The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by oldsmobile1915, May 4, 2009.
Have you tried these guys?
Try these guys, I have bought numerous gaskets for my Jag V12 from them.
I don't know if anyone has addressed this yet, but I STRONGLY recommend leaving enough room to put a puller electric fan behind the radiator, especially if you're running a motor with known cooling issues. Pusher fans (mounted in front of the radiator) don't work near as well.
Just my .02
I'm guessing that you didn't follow the link. The XJ12 in the pic is already running 2 Delco 808 computers. Its not all about injector impedance. Notice the coilpacks on the firewall? No more distributor. And fully programmable ignition advance, unlike most of the injected V12s.
I haven't done it myself yet, but I don't see why there would be a need for multiple sensors. Not that that's a problem anyway when you consider how many sensors are already on a V12 Jag engine.
Unfortunately not. The BW equipped V12s had a different bolt pattern to the T400 version. The manual box from a '94 to '97 XJR might fit the V12, as they were available with the "same" gearbox as the XJ12 of the day.
The "known cooling issues" have nothing to do with pushers or pullers. They were due to stuck centrifugal advances. The motor would run retarded and that would lead to overheating, especially if a thermostat failed. Also, Jaguar recommended adding Barr's Leaks to the cooling system from day one - to perfectly good radiators - and this would plug them up.
The Jag V12 is approximately 300 HP. It produces the same amount of heat as any 300 HP engine. Power is power.
Furthermore, you will not get a puller fan in there because the Jag V12 engine has a temp sensor that protrudes from the front of the water pump. A pusher is the way to go with this motor in this car, and it will work just fine.
Get it running and sorted out with the stock ECU and then you can Megasquirt it or whatever later on. This way you are not messing with too many things at one time. There are enough items to sort out with a motor swap like this without adding to the amount of time before you can begin to drive it.
I wasn't making the assertion that Jag V-12's have overheating problems due to a fan....I have no experience with Jag engines. I was merely repeating what seems to be the overwhelming consensus of all the posts on this thread....namely that they have inherent overheating problems, whatever the cause.
Regarding your comment that ANY 300HP motor will produce the same heat: that's nuts. Engine design has a HUGE impact on how that heat is managed. Take a Chevy 400 small-block for example. In stock form it produces under 300HP, yet anyone who has ever run one knows they run VERY hot, as there are no water jackets between the cylinders due to bore size. By the same token, a built SBC350 producing well over 300HP will run nice and cool on the same size cooling system as the above 400 small-block. The bottom line is that engine design is the primary factor in an engines cooling needs, not the amount of horsepower it produces.
As for pusher vs. puller fans: puller fans are about 20% more efficient than pusher fans, given the same diameter and speed.
I'm not trying to impugn Jag engines here, but the guy who started this thread wants all the info to make an informed decision. Puller fans are more efficient than pusher fans, so if cooling capacity is a concern, a puller fan would be the best option. Plug the temp sensor port on the water pump and relocate it, then run the largest diameter, highest CFM puller fan you can fit.
I stated the reasons for their reputation. Again, it is due to seized centrifugal advances, defective thermostats, and the official Jaguar recommendation to use Barr's Leaks from day 1. None of those facts have anything to do with the use of one of these motors in a hot rod.
The HUGE difference is between generating heat and managing heat. What happens if you don't add coolant? Answer: the engine does not manage heat very well. The fact of the matter is that one of the things that doomed the Jag engine from production was the extraordinarily large volume of coolant that they carry in the block - the aluminum block - around the ferrous liners. The large coolant quanity took a long time to heat up. Therefore the Jag V12s take a long time to heat up enough to switch from open loop to closed loop. Therefore it was tough for Jag to meet ever-tightening emissions requirements with these engines. Modern engines are designed to manage heat such that they warm up a lot quicker - one way they do this is with diminished internal coolant volume. The Jag engine is a good performer from this perspective. Reread the reasons for their overheating reputation. It has nothing to do with the way that the motors are designed. If anything, the overkill design of the short block probably get most of these motors from melting into a slag heap when their Barr's Leak-clogged cooling systems were challenged by a high power engine running with the ignition retarded (now that does a lot to the challenge of managing heat). They would be on the edge for thousands of miles and then one sticky thermostat could cause a real problem. Interestingly, Jaguar never acknowledged the sticky centrifugal advance issue. Disassemble the dizzy, free the stuck parts and wipe down the inner shaft with synthetic oil to permanently solve the problem.
