Club 80-90 Forums

Swapping out my CS engine with either a 1.6 JX or 1.9 AAZ. The 1.9 is $1000 USD more. Is the 10HP increase from the 1.9 worth the money? Will I actually get the 10HP increase if I'm bolting on the bits from the JX? This is on my 1982 Westfalia 1.6D. I'm in America so pardon my differences in specification language if anything looks odd. I have all the factory air plumbing from a JX engine German van. 

I don't know much about either of those engines, except that to get the real benefits of either you will need longer gearing because the CS doesn't have much torque so needs shorter gearing and revs harder.
A long time ago now I changed my CS engine for a 1.9, and it just cried out for longer gears. I did this by changing the 4th gear set from .8 to.7 approximately (Aidan will know the exact figures) and it made a huge difference.
Others will know more about the engines than me.

The main benefit of the AAZ is the better reliability.
The JX cylinder heads are known to cracking between the valves, where the AAZ will last long.
When maintained right, the engine should last long.

The head being improved is reason enough to justify the extra cost for me. The gearing will be dealt with when I have a gearbox built. What's the issue about using the JX intake with oval ports and the AAZ head port being D shaped? 

dieselvw4ever wrote: ↑10 Sep 2026, 12:14 What's the issue about using the JX intake with oval ports and the AAZ head port being D shaped? 

The 1.9 D shaped ports cannot be matched exactly with the 1.6 manifolds as the mating area gets a bit narrow at the pointy bits of the D. You can do a bit of improvement , but the mismatch won't be a big deal as it's just at those corners. I suppose you could build up the manifold with a bit of welding, but I wouldn't think it's worth it. This isn't F1 after all.

colinthefox wrote: ↑10 Sep 2026, 19:48

dieselvw4ever wrote: ↑10 Sep 2026, 12:14 What's the issue about using the JX intake with oval ports and the AAZ head port being D shaped? 

The 1.9 D shaped ports cannot be matched exactly with the 1.6 manifolds as the mating area gets a bit narrow at the pointy bits of the D. You can do a bit of improvement , but the mismatch won't be a big deal as it's just at those corners. I suppose you could build up the manifold with a bit of welding, but I wouldn't think it's worth it. This isn't F1 after all.

Further to this, there's a picture of this partial port matching at https://www.brick-yard.co.uk/forum/1-6c ... KW=#413096 Its for an AEF engine, but the principles are the same for AAZ.

Hope this helps.