Saw an average looking 914 for sale at a decent price. But, it has a VW Bus 2.0 litre engine. Hydaulic lifters aside, why did that engine produce 20 HP less than the 914 version?
SAme L-jet FI wasn't it??

S-M-O-G Regs.

.... IIRC they didn't start using the 2.0 in buses until 75 or 76, so it's got comparable or greater limits to the 75-76 914 2.0's which dropped from 95 down to 80 or 86 hp due to the smog eqpt. added

I thought the buses & Vanagons with 2.0s were D-jet like the 73-76 2.0's , but I really don't know.

The 2.0 914 heads are performance oriented in design, and radicaly different from the 2.0 bus heads. Improved spark plug angle and bigger valves and ports on the 914 heads. The combustion chambers are larger too and designed to work with smaller piston dishes.

The old 2.0 bus heads are usually garbage at this point having been overworked and overheated countless times in their abused lifes. They only have value as scrap IMO.

I think the oil dip stick location is different.
Dished pistons not flat top were used.

2 liter buses started a little later than 74-75 I think, before that, they were 1.8's. All FI buses were L-jet. 79 and Vanagons (80-83 air cooled) have square exhaust ports unlike our 914 oval ports. Vanagons have a different part where our 914 oil filler/PCV tower is. It's like enclosed with a breather where 914's have a rectangular opening into which the black filler is located. Lower compression with larger dishes in the pistons, hydraulic valves (on later years), to the best of my recollection. 71's were type I motors; type IV started in 72 with carbs. Much of the internals are same as 914's (maybe not camshaft). I would say the cylinders are the same 039's as 914's.

http://www.thesamba.com/vw/archives/info/engine_letters.php

I have a 78 bus GE motor in my 914. I can answer pretty well, the motor has low end but REALLY peters out above 4500. At about 5500 the valves start floating from the hydraulic lifters. It will move the 914 just fine, but won't be anywhere close to a GA. I had outrun 1.8's in the past with it, but the heads have since gone bad. The heads have tiny valves, big dished low compression pistons, a different cam, and some say the rods are a few grams heavier than the Porsche, but I have never weighed them.

...Type 47 pretty much states it
(popcorn for everyone!!)

Yes, bus 2.0L engines had Ljet not Djet.
Biggest differences are the heads with smaller valves, CR is 7.3 to 1, same cam except when they used the hydro lifters, different flywheels.
Crank, rods, lots of everything else is the same parts.

Didn't Hans Mezger (Porsche) design both of these 2.0 engines for VW? That is the Bus and 914 versions.

The heads and compression are what make the difference in performance for sure. Also, The 912E shared the same engine as the last 2.0 914s exept it had the newer L-jetronic fuel injection.