some of you guys on here have been talking about building he v12s for power, and I just found this picture on google that you might like

 

interesting..
removes the "swirl" porting from the exhaust port, improves exhaust outflow, and slightly lowers the CR
Is there any report on what difference this made?

 

not that I could find, but im sure this would make a world of difference if you were stroking and using big cams.


Im debating doing this to my extra set of heads maybe for my next project.

 

If any of you are interested in making serious power, I have a pair of bare heads made for the group 44 race teams. Supposedly, there were only 20 sets cast. I spoke with Lanky Foushee personally prior to his passing. He said that these heads could easily produce 600HP in streetable form. Said the biggest problem would be making them quiet enough. Said they made the v12 extemely loud. Told me that the forces that be, used that as thier excuse to outlaw thier use. He felt it was a ruse to keep them from kicking @$$.

 

Pictures needed I am extremely interested

 

Gotta wonder how much that lowers the CR.

 

It appears that the electrode on the spark plug is still partly shrouded. I wonder if there would be anything to gain by peeling back the extra material around the spark plug (marked in red, in the comparison photo below), so that the plug fires directly into the combustion chamber, rather than in a shrouded alcove.

 

Porting HE heads is quite an art and it is (I have read) not easy to do. The most important bit of the combustion chamber is in the HE head and it is the bit the plug is pointing into. As the piston rises, the mixture that has entered via the inlet valve (the valve not next to the plug) is squirted into this chamber and is set fire to in it. This enables a leaner than normal mixture to be lit as the mixture is all squashed together in a small volume, thus providing a localised mixture rich enough to light. Once this initial charge is lit, the weaker mixture present elsewhere (not much) will burn also. This is how the HE manages such good part-throttle economy - relatively speaking!

Removing this specially designed combustion area will partially defeat the designed intention. Depending upon how radical the metal removal is, it might defeat it. The tuning problem with the HE head is getting bigger valves into it in such a way as to allow better flow at high revs, as in over 5000 rpm. Because of the 'combustion hole' idea, even if bigger valves are installed, the sides of the hole still defeat better flow as they shroud the exit of gasses. That is the reason that all the serious racing XJSs, including TWR's ETCC-winning cars used the previous 'flat head' design of heads as used on all the pre HE V12 versions. This head could be far more easily modified to accept bigger valves and thus better high RPM flow and consequent cylinder filling, as the valves were not as shrouded as the HE valves are. Of course, effectively changing the HE head by removing so much metal it resembles a flat-head is somewhat pointless.

So I have some doubts (always open to correction mind) about what this sort of mod will actually achieve.

Greg

 

The he heads suffer mostly from exhaust restriction. The intake valve is very similar to the pre he. Which is what I believe they were trying to achieve here. Its also why I would imagine a proper set of headers that scavanged really well would seriously benifit the he motors. Because if the port suffers you would want to increase the flow in the headers to help make up for it.

This is what I've learned from my owneexperience and talking to chad bolles

 

Reworked HE head would not be ideal. There is really no way to get all the cylinders the same with out a CNC machine. So you'd end up with 12 unique compression ratios and 12 different intake flow rates. This would be nearly impossible to fuel properly and make good power. A pre-he head smoothed with a D shaded combustion chamber in the piston would be consistent and ideal.

 

Quite true, it is the restricted flow out of the exhaust port (the one in the 'combustion hole') that is the larger problem. To get better high RPM flow the hole has to go to enable the exhaust gas to get round the valve and out of the exhaust port.

So it would seem, but if the exhaust valve 'hole' is removed to the extent that the mid rev range lean burn characteristic is lost, then there does not seem to be any reason not to replace the head with the previous flat version, which will develop far more high RPM power far more easily than the HE head ever will.

This has got to be true, but an exhaust manifold designed by a genius and fabricated by angels will still be at best an improvment, rather than a solution, to the high RPM flow difficulties of the HE design.

FWIW, my view on all this is: outside racing, when was the last time anyone here took their engine above 5,500 RPM, and if so, how frequently do they do it? Up to this point the HE engine works well in a road car. NONE of this is to say that I am anything but full of admiration for all you are doing, CDK. If I were younger and richer, I would be doing it too (though not as well as you, that's for sure)! Just that IMO a good HE engine is a great road driver's tool and gives MPG that is STILL comparable with quite a number of performance cars still being made and sold. If you look at real world MPG on big petrol engines Astons, Range Rovers, Maseratis etc etc, 18 MPG (UK gallons) on my XJS is not at all bad considering, nor is the performance.

Greg

 

100% true, and exactly what the TWR XJS racing engine guru, Mr. A Scott, said in his book.

Greg

 

If you do have a CNC mill, is there a pattern/shape that does make the head perform?

 

Ummm...that would be me.

I make it a point to do it at least once each time I drive (road and traffic conditions allowing). It's amazing how much these engines wake up when they're taken above 4500rpm. They become a completely different animal, and begin to live up to the V12 myth which we all perpetuate, and, that a few of us aggressively and blindly chase (no need to name names, we know who we are).

 

My thinking is that in 10 years nobody will be able to find flathead heads anymore. If someone could come up with a way to make properly set up heheads for power. It would solve the pproblem of he heads and there scarcity.
I believe the company that did this head did it with a cnc. It appears to be how they do everything else.

Also I do have an ECU that does allow Individual adjustment of the fuel and spark to each cylinder. So it could be a solution or atleast a remedy to slight valuations in the combustion chamber

 

All I need is the design, CNC'ing the heads is not a problem, or is this a trial and error sort of thing?

 

I posted pics of my pair of Group 44 heads in photos. You have to enlarge the pics, and compare the size of the intake ports, the shape of the exhaust ports, and the distance between the valves to get a idea of how radically different these heads are. The valve openings are much larger as well

 

Yes I can see what you mean, they are different indeed. Thanks for posting the pics. Out of interest what are you planning on doing with the heads?

Back to the HE heads, its got me interested now on how they can be enhanced, when I get the chance Ill go and have a chat to a motor re-builder friend of mine, just to pick his brains a little.

 

i'm with JagZ on this one ,i rarely go past 4000rpm( i like my license), but when it goes above 4250-4500rpm you can feel the torque curve move up, of course speeds are way over the limits!
wish i had a real long stroke!! (stick to the subject).

question? why would jag build such an odd situation,5.3L, when only 1-2% drivers would use it, in that rpm range?

and i'm betting those GRP44 heads were the so called California heads, cast and machined in Cali. after Tullius talked with a california Hot rod guy about factory heads.

 

Ron,

I have a bit of immunity when it comes to speeding tickets (at least in certain police jurisdictions), because, my wife is a cop

I think superchargedtr6 may have a different story to tell concerning the origin of those heads.