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There was 4 or 5 different block castings but these were mostly modifications for the bellhouse and rear main seal. Most other things are bolt on compatible until you get to the 6.0L where most engine bolts/studs turned metric.
A few have used XJS fuel injection to bolt to carby engines.
From a performance point of view there is not much in it, their power outputs are pretty similar. From a fuel economy view, the HE engine (whether Marelli or Lucas ignition) is far more economical at everyday road speeds. It is quite hard to get less than 16 to the gallon whatever the conditions and speeds in a properly functioning HE XJS, and you should get a real world 18 or 19. By contrast it is quite hard to get even 15 in a carefully driven V12 E type.
If you are not worried about originality, an HE engine in an E Type V12 is a good swap from both emissions and fuel economy points of view. The carb'd V12 is particularly inefficient while it warms up. Roger Bywater wrote somewhere that as much as a cupful of petrol could accumulate in each inlet manifold during warm up!
Specific differences between the two engines are the heads, the inlet manifolds, the fuel injection/carburettor systems, the oil cooling system, the ignition system, and the pistons. The gearbox to engine interface is also different, but can be made Ok with an adaptor plate.
I would get an manual V12 E Type in a moment if I win the lottery! It is the only version I have ever fancied. But aircon is an absolute must, engine heat-soak makes them undriveably hot inside in the summer, I am told.
One thing I thought to add: The E type is far less stable at high speed than the XJS. One of the points the designer of both cars - Malcolm Sayer - made to Sir William Lyons, as part of the design brief for the XJS, was that the XJS had to be far more stable at high speeds.
Last edited by Greg in France; 10-03-2018 at 07:11 AM.
Can't really common on early V12s in the E but a local in the German Jaguar Club had an E Type with an HE running 2 K Jetronics on it. And his own word was: Death-trap. Quite a handfull at any speed.
The K Jetronic (common on VAG and Mercedes products in the 80ies) is basically a mechanical fuel injection with a big flap to determin how much fuel is needed. So rather simple to adapt to other engines.
It makes loads of power, but is probably greedier than a carbed E.
He also wouldn't go any faster than 100 mph in it. As Greg said, it gets unstable at higher speeds. Where the XJ-S is planted, the E is every where and ultra-nervous.
Again, nothing is imminent. Just something I thought about, given that I have a second XJS V12 HE with a dropped valve sitting in my garage. It seems like I swapped things I needed to swap to make '85 XJS running pretty good (knock on wood). Did not take that much, surprisingly.
How much of the remaining V12 HE engine (almost the whole thing) can be used/re-used as spare parts in case I come across an offer on an E-type I "cannot refuse"?
There should be documentation on strengthening the E type frame etc if your going that route, they did race them afterall and some improvements were made to handle the weight of the v12.
One thing I thought to add: The E type is far less stable at high speed than the XJS. One of the points the designer of both cars - Malcolm Sayer - made to Sir William Lyons, as part of the design brief for the XJS, was that the XJS had to be far more stable at high speeds.
Whatever Jaguar did, worked. My XJS was the most secure and stable high speed car I've owned, including other Jaguars. Driving 100 mph in my XJR put me a bit on the edge of my seat. I never felt truly secure. Driving 100 mph in the XJS felt no different than 55 mph. Rock solid.
Whatever Jaguar did, worked. My XJS was the most secure and stable high speed car I've owned, including other Jaguars. Driving 100 mph in my XJR put me a bit on the edge of my seat. I never felt truly secure. Driving 100 mph in the XJS felt no different than 55 mph. Rock solid.
Cheers
DD
I 100% agree Doug. I think it was one of the US drivers who raced the XJS, forgotten the name I'll try to find it, who was quoted in a road test as saying "When Jaguar told me the XJS was far more stable at speed that the E Type, I thought it was 75% wishful thinking and 25% BS. Then I found myself driving it at 150 mph round the banking at Daytona [I think it was] with one hand on the wheel, and it was rock steady!"
There should be documentation on strengthening the E type frame etc if your going that route, they did race them afterall and some improvements were made to handle the weight of the v12.
I m on a E type V12 restauration. I do have an xjs Marelli engine as the E I ve got do not have any engine nor gearbox seats windscreen blabla.....
