SOHC VTEC Explained
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Once boosted now i-VTEC
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Originally Posted by 4drcivic2k1
You stated that it was the top dead center for CYLINDER 3. THAT WOULD IMPLY THAT THE PISTON IS AT THE TOP OF ITS STROKE. THAT WOULD MEAN THAT THE VALVE SHOULD BE CLOSED COMPLETELY OR JUST STARTING TO OPEN, depending on if it is compression or intake stroke. If you have a valve completely open at TDC you will have bigger problems than VTEC engaging.
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Originally Posted by caorndorff
Here is the proof that only one valve opens until VTEC engagement. I tore apart my entire F****** motor to prove you wrong 4drcivic2k1 (and I was doing some other stuff too but you will see that in the DIY section soon). This is at top dead center for cylinder 3. 
Originally Posted by caorndorff
Here is the proof that only one valve opens until VTEC engagement. I tore apart my entire F****** motor to prove you wrong 4drcivic2k1 (and I was doing some other stuff too but you will see that in the DIY section soon). This is at top dead center.
Way to change your story now eh?
He ment the engine was at TDC and the picture was of Cylinder 3. You are only trying to make a big point of this because you were wrong about everything elce.
You need to grow up and admit you were wrong 4drcivic2k1
and stop this back and forth crap.
You need to grow up and admit you were wrong 4drcivic2k1
and stop this back and forth crap.
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Maybe you two should stop arguing. I didn't believe any of this at first, but now I'm willing to admit I was wrong about engagement conditions. Atleast we're learning to real way it works.
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Originally Posted by FingerJ
He ment the engine was at TDC and the picture was of Cylinder 3. You are only trying to make a big point of this because you were wrong about everything elce.
You need to grow up and admit you were wrong 4drcivic2k1
and stop this back and forth crap.
You need to grow up and admit you were wrong 4drcivic2k1
and stop this back and forth crap.
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Once boosted now i-VTEC
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Originally Posted by 4drcivic2k1
You need to specify which cylinder is at TDC. There are four in the motor.
http://www.honda.co.uk/owner/CivicManual/index.html
BTW: TDC for the engine is when cylinder 1 and 4 are at TDC and 2 and 3 are at BDC.
Last edited by caorndorff; Mar 1, 2005 at 02:34 AM.
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Originally Posted by caorndorff
Hey genius, the engine was at TDC. It is when the groves on the cam gear line up with the head, and the grove on the oil pump gear lines up with a forge mark on the block. Next time read up. Here’s a link Jr.
http://www.honda.co.uk/owner/CivicManual/index.html
BTW: TDC for the engine is when cylinder 1 and 4 are at TDC and 2 and 3 are at BDC.
http://www.honda.co.uk/owner/CivicManual/index.html
BTW: TDC for the engine is when cylinder 1 and 4 are at TDC and 2 and 3 are at BDC.
Originally Posted by caorndorff
Here is the proof that only one valve opens until VTEC engagement. I tore apart my entire F****** motor to prove you wrong 4drcivic2k1 (and I was doing some other stuff too but you will see that in the DIY section soon). This is at top dead center for cylinder 3.
BTW, FingerJ, Shut the **** up. No one cares about what you have to say.
I don't understand the arguement. On Dec 19 Civic04 asked:
Everyone agrees this is the definition of VTEC.
The picture of the valve at TDC was errantly described as "TDC for cylinder 3" and explained it is cylinder 3 at engine TDC. Therefore, correct me if I'm wrong, the picture shows the one fully opened valve at 38.604 mm (using the numbers from post #1), one valve that is cracked at 32.848 mm, and the exhaust valves closed. If VTEC were engaged for the picture, both intake valves would be at 38.604 mm and the exhaust closed. VTEC does not affect the height of the exhaust valves, which are both the same height (38.784 mm).
Originally Posted by Civic04
so normal running conditions (pre vtech) both exhaust valves open all the way and 1 intake valve opens all the way and 1 intake valve opens part way. When vtech kicks in under the preset conditions both exhaust valves open the same as before (becase no vtech on the exhaust side) and both intake valves open (fully) in the hotter cam profile .
Yes? No?
Yes? No?
The picture of the valve at TDC was errantly described as "TDC for cylinder 3" and explained it is cylinder 3 at engine TDC. Therefore, correct me if I'm wrong, the picture shows the one fully opened valve at 38.604 mm (using the numbers from post #1), one valve that is cracked at 32.848 mm, and the exhaust valves closed. If VTEC were engaged for the picture, both intake valves would be at 38.604 mm and the exhaust closed. VTEC does not affect the height of the exhaust valves, which are both the same height (38.784 mm).
...About my '02 EX
I thought I got this **** like 2 weeks ago, but now when I read the entire thread, I'm just confuddled about sumthin. The VTEC allows for milleage saver UNDER 4500 RPM's, right? If yea, then over 4500 is like driving the engine without VTEC but under is where we actually see the use of it?
Bottom line: Does the EX get ANY extra power from the VTEC or does it just help me save gas under 4500 RPM?
Sorry for being such a noob, but I drove GM suv's all my life and then I went to 95 civ DX economy. I know nothing about performance tuning with Hondas.
BTW, I love seeing arguments like that
I thought I got this **** like 2 weeks ago, but now when I read the entire thread, I'm just confuddled about sumthin. The VTEC allows for milleage saver UNDER 4500 RPM's, right? If yea, then over 4500 is like driving the engine without VTEC but under is where we actually see the use of it?
Bottom line: Does the EX get ANY extra power from the VTEC or does it just help me save gas under 4500 RPM?
Sorry for being such a noob, but I drove GM suv's all my life and then I went to 95 civ DX economy. I know nothing about performance tuning with Hondas.
BTW, I love seeing arguments like that
Last edited by JesterMasque; Mar 16, 2005 at 03:07 AM.
First, there is still heated debate about when VTEC engages. Please save that for the other thread.
http://www.7thgencivic.com/forums/sh...d.php?t=199350
VTEC allows for less gas to be used before the more aggressive cam engages. Therefore, it is to enhance better gas mileage before VTEC engages and to provide additional gas (more power) after VTEC engages.
http://www.7thgencivic.com/forums/sh...d.php?t=199350
VTEC allows for less gas to be used before the more aggressive cam engages. Therefore, it is to enhance better gas mileage before VTEC engages and to provide additional gas (more power) after VTEC engages.
Joined: Sep 2002
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Rep Power: 812 According to Honda, vtec provides hp increases throughout the powerband. That's why vtec engines make 127hp and non-vtec makes 115 at the crank.
This is ridiculous. 
Caorndorff 
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Rep Power: 0 EX's have roller rockers, both intake valves work off the same cam lobe over +/- 4500 rpm's when a hydraulic plunger locks both roller rockers together. Below vtec only one valve opens fully and the other partially, working independentaly.
Originally Posted by SUPERFLY
EX's have roller rockers, both intake valves work off the same cam lobe over +/- 4500 rpm's when a hydraulic plunger locks both roller rockers together. Below vtec only one valve opens fully and the other partially, working independentaly.
If you didn't notice, this topic has been finished for a while. And do some research before you post any kind of technical stuff on here. We do have n00bs running around you know
