I couldn't find anything on our super search engine
Soft versus Hard Combustion chambers?
Moderator: Team
Soft versus Hard Combustion chambers?
Can some of the more enlightened folks describe "soft" vs. "hard" chambers and their application differences?
I couldn't find anything on our super search engine
I couldn't find anything on our super search engine
He who is in me is greater than he who is in the world.
Re: Soft versus Hard Combustion chambers?
It's an "adaptation" of chamber configurations for medium-duty OEM trucks & heavier vehicles.
Look at this example, then Google search images for "soft chambers". You will recognize the similarities.
Re: Soft versus Hard Combustion chambers?
I know nothing about it, have heard the term.
I found this much though.
https://www.google.com/search?q=Soft+ve ... 66&bih=635
I found this much though.
https://www.google.com/search?q=Soft+ve ... 66&bih=635
Jim
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AaronMcCoy
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Re: Soft versus Hard Combustion chambers?
http://www.theoldone.com/articles/default.asp Several articles on the concept.
I believe Larry Widmer also discusses the idea in his Speedtalk interview from 2005.
I believe Larry Widmer also discusses the idea in his Speedtalk interview from 2005.
Re: Soft versus Hard Combustion chambers?
Are you talking in reference to boost and nitrous compared to n/a?
Re: Soft versus Hard Combustion chambers?
“Softening” a chamber as I know it is scalloping out the chamber & quench area to reduce the flame speed in a nitrous engine. The added oxygen release with nitrous can speed up the flame travel too much on small chamber heads making the tuning window very narrow.
The added area and less sqish allows for a slower more controllable “explosion”.
The added area and less sqish allows for a slower more controllable “explosion”.
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grandsport51
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Re: Soft versus Hard Combustion chambers?
This discussion on Speed Talk
Is very interesting
https://www.speed-talk.com/forum/viewtopic.php?f=1&t=2807
Larry is very well respected in the Honda world and Became a huge contributor to Bob Gliddens success
From Boss 302 registry and Larrys TOO columns
I found the article from Endyn's Larry Widmer (The Old One or T.O.O.)
Some History - Bob Glidden
TURNCOAT AND ALL,
As I mentioned in my brief reply, the heads in question were a set designed for a blown drag boat application, and Goletta Marine was the customer. The head castings were designed for Alan Root's all aluminum BOSS 429 engine packages. The designer of the heads was Tom Roberts who at the time worked for Nick Arias, in fact Arias was a 30% partner with Root. Their redesign of the BOSS components began in 1983, and the first parts were available in late ' 83 - early ' 84. The head redesign reflected the typical Arias port configuration which favored blown applications. Blown fuel was what Nick and Alan were after, however, as there were no takers, other classes were considered, ie. ProStock.
In late ' 83 Alan and I struck a deal to make the heads more appealing to the Pro ranks. This program included a crash effort to make the standard Arias Root head work, and I immediately began a redesign of the head incorporating swirl pads in the chamber, redesign of the inlet port to promote mixture swirl, and a major redesign of the exhaust side using my "super critical area rule" to achieve supersonic exhaust flow. The prototype heads were the std. AR castings with several pounds of my aluminum welding rod used to reshape all the necessary surfaces. The castings were then normalized, and re-heat treated to spec. All surfaces were remachined, and the new chamber and ports were laboriously executed, and the heads flowed as the formulas' predicted. During this same period Alan and I felt that there would be a considerable market for finished heads and manifolds, as well as proper pistons, cams, and advice on rod length, stroke, bore, etc. In other words, all the right pieces, some assembly required. The Super Swirl heads (complete), and worked manifold were to be priced at $10 K per "package", and available in no other form.....remember, however, this was a separate head entirely from the std. AR 429 "HIGH PORT" heads. In order to get the ball rolling, we wrote a computer program to allow a multiaxis mill to "rough in" the chambers, and I spent considerable time at Aerocast in LA scraping the sand cores to produce 10 pair immediately without welding. I also began revision of new tooling to allow casting without the custom scraping, so when I received the heads we at Endyn would do all finish machining, porting, assembly, etc., and the "super swirl" heads would go directly to the customer flow sheets and all other engineering data included. The head package was given part # M-6049-A443* by Ford and included(without) picture in the 1985 Catalog. We ran our prototype super swirl engine in November,84, and produced the dyno figures partially quoted in the soft head article, however, max. power was never revealed until my lengthy book to Sentiniel, this AM. Bob Glidden heard about the dyno run at the SEMA show which was going at the time, and wanted to buy the engine, and all the other hand scraped castings we were finishing. The price was right, and as the NASCAR programs needed tending , we agreed.....thinking that our head deal with Ford was intact. Little did I know that Bob had negotiated to buy out Nick Arias share of AR, and of course he then went directly to Ford and mandated that the "super swirl" head program be cancelled. It was and that's that. Bob didn't want anyone else having access to the same "stuff" he was running, and I can't blame him.
