Ideal Flathead combustion chamber shape

[Hemi Joel]

I'm busy at work today so I don't have time for a full reply, but you guys are awesome! Great stuff coming out here! Thanks

[frnkeore]

Joel hasn't said if he's going to be working with the 239/255 Ford/Merc or the 337 Linc. I don't know anything about the Linc but, the 239, is a real challenge.

The first problem, is finding a sound block, to start with. I know of people that have spent more than $2000, just trying to find a block that will mag & pressure test!

3 mains isn't to much of a problem, a girdle and a 180 crank, will solve most issues. Farmall "H" tractor cranks, with welding and machining, can make a 180 crank, for a FH.

337 is attainable but, it takes 8, 3.5" sleeves and a 4.375 crank. The bore centers are 4.000 and 5.125, in the center. If try to go bigger than 3.5, you run into the center exhaust port.

After that, induction and exhaust are the main problems. Not so mush as being a L head but, the size and routing. The intake port, is almost unusable. It's design never changed from the orginal, 221 ci, '32 engine. The intake port, is only 1.312, in diameter and narrows, in the valve guild area, to about .85. As Brent says, the flow is very limited, compared to any OHV engine. I'm adding a actual flow bench test, as well as Ford's drawing of the port. They got this one to 144 cfm. The exhaust ports flow much better but, they are in the cooling system and heat and block, the coolant, as well as being Siamesed, for the center ports.

Using the intake ports, for the Ex is a way to go and make your own, intake tract, with 1.75+ valves, not much you can do, using the intake ports, as ex.

Compression, is your only friend and even that, is hard to get. With the overlap, that you will have, 9/1 should be minimum.

There are modern F head conversions out there but, the Ardun, is the only real way to make hp on a FH.

Like I said, I don't know anything about the Linc, 337 but, it might be a better starting point, although it's very heavy.

In my oppinion, the best hing to do with the original FH, is to build a small 221 engine, for class racing. It's much easier to feed a small cylinder, with what you have available, with the FH.

[Hemi Joel]

This is the lincoln/ ford f8 337 flathead.  I can't do valves in the head, and the cid limit is 375 - class rules.  So if the intake ports are small, can that be overcome with more boost, or does it hit a wall where more boost just makes heat and no more power?
We have a scrap block to cut up and look at the port wall thickness. I did sonic test it, and a .100 overbore is feasible.

Considering the risk of destroying blocks while racing, I would like to keep the amount of time and $ inverted into the block down. The major moving around of ports would be a last resort.

[Royce]

Without speaking out of turn, Joel is talking the 337.. Lots of new ground to plow on this one.. I am still under the opinion that enough boost will get the power to where he wants it to be  And, the 337 is one stout MF block.. BUT ... 3 bearing crank..

[Royce]

Someone versed in fluid dynamics could probably created a pressure vs flow graph to estimate the point of diminishing returns. The import guys do 40 lb , but that's with a turbo..  A screw or centrifugal type blower should not heat up the air as bad as a rootes type

[frnkeore]

I would give Ted Eaton a call. He is very innovative and has some real experience with the 239 FH. I don't know if he has ever worked with the 337 though but, he would be the first one that I would ask about this.

https://www.eatonbalancing.com

[gt350hr]

  Hemi Joel,
     The problem with a flat head is the lack of separation between the valve area and the bore. This creates allot of "chamber volume" so to speak. Obviously "any" combustion that isn't directly "on" the piston is wasted energy. Please consider a "high wall , dished " piston design. By that I mean one that comes "above" the deck and within about .060-.080 of actually hitting the head. Keep following me as it's tough when you can't draw a picture ( well I can't) for you to see.  What I am suggesting is that at or approaching TDC the outer "ring" of the piston coming above the deck would shut off flame travel into the valve area BUT on the "down stroke" after ignition, the piston will scavenge that area , plus it still had some pressurized air trapped, and burn any residual fuel. At the same time , the "round dish" traps "most" of the energy on the piston instead of losing some "sideways" to the valve area. Higher energy pushing on the only movable object. I also feel it would be easier on the head gasket as it wouldn't "see" direct cylinder pressure. I'm pretty comfortable that if I had some dimensions from you, I could make a piston like this.
     Randy
     

