I hadn't planned to buy an engine so soon, but one came up VERY cheap locally. I thought about it a few days and decided to buy it.
The engine is a Holden 5 litre V8. As you can see, I got it with all front accessories, ECU, wiring harness and transmission.
I had to do a trial fit, to make sure it would fit. I was worried about how wide the front accessories sat, particularly the alternator and power steering pump. But my worries were unfounded. Even with the engine sitting way too low and tilted too far tail down, there is plenty of front room and plenty of exhaust room.
Even the bonnet clearance looks like it will be fine.
The transmission is a TH700R4 4 speed auto and is a pre computer controlled version, so all I need to hook up is a switch for torque converter lockup. The Holden V8 is multi point injected and makes about 50 ft/lbs more torque than the V12, despite being smaller in displacement.
The Holden it came out of had a 3.08 diff ratio, the XJS will be 3.55. So I am assuming that with the much shorter first gear in the 4 speed auto, shorter diff ratios and more torque, it should be a good match and will likely be faster than a V12 powered car, and get much better economy with the overdriven top gear. The new engine and transmission is also around 100kg lighter than the old combination.
Plus I won't have to look at the temperature gauge every two minutes as if it were a V12!
Jaguar used GM automatic transmissions in the V12 cars (Turbo 400) and I'm reliably informed that the shifter will bolt right up to the transmission and converting the electronic speedometer drive on the transmission will be as simple as using factory GM parts as well. Even the tailshaft yoke should slide right in. Tailshaft will probably not be the correct length though.
The plan is to do all the body repairs and keep an eye out for a cheap donor car for suspension crossmembers etc. Then when I have the rear and front crossmembers, I can fit the engine in, make up engine mounts, wire the engine up and ensure it will all work. Then I will remove everything again, paint the body and engine bay and refit it all. This will hopefully minimise the amount of damage to the body fitting the engine may cause.
Once the engine is finally back in I will tidy up all the wiring in the car, including engine swap and ensure it all works before I work on the interior. This will allow me full access to behind the dash and to run any wiring I need.
By using the original Holden wiring harness and ECU, I can take advantage of a few things. The Holden ECU will trigger electric fans, it will engage the air conditioning clutch (and automatically provide idle up at the same time) and also has an immobiliser signal terminal, so I can wire up a simple aftermarket remote door lock kit and automatically immobilise the car at the same time. By using the Holden ECU for air conditioning, I can also bypass the sometimes troublesome Jaguar airconditioning unit, all I need is for the Jaguar aircon switch to signal the Holden ECU when it wants the compressor to run.
The best part about the Holden ECU wiring is that it's complete. All it needs from the Jaguar is a few ground points and a couple of constant 12v and switched 12v inputs.
The engine is a Holden 5 litre V8. As you can see, I got it with all front accessories, ECU, wiring harness and transmission.
The transmission is a TH700R4 4 speed auto and is a pre computer controlled version, so all I need to hook up is a switch for torque converter lockup. The Holden V8 is multi point injected and makes about 50 ft/lbs more torque than the V12, despite being smaller in displacement.
The Holden it came out of had a 3.08 diff ratio, the XJS will be 3.55. So I am assuming that with the much shorter first gear in the 4 speed auto, shorter diff ratios and more torque, it should be a good match and will likely be faster than a V12 powered car, and get much better economy with the overdriven top gear. The new engine and transmission is also around 100kg lighter than the old combination.
Plus I won't have to look at the temperature gauge every two minutes as if it were a V12!
Jaguar used GM automatic transmissions in the V12 cars (Turbo 400) and I'm reliably informed that the shifter will bolt right up to the transmission and converting the electronic speedometer drive on the transmission will be as simple as using factory GM parts as well. Even the tailshaft yoke should slide right in. Tailshaft will probably not be the correct length though.
The plan is to do all the body repairs and keep an eye out for a cheap donor car for suspension crossmembers etc. Then when I have the rear and front crossmembers, I can fit the engine in, make up engine mounts, wire the engine up and ensure it will all work. Then I will remove everything again, paint the body and engine bay and refit it all. This will hopefully minimise the amount of damage to the body fitting the engine may cause.
Once the engine is finally back in I will tidy up all the wiring in the car, including engine swap and ensure it all works before I work on the interior. This will allow me full access to behind the dash and to run any wiring I need.
By using the original Holden wiring harness and ECU, I can take advantage of a few things. The Holden ECU will trigger electric fans, it will engage the air conditioning clutch (and automatically provide idle up at the same time) and also has an immobiliser signal terminal, so I can wire up a simple aftermarket remote door lock kit and automatically immobilise the car at the same time. By using the Holden ECU for air conditioning, I can also bypass the sometimes troublesome Jaguar airconditioning unit, all I need is for the Jaguar aircon switch to signal the Holden ECU when it wants the compressor to run.
The best part about the Holden ECU wiring is that it's complete. All it needs from the Jaguar is a few ground points and a couple of constant 12v and switched 12v inputs.
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