For the last few days i have read on this fourm triying to make a decision on weather to build a Jag V12 or BMW V 12. For my Expermental Aircraft an Curtiss O-1. I need a V 12.!
From what I have read It has been don’t before. But there is not much mentioned lately and where custom parts might be available. Can you all help me get going . I live in northern Wisconsin.
Ill assume you are an EAA member?
Not yet but will soon be. I have read there forum too.
Is this to be a full size replica, or scaled smaller?
I suggest you get in touch with Bill White in Christchurch, NZ. He once built a Jaguar V12 for a scaled Spitfire replica.
Full size
Original had 435 H P. Eng.
Im betting EAA will have good information on this: my guess is, the BMW engine would be better.
One of our club members has a Bill White 7litre V12 in his XJ with custom designed and built quad throttle bodies, very professional looking engine.
VERY interesting report.
A lean running Jag V12 !! A Jag with fueling problems !! Surely not !! Arguing over acceptable oil pressure and coolant readings !! Has someone been eavesdropping on Jag Lovers !!
But seriously, I would encourage anyone considering running a standard Jag V12 at 6,000 rpm (or more) for any length of time to consider replacing the main bearing caps with steel. Especially if they happen to be sitting aft of the engine, 3,000 ft in the air!
(Curious thought. I wonder how much money and time was spent on that aircraft? Why would you NOT spend a little more to get the engine tuned correctly? Or have an EGT readout? Or lambda feedback?)
Actually I don’t need to run it 6k rpm. As I want to run prop direct drive so max rpm would be about 2800 rpm. That’s why I need as much cu.in. As I can get. I dont want the expense of having to design and build a reduction drive unit. No turbo unit either.
Or, a completely different ECU?
“The ECU, of a type normally used in cars, is programmed to compensate for altitude and pressure changes. It was not reprogrammed for this installation.”
GULP!!!
Yeah, but aircraft engines are rated differently than car engines. Using the aircraft rating method, you’ll probably be lucky to get 200 hp out of a stock Jaguar V12. Plane would be a dog.
To make it work well, you’d probably want to soup up the V12 some, and you’d probably want to run a gear reduction to the prop – possibly using a toothed belt.
You also probably want to turn the engine around backwards so you’re driving the prop from the flywheel end rather than the damper end. That might result in the prop turning the wrong way, I dunno. If so, you might want to use actual gears for gear reduction rather than the toothed belt.
There are four different OEM and at least one or two aftermarket ignition systems available for the Jaguar V12. If I were flying this thing, I’d insist on dual ignition systems – which is likely to be a serious chunk of the work involved. You could install dual distributors I guess. One idea might be to use an engine with a distributor and ADD the distributorless Nippondenso ignition that was fitted to the 1995 model. You’d want to use an MSD Automatic Coil Selector – or perhaps 12 of them – to allow either ignition system to fire the single plug per cylinder. Getting a second spark plug would be too hard on this engine, but I wouldn’t care unless there’s a regulation involved. If one plug goes bad, you can still make it home on 11 cylinders, but if one ignition system goes bad and it’s the only one you’ve got, you’re in trouble.
I’d also insist on dual fuel pumps.
Oh, one other thing: I know you’ll wanna run 12 individual open exhaust pipes, but if you use an '81 or later Jaguar V12, it’ll have feedback control in the EFI system so it’ll need an oxygen sensor in each bank. And that means you have to bring those six exhausts together on each bank.
That actually would make the prop rotate in the correct direction; ever since Cocky was an egg, planes have had the prop on the “flywheel’ end of the engine.
It’s also why, I think, the XK engine’s Nu. 1 cylinder is the one nearest the flywheel. I think it was an homage to that tradition.