something) and the light stays on.

Jrfish007

iTrader: (3)

So I wonder if there is a big difference in gas mileage between 65 and 75? Or if the extra 10mph is enough to compensate for the gas lost?

Wolfgang5884

iTrader: (3)

who cares our motors suck, nuthin can help them

DAQIUN

thanx for the info

psychotic_z

So it's true - you ARE retarded! Hah, low blow... just playing.

Go back to post #18, I contributed - when people start spreading misinformation to others (especially when people are looking at this thread to explain to them how their VTEC works) is when I stepped in (i.e., the "3-disc clutch", "all K-series have 5-speeds, etc.). Now, I'm just pointing these out, not flaming.

The whole reason cruising speeds were brought up was for this simple reason - our cruising speed is a function of gearing, NOT where VTEC activates. Honda sets the VTEC crossover at the point of greatest effectiveness for a gentle and efficient transition (which requires some research into the general flow and air consumption of the engine to find this point). They don't go set the VTEC point by where most people will be cruising.

Honda will set the VTEC point around the engine speed that creates the most benefit (and not as a function of cruising speed) even if that VTEC point means that VTEC is activated at 70 mph in 5th. As I said before, VTEC doesn't create instant power - it increases the airflow when it's needed most in the engine. If the engine requires airflow at that engine speed, REGARDLESS of what speed that car happens to be at in 5th gear, then VTEC will be activated.

Illustratation: Activating a DOHC VTEC at 1,000 RPM will open both valves extremely wide which allows more airflow, but flow velocity is decreased - less air will rush into the same space during the intake stroke - and low end power is LOST, not gained.

The point is, and maybe this is nitpicking what you said, but VTEC is set at the point that our engine's require, not that gearing dictates. I think the "is VTEC open in 5th gear, if so then it probably doesn't activate that low" argument is moot. Besides, does opening another intake valve on the highway instead of only one really affect gas mileage so much? Gas mileage is more a function of pedal position than RPM or valve opening at that engine speed or any engine speed.

Has ANYBODY asked a Honda technician what RPM we switchover at? It would save all this time theorizing...

4drcivic2k1

iTrader: (2)

Most (common) honda technicians won't know. I've talked to the dealer here in town.

Jrfish007

iTrader: (3)

yup, lol is about the only thing I can read correctly

the 3 disk clutch thing wasn't me, I have no idea about that.

I did say all K's have 5 speeds, but my point for that was that they have a lowwer RPM at 65 mph than the auto civic and for that matter even the 5 speed civic. Yes I know some like the RSX-S have 6 speeds, but that will make the RPM even lowwer at 65 mph. My point is that all K's have at least 5 gears. I forgot the "at least" part though, that's my fualt.

I never ment that cruising speed was a function of VTEC. what I ment (and I guess I didn't say it clearly) was that VTEC is a function of cruising speed. Of course, the main factor in cruising speed will be the gearing, and the engineers at Honda have made what they think is the best comprimise between performance and economy when selecting the gears to use.

Well, here, my theory was that Honda would want to keep air flow at a min to reduce fuel consumption, but with gearbox's help, I see I was wrong. I guess when the car is maintianed at 70 mph, the drag on the car is to great for the engine to pull the car effiecently without the extra air/fuel. So if you look at this in the big picture (VTEC activation point, gearing and drag on the car), it shows just how much engineering and thought Honda has put in to this topic. But they have far more reasources than we do, so I would trust their calculation to be accurate adn already at maximum effientecy.

Yes, this is why many 4 valve per cylinder engines lack low end torque. Well, okay it can be one of many reasons. Most people don't relize that VTEC actually helps down low too by increasing air velocity at low RPMS.

you are right, opening another valve isn't going to make much difference in this case becasue the valve is already opening, just not that much. I think VTEC on the D17 is less potent than on previous civics (D16's) where the VTEC valve had a much hotter cam lobe than the current D17 set up.

