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Old 11-19-2006, 09:02 PM   #1 (permalink)
FordCrusherGT
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Doing a 6.2 conversion in an '82 Jag XJ6

My fiancee wants a vehicle that will get better mileage than the gas-guzzling SUV she's currently driving, specifically she wants a diesel so she can run on WVO. A few years ago we got her an '82 Jag XJ6, which at this point has a useless engine and transmission that are going to a friend of mine to rebuild for his '87 Jag. We figure that the '82 then becomes a prime candidate for this swap. People put big blocks in these cars all the time, so making a 6.2 fit I don't foresee being a significant issue. When I used to have a 6.5, it always seemed to me that the motor looked about like a big block Chevy. I might have to play around a bit with the exhaust manifolds to make that fit, but so long as the external dimensions of the motor is roughly similar to that of a big block (or even better, small block) I'm fine.

So, here are my questions, as my familiarity with the 6.2 is fairly limited.

1) Approximately how much does one weigh?
2) Am I correct in saying this engine is roughly the size of a big block dimension wise? Does anyone know if the engine mounts are about the same as on a small/big block?
3) What pitfalls should I be aware of and look for on a 6.2?
4) On truck applications, what kind of mileage increase is generally had by a turbo kit? I may fabricate a twin-turbo setup for this motor as well, if there's a significant mileage benefit to be had.

Thanks!
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Old 11-20-2006, 01:38 AM   #2 (permalink)
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I think they weigh around 1000-1100 lbs dressed. Engine mounts work like those on a 350. Just heavier duty to deal with the heavier more torque rich motor. Banks claims an 8-10% increase in fuel economy with there sidewinder turbo kit. Check for any signs of injection pump failure (not a bad injection system just expensive to fix). Check for head gasket problems (factory torque to yield head studs). If a big block will fit then a 6.2 should definitely fit.
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Old 11-20-2006, 09:00 AM   #3 (permalink)
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350 motor mounts? I thought the 6.2 took big block motor mounts?
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Old 11-20-2006, 09:52 AM   #4 (permalink)
High Sierra 2500
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Welcome to the forum! That sounds like an interesting project...

Quote:
350 motor mounts? I thought the 6.2 took big block motor mounts?
Yeah, 350 motor mounts. Although the big block mounts are pretty much the same...

rock_shoes pretty much summed it up. It is heavy, but it will fit. The head gaskets are the weak link (as on all diesels), especially when the engine is turbocharged.
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Old 11-20-2006, 09:54 AM   #5 (permalink)
jdemaris
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6.2 in Jag

Quote:
Originally Posted by FordCrusherGT;1420810;
My fiancee wants a vehicle that will get better mileage than the gas-guzzling SUV she's currently driving, specifically she wants a diesel so she can run on WVO.
So, here are my questions, as my familiarity with the 6.2 is fairly limited.

1) Approximately how much does one weigh?
2) Am I correct in saying this engine is roughly the size of a big block dimension wise? Does anyone know if the engine mounts are about the same as on a small/big block?
3) What pitfalls should I be aware of and look for on a 6.2?
4) On truck applications, what kind of mileage increase is generally had by a turbo kit? I may fabricate a twin-turbo setup for this motor as well, if there's a significant mileage benefit to be had.

Thanks!
6.2 dimensions - Length:29.5 inches Width:27.2 inches Height:27.4 inches
6.2 weighs 700lb.s stripped of accessories.

The 6.2 is probably one of worst choices for WVO fuel - unless you make some mods. to the injection pump. Rotary pumps, in general have the most wear problems with vegetable oil fuel, and of that group - Stanadyne, as used on the 6.2, is the MOST lprone to wear. They have been extensively tested - and if the optional hardened "Arctic Parts" are installed, they hold up much better.

In regard to fuel mileage increases with a turbo - in real-world driving, fuel mileage tends go go down, not up - for several reasons. But it depends on how you build the engine and how you drive it. First - adding a turbo to gain power requires turning up the fuel delivery - and you make more power and use more fuel doing it. And driving? You find yourself climbing hills faster than before - so you're actually doing more work - and using more fuel. As the 6.2 engine evolved - over the years until the bore was slightly increased and it became a 6.5, many changes were made to allow more power production - and efficiency went down along with those changes. Those changes included larger precombustion chamers, valve-head diameter changes, injector angle changes, and the compression ratio lowered to allow more boost. Pistons directly affect mechanical compression ratio, but a turbo can effect effective compression ratio. So, engines made to make big power and boost levels over 10 PSI use lower compression-ratio pistons.
So - in your case? I'm not sure high-power is big issue since you're installing into a car. A stock NA 6.2 is equal in power to a 305 gas engine. A 6.2 built with reliability and fuel efficiency in mind can easily have the power of a 350 gasser. If you used an older engine with small precombustion chambers, and kept the stock high 22.5 - 1 compression pistons, added a Banks turbo with a max. of 10 PSI, and had it all geared so highway cruising was at the peak of the torque-curve - i.e. 1800 RPM, that Jag could probably cruise at 65 MPH and get 30+ MPG. A 1/2 ton 4WD truck, setup the same can get 25 MPG pretty easy.
I built several Jags with Chevy gas V8s back in the late 60s. I cut up many XKEs with V-12s. I wish now - I'd left them alone and saved a few.

