I have a 76 VW van and a 74 914, both with 2.0 Type 4 motors. I have been searching the internet, without much luck, trying to find out what modifications Porsche did to the internals of the VW Type 4 motor to bump horsepower from 67 to 95, and torque from 101 to 119. I see the heads are different. It also looks like they both used dished mahle pistons, with the Porsche having a 7.6 compression ratio, and the VW a 7.3 compression ratio. Anyone know what else was modified such as camshaft specs, crankshaft, etc. Thanks.

The bus pistons have a larger dish, which I've read is part of what gives them the lower compression ratio

Jake Raby covered all the information you need to know in depth. He developed a engine kit specifically for the VW Bus to maximize horsepower for it. Check Type 4 store for kit information.

The bus motor has hydraulic lifters with a different csm and has a lower red line.

2L bus has 1.8 heads and valves, lower compression, deep dished pistons. Not a true 2L.

They're all 1971 cc — not really 2 liters

Here's a chart from the old tunacan site
Click to view attachment

If I recall, the 76 912E had L-Jet. Table says D-Jet...

I think you're right, Wikipedia confirms it.

Trying to verify that, I came across a thread on 912bbs.org saying that 912e engines didn't have numbers stamped on the block, and the number on the fans shroud started in "406" and not 2 letters. I don';t have much experience with 912's to know for sure.

912E is L jet.

bus motor is more or less a bored out 1.8 as @TheCabinetmaker says.
its all about torque. its a truck engine (thats not an insult - just what it is).

the 914 2 is a porsche re-engineered VW engine.
i think Hans Mezger did the design work on it?

EDIT
maybe the most interesting engine of them all is the least known.
1.8 AN engine for europe only.
8.6:1 compression ratio and 85 hp.
pumping out nearly the same as the USA 2.0 L from 75 on.
but carbies and no emissions gear and a taste for high octane fuel.
if they had stuck L jet on that i reckon they might have pulled 90 hp out of it.
but it would have required its own tuned L jet system = more research development $ they didn't have budget for?