[v12-engine] turbo V12,6.0L

V12-Engine
1

Question??

what do you guys think about twin turbos on a stock 6.0L.

and what yrs would be more or less suitable.

lookin for lotsa torque down low, want to stay away from
hi-revs.

YUP, I been thinkin. and learned a lot about 6.0s from
this site.

THX Ron–
Ronbros
daytona fl. / Austin TX., United States
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2

In reply to a message from Ronbros sent Thu 24 Feb 2011:

I personally love the idea
Just waiting on you to post some pics so I can figure out were to
put the turbos.LOL
Nick–
The original message included these comments:

what do you guys think about twin turbos on a stock 6.0L.
and what yrs would be more or less suitable.
lookin for lotsa torque down low, want to stay away from
hi-revs.

–
Nick Morland 86XJ-S 88XJS6.0L5spd 73xj6 91VdP 97XK8cvt
Scotts Valley Ca, United States
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3

16:15, Ronbros wrote:

what do you guys think about twin turbos on a stock 6.0L.

Obviously not good. The compression ratio on the stock 6.0 is 11:1.
You wouldn’t be able to apply enough boost to make the installation
worthwhile.

Now, forget about stock, rebuild engine with different pistons to get
the compression down around 8 or 9 and we’ll be talkin’. And while
you’re at it, replace the H.E. heads with pre-H.E. flat heads, as the
swish area of the H.E. head isn’t going to work with the lowered
compression anyway. Of course, while you’re doing that you might as
well go for enlarged bores…

and what yrs would be more or less suitable.

AFAIK, all years of the 6.0 are internally alike.

lookin for lotsa torque down low, want to stay away from
hi-revs.

Then I just gotta ask: Why are you even talking about turbos?
Turbos are for power up top, provide little or no benefit down low.
For down low you want superchargers, not turbochargers.

– Kirbert

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4

That’s exactly what I was going to say :slight_smile:

I’ve been dreaming bout forced induction for about a decade now. Never found a good way to make it happen, but I do believe it is possible, and would love to see it done.

In response to the original question, the bottom end will handle it no problem, but I suspect you would run into difficulty with the high compression ratio of the 6.0.

11:1 is pretty high for a NA engine and near impossible to run any amount of boost on top of that.
I just finished a project installing a supercharger on a 1FZ powered Land Cruiser. With 9.0:1 compression, 7psi boost, and 91 octane it was on the ragged edge of spark knock. Boy did it move though.

I can’t imagine trying to do that at 11:1 on pump gas. So at minimum I expect you would be looking at a set of forged pistons with which to drop the CR. Another way would be to CNC mill the heads to open up the pocket around the exhaust valve for better breathing and reduced compression at the same time.

-GaryOn Feb 24, 2011, at 7:25 PM, konrads wrote:

In reply to a message from Ronbros sent Thu 24 Feb 2011:

I personally love the idea
Just waiting on you to post some pics so I can figure out were to
put the turbos.LOL
Nick

The original message included these comments:

what do you guys think about twin turbos on a stock 6.0L.
and what yrs would be more or less suitable.
lookin for lotsa torque down low, want to stay away from
hi-revs.

–
Nick Morland 86XJ-S 88XJS6.0L5spd 73xj6 91VdP 97XK8cvt
Scotts Valley Ca, United States
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5

In reply to a message from Kirbert sent Thu 24 Feb 2011:

Just pull the pistons and machine them down like Chadbourn does
with his 6.2L.

doesn’t the boost effectively raise comp back up so the HE head
shouldn’t hurt plus why go bigger the turbos should be more than
enough.
Nick–
The original message included these comments:

Obviously not good. The compression ratio on the stock 6.0 is 11:1.
you’re at it, replace the H.E. heads with pre-H.E. flat heads, as the
swish area of the H.E. head isn’t going to work with the lowered
compression anyway. Of course, while you’re doing that you might as
well go for enlarged bores…

–
Nick Morland 86XJ-S 88XJS6.0L5spd 73xj6 91VdP 97XK8cvt
Scotts Valley Ca, United States
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6

I have read that the piston crowns are only 0.35" thick at the center. I would be hesitant to go thinner than that on a forced induction motor.

Does anyone know if the 6.0 motor uses shorter rods than the 5.3, or does it have the same rods and a lower pin height?

I always wondered if it would be possible to fit the pre-he pistons in the 6.0 block, or would they pop out the top?

