10 valve or 20 valve

Whats the obvious way of knowing which is which on the 850 series?
Does the 20 have more ooomph!!!?
And finally is either type the one to avoid?

 

The 20 Valve will say so right on the engine in big obvious lettering. Yes
it's significantly more powerful, and no not really any reason to avoid
either, both require careful attention to the timing belt replacement
schedule.

 

10's will say "DOHC" and 20's will say "20 valve" on the black plastic cam
cover.

Also can determine which engine and number of valves from the engine code,
which willbe on the cam belt cover on a white sticker:

EG

B 5 20 4 F x

5 cyl 2.0 liter 4valves/cyl naturally asp sometimes
extra digit present, sometimes not

B5234T4 would be 5 cyl, 2.3liter, 4 valves, turbo. (in this case high
pressure)

As general rules:

Avoid the both variants of the 2litre- especially with auto box; not really
powerful enough

2.5 10v auto, again struggles abit, but capable 8 out 10 times.

2.5 10v manual entirely capable unless regularly fully loaded. Most common.
Good engine, abit lazy in power delivery but a good slogger. Pulls well from
2500-5000rpm. High gearing on manuals blunts it, but effortless cruiser once
upto speed. Happier at 100mph than 70.

Only thing to watch is the exhaust manifold is unique to this engine
(B5252S ) and the flexi pipe occasionally begins to leak after 80-100k
miles. Good 2nd hand manifolds are vvvv rare, new ones 400quid. Check
carefully.

2.5 20v- carries on where the 10valver becomes uninterested- after 5000rpm.
mpg only very slightly lower than the 10v. Better choice if you want an auto
or tow.

2.5T best engine of the lot. Power at any revs, any gear. Deceptively fast
and effortless. Mpg late 20's to early 30's. Rare. Front tyre wear a slight
issue.

2.3T5. at times violently powerful. Traction control attempts to control it
but usually fails. Front Tyre wear a serious issue- manuals especially
savage. Can be heavy on fuel, and slightly more susceptable to poor
maintanance.

With all engines- broken timing belt results in scrap engine. Not known as a
belt breaker though. Belt change interval on cam belt cover. Regular fresh
oil (every 5-6k miles) and fresh coolant every 24months and they'll all do
200k without problems.

Hydraulic tappets should be silent immediately from cold start. If not- walk
away. Head gaskets occasionally go at over 100k- purely from lack of fresh
coolant. Due to engine construction its neither quick nor cheap to change it
and expect it to remain leak free done on the cheap.

Manual clutches last well- over 100k miles usually (except on t5's) but
again not cheap to replace due to complexity. A cheap job usually always
results in recurring problems after.

Autoboxes can pack up around 100k due to lack of specified fluid changes.
Will go for along time if fluid is changed every ~20k miles though.

Air con evaps often burst- dash out job to replace. ($$$$)

Sagging rear susension, & knocking front wishbone joints suggest a hard
life- about 250quid to sort.

Condition and evidence of proper maintance is more important than mileage.

Tim..