[FrozenMerc]

The 337 is very underappreciated from a performance standpoint.  Remember, at the time, the 337 was competing directly against the OHV Cad 331 and was very comparable in power output (154 hp vs 160) and torque (265 ft-lbs vs. 292 ft-lbs).  That said, there is lots of room to improve.  I would start by studying the Harley Davidson KR engine.  Harley coaxed 60+ hp out of 45 ci in order to exploit a loop hole in the flat track rules at the time that gave flatheads a LARGE displacement advantage.  HD achieved this incredible 1.333 hp/ci with only 6:1 compression.  This would be perfect for a highly boosted application.  Imagine a 337 Lincoln with this same hp/ci ratio would produce 450 Hp!  The other place to look would be to get ahold of Rick Schnell up in Anoka.  He has the word's quickest flathead powered dragster.  The "Slider" is a 950 Hp+ Nitro huffing FED.  Obviously Nitromethane and a 4-71 blower will cover up a lot of sins, but I guarantee you Rick has a few flathead tricks up his sleeve.



https://www.youtube.com/watch?v=9-OXWC7Ufv4

[bsprowl]

Many years ago I looked into supercharging the 239.  The problem was getting the exhaust out of  those ports without over heating the engine.  The center siamesed ports seemed to want to boil the coolant.  Yes you could get a lot of combustible air into the engine, but it seemed to hit a early limit because the exhaust gas just couldn't get out. 

Using an early opening valve to push the exhaust out just added to the coolant problem as the mixture wanted to burn in the exhaust port. 

[428 GALAXIE]

Following!!!
I have a Cccp era motorcycle project with 750->900cc plus project.
I tig welded the chambers an re machinined and reshaped the combustion chambers.
I'm not certain that I made all the right moves because way I think the flattie combustion chamber is balancing act between flow and compression ratio.
This kinda freeflowing project with only ambition to make as much my own engine parts:stroker crank ,rods,cam,etc.
Will it ever run probably not but if it will it will see some flat track action

[WConley]

Bob Sprowl nailed a really important point about the flathead V8 architecture.  I got to spend a bit of time looking at the Flatfire streamliner at Bonneville a while back.  They had the reversed ports and handled all induction / exhaust in the valley.  This eliminated the cooling issue.  Read here:

http://www.flatfire.com/flatfire2.htm      Very cool engine!

Even early stock engines had cooling problems because of the way the exhaust was run.  This will most likely be the big power bottleneck if you want to run hard for more than a few seconds. 

[cjshaker]

What I am suggesting is that at or approaching TDC the outer "ring" of the piston coming above the deck would shut off flame travel into the valve area BUT on the "down stroke" after ignition, the piston will scavenge that area , plus it still had some pressurized air trapped, and burn any residual fuel. At the same time , the "round dish" traps "most" of the energy on the piston instead of losing some "sideways" to the valve area. Higher energy pushing on the only movable object. I also feel it would be easier on the head gasket as it wouldn't "see" direct cylinder pressure. I'm pretty comfortable that if I had some dimensions from you, I could make a piston like this.
     Randy

I'd respectfully have to disagree with some of this. I don't believe that any part of the piston that isolates the valve area is going to help performance in a flathead. It will only hinder flow and exhaust functions. And I highly doubt that you'll "trap" anything above the piston. Pressure always finds the escape route, and the only thing that would be trapped would be spent combustion gasses, which just dilutes the incoming charge. Another thing, plugs on flatheads are always centered over the valves, so a piston that traps or isolates that area will hurt power in a major way and create all sorts of flame front issues. Sure, the plug can be moved to center over the piston, but Ford did it the way they did for a reason, and I'm guessing that would lead to other issues in regards to burn characteristics. Starting the burn over the piston sounds good, but as the piston starts on its way down, the burn front would be working its way into the valve area. So starting the burn in the valve area prevents those issues. It would be easy enough to double tap heads to try each spot and see what works best, but I'd bet it's location was not just a best guess, even back in the day.

