V12 heads

E

elcid

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Anybody around here that have done some "serious" work on the heads of an V12 HE engine?

My question is how much can you port the inlet and outlet canals from stock?
It seems that they're very choked down from originally (gasket has around 1 cm bigger diameter than the canals).

Regards
 
Hi Elcid and welcome to TorqueCars. If you get it done on a flow bench you will see where the optimum gains are. I'm sure the engine can also cope with bigger valves.

If you are doing this on a DIY basis it would be worth doing it in stages of say 2.5 - 3 mm at a time. It would definately be worth getting the whole head off and gas flowed properly. Theres a lot of power in them v12's just waiting to be tapped.

Are you planning to increase the intake pipe diameter - you might just move the bottleneck from the ports to another part of the intake. Take the area of a cross section of the intake and compare this to the area of the intake port.
 
Hey Waynne. Thanks for your time and answer.

Sorry to disappoint you a little. Don't think to tune it up - it's powerful enough as it is.
I started to wonder when i had the manifold off for some vac sealing and other maintenance. Saw the choking (or seemd like) and the rough innards on the manifold.

Mmmm. Have to agree on that. Doesn't seem smart to have the heads attached to the engine when drilling out a lot of material ;).

Good advice about flow testing.


Regards.
 
The last thing you want is the metal particles getting into the engine and oil. It will act like sandpaper and wear away the surfaces.

The bonus is that with the removal of the restriction you will make the engine more efficient therefore you can enjoy more power and better economy.

A 3 or 5 angle valve seat grind does wonders for economy/power.
 
mmm. True. Cleanliness is the word.

Have to admit that the V12 would benefit for that kind of tuning. Running cleaner and give a lot of extra punch - most certainly. It's quite asthmatic as it is (a regular two litre engine today has bigger air filter intake than what's original on the jag).

Have been fantasising about getting the potential out of the engine but it's far down the priority list (the electrical is on the top, upholstery and redo the paintjob comes first).

thanks waynne

Regards
 
Sound like your doing a complete restoration? Take lots of pics - I love to see before and after photos. ;)
 
No problem Waynne.

You'll get a ton of photos. I take them as i work on the car anyway to document what I have done on it.

It's in pretty good condition but I'm not satisfied with the paint job and upholstery. Planning on paint job this winter and the interior next winter.

Who knows what will happen after that ;) You tempted me there with that suggestion.
 
Hello :-D

A small update on the jag. Changed out the old asthmatic exhaust system on it. Now it's stainless steel 2,5 inch until the rear axle then reduced to 2 inch the rest of the way. Now it has only one silencer on each side. Hehehe :) full flow system in stainless mounted on the car for 700 pounds.

It's undescribable. When the kitten roars now, my hair stands straight up
 
Sweet - I'd love to hear that. Maybe you could put a video up on Youtube, possibly? Its amazing how much difference a nice sounding exhaust makes to the character of the car.

:lol: A kitten - wouldn't like to meet your idea of a Tiger then?
 
Hehehe ;).

Will call it a tiger if it get unchoked again and put back into the condition it was ment to be (back to how the R dept. had constructed it).

If I'm able to borrow some good recording equipment I'll put an mp3 out on youtube
 
hehe :)

Had a driver on the jag today since I was drunk. He didn't want to go faster than 260 kmh but the car CAN go faster. Now, I'm interested in more... Love this vinter - a new v12 is on my christmas list. cheers
 
Nahh. A little more sober than that I'm afraid.

One valve guide or two are worn. The spark plugs needs to be changed. Might give the third and most valid reason to swap the engine:
Jaguar built in a heat exchanger into the oil tray (which the coolant meant for the engine heats/cools the oil). The only thing separating the coolant from the oil is a 23 year old rubber gasket.

It's easier to buy a new v12 and work on that one and then swap engines instead of pulling the old, do the work and then put it back into the car.
 
hello, just been reading the thread and would like to add on a little info
HE heads are not the easiest to modify ( mainly due to the pre swirl chamber ) so oversize valves are impossible to fit without loosing the head swirl chamber . you can still enlarge ,polish and cc the inlets plus re profile the valve stem collet retainers . exhaust side isnt a major problem as its is at high pressue and will flow easier than inlet .
the big advantage of the HE is they can run much higher compression than pre HE . i would recommend an early v12 engine as a base for modifications if your serious , the cheapest way to liberate horses is a manual gearbox ( the difference is remarkable ) lots of people do the conversion kits or build your own
good luck with the project
 
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