The 1.8 L-Jet was rebuilt several years ago. The mechanic installed a 2.0 crank and larger pistons. It's still FI and runs fine-but not quite like a 2 liter

Does the motor require 2.0 heads to get the extra hp ? or is ther more to this ??

Horsepower is all about the characteristics of the heads ....

Would 2 liter heads be a bolt on ?

Yes. There will, of course, be intake manifold issues, but you can work around them.

Edit: Another issue may be the configuration of the pistons. Bus pistons have a substantial dish, and work well with earlier heads because of the smaller size of the combustion chamber.

The Cap'n

IIRC , the 2.0 heads would be a bolt on but because the spark plug location is different than the 1.8's you would need the 2.0 cooling tin over the head area.

BTW, I did that conversion to my 1.8 which is now a 2056 L-jet with a mild cam. My intake and exhaust valves on my 1.8 heads were increased to 2.0 spec.

Hard to know what the mechanic used but 2.0L crank with bus pistons gives you 7.3 to 1 CR with Bus heads (which have a smaller chamber). Same setup with 1.8L heads (52CC chamber) is even less CR.
914 2.0L heads are 55cc so with bus pistons your CR falls even lower. You have to match the whole setup to get the HP- 2.0L USA or Euro flat top pistons and 914 2.0L heads to get the 100hp.
Bus stuff gets you 67hp......

I run into so many engines where the guy who built it doesnt even know how to set compression or what head cc means.

even if you pull the valve covers to see what heads you have, its hard to say how deeply they are fly cut, did he use head gaskets, what shims are under the barrels...

if it runs well, leave it alone

Thanks for the input; I'll stop by and ask about the parts mentioned above. Yes it runs really good, I drive it daily. Will post my findings...

Talked to mechanic this a.m. to answer some of the questions:

1. Valves are 1.8
2. Not bus pistons, but flat top
3. No flycut made at rebuild
4. No shims under barrels

His thought on perfirmance is related to the AFM setting/throttle body size, and possibly the injectors.

I would stick my wide band meter up its tail pipe. AFR should be checked.

L jet is tunable