On Sat, 19 Oct 2019 07:42:27 -0700 (PDT), wrote:

On Wednesday, October 16, 2019 at 4:48:55 PM UTC-4, wrote:
So when I retire in a few years I want to build a sports car from
scratch. I have the equipment and knowhow except for the bodywork.
Which means I would get to butyand learn how to use an English wheel.
I don't know which engine to use though. So I'm looking for
opinions. I want to use a 4 cylinder engine. The engine needs to be
fairly common and parts must be available for hopping it up a bit and
for general rebuilding.
Very important the engine needs to look great. So I'm looking for
opinions here. A great looking engine that's fairly common, can be
hopped up some, and won't break the bank to work on.
Thanks,
Eric

"Looks great" caused me to slam on the brakes. g As for your other requirements, it's hard to beat Hondas for most of them. Japanese law required that engines be changed at 40,000 miles a decade or so ago, which put a lot of used ones on the US market. Moderate speed equipment is readily available.

I rebuilt two Alfa Romeo 1300 cc engines in the late '60s. They were beautiful. One had a Veloce head with twin side-draft DCOE Webers. I don't know of anything that looks that good today, but it's hard to tell until you get all of that plastic junk off the top of them. I own a 2018 Subaru Crosstrek, and I've seen it with the plastic off of it. Not exactly a thing of beauty, but I do like the engine.

If you want real sports car performance, avoid turbos. The turbo lag is antithetical to sports-car type responsiveness, unless you spend megabucks. Garden-variety turbos are not sporty engines. They just wind up -- eventually -- and put out a lot of power. In a light sports car, you don't need that much.

What you need is great throttle response and good breathing. There are a lot of good engines out there today. Your project is one I've dreamed about off and on over the years, and having done some sports-car racing between 1967 and 1972, I have a good idea of what I'd want my engine to be good at if I ever did it. I'd look at Honda, Toyota, and Nissan. If one dropped in my lap, I'd look at a 3-Series BMW. But I'd make sure that aftermarket parts are readily available for anything I chose. Oh...and make sure you can mate it up with a transmission for rear-wheel drive. Maybe an engine that's used in a small pickup.

Good luck and have fun!
I am also considering motorcycle engines, though I dont know how I
would marry one to a transmission. But a V twin, a BMW boxer twin, and
a 4 cylinder boxer engine have all crossed my mind. There are some
older foreign engines I really like but then that may make parts hard
to get and expensive.
Eric