ok so sure a 4 valve per cyl would flow better than a cvcc, but we dont really have that option unless you go teg head or whole engine.
This really isn't as hard as you'd think- just a matter of using different parts when you rebuild.
how does cvcc change the flow when the prechamber has its own seperate valve? the other valves would still flow the same would they not? or is it the cvcc runners inside the head are taking up space where there would normally be the normal runners?
flow is affected in that there is a very limited amount of potential improvement due to the cvcc pocket and flame travel time at high rpm- in theory. either way, when you're making power you really don't want to have anything in the way of your spark nor do you want lean conditions. CVCC helps run lean more compression on lower octane, most which can be done just with the quench pad! The rest can come with better ignition and modern fuel injection... only the end result is more efficient than the cvcc setup. CVCC might have been good for its day in producing low HC emissions but it did just as bad with NOx (iirc it was nox)
The other valves are, I believe, almost as big as the Si/ew5 valves (1mm smaller as I've been told)- I could speculate, though it would be a stretch without accurate comparison, that the dx casting flows less due to the space taken up by the CVCC components.
No, both cvcc and non cvcc manifolds are directly compatible, the CVCC "holes" don't get in the way of anything (but performance)
i believe CVCC died because people stopped caring about fuel mileage. CVCC helped produce less emissions and better fuel economy... and thats what supposedly the world is worried about right now. i think CVCC needs a comeback with new age tech...
I think it died because it became obsolete with more advanced PGMFI but even if that were not the case, it would come back out if it really were that helpful, it would resurface out of necessity- it would save honda a hell of a lot of money in tech development. With direct injection, ivtec, avtec, vtc, and advanced computerized engine management CVCC offers much less and doesn't really offer much in comparison.
im not saying i know better or anything, i only argue to understand better... instead of sayin "oh well that just doesnt work that way" KNAWMEAN?
I agree completely, I find myself digging through threads that I've posted on hoping that somebody has substantiated, hard info on why I am wrong. I love to learn about this stuff!
oh and yes there is a rubber O ring that seals the CVCC valve and is cheap to replace and easy to get to, just pop the VC and unscrew the valve. thats waht i was told by a machine shop when i asked them about fixing my honda head.
meh...
and yah i would agree that the CVCC head probably aint great for high RPM flow, but then again what 1/3g civic engine is great for high rpm flow? the SI is better but is it phenomenal? i kinda wonder why no one has tried combining a turbo with the lean burn effect of cvcc... i kinda wonder if honda wasnt trying this at some point and just scrapped the turbo part. this is around the time they did the City Turbo innit?
With decent, home brew porting, the Si head does well enough unless you're talking about putting down big numbers with turbo... then again Sawchuck proved that it is possible. There are plenty of racers that, with big cams, run their engines over 8krpm all the time using the Si head... I'm sure they've done it with the CVCC head too due to class rules but at a major loss in potential power and would rather be running a non cvcc head if it were legal- I'm sure they had a hell of a time finding valve spring upgrades for the cvcc valve too.
Lean and turbo do not go together period. with the proper amount of fuel, it is thought that cvcc could help lower the possibility of detonation though the costs would likely outweigh the benefits as the cam and flow issues would arise again. I also imagine it would be funky to tune and, due to being over 100% VE, the cvcc effect would be minimized.
I believe you are correct about the city turbo, but then again, that would go with my point that CVCC just gets in the way with a boosted engine when you could, instead, just have better electronics to get the same effect.
Keep in mind that CVCC was developed back in the early 70's and did a good job at being superior tech to the day's tech competition. Honda isn't the only company that use such technology, I know that at least mitsubiti used it in some of their engines including the Starion. Even in the Starion community, their version of CVCC is/was very unpopular for performance and is usually done away with.
PS I don't expect everyone to read all that bs! Cliffs: CVCC- obsolete, good for low tech fuel systems like carburetors, bad for high rpm, its a waste of time for most people especially when the car will make almost the same fuel economy without it
He who dies with the most toys, wins.