Ideal Flathead combustion chamber shape

[Hemi Joel]

Sorry, this is not FE, but this place definitely has a lot of smart people, maybe some one knows this? This is a max effort, blown racing ford flathead where the heads and pistons will be custom built. What is the proven best design for power? Thanks, Joel

[cammerfe]

If I were to be going to build a flathead, I believe I'd look at an Offenhauser 8BA head. The only thing better is an Ardun, and since the Ardun has an OHV layout, you can't do any copying. You say you're going with a custom head? I don't think the extra effort would be worth it. Is the engine going to be "ported and relieved and stroked and bored"?

KS

[Hemi Joel]

It's not going to be the Ford flathead that you are thinking of. It is the 337 Flathead. So not too many parts are available

[frnkeore]

So, is this going to based in the Lincoln FH?

[blykins]

Sorry, this is not FE, but this place definitely has a lot of smart people, maybe some one knows this? This is a max effort, blown racing ford flathead where the heads and pistons will be custom built. What is the proven best design for power? Thanks, Joel

The proven best design for power on a Flathead is to reroute the intake ports and exhaust ports.   You mill the lifter valley down so that you expose all the ports.  The exhaust ports on the side of the block are covered.  The exhaust is routed on top of the engine.   

You will also want to relieve the deck of the block around the valves. 

Roller cam conversions are also available. 

Obviously, lots of block prep is necessary, with only 3 main journals. 

[allrightmike]

Barron offered a high dome head&piston design that used a full radius piston dome with a raised hemi shaped combustion which made for much improved breathing.He copied from a Harly Havidson design for flat track racing.

[cjshaker]

While Brent is right (there have been a couple of high horsepower flatheads built using that method), it's an extremely aggressive approach that requires an insane amount of work. The examples I saw also used a lot of epoxy, which I would not consider very acceptable for long term use.

If you're wanting a modern chamber design, this is about the only modern type chamber I've seen. This is an old head that you'll never find, but could be reproduced in a custom head. I saw this recently at the Early Ford V8 Museum. Can't say as I've ever seen anything that was more high tech than this for a flathead head.



One of the big issues is getting enough area above the valve to get good flow. If you open that area up, you lose not only compression, but much of the combustion pressure is wasted in the valve area. The head above seems to use a 'depression' from the valve area to the combustion chamber, to help promote that flow. It may not be the best design, but it's a sound idea that could be used in a custom head.

I hope you give some updates on this. This is the Non-FE area, so it fits here.

[blykins]

While Brent is right (there have been a couple of high horsepower flatheads built using that method), it's an extremely aggressive approach that requires an insane amount of work. The examples I saw also used a lot of epoxy, which I would not consider very acceptable for long term use.

If you're wanting a modern chamber design, this is about the only modern type chamber I've seen. This is an old head that you'll never find, but could be reproduced in a custom head. I saw this recently at the Early Ford V8 Museum. Can't say as I've ever seen anything that was more high tech than this for a flathead head.



One of the big issues is getting enough area above the valve to get good flow. If you open that area up, you lose not only compression, but much of the combustion pressure is wasted in the valve area. The head above seems to use a 'depression' from the valve area to the combustion chamber, to help promote that flow. It may not be the best design, but it's a sound idea that could be used in a custom head.

I hope you give some updates on this. This is the Non-FE area, so it fits here.

Ole Henry never knew we'd be trying to sneak out these levels of horsepower from the flathead.   

What really stinks is that you have two really sharp 90° turns in airflow, it's a like a chicane for flow.   I've seen some guys online put a flathead block on a "flow bench" and they can only squeak out about 130 cfm on the intake side.   

[allrightmike]

Barney Navarro told me that the flathead had such a turbulent chamber that 18-22 degrees of advance was all they wanted. All that turning and twisting on the way in? Also is was a short distance for the flame to travel.

[Dumpling]

A little knowledge is a VERY dangerous thing, BUT, the OP stated this was going to be a max effort, BLOWN, engine. With a lot of pressure filling the chamber, do you need to really do anythy more than to hog out the ports to get the air in and out? Ardum heads are hemi-shaped? Those with matching pistons with a good blower?

[e philpott]

https://www.bing.com/images/search?view=detailV2&ccid=HwMGd24R&id=3E523AADD81D31963464ADD97805659307437691&thid=OIP.HwMGd24RiYatSvwuqYnL4AAAAA&mediaurl=https%3a%2f%2fwww.blossomracingengines.com%2fimages%2fsP1010012.JPG&exph=150&expw=200&q=junior+dragster+rhino+cylinder+head&simid=608030239762550508&ck=8E842E4604350B9B22B858DC748306A0&selectedIndex=14&FORM=IRPRST&ajaxhist=0

the block being relieved is just as important as the cylinder head , if you want to see the best shape for a flathead look no further than a 7.90 junior dragster engine

[Royce]

My answer would be to do all you can to unshroud the vales and even more important help the exhaust as much as possible. Give it an 8:1 open chamber. 20 psi of boost will cure a lot of design sins.. LOL  Find an old guy that runs a blown flathead on nitro.. See what they did..

[blykins]

https://www.youtube.com/watch?v=2E9LOddDk6g

[drdano]

I'd reach out to Ron Main and get some ideas from his group.  They had 700hp out of ~300cu/in.  http://speeddemon.us/flatfire.html

[My427stang]

I wonder if this is an application where you could go with a piston deep in the hole, use the valve area for most of the combustion and build a wedge that protrudes into the cylinder to get the compression back. 

It'd be full custom, but you may be able to then relieve to the point that the new "chamber" acts more like a modern design, just offset