[v12-engine] GMC V12 vs. XJS V12

V12-Engine
1

When we complain about the our Jaguar V12s, take a look at pp. 10-
11 of the September, 2012 Car Craft magazine that features the GMC
truck V12 from the 1960s now being rebuilt by a compnay called
Thunder V12. 702 ci and 630 ftlb at 1,800 rpm. An iron block
with ‘‘shortened’’ push rods, an external oil pump and lines; and
1,485 lbs. Absolute max rpm is reported at 5K.
One can only speculate about its gas mileage.
Not certain that this article is on line but you can try
CarCraft.com
A very different design philosophy from our Jaguars. Even the Car
Craft guys suggest the GMC monster could power a 1/10 model of the
Titanic.
Enjoy your V12s.

George Goodridge–
ggoodrid
Durham, NC, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

2

In reply to a message from ggoodrid sent Sun 30 Sep 2012:

I have some knowledge about that engine, mainly used in
FIRE trucks, 1960s, they were two V6s bolted together, they
made a lot for marine use in V6 form, most internals were
interchangable thru out that engine line! and they also made
some as V8s,and experimented with V16s

they even made some into diesel engines, both as V6s and
V12s,

the gas engines, nobody could afford the fuel consumption,

the V12s were monsters,super heavy! 3-5mpg.

oddly the diesels were very good on fuel, they would easily
be as good as any diesel today!

HOW do I know! I have overhauled many V6s and V8s, both
turbo and non-turbo, quality build of those engines was the
best,machine work ,material like forged pistons, hi alloy
steel crankshaft, the 1st,for me, rolled and ground threads
on all components.

the cylinder port arraingment, had both inlet&exhaust on
the outside of the head, for diesels.

and GM did it all, its all about the war efforts, as soon
as word came down that Nam was ending all production ceased.–
The original message included these comments:

11 of the September, 2012 Car Craft magazine that features the GMC
truck V12 from the 1960s now being rebuilt by a compnay called
Thunder V12. 702 ci and 630 ftlb at 1,800 rpm. An iron block
with ‘‘shortened’’ push rods, an external oil pump and lines; and
1,485 lbs. Absolute max rpm is reported at 5K.
Enjoy your V12s.
ggoodrid

–
Ronbros
daytona fl. / Austin TX., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

3

In reply to a message from Ronbros sent Sun 30 Sep 2012:

add to the topic; anyone who knows about Chevy 350 cylinder
heads,called VORTEC, should know that the port shape was an
almost copy of the port on that engine and it was called
TOROFLOW, both were designed to increase hi-swirl in the
chamber, thet both worked quite well!

Toroflow and Vortec mean about the same thing.

GM for YA.

HECK may as well add this, the Jag HE chamber is closely
related to the early Chevy. chamber,6 cyl, inline.
that was bought by GM from Buick car company, late 20s.

Yeah! nothing new under the sun, just redevelopment of an
old idea.

what is new!!! chamber shapes of Direct injection
technologies,BUT even that has some OLD theories in it!–
The original message included these comments:

I have some knowledge about that engine, mainly used in
FIRE trucks, 1960s, they were two V6s bolted together, they
made a lot for marine use in V6 form, most internals were
some as V8s,and experimented with V16s
they even made some into diesel engines, both as V6s and
V12s,
the gas engines, nobody could afford the fuel consumption,
the V12s were monsters,super heavy! 3-5mpg.
oddly the diesels were very good on fuel, they would easily
be as good as any diesel today!
Ronbros

–
Ronbros
daytona fl. / Austin TX., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

4

In reply to a message from ggoodrid sent Sun 30 Sep 2012:

I suppose this whole thread is off the radar!

just read the one from Thunder V12, me bad, block is a one
piece, but uses 4 heads from V6s. and probably many parts
from both the GMC V6s & V8s.

been 15-20yrs since I worked on those engines!

my opinion is they bought up a lot of Government surplus,
truck stuff,cheap!

he does not talk about fuel milage, I can just imagine at
75% output, what it would be, loaded down on the dyno.

true, it is a novelty, and not many around.

front suspension would be interesting at 1500lbs?

i’m thinking that,around that time GMC found out,DIESELS
were a better way to go,still are. lotsa torque at low rpm,
just where working vehicles run.

the last I seen of that type engines, were a scrapyard with
a bunch of them laying in the mud, in Florida, wanted $200.
each, I checked parts availability, nothing, that was 15yrs
ago.

OK, enough rant, like anything(to each his own).–
The original message included these comments:

truck V12 from the 1960s now being rebuilt by a compnay called
Thunder V12. 702 ci and 630 ftlb at 1,800 rpm. An iron block
with ‘‘shortened’’ push rods, an external oil pump and lines; and
1,485 lbs. Absolute max rpm is reported at 5K.
One can only speculate about its gas mileage.
ggoodrid

–
Ronbros
daytona fl. / Austin TX., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

5

In reply to a message from Ronbros sent Tue 2 Oct 2012:

Re the GM V12…Truck web sites describe the petrol 702 as Legendary
and in early GMC ‘Crackerbox’s’ was said to be super quick… a chap
down here built a '32 Ford coupe with a 702 for motivation and I
understand that the rebuild, especially new pistons, was not cheap.
If you search youtube, V12 - Elvis New Project Update2 , you can
see, hear, it running at;


The 1st start up is at, V12 Elvis new project ;

There are quite a few other examples on youtube as well… I love it
but I’ll stay with my 6.4, nee 5.3 thanks., though the GM would
look the part in a 1930’s style wooden ski boat / runabout.–
Wayne XJC
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php –

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !