Combustion chamber turbulence

[allrightmike]

  As I understand it combustion chamber turbulence (call it CCT) helps promote flame propagation and reduces total spark advance requirements. Barney Navarro once told me that flathead Fords only wanted 18-22 degrees total because they had an extremely turbulent chamber. This leads to my question, modern chamber and coordinating piston shapes seem to have very little squish area which would tend to create less turbulence thus slower flame travel thus more spark advance requirement. I know that this is not the case so how do these modern designs create such rapid flame travel?


Mike.

[cjshaker]

The chamber design is everything in modern engines. The chambers are designed to produce a swirl effect as the intake charge enters the chamber/cylinder. Look closely at the contour of the chamber around the intake valve, where the intake charge enters the chamber, and you'll see flow "directors" that promote that swirl. If you look at modern heads for the FE, most incorporate these more modern designs into them, at least to the degree that the intake port allows. Oil jets for piston cooling also help a great deal in controlling heat and hot spots in modern combustion chambers, as well as the increased heat transfer that aluminum heads promote.

[gt350hr]

   Modern piston shapes have changed to enhance the swirl effect noted by cjshaker. Older chambers HAD to have squish pads to limit detonation and they had virtually no swirl.
     Randy

[FrozenMerc]

The old Flathead may have had alot of turbulence in the combustion chamber, but the flame front also had a very long distance to travel compared to OHV engines.  That long travel distance promotes poor combustion and un-even burning.

https://www.youtube.com/watch?v=jdW1t8r8qYc

[Katz427]

When I retired about 7 years ago, the buzz word was "tumble". A lot of CFD  work on computers to design a port where the air literally "tumbled" down the port, and into the cylinder. It is all about breaking the fuel molecules down as small as possible so when the chemical reaction is initiated, the combustion is complete, and what doesn't burn is handled by the catalyst. Let me say , I've seen the time from open chambers, to air injection 2 cycle, to tumble ports, with the end game being to  "of course" (eliminate pollution) improve efficiency.

[Katz427]

I think maybe Randy probably has a recollection of a company called Endyn and an aerospace engineer who if memory serves me named Larry Widmer. Larry was promoting a "soft chamber" with a fair amount of swirl for Ford NASCAR program. As I remember Ford engineers thought pretty highly of Larry's work. This was back in the 1980's. Larry and his company were in California.

[allrightmike]

Concerning the flathead chamber, about 3/4 of the area above the piston is quench so maybe not so large a chamber as it might appear

Mike..

[Katz427]

It's still up http://www.theoldone.com  tells Larry's story with his theory on chamber, port design and the boss 429 Pro stock program in the 1980's. An interesting read.

[frnkeore]

Who was it that did Bill Elliott's heads, in the '80's.

As I remember, he went from 2.19/2.25 intakes, down to about 2.06. He got about the same HP but, better fuel mileage, allowing fewer pit stops. I believe they where done in TX, somewhere.

[427mach1]

Who was it that did Bill Elliott's heads, in the '80's.

As I remember, he went from 2.19/2.25 intakes, down to about 2.06. He got about the same HP but, better fuel mileage, allowing fewer pit stops. I believe they where done in TX, somewhere.

I thought Ernie Elliott did them.........

[DuckRyder]

When I was into BMW’s Jim Rowe of Metric Mechanic promoted turbulence, I actually had one of his first 2.9 Hi Flow ST engines (I came by it used) and it ran good.

https://metricmechanic.com/

While I longer see all the information on his website about it, he cut crescent shaped grooves in the ports to cause what he called “surface turbulence” they even would do the intake and exhaust manifolds...

I always wondered what that treatment would do for a hot rod v8...

[frnkeore]

Who was it that did Bill Elliott's heads, in the '80's.

As I remember, he went from 2.19/2.25 intakes, down to about 2.06. He got about the same HP but, better fuel mileage, allowing fewer pit stops. I believe they where done in TX, somewhere.

I thought Ernie Elliott did them.........

No, not in the '80's, when Bill was winning all the races.

Bill's team tried to keep the guy hidden, as long as possible. It's my recollection, the they would not, tell Ford or any other team, what they were doing.

Again, as I remember, Penske also used the same guy for his NASCAR, AMC program.

[gt350hr]

I think maybe Randy probably has a recollection of a company called Endyn and an aerospace engineer who if memory serves me named Larry Widmer. Larry was promoting a "soft chamber" with a fair amount of swirl for Ford NASCAR program. As I remember Ford engineers thought pretty highly of Larry's work. This was back in the 1980's. Larry and his company were in California.

  Texas. Larry is ahead of his time for sure. Those who he helped with initial concepts , took the information and did their own take on it.
   Randy

[gt350hr]

Who was it that did Bill Elliott's heads, in the '80's.

As I remember, he went from 2.19/2.25 intakes, down to about 2.06. He got about the same HP but, better fuel mileage, allowing fewer pit stops. I believe they where done in TX, somewhere.

    "Some" of them were done by Endyne , but not "all". Ernie is fairly vocal about how much Larry helped. There are other guys like Carl Foltz and Don Losito to name a couple , that are at LEAST as capable as Larry.
     Randy

[frnkeore]

So, Randy, was it Larry Widmer that was doing Bill's heads, back in the 80's and also Penske's AMC project?