I appreciate all your work here! I will likely never live long enough to be able to buy one of these, but since you asked for input. If building a performance head I would try and move the intake valve away from the cylinder wall and go with a slightly larger intake valve. Maybe 1.8" & a slightly smaller exhaust valve. The last race heads that Mike did had 1.76 & 1.46 valves in them. At least mine did. And the Slant 6's intake to exhaust flow ratio is higher than a lot of engines. So the smaller exhaust valve should not hurt much at all, and could be figured into the camshaft choice. With a bigger intake valve and a nice size overbore(.100) it should be better able to fill the cylinder.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I always thought a 1.75" intake and a stock exhaust would be good for a nitrous motor to keep the seats from cracking between the valves.

LS-1 Chevy has 2.0 and 1.5 valves. Works pretty good for them.

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Official Cookie and Mater Tormentor.

To follow up on my thoughts of a head that most folks could use.
The swirl port seems to be a port shape that starts the mixture flowing in the best direction.
If that best direction is for emissions, fuel economy or performance, I would guess a it's a compromise.
Some swirl port could be designed to direct the flow, but you would need a dyno and a flow bench.
The Heart shaped chamber is what I really meant to include i the design.
This I think could be modeled in your head design.
Here is Edelbrocks Victor shape for a small block LA engine.

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Hyper_pak

Port swirl has to do with the directional shape that the intake charge takes as it passes by the intake valve and moves into and through out the cylinder.

Getting the swirl, and actually some combustion engineers can make a case for tumble, to the desired value takes: math data and extensive computer modeling. And then actual engine testing to confirm that the assumptions made were correct, or not.


As a custom head designer, you should not worry much over port swirl, and to a good extent, even port flow.
The best you can do is provide ports with: minimum obstructions (thin valve guides & stems and a straight line of sight shot to the back of the valves) and maximum opportunity (large to decent size valve openings and thick and consistent walls around the port bowl) so persons purchasing the heads can make their own one-off port swirl-port flow experiments. Someone is bound to find the magic shape. You just need to provide a robust structure for them to work within.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Lou, you may or may not remember the aluminum inline Chevy 6 cylinder race head I brought to one of Slant banquets a few years back that I manufactured at that time. That cylinder head was a U-flow design and one identical to it was CNC ported by Mike Kirby at Sissell Automotive and it flowed 400 CFM, to give you an idea of its potential. So the Crossflow vs. U-Flow debate is a never ending one. What decades of testing has shown is that one doesn't really have any HP potential benefit over the other. In an inline engine, a U-Flow can make the engine compartment more cramped, but you don't really gain or lose anything from having a U-Flow design. From a production standpoint, it's an easy way to have the intake heated by being on the same side as the exhaust, instead of having to run some form of piping from the other side of the engine over to the intake. Pros and cons for sure, but one having a HP advantage isn't one of them.

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There's no such thing as too much cam....only not enough engine!

100% correct. I challenged anybody to prove to Me why a "crossflow" is better on FABO, crickets. The only real advantage in a race situation is heat isolation of the intake tract, and Hemi/4 valve in-line scavenge velocity...as long as You don't care how much fuel goes right out the exhaust.
The "U" tract actually helps encourage & maintain chamber/cylinder swirl being generated by the inlet in the same direction of rotation on exhaust. If You have an actual Squish piston/head relationship, it can disrupt this greatly if this dynamic is not considered & accommodated, one of many reasons why often flat top pistons with a superior head chamber are the best power makers.

Hmmm. Thanks for these points. I'll think more about this, but it seems correct to me.

Lou

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Home of Slant6-powered fun machines since 1988

It doesn't make much sense to develop a cross full head when it won't fit the chassis.

I think the U-flow head is the best overall. I think the straight intake ports would be raised, but we could probably still use the OEM type intakes - with a spacer to replace the triangle washer. Ports wouldn't be raised a lot, but maybe a remote air cleaner might be necessary for some hood clearance with carbs.