-GaryOn Feb 24, 2011, at 10:26 PM, konrads wrote:

In reply to a message from Kirbert sent Thu 24 Feb 2011:

Just pull the pistons and machine them down like Chadbourn does
with his 6.2L.

doesn’t the boost effectively raise comp back up so the HE head
shouldn’t hurt plus why go bigger the turbos should be more than
enough.
Nick

The original message included these comments:

Obviously not good. The compression ratio on the stock 6.0 is 11:1.
you’re at it, replace the H.E. heads with pre-H.E. flat heads, as the
swish area of the H.E. head isn’t going to work with the lowered
compression anyway. Of course, while you’re doing that you might as
well go for enlarged bores…

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7

In reply to a message from Kirbert sent Thu 24 Feb 2011:

Besides, isn’t it MUCH better to install turbos AND
intercoolers? (Don’t want to say essential) I don’t see how
all that new stuff can be put in a normal engine bay…–
The original message included these comments:

Obviously not good. The compression ratio on the stock 6.0 is 11:1.
You wouldn’t be able to apply enough boost to make the installation
worthwhile.
Now, forget about stock, rebuild engine with different pistons to get
the compression down around 8 or 9 and we’ll be talkin’. And while
you’re at it, replace the H.E. heads with pre-H.E. flat heads, as the
swish area of the H.E. head isn’t going to work with the lowered
compression anyway. Of course, while you’re doing that you might as
well go for enlarged bores…

–
Luis Gasperini / '91 V12 XJ-S conv. 5sp
Montevideo, Uruguay
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8

In reply to a message from Gary Evans sent Thu 24 Feb 2011:

Gary, The 89 1/2 and up one piece rear seal 5.3 block and the
6.0. The major differences are 1 the crank, 2 the sleeves
are shorter 3 the 6.0 block has a waffle look to the outside.
4 the pistons are different.
Other than that you can take 6.0 parts and put them right
into the 5.3 block. The 5.3 and 6.0 rods are exactly the
same.
That is the block setup.
The pistons, I have found are around .350 thick in the
center.
Chadbourn Bolles–
Dr. Chadbourn Bolles, JaguarXJ_S@Yahoo.com
Leesville, SC, United States
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9

In reply to a message from Ronbros sent Thu 24 Feb 2011:

The first question is surely how much torque do you want are
you going for torque or peak power.

turbocharging requires exhaust gas flow which is sometimes
hard to get at low rpm. In that respect supercharging is
better. You dont have to worry about pressure equilization
across the banks either.

Quite how you would fit it all together is another thing
and better have really deep pockets.

Alex P–
alex paterson
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10

Gary Evans wrote:

I’ve been dreaming bout forced induction for about a decade now. Never
found a good way to make it happen, but I do believe it is possible,
and would love to see it done.

I’m sure the photos of Bradley Smith’s car are still floating around
someplace.

– Kirbert

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11

konrads wrote:

doesn’t the boost effectively raise comp back up so the HE head
shouldn’t hurt…

Uhhh, no. The whole point of the H.E. head is the squish area, where
the piston comes close enough to the intake valve as to force the
charge to relocate to the recess around the exhaust valve. If you
cut the piston back to lower compression, the squish area is gone.
All you’re left with is a pocketed exhaust valve with poor flow.

plus why go bigger the turbos should be more than
enough.

“You cannot know how much is enough until you know how much is too
much.”

– Kirbert

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12

Luis Gasperini wrote:

Besides, isn’t it MUCH better to install turbos AND
intercoolers? (Don’t want to say essential)

As I understand it, you can go with a little bit of boost without
intercoolers, but the more boost you go with the more you need
intercoolers.

I don’t see how
all that new stuff can be put in a normal engine bay…

So, put it in the trunk!

– Kirbert

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13

Hm, interesting. So one could conceivably install the 7.8:1 pre-he pistons with the 6.0 crank by removing the 1 or 2 mm of the squish band that protrude above the deck, leaving a portion of the dish intact.

I wonder what CR that combination would yield with the HE and/or pre-HE head. Seems like that would the cheapest way to change the CR of the 6.0 without having a set of pistons specially made.

