XUD to XU conversion?

B

Blufires

Member
Fellow Frogger
Joined
Nov 7, 2010
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279
Location
Half way between Brisbane and Ipswich
I've got an XUD9TE in my 405 SRDT wagon. I've started to get the itch for a revvy petrol engine with cams and individual throttles, and I'm tossing up between:
*getting an XU10J4R/RS engine to clean up and eventually install.
*getting just the head and putting it on the XUD9 block that's already in the car.

Both are iron blocks, though the XUD9 has the same bore and stroke as the aluminium XU9J4. Are there any other differences I'm missing?

Also, if I wanted to increase the compression, would I want to mill down the head or the block?
Would I be able to avoid a modification plate, as the XU10J4 (non-R or RS) was a stock engine for the series 2 405?
 
You could certainly use the block and crankshaft. You'd need to bore out the block to suit an XU10J4 piston and use an XU10J4 rod. There will be heaps of compression, ie approx. 11:1.
 
PeterT said:
You could certainly use the block and crankshaft. You'd need to bore out the block to suit an XU10J4 piston and use an XU10J4 rod. There will be heaps of compression, ie approx. 11:1.
Click to expand...
Do the diesel ones sit further up in the cylinders to make the ~22:1 compression? I thought it was just a smaller cavity in the head. Could you avoid boring the block by using the pistons and rods from an XU9?
 
I can only guess that an XUD head basically has no combustion chamber and the valves are vertical therefore the xud9 pistons would not have valve cutouts - only a pocket to help with combustion.
 
XU9J4 rods and pistons won't work. They're too short.
 
XUDTE blocks are sought after in the UK. They're used for race engines to make 85x88, ie 1997cc, for under 2L class. The diesel oil squirters are replaced with petrol versions, as their excessive orifice wastes a bit of oil pressure.
 
What if I put the diesel pistons on the lathe and trimmed a few mm off the top (until it's flat) and add some valve fly cuts on the mill? It looks like there's plenty of space above the rings. If the XU10J4R head has a 34cc chamber then removing 2mm from the piston would give 10.6:1 compression. Removing 4mm would get down to 8.5:1 for a turbo. Would that mean the engine would still be capable of the cylinder pressures the XUD9TE generates (22:1@20psi = 55:1 effective)? Then it would only be held back by the limits of E85.
XUD9 piston.jpg
 
If the head is good I may need it, located close by. Will be in touch?
 
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