quench is quench

[Ape]

Ok, well i think one of the reasons why those guys, use that lil advance is not just solely the squish speed its also the ignition sytem involved, im not quite sure if they still do use conventional spark ignition on nascar or any other v8 race class high budget engines. There is currently some effort to get rid of sparks in general, In order to achieve faster burn through of the mixture and thus less advance universitys and for sure f1 and gt teams are experimenting with plasma ignitionsytems. Meaning a small quantity of highly compressed mixture will be shot into the chamber thus resulting in a exceptional fast burn rate.

About the point that :

Posted: Sat Jun 04, 2005 3:27 pm Post subject:

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SStrokerAce wrote:
1. a sphere with the ignition in the middle of the sphere so the flame can start burning and go out from there in all directions.

headman wrote:
However, I agree the "sphere" is the intuitive solution.

If that were the case, you'd think you'd see one in use (competitively) in race environment

I do not know why they still do use bath tub chambers on some us engines, but dual squish hemi style chambers where standard on 2valve high perfomance bike engines for the last 30 years with great success. Im convinced that that architecture was being used on race engines too, since the initial development for such heads cam through weslake (now cosworth??) engineering somewhat in the 50´s. Also im pretty curious how long ti will take to see the new hemi on racecars(dunno know the rules thoúgh). I myself use a welded up hemi , biased intake port head on my 2 valve (34cui)single cylinder with good success and about 22° adv. since thats all thats needed.
Still though some info seems ambivalent, whereas most theoretical essays debate the quench issue in so far that too much quench will provoke deton. beacuse of too high turbulence and added effort to overcome the compression by the quench area, most articles i read by us tuners, state that they use ultraclose distances.

anybody out ´there using software for that task, since i think its a combined ratio of quench area and included distance???

Oh by the way, here are the links for the plasmaignition:

http://www.atlasf1.com/99/oct06/burckmyer.html

http://www.adrenalineresearch.com/race.htm

[Ape]

Oh by the way BMW conducted extensive testseries in the seventies concerning squisheffincies, velocities and designed because of that data combustionchambers for their then 2valvers, unfortunately cant find any pictures on the net of the "dualsphere2, (nonetheless it was used on their 2002 engines and on the TI-kugelfischer injection cars), to put urls here. What a coincidence higly efficient harley heads look similar:-))

Wonder do you guys know if anybody ever welded up hemis on chryslers?? It would seem like the obvious thing to do???

[gas]

Also im pretty curious how long i will take to see the new hemi on racecars(dunno know the rules thoúgh).

It may not have been clearly identified/conveyed, but yes, my intended focus was to be on 'sphere'.

I believe hemispherical chambers are allowed in some classes of racing. However, today's racing hemi [sic] chamber is far removed from the street (real) hemi of yesterday, and to a lesser degree, from the new (as commonly identified/marketed) hemi head of today (5.7).

EDIT: Here's a pic of a 'racing' hemi [sic] combustion chamber. This pic was posted on another forum, by/and courtesy of 'maxracesoftware' (Larry). If I'm reading the true intent of identifying that chamber as a hemi correctly, what is this telling you about the competitiveness/superiority of a (true) hemi combustion chamber in today's racing?

http://www.maxracesoftware.com/P5_ProSt ... hamber.jpg

[Leon Sterett]

The answer IS...'IT DEPENDS' on what engine/combo one is talking about. For sake of the discussion a Cup engine will have a lot of quence 'area' because it has around 44cc. chamber (but still about .030" quence), the compression height/rod length and a hole host of factors make this 11 degree head combo work. This is 'a' reason why they only need 26 max degrees total timing.

Leon

[gas]

The answer IS...'IT DEPENDS' on what engine/combo one is talking about.

I believe you are missing my point. ANY form of racing will choose/use the most effective (read HP/TQ generating) chamber available to them. If a true hemispherical chamber were more competitive, for any given form of racing, I believe they would utilize it.

As for the example you offered. I agree with your comments. I'll add, they use the chamber they do, cuz it gets them around the track quicker. That is the object of the race.

[Ape]

With a true hemisphaeric chamber one will have, depending on the bore size, problems with less turbulence in comparison to squish type heads, also the surface heat dissipation seems in comparison to the added gains of turbulence negligable. One would have to use akward outdated (less brun trhough)) piston shapes in order to raise the compression for comp. engines, because the chamber would be so deep.

regards christian

[gas]

I agree, even omitting the deep, large volume chamber arguement, which Chrysler has addressed with their new OEM chamber, being smaller and noticeably shallower.

The alterations Chrysler has made to their original hemi chamber, (which by the nature of the modifications, renders it no longer a hemi chamber) has made it more efficient/effective. However, it still (apparently) falls short competitively, of the chamber that is considered today's race hemi [sic] chamber, (as identified in the link provided) which is an even more radical departure from their original true hemi chamber. This is the chamber, I believe, would more apt to be utilized in open competition, if the engine were to be packaged/identified as a 'hemi' engine. Thus to reply, now in more direct fashion, to the (your) statement I originally quoted...

Also im pretty curious how long i will take to see the new hemi on racecars(dunno know the rules though).

.... IF you are referring to open competition, such as nascar, AFAIC, I don't see it happening. In 'class' competition, I view the OEM head as competitive.

[Ape]

Well as said i dont have a clue about rules, since over here(middle of europe) there is not really a lot of big V8 racing. I was just wondering because having read the article by vizard about the port architecture, it sounded like magic(even more looking at the cut through diagrams, being a real downdraft port, and noticing the lil hump between intake seat and exhaust seat) relating it somewhat to old small block ports and invloved architecture. One of the reasons im particulary interested in small blocks is there similar architecture to big singles, and trying to somehow gain knowledge through similaritys. Thats also why im referring to weslake and others. Looking at the pictures of the raceheads im still not convinced that there might be not too much swirl at high (8-10000rpm) Rpm´s. I know the stuff is done in a well thought out way, its just i have never seen such swirl inducing offset on bike engines. From what i know they even reduced the offset(or angularity) on some off the big flat track singles, but then maybe it was just empiricism, back then. Also i know that that was allready a big issue in the late eighties, "more swirl less swirl"
But interesting how on the pictures the head looks similar to the superswirl head by endyn(widmer) whose work i greatly appreciate.

nice greetings
christian