Ron
I agree 100% with you, for a usable car I wouldn't want all my power up around the 8k mark, like you said I too am rarely over 4k. Correct me if I'm wrong hasn't most of that got to do with the cam's, I can see improving the head will be an improvement across the board not just at top end.

 

Cams are an important part of engines characteristic but so is the intake size, intake length and exhaust port shapes but to a lesser degree. It all has to work together. Generally speaking, a large intake port will have a port lower velocity for any given RPM. If the intake charge is too slow you'll get poor air fuel mixing and poor charge velocity which all adds up to poor low RPM performance. Its hard to explain in writing but when the intake is size correctly the intake charge is still moving right before the valve begins open again and accelerates the intake charge again. If the port is too large the intake charge will stall and the too much of the piston motion will be spent re-accelerating the intake charge and not on cylinder filling.

Case in point...Chevrolet has made a larger number of iterations of 350 CI engine over the years, the power has varied from a low of about 140 HP to a peak of about 300. All with 1.94 inch intake valves and cams that are with in 8 degrees of each other, counter intuitively the 300 HP version had one of the smaller cams. The major difference is the intake port shape and intake length.

One anecdote I've discussed with Mark Anderson from 928 International involved a set of heads he had worked for his GT something race car. The flow was much improved on the flow bench but on the track there was no improvement at all.

I see this all the time in the Chevy circles. Guys get huge heads, then port them even larger, install a large intake manifold and cam, 3 inch dual exhaust then complain the engine has no torque or power. Typically... it's got no torque because the cam is too big, the port / intake velocity is poor and it makes no power because mega bucks wasn't spent on a valve train that can work at 7500 RPM or a displacement increasing stroker kit.

One thing I often hear is that an engine is just an air pump, this is not really an ideal way to think about it. Those who think this way tend to over size the wrong parts. It's more constructive to think of an engine more like a pipe organ that has to be tuned.

 

The heads I posted were part of 20 pair that were cast for Group 44. Supposedly, Jaguar spent a couple of million on the development of these.

I have no idea what to do with them now. I bought them with the intention of building a 6.0 street screamer for my 71 XKE. A turn of financial events has me no longer owning the E type. Ideally, I would like to sell them (I think), but I gave a fortune for these, knowing that it was a once in a lifetime event.

 

Thanks for posting the head pics. These look to me to be basically a flat head design from their appearance. Presumably the chamber was in the piston crowns. Certainly they seem to be nothing like an HE head from the combustion chamber in the head point of view.

Greg

 

hey,superchargedtr6, could you repost those pix or direct me to the 1st pix.

thanks ron

 

comparing the size of the valves V12 and XKE 4.2. inlet 35mm-42mm. forgot to measure exhaust

 

process

 

The photos are posted in photobucket superchargedtr61's Library | Photobucket

and <iframe width="480" height="360" src="http://s42.photobucket.com/user/superchargedtr61/embed/slideshow/"></iframe>

 

Btw, I am a builder, so I read tape measures, not micrometers. The intake ports on these Group 44 heads measure 1 5/8". The stock set of flatheads I have, the intake and exhaust ports are far smaller.

 

looks like a nice set of performance heads, they will be valuable to someone interested in a hi-output engine V12 Jag!

and if they do sell i would deffinatly recomend the larger tappets for a high lift cam arraingment.

the oversize valves in my present V12 are 3mm larger than stock, and i fitted them into ported and matched stock pre-he heads.

bought them from Lanky Fooshee, around 1994. from left over inventory.

it comes to mind that you live somewhat close to Grp44 original race shop, so stuff may float around the local markets/swap meets.

thanks for pix, those heads must be Tullius pieces(i think), a recent interview(2012-13) he spoke about heads being cast and machined in California, by a race business!

 

and donno if anyone noticed sjsv12, uses an unusual porting tool ,never seen anything like that!

could really hog out the port with a set of those,(and keep port round), and it looks like they can be resharpened.

veerry interesting!

 

They are interesting and seem like the right tool for a European style round port. I think we don't see tools like often here in 'merica because since about the late 40's domestic performance intake ports have been square.

 

As mentioned by Jagzilla, I bet this puts a significant dent in the compression ratio... enough to make me not want to do it!

Also, is it just me, or is this porting example entirely backwards? It seems like all of the ported heads I ever see are, well... "ported." The intake and exhaust ports and runners are optimized... not the combustion chamber. Is that because newer combustion chambers are already optimized as-cast? What about the ports & runners on the Jaguar heads? There has to be some gains there, too.

This does not really relate to my point, but I had to repeat it because it is so true. However, I feel like this doesn't relate so much to the Jaguar engines because there isn't a plethora of aftermarket big valves, huge cams, high port volume heads, etc.

 

Yes, the heart shape combustion chamber is now thought to be ideal for 2 valve wedge head motors. There probably is enough material on an HE head to replicate that profile with a CNC but it still wouldn't be a wedge though. Only testing could prove if it works or not. Perhaps someone with the time and resources will try it someday.

Not Jag related but when I was building my SBC with Trickflow heads I was instructed by Trickflow tech support to use a specific piston profile that matched the head. The combustion chamber has the heart shape to promote swirl and flow. It was CNC'd that way so the piston has to match to get the right squish on the flat part of the chamber. The squish is what quells detonation. The heart shape is an LS engine development technology that found is way back to the earlier engines giving them a new lease on life and a 50HP bump.

more about it here.
Chevy LS - LS6 Performance - Chris Endres - Google Books

 

a round port,or conduit passage, will flow more air for its cross sectional area than any square passage, and does not take up as much space in an engine.

now lets be fair here, USA engines(especially LS ) has done miracles with what they had to work with(not counting cathedral port,it aint square.



the Russian guys tools are unique, but he did remove some metal in the ports(as i see it),that took away some induced swirl in the bowl area just before the the valve seat.

could be corrected by welding in a small bump or deflection wall swirl shaped.
(i tried port reshaping back 1964-65, using,then new Epoxy, worked OK but as time went on pieces broke away,might work better with improved compounds.

look what the GM Vortec ports did for SBC! great improvment over the old shapes, like the famous Fuelie heads of yore, they are a joke by todays ideas.

and when was the last time you seen an F1 engine with square ports? really!

i have never seen a 4 valve chambered engine with square pts, yes oval but a modified round port, but turns into full round with a swirl in the valve pocket!

anyway we can beat this topic to hell, do what works for you,just do it.

porting debates have been going on since they invented an engine.

 

Hi there did you sell the heads I wo love them email me jockeyb @rocketmail.com QUOTE=superchargedtr6;1017312]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 @$$.[/QUOTE]

 

I have commited to sell the heads to a fellow forum member. His plans are to copy the heads, and be able to sell them. I hope he is successful

 

I would be very i terested in a set of these heads for my XJS race car. Any ideas of the cost?

 

excerpt from Bob Tullius info about those heads!

 

It reminds me of all the modified A-Series heads from years ago.