Chamber softening

would our BBF heads need chamber softening for heavy nos applications --- i guess chamber softening is altering the flame travel as well as giving it certain direction. Some heads don't have enough quench pad to be able to do this. A slight taper on the pad will give it direction and create the desired turbulence

just curiuos

here is a pic of one done

It looks like they are taking all the edges off the chamber, "softening" to remove hot spots I guess?

Bill

here is a pic of another chamber done ..... this is to slow the burn rate down

where are you pulling these photos from...?

one was from Steve's site and the other was from yb

somebody is..

I have seen something like this on a set of Thor heads. Didn't know what it was called at the time. Charlie actualy showed me the set.

good to know that Charlie knows the benefits from this ...would like to get my new heads done with that feature

bruno wrote:good to know that Charlie knows the benefits from this ...would like to get my new heads done with that feature

I don't know if he knew the exact benifits as it was a set of heads that was being repaired. I believe Laws (sp) was doing the repair work. This was a couple of years ago Charlie and I was roaming Kentucky! LOL

Doesn't it seem like you could accomplish the same thing with an altered piston design? That way if the modification doesn't work out it would be a lot easier to reverse.

so they are doing this to the heads to increase the cc of the chamber and to increase the quench .... i dont think you could acomplish that with piston design ???????

Look around and see if you can find that article by Larry Windmer about "The Soft Head". The idea is not so much one of increasing the chamber or quench size but rather using those areas to try to move the mixture around once it's in the cylinder and being compressed into the chamber for combustion. I think the whole point is to try to reduce charge stratification and to make the mixture very even and this is supposed to allow better combustion as well as higher compression ratios to be used without detonation.

All seems mostly theoretical but it might be worth an experiment. There are also some ideas about exhaust port sizing which are also in that article. Sizing the port so that it deliberately goes super sonic for more of the exhaust cycle etc. Who knows, maybe that part just acts like an EGR valve and THAT'S what makes it reduce detonation...

http://www.theoldone.com/articles/The_Soft_Head_1999/

thxs for the info Dave, great read

I remember reading the original article about Widmer's airflow theories. His list of customers included the Elliott's and Glidden. Elliott's engines were at the top of the field during that era. Glidden being Glidden mentioned Widmer didn't know sh*t about cylinder heads, although he had set the NHRA P/S speed record during the Winter Nationals with cylinder heads on his engine bearing Widmer's logo! I think the Texan was on to something, and others wanted the idea for themselves! Couldn't imagine that!

Dave.

bruno wrote:here is a pic of another chamber done ..... this is to slow the burn rate down

You would NEVER want to slow-down the "burn rate" presuming that the fuel octane is not constrained. You may want to CONTROL the entire burn rate so it doesn't CHANGE rate throughout the burn process or induce a more COMPLETE burn or not have more than one flame front which can colide with one another.

The slower the burn of combustion, the more power goes out the exhaust valve when you open it sooner.

so have you used this technique in any of your builds Randy ?

bruno wrote:so have you used this technique in any of your builds Randy ?

When the heat of combustion is quenched enough; (to much), where it actually hinders a complete burn and excessive hydrocarbons are being released unused, is a good time to institute a procedure like this. You can almost never quench an octaine constrained engine "to much".

Boosted engines and engines which DON'T have an octane problem are good canidates and I have used similar alternatives. When the chamber is active enough, (piston topography has a lot to do with this), and doesn't need help with turbulence, (the second function of a tight quench area), the piston can actually be run quite far "down the hole"; (if the engine is large enough to still get the compression ratio you want).

sounds as if this is a bandaid for mis-matched components

i used some c125 fuel and slowed me down 2tenths.a fellow racer said it had a very slow burn rate.i didnt know it could be that big a deal.is this the same kinda idea?

As fast a burn rate which can be CONTROLLED is optimum.

It's tough to explain the actualities but, like everything else; it all needs to work together.

cool40 wrote:i used some c125 fuel and slowed me down 2tenths.a fellow racer said it had a very slow burn rate.i didnt know it could be that big a deal.is this the same kinda idea?

I learned this one night at the track when I ran out of pump gas. I filled the tank with 114 and slowed way down!! I had always heard of this being a problem but had never experianced it first hand until then.

What Randy said is 100% correct.

rmcomprandy wrote:As fast a burn rate which can be CONTROLLED is optimum.

It's tough to explain the actualities but, like everything else; it all needs to work together.

This is the key element "Controlled" in a heavy spray N20 Application with very effeicint heads you must soften the chamber due to the Uncontrolled burn, this allows you to run more timing and therfore make more power even with todays N20 Specific fuels. a perfect example is the Yates D3 head this head is super efficent and makes a ton of power and has a very fast burn rate. this fast burn rate has to be slowed in a heavy N20 application or the motor will torch stuff. i have seen this personalyl on a motor with 400hp worth of spray single kit, it would be in negative-1-2 degrees of timing to live with 14.1 compression after the heads were softened the motor ran faster with more timing.4- 6 degrees total timing and same compression. ran faster and was easier on the pistons and rings in the motor. Not saying that parts were mismatched but they dont make one head that works flawleslly in every application.

Just my .02

what are your thoughts on the design of the a-heads and how can they be improved? what about larger exhaust valves? I'm pondering a pump gas build with about 3-400 in two stages. and how would a set of these heads being setup for nitrous function if they were converted into a procharger or turbo application later on...

there is not enough people in my area running the a460 head to know weather it will help, I would think that with 72 cc chambers it will not be as timing sensitive as some of the sbf stuff, most of the technology that has went into the sbf makes the head designs so efficient due to the research in nascar, I am sure there are some guys spraying it hard i just have not seen any. if i was not into this new SBF build i would have love to build a short stroke large bore a460 headed motor with about 600 -700 N20 on it about 500-550 cubic inch with a 4.50 or larger bore. and see exactly what they like. There has got to be somebody on this site that is spaying an A460 motor hard.