Now I'll address your head related questions: With the exception of blown applications, ports don't just flow one direction. Intake ports pulsate back and forth, and exhausts flow backwards too. This occors primarily at overlap, when the cylinder still has positive exhaust trying to exit the exhaust port ...where header back pressure is pushing backwards. Now the intake valve (which is larger in diameter) opens, and exhaust gasses seeking the path of least pressure take the easy way.....the intake port "exit". This is not a good thing because besides turning the intake port black "reversion" also contaminates the intake charge with inert gasses which will not burn again. My studies showed a direct correlation between low lift intake flow and reverse flow.....The better the low lift flow on an intake port, the better the tendency for reverse flow, or sucking exhaust. I designed my intake ports to not flow worth a $#!+ at low lift, and also to not flow backwards. I'll not detail how, but the approach to the inlet valve seat, and its blend to the chamber are how it's accomplished....remember the seat is only the 45 degree angle that's ~ .055" wide. were not talking about the seat ring itself. The assymetric shapes I developed for that area and the last .5" of the intake port (the wierd valve job) are why the port doesn't dare flow backward, and as for low lift flow......study the piston velocity when the valve's at .150" or less. You'll find that it's so slow that the port's not being sucked on at all(relatively speaking), so big flow #'s at low lift wouldn't do you any good anyway. If I had known how to design an intake port that flowed 0 cfm. up to .150" lift, I would have, but all things considered my "weird seats" worked well for their time.
Exhaust ports: Read my Re. to RX first. I've never had much luck with performance of engines with no exhaust valves, so I've never been inclined to design exhaust ports without valves included. All I'll say is that the some flow attaches itself to the head and stem on the exhaust side, so the valve is somewhat like a guide for flow. The thing you're missing when flowing with no valve is that the valve stem represents part of the cross sectional area of the port, and, as previously stated areas are critical when dealing with velocities over mach 1. My port phylosophy has always been to calculate how much air a given displacement engine needs to run at a given rpm range (taking into account the many variables such as bore / stroke / rod length, and of course rules), and design a high velocity intake port that's not too large or so small that the velocities will cause separation of a well prepared air / fuel mixture. With valvetrain life in mind, I also attempt to achieve highest flow rates at crank angles where piston velocity is highest (greatest sucking power). If you can obtain 90% of your max. flow rate at mid lift, you don't need to run a cam with spring killing lift. As for the exhaust side, lalve lift and the additional heat kill springs, so the more you can flow, the less lift is needed, and if it's real good you don't need to open the exhaust valve before BDC on the power stroke, releasing that last bit of cylinder pressure pushing on the piston, and you can close it earlier too. Most "head experts" agree that the exhaust should flow 80% of the intake, and assuming that they're talking flow with the manifold / injector installed, and the header on the exhaust, that's ok. But if I can design an exhaust port that flows twice the intake port flow, I will, because it allows you to run less lift and duration which makes springs happy, and on an engine like the Ford BOSS 429 remember the exhaust rocker arm is about 5" long, and I don't care what you make it from, all that mass takes considerable spring to control, and the less you move it the longer all the parts last. Over the years I've had customers go in and #@$% up my ports so the flow will be less allowing them to run the same cam they used to. What a world.
I was diagnosed with cancer in Sept.1979, a great thing to find after winning Indy 3 months earlier. Two years of continuous chemotherapy and I achieved remission, it bit my ass again after concluding the rules breaking Toyota program. Another year of chemo. and four weeks of radiation and they haven't killed me yet. One reason I'm still here is that after cutting off the bull $#!+ with the press, and I've been able to pick and choose what I work on and who I work for, and for the most part I set the rules and the schedules.
Now I appreciate your support, and I enjoy fielding some technical questions for you guys, but I don't and won't go through this bull $#!+ of being placed under a #@$%ing microscope, and having to justify who the hell I am or "am not". As your second remission doesn't last as long as your first, that puts me 3 years "over due", and I've had so much fun with doctors, I'm gonna roll with it this next go-round, and try to leave the world a little bit better place than when I came . I'm tired, I'm irritated, and I'm pissed, and now it's time for me to quit typing and get back to something more productive than trying to convince people that I'm alive.