Where did this statement come from? Can you back it up? Regardless of whether you can or not, we are not talking EFFICIENCY. Efficiency means how much power does it take to achieve a given CFM, The air does not know if it is being pushed or pulled (it is all relative anyway). CFM is important, as are the other variables that describe a heat exchanger: volume (flow rate) of coolant, thermal properties of the coolant, inlet coolant temperature, the desired delta t (output coolant temp), air flow in CFM and the air temp on the inlet side. Everything else is a variable that can be tweaked to arrive at the desired values (surface area, material of the tubes, number of rows, size of tubes, etc.). Efficiency (fuel mileage) issues are usually not a factor on a hot rod and certainly not when fundamental packaging issues must be addressed (getting the motor to fit under the hood LOL).
Those with experience with these motors know that this sensor has an oddball thread and is not straightforward to relocate given the design of the water pump and the space available. The OP already stated that the Jag V12 is approximately 6 inches too long for the engine bay. If he needs to gain a couple more inches by relocating that sensor, he sure is not going to then fill up the space with a puller. Let's keep the advice meaningful to his question and not sidestep with opinions based on a less than complete knowledge of these motors.
This is me "backing it up".
Pushers are only 80% efficient compared to a puller, just as I said.
for the turbo 400 tranny is the speedo drive electronic or cable? i may just be blind but i can't seem to see it on the trans
I haven't move the carbs, you may just let them hang out through the sheet metal.
My experience as far as reliability is that they are not reliable at all. Of course I never had occasion to work on any of them before the '90s. Maybe when they were new it was a different story. Naw, who am I tryin' to fool reliable Jaguar is an oxy-moron.
As I said, there is a difference between the amount of power taken to produce a given amount of CFM, and CFM.
The issue here is not how inexpensively you can produce x CFM. It is that you are not going to be able to fit a puller between the radiator and the V12 in the engine bay of a 49 Dodge. It's gotta be a pusher in this situation.
what is the rotation of the water pump on these engines ? CW or CCW . I'm trying to figure out what to do with the fan belt setup.
Should be clockwise (no serpentine belts). One mod is to install an electric water pump in the lower hose. Never did one myself but IIRC there was talk of it in The Book from some lads down under.
I worked for a shop that did some EFI development on the V-q12 Jagual engine for an OEM parts supplier. Under constant heavy load the engine tended to crack pistons and overheat pistons and valves. Subjected to the same tests most street engines would not have been damaged. Bottom line; although the engine gets by ok in normal street use, it has less built-in safety margin than most engines. Not cheap, but at a minimum, better pistons and valves would be needed if you plan to significantly modify the engine and/or lean on it a lot.
Putting SB Ford and Chevy engines in Jaguars is often done because that is cheaper than rebuilding the original engine. And at the same time, the end result is better overall than with the original hardware.
Installing Weber carbs was mentioned. I believe that entire set-up costs about $4,000.00 The V-12 Miata has changed hands a couple times. The first time it sold the entire car went for $4,000.00 including Webers!
I agree that Jag parts cost way more than those for a SBC or SBF, and of course a lot more is available for these common motors.
However I take exception to your statements about their durability. These motors are way overbuilt and, for example, commonly survive running for years with retarded ignitions due to the seized centrifugal advance problem that plagued these motors for years - a problem Jaguar never acknowledged.
probably been mentioned.. but yeah it could be a borg warner slush box.. if the vin has BW on the end of it it has that trans...