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Old 11-20-2006, 10:38 AM   #6 (permalink)
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Quote:
The 6.2 is probably one of worst choices for WVO fuel - unless you make some mods. to the injection pump. Rotary pumps, in general have the most wear problems with vegetable oil fuel, and of that group - Stanadyne, as used on the 6.2, is the MOST lprone to wear.
I agree, the injection pump is not the best for WVO, but it is by far not one of the worst choices for WVO. That is the same style pump used on almost all the diesels that you will find in cars. Mercedes used an inline style pump, and so did Volvo if I recall correctly, but most of the other automotive diesels used rotary pumps and are successfully converted to WVO. Also, Stanadyne is better than some of the Lucas pumps... Some of those simply can't be used with WVO.

So yeah, Mercedes is really the best thing for WVO, but the 6.2 can be easily converted. My WVO conversion has been quite successful. I am very pleased with the results. There are many others on this board who are running WVO and have excellent results.

In my opinion, more modern engines are by far worse for WVO. In general, the newer they are, the worse they will be, mainly due to the addition of electronic components.
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Old 11-20-2006, 11:13 AM   #7 (permalink)
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Thanks for the replies all. Sounds like the motor shouldn't be a problem and that this should work relatively well. Only question now is what transmission to use... I bought a 6.2 with a 4x4 TH400 attached (this is claimed to be an '83 motor with new injectors and a new injector pump), but I really would prefer to use an overdrive of some sort... plus I don't want to do a 4x4 Jag. So now for new questions:

1) Is the 6.2's bolt pattern the same as on a small/big block such that I could take a standard 700R4 and bolt it up?
2) How difficult would attaching a manual transmission be, specifically with regards to obtaining a flywheel?

It sounds like I'm going to want to try to do a low-pressure turbo setup of some sort for fuel economy gains. My appeal to the 6.2 over the 6.5 is the cost advantage... the 6.2s can be had quite cheaply, whereas the 6.5s are definitely more expensive.

jdemaris, I've owned 8 Jaguars in the past 5 years, most of which have been V12s. They're really sweet engines! I was actually able to get 30 mpg out of my '82 XJ-S V12... but that motor was fairly tweaked to be able to get that mileage. Put 35,000 miles on that car in one year (total vehicle miles at end: 165,000) with no problems.

Thanks for the advice so far, guys, I'm going to have a lot of questions over the course of this endeavor!
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Old 11-20-2006, 11:14 AM   #8 (permalink)
jdemaris
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Show me your data

