C20NE 8v to C20XE 16v

[GP123]

Hi all,

Ive been doing a bit of reading on the C20NE and C20XE engines. The blocks are meant to be the same.

For power would i be better off using my low mileage C20NE block and fitting a redtop head to it? Are the looms different?
The ECUs will be different im sure.
Then XE intake manifold. Gearbox should be ok but will need flywheel and clutch upgraded?

But instead of buying a redtop engine with god knows what mileage and rebuilding it for peace of mind, could i just not put the new pistons and rods into the NE block? And put a nice refreshed XE head on.

Im weighing up my options for the new cav. Id love to do a V6 conversion but keeping it 2 litre is also a food option but staying NE is just wasting money imo for very little gain..

Thanks for any input chaps.

[Robsey]

There are quite a few bits to change.

These will include
Oil sump (XE has an oil level sensor), or you could modify the wiring to fool the sensor wiring.
Complete ECU and loom.
The XE has some differences in sensors.
Cylinder head, manifolds, throttle body, MAF sensor and induction pipework.

The remainder of the exhaust should still fit though.
And the main electrical loom will still fit.

[Envoy CDX]

You'll need everything mentioned above, but I would recommend also looking at pistons, and rods too - pretty sure there are subtle differences that make it a non-starter. Pretty sure there is allowances in the piston crowns for valves on the 16V head for one.

You'd be better off getting a complete engine, loom and ECU from a known working car and rebuilding it to be frank, not that it can't be done. I just think you'll be at a better starting point.

[Robsey]

I would recommend also looking at pistons, and rods too - pretty sure there are subtle differences that make it a non-starter. Pretty sure there is allowances in the piston crowns for valves on the 16V head for one.

I think you are right Gary,
The 8 valve engines are of the 'non-interference' type,
But the 16 valve engines are the 'interference' type.

With an XE engine, I would want to strip and rebuild it anyway.
Most have been driven very enthusiasticly, especially by the Corsa / Nova brigade.

But when looked after, they are a very good unit.
Combining similar economy to the 8 valve units when driven leisurely.
And good raucous fun when driven enthusiasticly.

[Envoy CDX]

they are good strong engines, and put up with alot. But even a simple crank regrind, new bearings, bores rehoned and such will be good, service / replace the oil pump etc. Be lovely.

[vexorg]

The heads have their issues, search "porous heads" and you'll find a lot. Basically coscast were good, the other were suspect. A simple fix was available of inserting a pipe into the oil feed in the head, the casting were too thin between the oil feed and water jacket.

Rods are different, the 16v rods are a bit meatier, the xe has the same rods as the turbo.

Gearbox will probably be different, F20 / F16 I think. Flywheel was different too, pot / flat. Though probably the original will work fine.

If you are going ahead with existing block then you need to check the pulleys are the same, there is a square tooth and round tooth version of the belt, later heads will be the square tooth.

[chrisp]

Talk of porous castings reminds me of an Austin Maxi that I bought new in 1981, having previously had a very good secondhand one. Oil consumption on the new Maxi was terrible (about a pint every 100 miles or so) and after much to-ing and fo-ing with BLMC I eventually got them to pay for an engine rebuild - which I organised myself because BLMC garages were so hopeless. This showed me that the block casting was porous (thus absorbing oil into the walls and then burning it) and was an early-manufactured one that BLMC had initially rejected - but then "used up" in the last Maxis to be built. The engineering shop that I used for the rebuild solved this by sleeving the bores and, after that, I had no more trouble with it. But it put me off BLMC products for ever and I soon sold the Maxi and replaced it with my first Cavalier - a Mark 2 one which gave me no trouble at all over 100,000 plus miles. I then replaced it with a Mark 3 2.0 litre which eventually ran to 230,000 miles with absolutely no replacements - not even the clutch, eventually adding to it my 1993 V6 Auto, which I still have.

[Robsey]

The flywheel type is usually model year dependent, rather than engine specific.

Most post-92 cars have the recessed 'pot' flywheel.
Even the C16NZ2 and C18NZ.

Same with gearboxes.
F16 and F20 were used on earlier cars...
The F18 became the "standard" box from approx 1992.

Real enthusiasts will always recommend an F16 with wide ratio 5th gear.

[vexorg]

I'm sure the calibra had the F20 on all xe engines, cant imaging the cavalier was different.Same with the flywheel, I'm sure I've seen flat flywheels on late 8v cars.Maybe it was just lucky dip on what was in the parts store.

[Envoy CDX]

F20 was more a GSI / Calibra XE thing, however. F16 was common from 89 through to 93 for 8v engines. F18 replacing that, and introducing the deeper flywheel which ended 45 minute clutch changes. Cav Turbo's got the F28 box.

[vexorg]

Try find a decent F28 these day at a sensible price.

[Envoy CDX]

Try find a decent F28 these day at a sensible price.

Depends what power he is going for, and also you need the blanking kit for 2wd.