I confirm at least that nothing hAS to be done on the front frames.
To go ahead on my restoration one of the many (many many many too much maybe....) topics I need to solve is the connection of the "blue" solenoid valve uder the A bank manifold.
where go the different hoses to?
I ll be glad to get drawings or pictures to help understand it or explanation discribing the function.
As I said the engine I ve is a Marelli one from 1989.
cheers
There should be documentation on strengthening the E type frame etc if your going that route, they did race them afterall and some improvements were made to handle the weight of the v12.
engine weights for the cast Iron 4.2 six are slightly higher than the all aluminum V12. About 30 pounds according to my scales.
I built a race car out of a series 3 roadster. The front sub frame of an XKE is unbelievably thin steel. Thinner than sheet metal. Strong though, the rear 1/2 of the body is plenty secure and capable of enduring a great deal of abuse without yielding damage to the occupants.
But it is light. Conforming to the then SCCA rules The car weighed only 2100 pounds. The lightest I was able get a XJS to race standards was slightly under 3000 pounds. In addition to the weight disadvantage the frontal area is much greater on an XJS than the much narrower XKE while the CD of the XKE is higher the area is so much greater on the XJS.
Power wise in a racing configuration the carbed XKE can easily distance the fuel injection.
In theory the Fuel injection should exceed carbs but the difficulty of modifying fuel injection eluded most and only with great inputs from the factory ( financial and technologically) was the potential reached with Group A.
I used both the E type engine and those out of later sedans. Pretty well interchangeably. I did prefer the aluminum oil pan of the E Type but never got a chance to try it on a 6.0 so I’m not sure it will fit.
Last edited by Mguar; 09-03-2019 at 08:04 PM.
Reason: Missed information
MG ancient history; Grp 44 raced both cars , 73 XKE V12 much modded best equipment ,money supplied by Jaguar factory!
after 2 seasons with E type the XJS showed up they used a lot of the engine mods+ somemoney from Jag!
simply put the XJS would out handle the E anytime everytime, to the point of dangerous, driver saying the polar moment of inertia , was way out of balance, lots of weight over the front and little grip in rear.!
pix ron Etype V12 1973 XJS V12 1975
MG ancient history; Grp 44 raced both cars , 73 XKE V12 much modded best equipment ,money supplied by Jaguar factory!
after 2 seasons with E type the XJS showed up they used a lot of the engine mods+ somemoney from Jag!
simply put the XJS would out handle the E anytime everytime, to the point of dangerous, driver saying the polar moment of inertia , was way out of balance, lots of weight over the front and little grip in rear.!
pix ron Etype V12 1973 XJS V12 1975
My XKE had 4% more on the rear wheels than the XJS. Full disclosure, my bonnet was carbon fiber and I think it weighed something like 33 pounds. To be fair I could only semi replicate the First XJS. The last one, the tube frame one had the engine 12 inches further back. And! I was only 2100 pounds they had to conform to SCCA’s B production rules something like 2650 pounds.
Also I mounted my E type engine almost 8 inches back and 2 inches lower than the pictures you see of Group 44’s E type.
No Jaguar did not! Jaguar. supplied money and parts. The technology Group 44 developed was their own, Same with Huffaker
But when they got together both teams had pretty well solved issues similarly. Although they both felt the Huffaker car had more power while Group 44 had superior handling.
Me? I shamelessly copied everything I could. Right down to the Weaver 4 stage dry sump system!. I did use Piper camshafts because the profile Crower was grinding was not as developed as Piper’s.
I used Aries forged pistons. 13-1 ( still have one ) bored as big as I could. I around 3&5/8ths. but shortly after that Cosworth made a new lighter piston using the heart shaped combustion chamber which is reportedly good for an additional 30 horsepower and better fuel mileage. I used an offset ground crankshaft and a set of 6” Chevy rods made by Scat.
To be fair I built mine many years after Group 44 After spending every second I could checking them out, talking with them. Taking pictures and asking questions. They were remarkably open about everything, vague only with regard to real minutia.
There is still a picture of it on my Facebook page. shortly before I put it up for sale.
HMM? you had a Carbon fiber hood back in the 1970/early 80s?????
ron
Yes but not a prepeg autoclave vacuum bagged based version. And it was well into the late 80’s.
