[Diy_efi] The Hunt effect

[Bret Levandowski]

Better stated than my reply. Ski

John Gross <jogross3 at hotmail.com> wrote:>> There is most definitely a combustion chamber in a
>> cylinder,

>Yes, there is. I didn't say that, though. I said
>there's no combustion chamber *in* the head. The
>combustion chamber is composed of part of the head,
>part of the cylinder, and the piston crown.

Oops...sorry about the *typo*...I guess I should take better care when
crafting my emails, even when exhausted after a long day of trackside
engineering.

>> where the last "face" of the 3D volume is an
>> imaginary face coplanar with the deck of the
>> head.

>Then it's not a chamber.

Now you're playing a semantics game...by Webster's definition, you're right,
it's not a chamber. But when looking at a cylinder head, it is referred to
as the combustion chamber of the head.

>By definition, it is an imaginary distinction. 

See above comment about Webster

>What's more, it has very little in and of itself to do with turbulence,
squish, combustion, and even spark advance.

It does? So the shape and configuration of the head has little to do with
spark advance, turbulence, squish and combustion? So I guess it's primarily
the piston then that results in 4-valve center plug headed engines typically
running with MBTs in the low to mid 20s, while 2-valve wedge headed motors
are typically in the 30s. And the fact that large portions of the cylinders
cross-sectional area is closed off at the deck of the head on a wedge headed
motor has little to do with the tremendous turbulence generated by the
asymmetrical squish present when compared to a relatively open and
symmetrical 4-valve chamber?

>You can't figure out what is going on with only half the important data
>about the shape of the confines.

Yes, you must know what is going on with the piston shape, installed height,
head gasket thickness, and many other things to know the WHOLE picture. The
whole point of the original posts, however, was in reference to "Hemi"
chambers, and for the purposes of categorizing different engines, engines
with hemispherically-shaped *I don't know what Adam calls them* in the head
are technically "hemi" engines. 

>> While it is in and of itself not a physically
>> closed volume,

>And therefore, is not a chamber...

Yes yes, Webster, semantics, etc, etc

>> it is ALWAYS called the "combustion chamber"

>By whom? I've never heard anyone who actually knew
>what they were talking about who did not include the
>shape of the piston crown in their discussion of the
>combustion CHAMBER, and in fact it is meaningless to
>discuss only a partial description of the space in
>which combustion takes place. See my above comments.

See my comments above. Again, trying to discuss differences in the "part of
the combustion chamber made up by the head", which all of the Detroit, IRL,
and NASCAR engineers I have worked with over the years refer to as the
chamber, but apparently, they don't know what they're talking about either,
right?

> Oops, sorry for not knowing what you've been working
> on for the last 20 years...

>Ah, sarcasm, how delightful. I can see you haven't
>read any of the archives, either. Or clicked the link
>in my sig file, for that matter. A shame, regardless.

No, I haven't read the archives, because some of us have more important
things to do with our time than sift through endless archives of emails
mostly containing information already known to them, and what content is in
there that isn't already known to them, will be more efficiently obtaining
working on the dyno at work, looking at IMEP traces, studying combustion
events, etc, etc.

>In fact, my comment was a subtle hint that if you
>could not even remember what was written in the post
>to which you were replying, with it there in front of
>your eyes, that perhaps that would lead people to
>consider the possibility that your replies were
>crafted with the same amount of attention on your
>part. I'm sorry it had to be spelled out for you...

I'm sorry that you had to prove to me that the warnings I privately received
from some folks about certain members of this list being pompous,
self-righteous asses is true.

Have a good day folks.
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