Quote:
Originally Posted by High Sierra 2500;1421750;
I agree, the injection pump is not the best for WVO, but it is by far not one of the worst choices for WVO. .
I've read a lot of test data, done by the U.S. military and several organizations throughout the world. Much based on internal wear of metal parts - with many types of fuel. I can give you endless source-citations. Show me some that differ? The standard Stanadyne DB rotary pump is by far - the most succeptible to such wear - so yes, by most uses of the word "worst", it IS the worst. The US military had so many problems with D type pumps, et. al. - much due to third-world fuel problems starting with Viet Nam - that a new military fuel JP8 standard was established, and - with the later DB2 pumps used on 6.2s - the optional internal hardened parts are used with the 1.2 cSt spec. There are still major problems even with the hardened parts - especially in Iraq an Afghanistan because of the TS1 and Jet A1 fuels being used.
That does NOT though, make the DB2 inherently bad. SVO can work in any mechancial pump. In regard to your comments on Lucas rotary pumps worse than Stanadyne? Not from what I've experienced first hand, and read in the test data. Lucas/CAV/Rotodiesel paid for permission to copy the Stanadyne pump - and improved upon it greatly.
The rotary pump was invented by Vernon Roosa in the late 40s, and the first models sold in 1952 - I have a couple. It offered incredible space-saving for its time - and allowed many companies to build small lightweight diesels - that could not previously. CAV bought their first rights to copy in 1953. It's compact and that is why it's so often used. But - inline pumps have evolved since then, and are MUCH more durable - and are common overseas.
In regard to in-lines over here - for automotive use? I don't have a list, but some Isuzus use the Zexel inline, so do some Cummins, Mercedes, Peugot, etc. You mentioned Volvo - but all the Volvo diesels I've worked on had Volkswagen diesels. My point about the Stanadyne/Roosamaster DB2 is not that it cannot be used - it is - that it is very prone to wear with SVO fuel unless it has the hardened parts or a fuel additive is used. Overseas - canola oil is often added to bio fuel to enhance rotary pump life. And, in regard to quality - in my own experience, the Stanadyne has always been the most trouble prone - as compared to Lucas/CAV/Rotodiesel, Bosch VE, Diesel Kiki, American Bosch, etc.
When you say your's works fine - I guess you need to define "fine." I've rebuilt many pumps and seen the inside - many people do not and also assume the pumps are normal "wear items." And to a degree, they are - but they are also - with proper fuel - capable of lasting well over 200K miles. I doubt, if someone shortened the effective life of a 6.2 pump from 200K to 100K they'd even notice. Most of public with diesels seem content to be more-or-less clueless about the internals of the injection pump - and "fixing" usually means "replacement."
Tell me where you get your data that shows the Stanadyne is NOT at the bottom of the list in regard to reliability and SVO fuel.
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Old 11-20-2006, 12:55 PM   #9 (permalink)
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On the bright side, 6.2 IP's are pretty cheap and plentiful. So - if you only get 50k miles out of one - it only costs a couple of tanks of diesel to replace it. If you are burning WVO for much of that 50k miles, you are WAY ahead!
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Old 11-20-2006, 01:07 PM   #10 (permalink)
jdemaris
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Jags and 6.2s

Quote:
Originally Posted by FordCrusherGT;1421805;
1) Is the 6.2's bolt pattern the same as on a small/big block such that I could take a standard 700R4 and bolt it up?
2) How difficult would attaching a manual transmission be, specifically with regards to obtaining a flywheel?

jdemaris, I've owned 8 Jaguars in the past 5 years, most of which have been V12s. They're really sweet engines! I was actually able to get 30 mpg out of my '82 XJ-S V12... but that motor was fairly tweaked to be able to get that mileage. Put 35,000 miles on that car in one year (total vehicle miles at end: 165,000) with no problems.

Thanks for the advice so far, guys, I'm going to have a lot of questions over the course of this endeavor!
I don't pretend to know anything about modern Jaguar V-12s. I owned - and ruined - many XKE Jags from the 60s. Those had sixes had pretty good reps. when compared to other UK cars. But - the V-12s had awful reputations - why - I don't know. I think they were 320 cubic inches, 5 point something litres. The V-12s were the ones I was able to buy a lot cheaper than the XKEs with the sixes. I used to be very interested in "foreign" cars back when they were a rarity in the U.S. Many had advanced technology as compared to the U.S. stuff - e.g. superchargers, overhead cams, etc. and others just plain interestings. Several had two-stroke cycle engines (Saab, DKW, Subaru, etc.), some used motorcycle engines i.e. BMW and Royal Enfield, and some just had nice style along with lower-quality technology - e.g. many British cars. I cut up many a Triumph GT6 , Jag XKE to put a small block Chevy in. I also owned over a dozen Sunbeam Tigers that used British Alpines and U.S. engines - Ford 260 and 289 V-8s, Jeep rears, and Ford top-loader transmissions. Of coure, there was also the AC Bristol made into the AC Cobra - but those were always out of my price-range.
Anyway - in regards to a modern Jag V-12 getting 30+ MPG - seems to me that nowadays, such mileage is expected and common. I will assume though, that a 6.2 diesel in any application will be limited, in regard to fuel mileage potential, by its 379 cubic inches. I wish I knew the specs now on a few Chevy stationwagons I saw with 6.2s. I was told by the dealer in Texax that they were special order but OEM. True or not - I don't know. I probably shouldn't have mentioned it, since now someone will tell me it never happened. The reality is - probably even General Motors - today - could not tell you for sure.
In regard to transmissions and flywheels, there were many 6.2s with standard trans. I have three with the NP four-speed manual overdrive - all original. The HD truck fourspeed with granny unsynchronized low and no overdrive was also used. Seems an auto e.g. a 700R4 might be easier in a swap, though. Used 6.2 manual flywheels are constantly for sale on Ebay.
Since you want to build a fairly LD application, seems there are many cheap five-speeds for sale that will fit.
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