Crossflow might work best if the intake was on the passenger side. Intake could be a "candy cane" J-shape that looped over the valve cover (too costly) The classic Jag XK6 4.2 has the intake about where the distributor on the slant six is - not a lot of space, but it did okay in a sedan that weighs about the same as a Crown Vic. Making cross-flow work with the pushrods is the trick. I'm a fan of the Toyota T series , they splay the pushrods to the inter-bore casting area so the ports go right up the middle of the cylinder. Its really a '50s Mopar influenced design. The aftermarket 3TC (1.8 liter) valve sizing would work best on the 170 slant six - but be better than what the 225 has. A "flaw" of the T series is it is a classic bowl shaped "hemi" with little quench, but it looks cool but pistons have a slight dome - that would be a cost factor.

With the U-flow head the OEM valve covers could be used. It would still look like a slant six. Because of bottem end limitations it is not going to be a high rpm motor. Even the Jag XK6 E-type which won many races in the 1950s had a similar rpm limit as the 225 - unless they spend big bucks on titanium rods and billet cranks, even then its strength was torque. Its like a truck motor with dual overhead cams. The E-type 3.8 wit the hemi chambers has a 4.17 in stroke, it could not rev super high stock. The 4.2 that you're likely to see in salvage yards also has a 4.17-inch stroke. On Jay Leno's show a man had a e-type that was pushing 400 horsepower on the street, but it was big bucks and he kind of babied it so as to not destroy it. I'd say that an improved slant six head could benefit the racers, but na 300 hp on the street would still be high expectations.

With electrification being pushed, the affordable car market in 2023 is doomed. In the low priced segment even the Toyota Yaris is not cheap anymore. Honda recently recently reported a 67 percent decline in Civic sales - for a number of reasons, mostly affordability(inflation) and supply chain issues. We should keep talking up the nastalgia head project because, like it or not the new OEM gasoline v8 era appears to be ending. The aftermarket could favor oddball choices like the slant six (not oddball for us). The SEMA market hasn't looked favorably on the slant six, but that could change. Maybe the Studebaker guys would finally get the new v8 head they have wanted for 50 years.

I'd like to see an aluminum Cylinder head in the drool tube design ( for no specific reason but I like the drool tube design better ) with improved runners and optimized combustion chamber. Even though it would be U-flow you would have the stuff that is already made aftermarket that would be usable. I think optimizing the Camshaft's lift/duration, LSA etc to exploit the U-flow is the key to the whole shebang.

Very true...! Often people overlook the fact that when specialty cylinder heads are discussed, the head is a small part of the total package. Because the passenger side compartment is so cramped, there is no existing intake that can work on that side if you choose that to be the intake side. And no available exhaust products that will either. That means, no Dutra Duals, no universal header tubing kit will work either, even if the head is made with the same bolt pattern as the stock exhaust....

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There's no such thing as too much cam....only not enough engine!

Considering no one has wanted to go to the trouble and expense to build (or agree to buy) an alum cyl head that would bolt up all the stock parts, I cannot see enough people wanting a cross-flow head. From my studies involving real-world head flows on Slant 6 racecars and street cars, a stock design cylinder head could easily flow 30-40% more than a stocker, which would be a HUGE gain in HP for anyone who would want to bolt one on.

Lou

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Home of Slant6-powered fun machines since 1988

Correct Lou, keeping it simple will broaden the market for potential buyers and minimizing the need to create additional specialty companion pieces to complete the change over. I think a cylinder head with an increase in flow as you mentioned is very doable, while retaining the usage of currently available intakes, exhaust and etc....

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There's no such thing as too much cam....only not enough engine!

It could be even worse
Was it Chevy or Ford that had one version of their inline 6 that had the head and intake manifold cast together as 1 integrated casting? I'd hate to see how much casting flash and such would be left within that setup that can't be accessed to port and polish? At least our engines have both manifolds and the head as 3 separate parts so we can get inside and at least make improvements, huh?

Ford 170 and 200 I think. Maybe the 250 also? I think they did get an aluminum head for their 250.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6