V8 Center Port Problems

[JAKEFORD]

From what I have been reading on this fine forum, the center port is one of the weaknesses of the Ford V8. Some of the models of running engines have eliminated the problem by exhausting from the top intake plane. This is because they could not machine the exhaust port passages in the block.

I have seen examples of switching the intake and exhaust ports via the camshaft so that the exhaust could blow out the top of the intake plane. This was done on full size engines.

This engine has been around for a lot of years and no one has come up with a solution to the hot center port exhaust. It has been reported that this is the cause on block cracking and other performance problems.

What say you?

[Capt Kirk]

My head just exploded!

[ford38v8]

from what i understand, switching intake for exhaust works well for the exhaust, but creates worse problems for the intake than the exhaust originally had.

[Pete]

"This engine has been around for a lot of years and no one has come up with a solution to the hot center port exhaust. It has been reported that this is the cause on block cracking and other performance problems."

I guess there are a bunch of us that just never heard these rumors.
A conventional port configuration, naturally aspirated, flathead Ford is capable of making over 400 hp on straight nitro.

[Mike B]

I've seen pics of the LSR cars, exhaust up the top, intake and carb(s) hanging off the side, I think the consensus is it was an exercise in futility, or else everyone would be doing it to get more MPH's.

[Ol' Ron]

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The center exhaust port handles the exhaust from one cylinder at time, so the port actually flows better than the end ports. Yes it gets hotter: however, I think the block is designed to handle that, or it would have caused more trouble at an earler date. As for racing, I think it depends on the type of racing. For short track, not an issue. For blown , or fuel, maybe alittle bit.

[40 Deluxe]

Originally Posted by Pete

"This engine has been around for a lot of years and no one has come up with a solution to the hot center port exhaust. It has been reported that this is the cause on block cracking and other performance problems."

I guess there are a bunch of us that just never heard these rumors.
A conventional port configuration, naturally aspirated, flathead Ford is capable of making over 400 hp on straight nitro.

Pete, How long will a flathead last at that power level? This is assuming that the builder/tuner is a knowledgeable individual.

[Bluebell]

1320feet??????

[Lawrie]

Our dragster does not use nitro ,but we do use a 4-71 blower,we run it about every four weeks at our local strip,three or four years with this setup, no cracked block, no buggered bearings still will run around 140 mph most meets.
Lawrie

[Tom Walker]

I think a shared exhaust port on a four stroke/cycle engine is only really a problem when you want to use a tuned exhaust system, which only really works on a head with an individual port for each cylinder. And even then it depends on the firing order. But with most V8s which have a shared centre port, the port has to deal with 2 pulses per crank rev, whereas the others obviously only have one per rev, and those two pulses are not evenly spaced in that one rev. There is often only one pulse separating them. This unevenness makes it impossible to effectively tune the header for the centre port.

All of this matters not one jot on your cooking flattie. In fact it is probably the reason they sound so luvly!

[rotorwrench]

Cadillac used the exhaust out the top on their flathead V8 and it worked OK but it was designed that way. They were quick to go overhead valve though so that tells a story in itself.

Most Ford V8 engines that experience cracks in the center deck likely had an overheating problem that went on just a little too long. A lot of folks didn't notice the problem until steam was gushing out from under the hood. There were no idiot lights back then.

[SofaKing]

Has anyone tried this stuff? I understand the general principle is to inhibit heat absorption into the piston top or parent metal. It might help keep exhaust heat from transferring into the port walls.
I had been wanting to try it, along with another product they have that is supposed to improve heat transfer, when I was playing with air cooled motorcycle engines.


http://www.cerakotehightemp.com/fini...Q/piston-coat/

[Henry Floored]

Guys I don't think exhaust porting on the Flathead Ford is that big of a problem.

When that piston goes up on the exhaust stroke it's gonna slam the spent gases outta the cylinder. I concentrate on the end exhaust port entrances and exits. Those four locations are where you find sharp turns and flow limiting passage sizes.

