Help me educate the press
Thread Starter
|
Member
Joined: Sep 2005
Posts: 718
From: Plainwell Michigan
Help me educate the press
Hey - I got this review link on google news for a recent Fit vs. Yaris test.
The article stated that the Fit was 16 valve. I wrote the author to correct him and I got this back:
He highlighted some presser that Honda NA sent him quote
16 valve SOHC VTEC
Anybody got a retort link I can send this guy back?
The article stated that the Fit was 16 valve. I wrote the author to correct him and I got this back:
He highlighted some presser that Honda NA sent him quote
16 valve SOHC VTEC
Anybody got a retort link I can send this guy back?
Member
Joined: May 2006
Posts: 63
From: Lewiston, ID USA
I don't know if this will help but it is an article about the L series VTEC and the i-DSI engines.
http://asia.vtec.net/Series/FitJazz/lseries/
About 3/4 of the way through the article you find this:
http://asia.vtec.net/Series/FitJazz/lseries/
About 3/4 of the way through the article you find this:
The VTEC mechanism on the L15A VTEC is that of a 1-valve/2-valve system for the intake side only. The exhaust side always functions as a 2-valve system. So the L15A VTEC is a 12valve/16valve system.
that might be what you are looking for.
Member
Joined: Apr 2005
Posts: 258
From: MD
The I-DSI engines have 1 exhaust and 1 Intake valve per cylinder (8 valves total, they had to make room for the 2 spark plugs) while the Vtec 1.5L sold in the USA and Canada has 2 intake and 2 exhaust valves per cylinder (16 valves total).
I think the article was correct if they are reviewing NA spec Fits.
I think the article was correct if they are reviewing NA spec Fits.
Member
Joined: May 2006
Posts: 599
From: Puerto Rico
Originally Posted by cliu
404 retort link not found.
LOL, you are misinformed, it is indeed a 16-valve system.
LOL, you are misinformed, it is indeed a 16-valve system.
This has been discused in earlier threads.
help me educate the members
Member
Joined: Jan 2006
Posts: 224
From: ATL GA
Originally Posted by hondanews.com
Depending on engine load and rpm, an electronic controller determines which cam profile will be used and exactly how the intake valves will operate (usually around 3,400 rpm). At low revs, where low lift and shorter duration provide optimal operation, the timing of the two intake valves is staggered and the lift asymmetrically skewed in favor of the primary valve. This helps to create a swirl effect within the combustion chamber that increases the efficiency of the burn process. At higher rpm, a hydraulically actuated spool valve causes a locking pin to engage the secondary rocker arm with the primary one, transitioning the secondary valve into a long-duration mode that increases the volume of air/fuel mixture moving into the combustion chamber. The additional air/fuel mixture helps increase power at high rpms.
http://www.hondanews.com/CatID2153?m...55013&mime=asc read all about it
Member
Joined: May 2006
Posts: 599
From: Puerto Rico
Originally Posted by Jetydosa
If you read that, we can determine there is a primary and a secondary intake valve. Now, it is not clear if they mean that during low RPM *only* the PRIMARY intake valve opens (effectively becoming a 12 valve engine) or not. But if thats the case it makes sense to be able to refer to the engine as a 12/16 valve engine.
http://www.hondanews.com/CatID2153?m...55013&mime=asc read all about it
http://www.hondanews.com/CatID2153?m...55013&mime=asc read all about it
AAAAHHHHHHHH
I think I am all wrong.
But I will learn .......
Anway, I wil never (hope) open the valve cover
New Member
Joined: Nov 2006
Posts: 3
From: Pacifica, CA, USA
I wrote the article referenced. I used American Honda's press information and it clearly states the engine is a 16-valve (4-valve per cylinder). Jonniedee went so far as to claim that he had a valve cover off and only saw 12 valves. This is wrong. It is most definitely a 16-valve engine.
New Member
Joined: Nov 2006
Posts: 3
From: Pacifica, CA, USA
I'm still waiting for Jonniedee to apologize. All Honda engines in North America with four valves per cylinder, regardless of VTec or not, are known as 16-valve (4-cylinder) or 24-valve (6-cylinder). Honda does not label their engines as 12-valve/16-valve etc.
It is correct in journalism to qoute the primary source. In the case of a car company that would be the car company.
It is correct in journalism to qoute the primary source. In the case of a car company that would be the car company.
Member
Joined: Nov 2006
Posts: 230
From: Michigan
Many engines with two intake valves cut off air to one of them at low RPM. The 2.5-liter V6 in a 1996 Ford Contour I used to own was this way. This is neither unique nor new with the Fit engine.
In most cases, the second valve opens and closes, but the intake to it is blocked by a butterfly so the effect is no different than if the valve remained closed.
I've never heard of an engine that simply left the valve closed, but the Fit's could potentially work this way.
In most cases, the second valve opens and closes, but the intake to it is blocked by a butterfly so the effect is no different than if the valve remained closed.
I've never heard of an engine that simply left the valve closed, but the Fit's could potentially work this way.
New Member
Joined: Nov 2006
Posts: 3
From: Pacifica, CA, USA
The Honda Vtec system engages/disengages a rocker arm, which in turn opens a valve. Below a specified rpm one valve stays closed. The system you describe essentially shortens or lengthens the intake runner by either using or not a secondary runner. Vtec allows two cam profiles, one low speed the other high speed.
Member
Joined: Nov 2006
Posts: 230
From: Michigan
I'm aware of the different cam profiles and how the V-Tec system works. But I wasn't aware that at the low profile one valve doesn't even open.
After thinking about your response, I'm no longer sure of my own knowledge in this area. What I thought I knew was:
In some systems each valve has its own intake runner, and one of these can be entirely closed. In other systems, the length of the runners is modified using a valve. Still others do both.
In my Contour's V6, I tought both were in play. As I understood it, one valve had a short runner and one had a long runner. At lower RPM the short runner was closed off.
Now I'm not so sure. Both valves might have been served by both runners.
Did find this bit on Toyota's system:
http://www.toyotacelicaonline.com/celica1/TVIS.htm
After thinking about your response, I'm no longer sure of my own knowledge in this area. What I thought I knew was:
In some systems each valve has its own intake runner, and one of these can be entirely closed. In other systems, the length of the runners is modified using a valve. Still others do both.
In my Contour's V6, I tought both were in play. As I understood it, one valve had a short runner and one had a long runner. At lower RPM the short runner was closed off.
Now I'm not so sure. Both valves might have been served by both runners.
Did find this bit on Toyota's system:
http://www.toyotacelicaonline.com/celica1/TVIS.htm
Thread
Thread Starter
Forum
Replies
Last Post