Ignoring the the technical challenges of each...
Which small, car-based, aluminum, pushrod engine would be the most interesting to you?... And what would you put it in?
a) 100+hp 90* V-twin.
b) 100+hp parallel-twin.
c) 200+hp 90* V4.
d) 200+hp inline-4.
I'll take the 200 hp inline.
More power and easier to package.
I'll take 200 HP in the V4 please. I like power and I love the sound of a V4.
An engine I would actually put in something? Make the V4 a 75ish degree engine for packaging it and I'll pick that one. There are already good I4s in that space so no real need for another one of those.
I love the sound of my Honda 90deg V4 motorcycle, so one that is twice as powerful would be awesome.
My favourite V4 was a narrow one with only one head - the Lancia Fulvias which used 10-20 deg. V so the single head would fit.
Generally a 90 deg. V4 just wastes space - the 60 deg. versions are better in terms of packaging.
Guess I'd choose an I-4. but I don't own a modern one with only 200 bhp.
In reply to gearheadE30 :
I don't know of any 200 hp pushrod I4s.
In reply to Toyman! :
Good point, I was just thinking in terms of I4s in general.
Which I guess brings me to a different question - are there any gas pushrod I4s left? The last one I can think of, outside of diesel engines which are often still pushrod, is the iron duke.
All of the good Honda VFR's used a 90 degree V angle. I'll take a 90 degree V four, please. And no pushrods.
Driven5, inquiring minds want to know why you're asking. I mean, it's like saying "Hey guys, which of these high heels do you like best"... it makes us wonder what you're up to...
Toyman! said:In reply to gearheadE30 :
I don't know of any 200 hp pushrod I4s.
Mercruiser? (The 3.7l half-a-460)
Pontiac Super Duty fours made well over 200hp depending on how you built it. They made up around 400hp in race trim. I saw a SD engined Fiero runs nines in the quarter mile so a fair bit more than 200hp at least. These engines are based on the Iron Duke.
Chevy, I think, also made a very, very nice pushrod four specifically for Midgets. Besides the usual massive lean to the left, the camshaft was on the exhaust side so the intake ports didn't have to snake between the pushrods. "Car based" is a vague suggestion here 
gearheadE30 said:In reply to Toyman! :
Good point, I was just thinking in terms of I4s in general.
Which I guess brings me to a different question - are there any gas pushrod I4s left? The last one I can think of, outside of diesel engines which are often still pushrod, is the iron duke.
I am pretty sure that Minis had A series engines right up to when they stopped making them in 2000 or so. 70% sure that one of the Japanese makes put pushrod fours in production trucks for a little after that.
There are probably companies in India or the Middle East locally making copies of 50s-60s cars, but I know little of them. Off to Google!
In reply to kb58 :
I would actually have a much better idea of what OP was up to in that case than I currently do.
In reply to kb58 :
It's really just an idle curiosity born of playing with a few dumb ideas in Fusion 360, to look for ways around the reasons that each will probably never work, while daydreaming about types of applications I'd like to use each in.
For what it matters, the basic challenge is figuring out how to accomplish it using as many of common off-the-shelf components as possible, as cheaply as possible... So pushrod V8 based, it is.
The motorcycle companies have sorted out all of those designs and requirements, why re-invent the wheel?
Moto Guzzi's big block twin is a great engine, gobs of torque, sounds great and gets used in Morgan replicas a lot. Looks, sounds and runs better than the Milwaukee paint shakers.
In reply to Driven5 :
One can apparently make about 200hp from a decently built Ford V4 engine. They are very compact 60 degree pushrod engines.
If you have ever seen a Ford 2.8 V6, it is 2/3rd of that. Or rather the V6 is 3/2s of the V4, as the V4 came first.
200hp V4
In reply to ShawnG and Pete :
I know you're just trying to be helpful, but this diversion is exactly why I didn't give any background at first. I also know I could just buy a Miata and have a much better car than building a Locost... But the existence of the former does nothing to diminish my interest in the latter.
V4 is my vote! I love the characteristics of my Honda motorcycle V-4 and often muse about putting one in a small light car.
Here's some pushrod V-4 inspiration if you haven't seen it already: https://americanv4.com
At 1650cc, it isn't simply a cut-down small block Chevy, but rather a scaled version based on the successful and proven architecture.
In reply to Driven5 :
Now THIS is OT:
I always liked the idea of a ACVW or even an older 2.2 Subaru engine for a Locost, provided that the front section was narrow enough that the valve covers would stick out the sides, all polished up.
In reply to ae86andkp61 (Forum Supporter) :
Yes, in my opinion Motus nailed the configuration, and in more ways than most people realize. About the only thing that would make it better would be if it used off-the-shelf components... And were more widely available.
Here are a few others that get my creative juices flowing:
How To: Build Your Own Sheet Metal Engine - Fortunately I saved a copy before lots of the pics went missing.
LS1 V12 Scraps Make LS1 V4 Block and Heads
I say LS all the things.
So, v4 I guess?
I should have added "and what would you put it in?"
I guess I should answer my own question too. Some of my thoughts include:
90* V-twin in an old VW Beetle.
Parallel twin in a Little British Car.
90* V4 MIATA.
The I4 being closest to 'conventional' for an automotive engine, is tougher for me to think of something that would actually be interesting to drop it in.
While my mind keeps running full circle through the configurations, the V4 is far and away the one occupying the most head space.
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