I don't trust Honda tech for doing anything more than changing my oil. My older civic had a B16 transplant. The tech said it had a 16 valve SOHC engine without VTEC (a D15), I told him I had a B16 in the car (it was the DX model, so he was right, if it had the stock engine in it), but he swore it had a D15 in it. SO I took him out side and lifted the hood, and he continued to tell me it was a D15 and that the modifications that I had preformed to it made the car to complex for them (the Honda dealership) to work on. I told him it had a 2000 Civic Si motor in it (my car was a '94 civic, so they where different generations). He told "that's imposible, those two cars are completely different, engine and all." I just left and changed the head gasket my self in the 15 degree cold.

gtracing

iTrader: (6)

i didn't even bother reading pages 2 and 3...but majority of 1...and just to let you know, we have something called a 3-stage v-tec, the vtec kicks in THREE times!

http://auto.howstuffworks.com/framed...whatsvtec.html

Jrfish007

iTrader: (3)

Right from the website you just quoted:

" All the work Honda has done on the VTEC mechanism are combined to make the 3-Stage VTEC system. It is not a rumor, the engine exists: D15B. The engine is used in Honda Civics in Europe and Japan. In short, it combines VTEC-E and SOHC VTEC to get both extraordinarily good RPM fuel economy, and excellent high RPM power. The D15B is a 1.5L engine that is capable of about 54mpg and is rated for about 128HP."

We do not have D15B's nor are they in the US.

4drcivic2k1

iTrader: (2)

Neat. Now go sit in the corner.

civicex9980

iTrader: (1)

I took the time and put in a vtec light from the diy forum and my vtec doesn't kick in till 3,300 rpm when like 1/4 throttle. It does come on a lot sooner when under hard acceleration. I agree with a lot of people that our motors suck and that we have vtec-e engines.

robo1040

iTrader: (5)

holy ****, first off i didnt read pg 2 -

but my 2 cents are that i have a Vtec light and i ran it off the wire from the ECM, and yes, mine was kicking in at 2800 like clockwork.

some of these kids on here have no clue what they are talking about, but thoes who do, thank you for the info.

82801BA

Actually several things can be done to improve the engine. But it's up to who and what we want to do.

One basic idea without getting into turbo/FI is the air path. Turning a lot of air in a curve dramatically reduce stagnation air pressure(that's what all kind of sensors see) getting into combustor. Our intake manifold has a big 270 degree turn. A turn creates all kind of mess within the flow, boundary layer, friction, etc. Worst case is that the high pressure/low velocity flow actually stops at the walls of tube and all low pressure/high velocity flow is in the center(boundary layer theory). Then during the turn, these two flows interact with each other, causing seperation of flow. Eventually, it will create rotations(recirculation) along the wall, which means it has created negative force with respect to upstream flow direction. Now it becomes a mess and it isn't doing any work in the flow(and energy is low too, you know that when the gas is burned in combustor).

One thing can be done is to get straight intake manifold with the filter sitting directly on top, but controlled in flow direction(cut a port on the hood, may be?). It should help to restore some pressure loss which will in turn raise the compression ratio.

For power, get intake manifold as short and as straight as possible. For fuel economy, slow down and restrict the flow.

Jrfish007

iTrader: (3)

Not this thread again

No the EX does not have the vtec-e system.

Key points to the vtec-e engine are:
1. reverse cyclic flow pattern in the engine to better aromatization the fuel
2. the flow pattern in #1 allows the engine to run super lean, EX motors do not, in fact they run rich.
3. less power due to #1 (it takes lots of power to do this, hence net power is down)
4. taller gearing, see the final drives in your Honda handout thing form the dealer (this has nothing to do with the engine, but is always paired with the vtec-e engine)

The vtec engine in the EX does not have any of the features listed above, there for it is NOT a vtec-e engine. IF it was a vtec-e engine, you would get 40+MPG and have about 10-15 less hp.

Jrfish007

iTrader: (3)

Yes functioning ram air civic

4drcivic2k1

iTrader: (2)

"Functional" ram air is significantly more sophisticated than a filter on an intake manifold.

82801BA

I can only agree some point on this. I only can say that, EX engine has some VTEC and some VTEC-E features in it.

