I’ve been looking longingly at speedster replicas for quite a while (including lots of lurking here) and am now getting serious about buying one.
I’m completely baffled, though, about how to think about the engine sizing and how that relates to real-world fun and driving performance. I have some very quick vehicles (997 911, M4, Rivian R1T, triumph Street Triple… you get the idea). I don't expect the speedster to keep up with those, nor am I buying one in hopes that it will, But I also don’t want it to feel boring and sluggish. I live in Western PA so I expect I’ll be driving it mostly on curvy, hilly backroads where lots of power is not necessarily required for a fun drive. That said, “More power, more better” has worked pretty well as a heuristic in the past :-)
It seems that standard air cooled engines run from 1600 up to about 2300 cc’s, and that HP and torque go up more or less with displacement. But it also seems that a given displacement can yield a wide range of output power.
I’m mostly looking at 2nd hand replicas from the major vendors on BaT, her, PCarmarket, etc. none of which really offer an easy way to try the vehicle out before buying. Most of them, though, list engine displacement.
So… should I steer clear of the 1600 cc’s (there seems to be some sentiment that way in the forums)? Is something in the 1900 range likely to feel quite lively and sporty, or should I be looking for a big air cooled engine (>2l)?
I realize this is fundamentally a subjective question, so please do share your subjective, opinionated thoughts on the topic — those are exactly what I’m looking for.
Thx.
Welcome to the group, Bubba. I'm a proponent of "too much is actually too much," but reading your query I will advise you thusly: You want a big engine with a spiffy cam and high compression, balanced, with a lightened flywheel, and as close a close-ratio gearbox as you can get.
You seem to be demanding an air-cooled deal. So I'll start out by saying any Subaru-powered Speedster will put you in the power position you seek. I put a 2.2 Subaru in my MG replica and its 137 hp is absolutely more than is prudent for that chassis. You would enjoy a 2.5 with 165+ hp. The Suby offers a modern torque curve with is very flat and broad—very different from a Type 1 with similar displacement.
For Type 1s, I think your minimum engine is the very popular 2110 CB Performance build with 150-ish hp. That's a reliable package: dual Webers, header, .460 lift cam and power peak about 5500-6000 with the long runover arc you get with solid lifters. Put a rev limiter on it and set that to 6500 just to be reasonable.
And more is more. A 2165? 2180? 2270? Sure. If built by reputable pros, dynamically balanced, etc., with cam and heads (Panchitos) that make it want to hang around the right hand sweep of the tach. You'll be looking at HP in the 165-185 range.
Then pair it with a transaxle with 3.88 ring and pinion and a .93 4th gear. That's a standard Beetle ratio and it's good for what you want to do. Do not be snookered into going for a "freeway flyer" highway 4th gear (.89 is ok but .82 is absolutely not). Do not get my favorite 3.44 r&p. It would be wasted on you and your car. If you really want to go crazy (I mean have fun) get with @DannyP and build a gearbox to his specifications with higher 1st and 2nd gears and a shorter 4th. Or get in line for a Berg 5 Speed.
Lots of Speedsters were made with 2110s, and most of those were built more or less to that 150 hp hotrod standard. You might get lucky. But probably not.
To get the car you describe, buy any Speedster that looks and runs well for an affordable price, and budget $10k for the engine/trans. Good luck!