I don't know much more about the engine than I posted. I am only telling you what I saw. Like I said, "the engine gets by ok in normal street use". But, it's also a fact that under sustained heavy loads the ones dynoed where I worked all had the weaknesses described. I realize that doesn't mesh with your thoughts on the engine, but what I posted I saw first-hand. You mentioned people getting by with driving around with the advance mechanism frozen. While that's not good, understand that normal street driving is a lot easier on things than "sustained high loads". Make of that what you choose, but the reality is, subjected to the same dyno development the average street engine won't have the failures I described.
I guess we agree to disagree on this one. Check the Jag forums; there are plenty of people running juice and what else through these motors and they stay together. A buddy of mine had a twin-Whipple supercharged V12 that put plenty of power to the rear wheels. He drove it all of the country and he flogged it and never a problem. I don't know what you saw, how you tested them or what you had to work with. Can you shed more light on exactly what aftermarket EFI company or project this was?
Unless you don't believe me there is nothing to disagree about. I saw what I saw. As I have already said, I am not claiming the engine is a POS. I am saying it doesn't have as much safety margin as the average street engine, and that is evidenced by the fact it doesn't tolerate "constant heavy load" as well as the average street engine. I don't see any obvious contradiction between what I saw and what you are claiming.
I think your enthusiasm for this engine may be causing you to miss my point. I could give you a list of engines that won't tolerate racing or severe use, but to one degree or another all of those are decent street engines. In many cases you can get by with upping the output of those engines in a street car. There is a popular V-6 that normally lasts over 100,000 miles on the street. The engine is frequently modified and even turbocharged. But..... in stock form it will blow a head gasket after a fairly short time of sustained full throttle on the dyno. If the original 426 Street Hemi was held at wide open throttle for more than 20 or 30 seconds(don't remember the exact number anymore) the pistons would begin to suffer. That doesn't mean those engines were junk. As I have already said twice, I am talking about, "constant heavy load". That separates engines that are just ok from the ones with more margin. With better pistons and valves the Jag might be bullet-proof, I don't know.
The program I mentioned was done around 1985 or '86. New stock engines were used. Fuel injectors were being tested, and possibly some related components. The work was done for an OEM fuel injector and fuel system component manufacturer. That manufacturer was being considered as an alternate source to Jaguar's existing supplier, who as I remember was Bosch. That was in the early days of EFI. Although fairly small, the shop was not a hole in the wall operation and there were some really smart people working there. They were on the leading edge of EFI and did quite a bit of EFI related work and consulting for all sorts of customers, including a LOT for Ford and GM. The company that absorbed that shop is now a major player in prototype and production automotive and non-automotive components and services. Point being, they knew what they were doing. And no, it wasn't Jack Roush.
Any update? I'm reworking an HE V12 sent by a customer (for the car in my Avatar -- 1939 Delahaye Type 165). He wants it carbeurated to make it look more period appropriate.
Also, do you have a link for the intake manifolds?
...since this 'work' was 25 years ago I gotta wonder why you are so secretive about the 'who' part...
Engine is ready to go but not installed yet. I sent you a private message on the manifold contact info.
"constant heavy load"
Can't figure out why this is even brought up on this thread.
Who the heck has their engine, regardless of use, on "constant heavy load"??
Thanks! When you say "ready to go," do you mean it has been run and tuned on the stand?
Not that the "who" has anything to do with the topic of discussion, my intention was not to be "secretive". The alternate supplier/customer doesn't matter. I said the shop had smart guys who know what they are doing. That doesn't change the fact the owner was a walking-talking POS, and to one degree or another most of his partners and key employees were similarly lacking. Not only do I not want my name associated with that operation, I wouldn't want to have my positive comments about their capabilities to benefit them in any way. You can either believe me or not. In the end you will believe as you chose. I have no personal/emotional feelings about the engine one way or the other, just passing along what I saw.
Like Jack McCoy says, it all goes to credibility.
Now, back to our regularily scheduled programme.......
No, maybe I should have said ready to run instead. I think it will run well though. Besides the stuff already mentioned I also added a 1" plenum balance tube under the intakes. I really don't want to run gas thru the carbs. until I'm getting close to installing it.
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