Thanks heroe and ghosttanker, you have given me lots to think about. I have a few questions I hope you can help me answer and I must apologize in advance, because I am going to have to create another table! Many options!
I have the opportunity now to decide what engine to drop in. I am getting the car in about 3 weeks and for a short period of time I can work on the Z and drive my current Rabbit, but then I will sell my Rabbit and use the Z as a daily driver. I don't want to do this work after it is my daily driver. So I am putting myself under this pressure to build as much as I can now.
I have no machine shop, garage, automotive tools (phillips head and a hammer! no sockets!), chock blocks, micrometer, etc. It has been over 20 years since I turned a wrench and even then I had variable success on the couple of engines I tried to rebuild (Audi 200 4 bangers) - first one blew a head gasket in Austria at 2 AM. The tranny I rebuilt worked well, though. I want a professional job done, since it is to be my daily driver. I'll have to pay for that.
I see now that it may be better to keep the e-31/L24 stock and in storage, along with the 4-spd and the R180 diff. This way, it can be restored to stock. I have read and you have mentioned that the e-31 head is valuable, as it has higher compression. I think it is already port&polished, it would just need the cam. But I think I should look into the p-79 or p-90.
A few questions:
Doesn't compression also dictate horsepower?
What is a reasonable upper limit to compression for street driving?
What is the most horsepower a L28 can deliver, with that reasonable compression, and what would need done?
Would a p-90 with its turbo be a good direction for max horsepower or is a turbo a big headache?
What is the story on these longer valves? It sounds like you are saying that whether I go with the e-31, p-79 or p-90 I need these longer valves.
I have a little money to spend and I found an L28 with a p-79. Since a) my car is completely restored/rebuilt and b) it's a daily driver so I am concerned about reliability, then I am considering whether to rebuild the engine. This takes me down a merry path because if I rebuild the engine, why not take the opportunity to overbore and put high compression pistons in? And if I do that, I really need to do head work, install better valves (which do I need and where could I get them?), a stage II/III cam, and invest in triple Webers! $$$
So decision matrix time:
|1||stock F54||worked E31||10:1||180||no||no||stock||stock||stock||stage 2||SU|
|2||stock F54||stock P79||??||??||no||no||stock||stock||stock||stage 2||SU|
|3||stock F54||worked P79||??||??||no||no||stock||stock||long||stage 2/3||triple Webers|
|4||rebuilt F54||worked P79||??||??||no||no||stock||stock||long||stage 2/3||triple Webers|
|5||rebuilt F54||worked P79||??||??||no||yes||HP||stock||long||stage 2/3||triple Webers|
|6||rebuilt F54||worked P79||??||??||no||yes||HP||HP||long||stage 2/3||triple Webers|
|7||rebuilt F54||worked P90||??||??||yes||yes||HP||HP||long||stage 2/3||triple Webers|
Option 1 is your recommendation, ghosttanker. Option 6 is kind of where I was headed in my mind and just do the whole thing!
A few more questions I hope you can help me answer, so I can completely understand my options:
What's a rough idea of the compression and horsepower for these options?
Which options should I just eliminate as bad price/performance?
Given that I can overbore and get HP pistons for a particular compression, what overbore and compression should I get, if I go there?
Given some money to spend now, what would you recommend?