In the center there is plenty if not too much exhaust port volume. The problem there is no structure to direct flow out the exhaust port. The heat riser should be filled to a point where it forms a curved back wall in the valve pocket area. A little thin tongue extending into the entrance of the center port would be icing on the cake.


In a non- compound actuated valve in block V engine like the Flathead Ford, (an example of a compound actuated valve in block V engine would be a Lycoming/Cord V8) the limit to airflow is all intake. A lot more intake flow has to occur, in my opinion, before we over tax the exhaust side.

To dramatically improve airflow in a conventional valve in block engine the entrance to the valve pocket or at least the shape of the port leading to the valve pocket could use a lot of improvement. The removal of abrupt changes of direction in the intake path is the first step to greater volumetric efficiency.

The next step and just as important is the relationship in valve to piston location. In the stock configuration we are almost literally asking the intake charge to "bounce" or at least deflect off an iron wall then head down into the cylinder.

If we want to move Flathead Ford airflow to the point where wholesale changes to exhaust porting become necessary I believe the stuff I mentioned need to be revisited.

[Pete]

Originally Posted by 40 Deluxe

Pete, How long will a flathead last at that power level? This is assuming that the builder/tuner is a knowledgeable individual.

Several seasons.
It is usually torn down and checked after a meet.

[V12Bill]

A few years back some one built a flat head with intake and exhaust ports both on the intake plane. The engine ran at Bonneville and set a new land speed record for flat heads. There were many other modifications of course. I am surprised that no one has mentioned this engine.

[1952henry]

Originally Posted by rotorwrench

Cadillac used the exhaust out the top on their flathead V8 and it worked OK but it was designed that way. They were quick to go overhead valve though so that tells a story in itself.

Most Ford V8 engines that experience cracks in the center deck likely had an overheating problem that went on just a little too long. A lot of folks didn't notice the problem until steam was gushing out from under the hood. There were no idiot lights back then.

Not true about Cadillac being "quick to go overhead". They kept the flathead v8 for many years, 1914-1949, if I'm not mistaken. The early thirties v16 was ohv, but came back in the late thirties as a flathead.

[Henry Floored]

Having not been around in the 30's and 40's I have to ask, was the Caddy and/or LaSalle ever considered a high performance engine?

I have no intention of disparaging the GM engines I just am still doubtful that top exhaust ports add that much power.

Now I do agree that longer internal ports add heat but Ford seemed to have that under control.

Maybe the ultimate solution would have been 4 exhaust ports with 2 running between the outer cylinders. That kind of reshuffling could have made more room for 5 main bearing webs. It probably would have also resulted in higher cost.

[rotorwrench]

Maybe sooner is the word I should have used. They certainly were sooner than FoMoCo. When Ford finaly went overhead, it was mostly for trucks.

[Henry Floored]

Originally Posted by rotorwrench

Maybe sooner is the word I should have used. They certainly were sooner than FoMoCo. When Ford finaly went overhead, it was mostly for trucks.

I heard Ford had an OHV V8 at least in design and prototype stages as early as 1948.

The limited resources that Ford had, (since they were on the ropes post war) were devoted to the '49 Ford, Merc, and Lincoln car lines instead. In addition I believe Ford felt that their refreshed Flathead was still adequately competitive at least for a few more years.

[Pete]

Originally Posted by Henry Floored

Having not been around in the 30's and 40's I have to ask, was the Caddy and/or LaSalle ever considered a high performance engine?

I have no intention of disparaging the GM engines I just am still doubtful that top exhaust ports add that much power.

Now I do agree that longer internal ports add heat but Ford seemed to have that under control.

Maybe the ultimate solution would have been 4 exhaust ports with 2 running between the outer cylinders. That kind of reshuffling could have made more room for 5 main bearing webs. It probably would have also resulted in higher cost.

There are several teams running flat Cad's at Bonneville.
I am part of one. Our engine is 375 ci and makes 600 hp.
It is in a 38 Chev coupe and has gone 189 mph.