-GaryOn Feb 25, 2011, at 5:42 AM, Dr. Chadbourn Bolles wrote:

In reply to a message from Gary Evans sent Thu 24 Feb 2011:

Gary, The 89 1/2 and up one piece rear seal 5.3 block and the
6.0. The major differences are 1 the crank, 2 the sleeves
are shorter 3 the 6.0 block has a waffle look to the outside.
4 the pistons are different.
Other than that you can take 6.0 parts and put them right
into the 5.3 block. The 5.3 and 6.0 rods are exactly the
same.
That is the block setup.
The pistons, I have found are around .350 thick in the
center.
Chadbourn Bolles

Dr. Chadbourn Bolles, JaguarXJ_S@Yahoo.com
Leesville, SC, United States
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14

In reply to a message from Kirbert sent Thu 24 Feb 2011:

OOps Kirbert.
While you are correct about the stock 6.0 HE and also correct
about the need to modify
Early 6.0’s have forged cranks later have cast cranks (er,…
sintered iron)
You also need to look up what the Germans are doing. They are
using small turbo’s to get power down low and large turbos for top
end power… Porsche has got a variable blade turbo to achieve the
same thing…
If low end power is the goal you can either use small turbo’s to
come up to boost quickly or have a custome set of turbo’s made with
smaller exhaust scrolls and larger boost scrolls… I’m sure I can
sit down with the books and come up with something workable…–
The original message included these comments:

AFAIK, all years of the 6.0 are internally alike.
Then I just gotta ask: Why are you even talking about turbos?
Turbos are for power up top, provide little or no benefit down low.
For down low you want superchargers, not turbochargers.

–
MGuar
Wayzata Minnesota, United States
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15

In reply to a message from Ronbros sent Thu 24 Feb 2011:

I like the idea except you can’t do it stock!Gotta swap out pistons
should swap heads…
Go to the racing site to see how to do it cheaply (but don’t you
have an aftermarket injector?)
OH for information the early 6.0’s were all forged cranks and the
later were cast(sintered Iron)–
The original message included these comments:

lookin for lotsa torque down low, want to stay away from
hi-revs.
YUP, I been thinkin. and learned a lot about 6.0s from

–
MGuar
Wayzata Minnesota, United States
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16

In reply to a message from MGuar sent Fri 25 Feb 2011:

WELL, I seem to have your attention, 14 hits, in 24 hrs,
so idea has some merit.

you guys have a lot of input, but many different
approaches, hard to seperate fact from fiction.

hear me out before I go down in flames!! no
superchargers,turbos only

CHAD, and MG(Frenchy),and the whole bunch of car guys, the
weak link in turbo engines is DETONATION correct, weak link
in most NA engines when they are forced to breeth,head
gaskets. they blow up later after you drive with blown
gaskets. most of the time(we talkin stock NAs)

but JAG did a lot of R&D to have May, develope the INfamous
HE(hi-effeincy) chamber.

BUT after learning more about it, I THINK IT CAN CONTROL
DETONATION better than the FLatH. all about the squish and
swirl,and turbulence. did Jag have some prototype 14-1 comp
engines? runnin on 93octane?

so MG or Chad,i ask? how close top the top of the liner
does the HE piston come, is it down,is it flush,or does it
protrude?? AKA space between piston and inlet valve?

KIrby, turbos can be sized for any place in the RPM range,
quite simple to get manifold pressures up by 1500RPM, up
to a usable peak of 5500revs, this is for a road car not the
Texas mile!

Luis, inter coolers are required for sustained boost
conditions, water injection can and will be used,great at
controling detonation,so no ICs.

now of course an aftermarket ECU will be used with crank
trigger setup, speed density configure,and EDIS ignition.
you gotta have some adjustability, on spark and fuel
curves. I have plenty access to injctors and controls.

and also(where is all this stuff gonna be mounted),
REMOTE mounted twin turbs, where factory mufflers used to
be, all cats and etc. out of system, turbos make a great
muffler. fab pipes up to TBs,

I dont intend to take the engine apart(providing I know the
history of it). wrecked OK, run hot ,no oil, no way.

OK lets go from here! have at it!!–
Ronbros
daytona fl. / Austin TX., United States
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17

In reply to a message from Kirbert sent Fri 25 Feb 2011:

But the piston stops shy of the top already so my thought is with
the extra cyl charge of the turbo it will still have to squish you
may loose it with low or no boost conditions but its a V12 so it
should cope better than the 4cyl with that no?
Nick–
The original message included these comments:

doesn’t the boost effectively raise comp back up so the HE head
shouldn’t hurt…
Uhhh, no. The whole point of the H.E. head is the squish area, where
the piston comes close enough to the intake valve as to force the
charge to relocate to the recess around the exhaust valve. If you
cut the piston back to lower compression, the squish area is gone.
All you’re left with is a pocketed exhaust valve with poor flow.

