Question - has anyone successfully machined the combustion chambers of the 5.3 HE head to open out the pocketed exhaust valve? The chambers are simmilar to the LS7 except the HE exhaust valve is recessed in relation to the intake.

The 6.0L looks slightly better flowing than the 5.3, but I am sure this can be improved further.

 

it should reduce compression just a touch.

i wonder if it would have any affect on the so called "Fireball" effect. according to several sources its supposed to create a swirling intake vortex. (for members that dont know)

 

i was just wondering this last night, i bet it would create more flow, and where would one go to get this done?

 

i sure wish i STILL had my machine shop,in FL.

no problem doing the chamber , more difficult to make the port & bowl shape.

 

Yes agreed this is why I have been asking around to see if anyone has done this before. With CNC only need to get one right and then the rest are milled in the NC.

The Fireball effect is so the engine can burn lean mixtures at high compression, good for fuel economy.

You still need swirl in the intake to keep the air fuel effectively mixed but I think the tradeoff in opening out the bowl with the increased flow will be much better breathing.

 

HI, warren,, its a bit of a stretch,comparing an LS7 chamber with Jag HE chamber, GM spent many millions on R&D different chamber&port shapes , for the LS series engines!
before finalising the 7.

the LS7 chamber,works in conjunction with the port-bowl shape, the swirl starts in the port &bowl before it reaches the chamber(lotsa flow bench R&D), for one off one would not need CNC, that would be for multiple 1000s of heads, me thinks there wont be many lining up for V12 heads!!hehe

but good food for thought, or just brainstorming,,anyway.

if one put bigger diameter valves it would mask the flow worse, not good.

a much larger bore would help tho.

FYI, the Fireball name comes from the old 1920-1940s Buick chamber, mr, Mays, paid tribute to Henry Buick for his developments, the design was for combustion control for the poor fuels of the era.

just opening the bowl larger,may not produce the results we are looking for, reshaping the bowl,with welding in a swirl dam,seems logical tho,(just thinking here).

let me add here, a compare pre-vs HE, when the HE exh. opens, its is shroudded by the chamber wall and doesnt open down into cylinder bore(that is where we want the air to go), pre valves both open down into the bore, a reasonably good air path(not perfect,the side of bore hinders flow somewhat) but large bore allieviates some.

pre can use larger valves easily, my pre are 1/8" larger diameter than stock, along with bowl blending.

and surface cutting the pre deck(.050 thou.) is like having the valves open .050 more ,win-win. valves go .050 deeper in the bore!!!!

believe me, if HE could be modded for racing,all the big money guys would have used them!

all in all tho,, some have had fair results with HE anyway.

Ron

 

Here in Aus it is almost impossible to buy pre-HE heads, so need to look at the next best thing. What I am talking about is unshrouding the exhaust valve with an angle like the LS heads.

I have spoken to the Australian guru of head design (this guy has done the head development many Bathurst winning cars). His advice is the V12 HE head bowl can be machined to flow better. He would hand flow one bowl run over it with the ARM then his CNC would do the other 11. He has indicated if I budget $2000 that will be more than enough for what I want. I can not buy pre-HE heads for this - by the time I ship them from OS most want over $1500 just for the shipping.

I am not looking to put bigger valves in - just better flow from the exhaust at all valve lifts.

 

Sketch up some designed for us when you know what youre doing!

 

What I am talking about is re-shaping the that chamber to smooth the contors around the exhaust valve, remove the steps and have a gradual radius from the bowl out.

This pic kind of shows but it is hard to mock up in Paint

 

OK warren, looking at the 6L chamber it seems as tho you could bring the wall out to the gasket edge and blend the hard corners of the exhaust recess. (yes it would lower comp.ratio slightly,but acceptable).

examine,the area where the valve comes close to the edge of liner,and maybe chamfer it??

suppers on gotta go!!!!!!!

 

That is exactly what I was thinking - smoothing the hard edges and then polishing.

I am not too worried about the CR as I will either turbo/SC or increase the displacement either way I will need a larger combustion chamber. I have estimated if I go 6.1L (93.1x75mm) the chamber will need to be increased 14cc for a CR of 10.0:1. Or to go 8.5:1 for turbo the chamber will need to be 53cc.

I estimated the 6.0L with CR of 11.5 = chamber 6cc bigger than the 5.3. So I have quite a bit to play with.

I am looking for a stuffed HE head so I do the prototyping - not an easy thing to find.

 

some times in life, one has to make choices that are regretful.

2007, moving from Fl. to Austin, things were changing to fast, i had three(3) complete Jag 12s, one Etype carbed,, and two XJS, all PRE-HE, tried to sell but no responses, so went to local junkyard, and got $75. dollars, for the bunch!

what really hurt was seeing the fork truck driver dumping them into some kind of SHREDDING machine, and hearing them be grinding to scrap. the guy said they get a lot of Jags for scrap value.

OH well, life goes on. aint the 1st time,, but i hope the last.

 

There is 1pre he engine for sale here and the guy wants $800 and being in Melbourne I guess $300 to ship it and 1 6.0l they want nearly $7000 for.

 

i cant even find any 6.0s for sale not even pre he heads

 

one of these days, the XJS's on this forum will be the only ones left in the states...... cant wait.

 

They are still plentiful in the UK. Pre HEs, HEs and 6 litres. There is a 6 litre on UK Ebay now for 600 UKP including gearbox, all looms and ECUs. HEs around 300.

There is also a Forward Engineering specially constructed 6.4 litre made for Lister for sale for 2,400 UKP which bis meant to be very powerful, but it looks a bit tatty in the photos.

A bit cheaper than 7,000 Aussies though!

Greg

 

i would buy a 6.0 for $900 in the blink of an eye, if it didnt cost $2,000 in shipping! lol

 

Yes and it is more expensive to ship to Australia. It cost about the same to ship a whole car as an engine. The are some TWR group C forged cranks for sale in the UK for 200 quid and 500 for shipping.

 

how much is a quid, in american money??

 

Roughly $1.50