adishman

Just got my wife a ASM 07 EX coupe 5 speed. just would like to know where
vtec is? only have 311 miles on it so keeping the rpm's under like 4 ..

MarchMadnessisM

6,000 rpm, go you tube it, you can hear when it kicks in it sounds so sweet

adishman

thanks...

02BLKCIVIC

iTrader: (8)

Last time i hit vtec at those speeds i almost lost the giraffe

But when you hit i-Vtec you’ll for sure through off the cow in the back!

adishman

Nice...

MarchMadnessisM

yea dude its great

adishman

is it vtec or Ivtec?

02BLKCIVIC

iTrader: (8)

you have i-Vtec and it kicks in around 5600 RPM's

i have Vtec, and felt like being a little nicer this time around.

and just too confuse you even more there is a Vtec-e

MarchMadnessisM

wut is the difference between all of em

Alpha 5

iTrader: (8)

Click me to see the Diff.

adishman

ya that was nice.cant hear it in 3rd

greeen01civic4d

iTrader: (7)

hahah alpha, ur a jerk

greeen01civic4d

iTrader: (7)

props to xproductions for the original post
VTEC Explained

VTEC for all SOHC cars explained. Before you even read this I want you all to know that all figures are from both 1996-2000 Honda tech book and 2001-2003 Honda Tech book.

To start there are three kinds of SOHC VTEC that Honda has ever produced. First there is standard SOHC VTEC this was found on the 1996-2000 civic EX (D16Y8), and the 1992-1995 EX and SI (D16Z6). This works the same as DOHC VTEC (only on the intake side no SOHC motor has VTEC on the exhaust side). By using three cam profiles and three rocker arms per cylinder, View diagrams. The second kind of SOHC VTEC is called three stage VTEC It is only found in the UK or Japan on a D15B. This kind isn’t really important to the USDM market, but if you want to read more on it follow this link.

Lee's Biases - Honda - VTEC - 3-Stage VTEC

The third and final kind of SOHC VTEC is VTEC-E This is found on the 1996-2000 civic HX and the 2001-2003 HX and (sorry to say its on the EX, yes that’s right the EX is a VTEC-E) VTEC-E is different because it only has two rocker arms and two lobes on the intake side (not Three) The way it works is from 0-4500 rpm one valve opens all the way while the other one opens less then when VTEC hits a Timing piston, spring and a Synchronizing piston all slide over locking the two together making the both open and close on the hotter cam profile. Here are the Cam specs for the D17A2

D17A2 (EX)
Intake Exhaust (Remember the bigger the number the more it opens)
PRI 38.604 mm 38.784 mm
SEC 32.848 mm

So from 0-4500 rpm it is like having the equivalent of two valves opening at 35.726 (because one Is opening all the way at 38.604mm and the other not as much at 32.848mm) (this is still hotter then a lx with a 35.299 mm (Intake) and a 37.281mm (exhaust) after VTEC hits both rocker arms ride the 38.604mm profile that much better then the LX. This is the exact same way the HX works only the HX has slightly different cam specs.

D17A6 (HX)
Intake Exhaust
PRI 38.427 mm 38.784 mm
SEC 32.197 mm

D17A1 (DX/LX)
Intake Exhaust
PRI 35.299 mm 37.281 mm

They both have VTEC-E; the VTEC-E is for economy.



Now on to older SOHC VTEC. Standard SOHC VTEC is the same type you will find in a DOHC car (only without the exhaust side) how it works is there are three cam lobes and three rocker arms on the intake side. First from 0-4800 the outside rocker arms open and close by the outside lobes. Then when VTEC hits two Synchronizing pins slide over and lock onto the Mid Rocker. The Mid rocker follows the VTEC cam lobe.

Here are the specs for the D16Y8 cam
D16Y8
Intake Exhaust
PRI 36.778 38.008
MID 38.274
SEC 37.065

So the Y8 head is better until VTEC hits on are cars then the d17a2 heads have a slight advantage.

Also another side note VTEC-E dose not use lost motion assemblies like every other kind of VTEC ever.

Here are the specs on what it takes to activate VTEC

1 Your MAP (Manifold Absolute Pressure) sensor must read 0hg (aka 0 inches of vacuum). When it reads this it will send a 3volt signal to the ECU.

2. Your throttle has to be open 100% because your TPS sensor has to send a 4.5-volt signal to the ECU.

3. Your coolant temp has to be at running temp.

4. Vehicle speed has to be above 20mph.

5. You have to have 65-80 oil psi.

6. The engine must be running at a minimum of 4500 RPM

When all of this happens your ECU sends a 12-volt signal to your VTEC solenoid.

Also a common misbelieve is that the louder you VTEC is the better. Absolutely not!

So this is it everything on SOHC VTEC. I did a lot of research (reading tech books) and a lot of talking to a lot of people. I know all the Specs here are absolutely correct because they all came from Honda Tech books.

Alpha 5

iTrader: (8)

I is what I is and that all that I be.

greeen01civic4d

iTrader: (7)

hey, im an *** too, great minds think alike