THE OLD ONE (FOR MANY REASONS).....
Logged
Offline somedaydone
Senior Member
Is very interesting
https://www.speed-talk.com/forum/viewtopic.php?f=1&t=2807
Larry is very well respected in the Honda world and Became a huge contributor to Bob Gliddens success
From Boss 302 registry and Larrys TOO columns
I found the article from Endyn's Larry Widmer (The Old One or T.O.O.)
Some History - Bob Glidden
TURNCOAT AND ALL,
As I mentioned in my brief reply, the heads in question were a set designed for a blown drag boat application, and Goletta Marine was the customer. The head castings were designed for Alan Root's all aluminum BOSS 429 engine packages. The designer of the heads was Tom Roberts who at the time worked for Nick Arias, in fact Arias was a 30% partner with Root. Their redesign of the BOSS components began in 1983, and the first parts were available in late ' 83 - early ' 84. The head redesign reflected the typical Arias port configuration which favored blown applications. Blown fuel was what Nick and Alan were after, however, as there were no takers, other classes were considered, ie. ProStock.
In late ' 83 Alan and I struck a deal to make the heads more appealing to the Pro ranks. This program included a crash effort to make the standard Arias Root head work, and I immediately began a redesign of the head incorporating swirl pads in the chamber, redesign of the inlet port to promote mixture swirl, and a major redesign of the exhaust side using my "super critical area rule" to achieve supersonic exhaust flow. The prototype heads were the std. AR castings with several pounds of my aluminum welding rod used to reshape all the necessary surfaces. The castings were then normalized, and re-heat treated to spec. All surfaces were remachined, and the new chamber and ports were laboriously executed, and the heads flowed as the formulas' predicted. During this same period Alan and I felt that there would be a considerable market for finished heads and manifolds, as well as proper pistons, cams, and advice on rod length, stroke, bore, etc. In other words, all the right pieces, some assembly required. The Super Swirl heads (complete), and worked manifold were to be priced at $10 K per "package", and available in no other form.....remember, however, this was a separate head entirely from the std. AR 429 "HIGH PORT" heads. In order to get the ball rolling, we wrote a computer program to allow a multiaxis mill to "rough in" the chambers, and I spent considerable time at Aerocast in LA scraping the sand cores to produce 10 pair immediately without welding. I also began revision of new tooling to allow casting without the custom scraping, so when I received the heads we at Endyn would do all finish machining, porting, assembly, etc., and the "super swirl" heads would go directly to the customer flow sheets and all other engineering data included. The head package was given part # M-6049-A443* by Ford and included(without) picture in the 1985 Catalog. We ran our prototype super swirl engine in November,84, and produced the dyno figures partially quoted in the soft head article, however, max. power was never revealed until my lengthy book to Sentiniel, this AM. Bob Glidden heard about the dyno run at the SEMA show which was going at the time, and wanted to buy the engine, and all the other hand scraped castings we were finishing. The price was right, and as the NASCAR programs needed tending , we agreed.....thinking that our head deal with Ford was intact. Little did I know that Bob had negotiated to buy out Nick Arias share of AR, and of course he then went directly to Ford and mandated that the "super swirl" head program be cancelled. It was and that's that. Bob didn't want anyone else having access to the same "stuff" he was running, and I can't blame him.
Now I'll address your head related questions: With the exception of blown applications, ports don't just flow one direction. Intake ports pulsate back and forth, and exhausts flow backwards too. This occors primarily at overlap, when the cylinder still has positive exhaust trying to exit the exhaust port ...where header back pressure is pushing backwards. Now the intake valve (which is larger in diameter) opens, and exhaust gasses seeking the path of least pressure take the easy way.....the intake port "exit". This is not a good thing because besides turning the intake port black "reversion" also contaminates the intake charge with inert gasses which will not burn again. My studies showed a direct correlation between low lift intake flow and reverse flow.....The better the low lift flow on an intake port, the better the tendency for reverse flow, or sucking exhaust. I designed my intake ports to not flow worth a $#!+ at low lift, and also to not flow backwards. I'll not detail how, but the approach to the inlet valve seat, and its blend to the chamber are how it's accomplished....remember the seat is only the 45 degree angle that's ~ .055" wide. were not talking about the seat ring itself. The assymetric shapes I developed for that area and the last .5" of the intake port (the wierd valve job) are why the port doesn't dare flow backward, and as for low lift flow......study the piston velocity when the valve's at .150" or less. You'll find that it's so slow that the port's not being sucked on at all(relatively speaking), so big flow #'s at low lift wouldn't do you any good anyway. If I had known how to design an intake port that flowed 0 cfm. up to .150" lift, I would have, but all things considered my "weird seats" worked well for their time.
