View Single Post
Old 11-30-2012, 02:33 PM   #20 (permalink)
Joeggernaut
EcoModding Lurker
 
Join Date: Nov 2012
Location: NC
Posts: 26
Thanks: 1
Thanked 3 Times in 3 Posts
Quote:
Originally Posted by ChazInMT View Post
So I was under the impression you were stating that a lot of cars driving on the road now all have CVVL systems in place which eliminate the throttle. This I contend is not quite the case, but it may not be long in coming.

I have to admit, I had a whole paragraph written up which was going to blast this whole CVVL as dreamland non-sense. Then, to make sure there wasn't really something to it, I Googled it. OK, I was really ignorant regarding these valve control methods. I have a VTEC Honda that I knew did some flibbity flu thing with the valves, but had no idea other car companies had gotten so far ahead.

I have revised the previous paragraph needless to say, since I'da looked quite troggish posting it.

OK, so I've read through some articles (find below) and educated myself on CVVL. I see it is mentioned that there is potential to eliminate the throttle, but, I don't see where anyone has done so completely yet.

I think that car makers want to get a few gazzilion miles under their belts running a CVVL with conventional throttle before they jump in whole hog on letting the CVVL thing take the entire load. I see BMW has a throttle for start up and backup to a Valvetronic failure (limp home), but does indeed open the throttle fully when the engine operates normally.

The main take away I'm getting from all this is that by closing the inlet valve before the piston reaches BDC (er... Bottom Dead Center) you can control the "charge" that way and thus eliminate pumping loss. It appears a small amount of "loss" is good in that it creates a healthy swirl to promote better combustion which off sets the loss and then some.

Interesting stuff, here, here, here, and here.
Notice - the red "here" is a big file if you have slow internet.

Thanks for bringing all this up. I learned a lot. It's one of the things I love about this Ecomodder family, it really gives us the opportunity to explore all things automotive keeping our minds sharp and growing.
Thank for you for the added information and insight. My main purpose of this thread was to provide some education but also to spark ideas or new theories on how new intake designs differ in terms of efficiency on new technologies. I already know how wai/cai/sri work on regular old MFI but I was curious how they work on these new valvetrains and intake systems and if their affect still holds true.

My personal opinion is that WAI is no longer an mpg booster since the main reason it increased efficiency was that it was "tricking" the ecu to open the throttle plate more but now that throttle plates are a secondary/backup systems wai only has negative effects now. CAI and SRI are still effective keeping in mind same size and length of intake tubes whether if it is a sri, cai, or wai.

Just for clarifcation when I say WAI I mean HAI as some kind of duct/piping that is drawing in warm/hot temps from the engine bay into the air intake. I think of a SRI is just a short length tube with a filter and that is all. A wai is a sri or cai + tubing to the exhaust hot/warm air.

Last edited by Joeggernaut; 11-30-2012 at 02:42 PM..
  Reply With Quote