You can get about 90% of the excess resin out of fiberglass/ carbon fiber simply by using a squeegee and patience. It not only helps the cloth to conform to the mold but if you push it out past the edge it gets most of the the weight out as well.
our source for carbon fiber was a funny car driver who had access to aerospace carbon fiber that had “timed out” Gerhome the guy who taught me Fiberglas work, making molds etc was my source for carbon fiber. He got a whole roll of it and didn’t use it all to make the funny car body. I bought some of his remnants for my hood but I too bought too much. All it took was 3 layers, each about 45 degrees off the previous.
But Wow does that stuff dull cutting tools quickly.
I find it hard to believe that your Etype was a better handling car than an XJS, ALL everyone i talked to said the V12 E types were dangerous at high speeds!
including Bob Tullius himself! read the posts 4 thru 9 on this thread!
also i think an Aluminum hood would be as light as Fiberglass/Carbon fiber back in the 80's, i have seen some old fiber parts and some were heavy!
ron
I find it hard to believe that your Etype was a better handling car than an XJS, ALL everyone i talked to said the V12 E types were dangerous at high speeds!
including Bob Tullius himself! read the posts 4 thru 9 on this thread!
also i think an Aluminum hood would be as light as Fiberglass/Carbon fiber back in the 80's, i have seen some old fiber parts and some were heavy!
ron
Perhaps the Trans Am XJS with its spoilers, big slicks, and fully developed suspension would have been better than the XKE that lacked most of that. My brief exposure to the XJS assembled to the $500 Chump Car rules that I had. Wouldn’t agree with that conclusion.
My XKE was fully sorted thanks to the guidance of Group 44. With Double adjustable Aluminum Koni’s. Proper racing springs and adjustable tubular swaybars. My prior experience racing the Black Jack Special in more than 2 decades of Vintage racing. Plus racing in SCCA D Production. With my XK 150.
All my previous racing had been with similar relatively narrow tracked Jaguars.
I found the width, length, and mass of the XJS awkward. In addition the lack of properly adjustable sway control, not to mention the lack of adjustable shock absorbers,plus the vague handling imparted by all that rubber mounting unsettling.
Is it possible that a properly sorted XJS would have felt better? Yes. However I’ve seen many XKE’s racing at speed-wheel to wheel with Corvettes and Camero’s using their handling to offset the greater power the Chevy brigade have.
Might I remind you that a XKE V12 with little more than a years preparation and some sponsorship took on the might of America’s Corvette and Camero and won the National Runoff’s
With regard to the weight of Aluminum versus carbon fiber if there really was no difference building race cars in aluminum then switching to carbon fiber would not have occurred. My hood ( or Bonnet as the British say) weighed 33 pounds. Now find out what it would weigh in Aluminum.
Yes I am familiar with overly heavy fiberglass usually using a chopper gun or Matt. Neither Matt or a chopper gun has much strength at all, they need all that heavy resin to provide enough strength to survive.
There should be documentation on strengthening the E type frame etc if your going that route, they did race them afterall and some improvements were made to handle the weight of the v12.
Look carefully at group 44 and Huffaker’s V12E types. The only real chassis work they did was heavy duty torsion bars. ( front) and thicker sway bars. Both had roll bars rather than roll cages. So the chassis were relatively stock , Though both did weld all the seams in the chassis rather than accept the factory spot welding.
They both raced with about 450 horsepower and easily beat the Corvettes of the era.
Their strength was in nimbleness. And lack of frontal area. Dramatically reduced the drag even though the CD was higher in the XKE Than the XJS 16 inches more narrow and no windshield than the XJS And slightly shorter.
On high speed Race tracks like 4 mile Elkhart Lake with its 3 long straights or the 3 mile Brainerd where 1/2 of the track could be driven flat out The Jaguars had no trouble beating Corvettes and Cobra’s
An XKE IS MORE NIMBLE THAN A XJS
An analogy would be like in planes. A great fighter is nimble but requires constant correction because of that nimbleness. An Attack type aircraft is far more stable but nowhere near as nimble.
So you are correct in a XJS is stable at speed but it lacks the fighters nimbleness.
10-02-2018, 10:49 PM
How does V12 in XKE compare to V12 in XJS (pre-Marelli)?