One last thing, later flatheads (24 stud, and I believe the Lincoln engine has a couple more) have 8 studs for each cylinder. That's a LOT of clamping force...more than Top Fuel or any other type of engine that I know of, so boost and head gaskets should not be an issue as long as the head is thick enough, and the gasket is correct for the application. This is one area where the flathead shines! Of course all that pressure is also exerted to the lower end, so the 3 mains becomes the limiting factor, but not the heads or head gaskets. Old head gasket failures were almost always related to overheating.

And yes, Flatheads used to have overheating issues, and yes, much of it is centered around the exhaust ports, particularly from the siamesed center ports, but modern water pumps and better radiators have pretty much eliminated those issues with modern builds.

I recently spoke with the owner of this car about this subject. He can drive this car anywhere, in any temps, and it never overheats or gets hot. These cars have very limited space for extra cooling capacity when it comes to radiators, but good tuning, modern pumps and a modern radiator have made it a non-issue. That may not be the case on a max boosted build, but I'm not sure extended street use is the goal here.

[gt350hr]

    Doug ,
     I am sorry I forgot about the spark plug placement on a flat head V8. I was thinking in terms of the Kohler stuff I had done extensive work with where the plug WAS over the piston where it should be. The dome + dish did work there.
"Dual plugs" have been used on the "Flatfire" and other cutting edge flatties. Lighting the spark in the valve area wastes allot of energy before it moves the piston , though the down stroke does pull the "fire" into the cylinder with it.
   My apologies for misleading anyone.
   Randy

[Heo]

A thing i thought about a flathead, How would it be with a popup
piston and a deeper chamber abow the cyl to get better flow without relieving
the block.

[cjshaker]

Randy, no need for an apology. I don't think you were misleading anyone by your idea, because Joel is talking about a custom head, so spark plugs can be placed wherever they're desired.

There are certain design limitations for any flathead engine. I wonder (just bench racing here), if 2 plugs would create 2 flame fronts? That would be a bad thing. If the plugs were side by side, it wouldn't be an issue, but spaced apart (one over the valves, one over the piston) it may become an issue. Just something to think about.

Edit to add that even the lowly little Briggs and Stratton flatheads placed the spark plugs over the valves. I'm sure that's not just a coincidence.

A thing i thought about a flathead, How would it be with a popup
piston and a deeper chamber abow the cyl to get better flow without relieving
the block.

Heo, domes are known to be a problem with flame travel, so I'm not sure how well that would work out. Plus, you'd have to make the head really thick to retain the strength over the piston, especially with boost. Then there's the issue with adding more head volume over the valves. This is the area that needs the most help in promoting flow from the valves, so I don't believe a dome over the piston would help much in terms of flow. Like Randy said, that area around the valves is basically dead air space, and cylinder pressure in that area doesn't contribute to any force being transmitted to the piston on the power stroke. I'd bet that there would be some advantage to your idea, but that you'd quickly reach a point of negative returns with the added volume, and no way to compress it.

If you look at the picture of the head that I posted earlier, you can see it's been opened up a bit to promote flow. Very similar to what you're suggesting. But I think the things I mentioned earlier might make it more of a problem than a solution. Again, walking that fine line between 'help' and 'hurt' is what making power is all about. Back in the day, there were probably 30 or more manufacturers that produced heads....at least. There may be a reason that nobody ever took that design and built upon it. Like I said, it's the only head I've ever seen made that way, and I've seen quite a few flathead heads.