VTEC features:
Burn rich
Higher compression(!?)
Modified ECU and MAP

VTEC-E features:
12 valve only operation at low rpm
VTEC-E rockers and rocker arms(exact same parts as the HX)
Two (2) intake cam lobes per cylinder
VTEC is pressure/load/throttle sensing, and max crossover point is 3250rpm

It leans more toward VTEC-E than VTEC. I do believe that some people can turn an HX to an EX with ECU, exhaust header and camshaft swap and still making same power(or within 1% limit) with the EX.

Jrfish007

iTrader: (3)

Yeah... but still your closer to functional than most people with their little hood scoops

Jrfish007

iTrader: (3)

No, there is a huge difference. The VTEC systems are the same, but just haveing VTEC doesn't make it a lean burn engine. The lean burn engine has been around before VTEC, see the civic CX. VTEC was simply added to the lean burn so that it could have a little more power, the old lean burn engine was at 70hp. GOta run to class, try to explain more later.

Jrfish007

iTrader: (3)

Anyway, you are missing the point that the VTEC-e engine runs lean, leaner than a normal engine can because of the flow pattern in the cylinder that is only characteristic of the lean burn engine.

But VTEC was added to the lean burn engine, so yes, the top end (looking in from the valve cover) is going to look the same. So why would the rocker change? They both still have to have valves. Both have same compression ratio, no big deal there.

You can put an HX ECU on an EX and not get much power loss, but all you have done is lean the engine out, to the point where it might even knock unless you swap the heads from an HX (Because the ports are rifled and valves are slightly tilted, and good luck getting an EX head to do that). I’m not 100% sure, but I think the cams are different too. To get the good MPG, you still have to change the final drive (HX=3.84 EX=4.41 http://www.hondanews.com/CatID2015?m...43094&mime=asc) and lighten your car.

Mike4831

That is good to know.

bradmanuwf

you guys are all idiots. why don't you just leave the vtec to the ecu and stop f.u.c.king with it. honda made it how it is for a reason. if you are wanting true performance engine, why the hell did you buy a civic. now if you swap a k20 into your civic, that's a diff. story. a d-series will always be a d-series. and yes, put a turbo on mine cause I wanted a little more go go and the tight *** bov. I didn't do it thinking my d-series SOHC would own down cars with engine way better than mine. props to gearbox and caorndorff cause they didn't get into a f.u.c.king spat about VTEC!

Jrfish007

iTrader: (3)

Dude, your frickin idiot. We have said nothing of performance. None of us, to my knowledge, has swapped the ECU's, it's only discussion, isn't that what forums are for? Are you trying to say we can’t even talk about how things work on here? I've said nothing of swapping ECU's, that was someone else. I am simply stating that the lean burn engine is different than the normal civic engine and that the HX gets good MPG because of the sum of it's parts (lean burn engine, tranny gearing, light weight blah blah blah), simply swapping in an ECU won't give 45-50 MPG. I don't even own a 7thgen anymore, why/how am I going to go screwing with VTEC if I don't even have a Honda? We never said anything of performance, I already know that you need a K20 or turbo to get any speed, known that for a while captain obvious.

We are talking about the difference in the lean burn VTEC-e engine versus the normal VTEC motor, nobody is screwing with VTEC or Honda’s stuff or even talking about performance. Please don’t just flame when you not even clear what we are talking about, or at least look at the dates and see what is be discussed today as opposed to 3 months ago. Someone simply ask a question on here and we are discussing it, they where smart enough to at least ask it on this thread instead of making a new thread.

Ashhole

iTrader: (5)

Whoa. thats alotta stuff to read and try and analyze. I know with my car, i dont feel any thing different in the 2500-3500 range. However, at around 4200, i feel and hear a noticeable difference in the car.

Is buying a VTEC controller worth the effort, or would i just be asking for a lot of trouble and headaches?

Jrfish007

iTrader: (3)

Hummmm... Gearbox has one on his car and I think he dyno tuned it too, so he probably knows better than me. But from what I've read, unless you have some major change in your car, like turbo or built motor (i.e. high compression pistons and cams ect.) it really doen't do much for ya other than maybe a couple of hp, just what I've heard.

gearbox

iTrader: (95)

I don't use the vtec part, only the a/f, which gave me 2whp more after tuning. Best to leave vtec stock. Oh and btw, when I priced out my car in 2002 online, the honda site said the engine was vtec-E for my EX.