Exhaust ports: Read my Re. to RX first. I've never had much luck with performance of engines with no exhaust valves, so I've never been inclined to design exhaust ports without valves included. All I'll say is that the some flow attaches itself to the head and stem on the exhaust side, so the valve is somewhat like a guide for flow. The thing you're missing when flowing with no valve is that the valve stem represents part of the cross sectional area of the port, and, as previously stated areas are critical when dealing with velocities over mach 1. My port phylosophy has always been to calculate how much air a given displacement engine needs to run at a given rpm range (taking into account the many variables such as bore / stroke / rod length, and of course rules), and design a high velocity intake port that's not too large or so small that the velocities will cause separation of a well prepared air / fuel mixture. With valvetrain life in mind, I also attempt to achieve highest flow rates at crank angles where piston velocity is highest (greatest sucking power). If you can obtain 90% of your max. flow rate at mid lift, you don't need to run a cam with spring killing lift. As for the exhaust side, lalve lift and the additional heat kill springs, so the more you can flow, the less lift is needed, and if it's real good you don't need to open the exhaust valve before BDC on the power stroke, releasing that last bit of cylinder pressure pushing on the piston, and you can close it earlier too. Most "head experts" agree that the exhaust should flow 80% of the intake, and assuming that they're talking flow with the manifold / injector installed, and the header on the exhaust, that's ok. But if I can design an exhaust port that flows twice the intake port flow, I will, because it allows you to run less lift and duration which makes springs happy, and on an engine like the Ford BOSS 429 remember the exhaust rocker arm is about 5" long, and I don't care what you make it from, all that mass takes considerable spring to control, and the less you move it the longer all the parts last. Over the years I've had customers go in and #@$% up my ports so the flow will be less allowing them to run the same cam they used to. What a world.
I was diagnosed with cancer in Sept.1979, a great thing to find after winning Indy 3 months earlier. Two years of continuous chemotherapy and I achieved remission, it bit my ass again after concluding the rules breaking Toyota program. Another year of chemo. and four weeks of radiation and they haven't killed me yet. One reason I'm still here is that after cutting off the bull $#!+ with the press, and I've been able to pick and choose what I work on and who I work for, and for the most part I set the rules and the schedules.
Now I appreciate your support, and I enjoy fielding some technical questions for you guys, but I don't and won't go through this bull $#!+ of being placed under a #@$%ing microscope, and having to justify who the hell I am or "am not". As your second remission doesn't last as long as your first, that puts me 3 years "over due", and I've had so much fun with doctors, I'm gonna roll with it this next go-round, and try to leave the world a little bit better place than when I came . I'm tired, I'm irritated, and I'm pissed, and now it's time for me to quit typing and get back to something more productive than trying to convince people that I'm alive.
THE OLD ONE (FOR MANY REASONS).....
Logged
Offline somedaydone
Senior Member
LIGHT 'EM UP
Re: Soft versus Hard Combustion chambers?
That is a stock smog way open chamber head if not mistaken.
Too lazy to dig my book out and put a number on it.
pdq67
Re: Soft versus Hard Combustion chambers?
Great responses all- I appreciate it!
He who is in me is greater than he who is in the world.
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racear2865
- Guru
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- Joined: Mon Sep 21, 2009 11:58 pm
- Location: tenn
Re: Soft versus Hard Combustion chambers?
I dug my old copy of HPBooks, "How to HR BBC's"..pdq67 wrote: ↑Thu Sep 13, 2018 9:58 pmThat is a stock smog way open chamber head if not mistaken.
Too lazy to dig my book out and put a number on it.
pdq67
The way open chambered BBC head can be either a;
-818;
-148; or a
-292.
The -148 head may be as small as 112 cc chamber size? And maybe the others as big as 122 cc's so you really need to cc them...
OT, but if you want to up the CR number then install an old pair of -206 true bathtub early closed chamber heads. They are down around 96.7 to 98 cc chamber size so them and .020: thick shims will up a mid -70's 454 P/U engine a good amount. Say from 7.9 or so CR to maybe up to 9 or so CR??
pdq67