–
Nick Morland 86XJ-S 88XJS6.0L5spd 73xj6 91VdP 97XK8cvt
Scotts Valley Ca, United States
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18

In reply to a message from Kirbert sent Fri 25 Feb 2011:

Rule of thumb 1 deg off the boosted air temp = 1 hp so not
essential but if you can cram them in there too all the better.–
The original message included these comments:

Luis Gasperini wrote:

Besides, isn’t it MUCH better to install turbos AND
intercoolers? (Don’t want to say essential)
As I understand it, you can go with a little bit of boost without
intercoolers, but the more boost you go with the more you need
intercoolers.
I don’t see how
all that new stuff can be put in a normal engine bay…
So, put it in the trunk!
– Kirbert

–
Nick Morland 86XJ-S 88XJS6.0L5spd 73xj6 91VdP 97XK8cvt
Scotts Valley Ca, United States
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19

In reply to a message from Ronbros sent Thu 24 Feb 2011:

Well if you insist on using the HE heads you need to know that the
biggest flaw with the HE heads is getting exhaust flow. If the
intake is pressurized (Turbo’d) the flaw on the intake side will be
overcome. Heck they get decent power out of the old Ford Flathead
and a supercharger to force it in…
The problem will be to get the exhaust out. Any exhaust left over
because it can’t get out will contaminate the intake charge and
drop horsepower. At 6500 RPM that occurs 108 times per second!!!
I’ve got an old flathead 5.3 engine sitting in the shop and I’ll
be willing to bet dimes to donuts that a pair of turbo’s on that
will make more power than your 6.0 HE
Wanna do a Dyno comparison? Here’s how and I think it will only
cost you $90 to confirm…
Go on line and buy a Engine analizer dyno program. Modify the
Profile of the Chevy six to duplicate the 6.0 V12 (same combustion
chamber shape) just cut it down to 30cc Put the Jaguar valve sizes
and port volume in. Work and adjust untill the dyno program
duplicates the stock engine performance.
Then from that point start to modify the V12 in whatever way trips
your trigger. Find out for yourself what works and what doesn’t.
(Without spending a dime for parts or machine work)
I’ve done it often enough that I know that if the information is
correct it’s within 2% of actaul dyno sheets any place on the power
curve…
I once bult a 430 cu in chevy small block with a set of early
Hillborn injectors.(for a vintage race car)I bought big new state
of art racing heads, rollar camshaft, 13-1 forged pistons Carillo
Rods etc.etc… etc… Things that I’d used to make over 650
Horsepower with a Holley 4 barrel.
Computer program said 430 horsepoer peak! Actual horsepower on
Dyno? 428…
I took off the Hillborn and replaced it with 3X2barrels and power
went up to 510. with the Holley 4 barrel 657 horsepower.
So Ron do yourself a favor. Before you spend the money run the
program…–
MGuar
Wayzata Minnesota, United States
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1 Like
20

In reply to a message from MGuar sent Sat 26 Feb 2011:

THX for the input MG.

I understand that the HE head,on 6.0 is slightly lower
ratio,than 5.3 HE, any truth to that?? even tho 6 is more
displacment than 5.3,comp. is lower so chamber must be
larger!!

not having the engine(6) in front of me, I would hve to
examine top with head off. maybe a blown up engine( Chad??).

i would like to NOT take apart a good runner.

anyway I dont think I will use a computor program,for
making modifications, mainly it would require takin the
engine apart,bad idea,== MONEY.
and most programs are designed around the incredible chevy
smb.

dont forget this is all about having fun with engines and
turbochargers.
and most of those programs dont deal with forced induction
in a realistic manner.

and with proper inlet manifold pressures you can force the
exhaust gases out, and reduce intake reversions. dont forget
we are gonna force FEED the cylinder volume.
alltho NEGATIVE OVERLAP CAM timing could come into play,BUT
i dont want to take apart the engine(at least just yet).

anyway we shall see, time will tell, and I got so many
ideas,i could write a book.

lets see what anyone else has to contribute, after I get
more info, then I gotta start pricing parts, I dislike that
part!!–
The original message included these comments:

intake is pressurized (Turbo’d) the flaw on the intake side will be
overcome. Heck they get decent power out of the old Ford Flathead
The problem will be to get the exhaust out. Any exhaust left over
because it can’t get out will contaminate the intake charge and
I once bult a 430 cu in chevy small block with a set of early
Hillborn injectors.(for a vintage race car)I bought big new state
So Ron do yourself a favor. Before you spend the money run the
program…

–
Ronbros
daytona fl. / Austin TX., United States
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