Originally Posted by ZeeOSix
Originally Posted by Skippy722
What do you plan on doing with it? Autocross, rallycross, road rally type things, drag racing?
^This ... without knowing the main purpose of the car, the suggestions will be all over the map.
Double on this.
Also define what kind of race car - straight line or handling? Is your idea of race 0-60 in 5 seconds, 4 seconds, 3 seconds, or 2 seconds? Budget of $10,000 or $100,000??
Originally Posted by IMSA_Racing_Fan
Question for Miata people; will the factory rear differential and suspension survive a Ford small block if not drag raced?
I am a HUGE fan of the Miata, there's a reason why people say "Miata is your answer" no matter what the question is. They're light, inexpensive, and can be made overpowered pretty easily. But that also depends whether 0-60 needs to be 5 seconds, 4 seconds, 3 seconds, 2 seconds... they are less suitable as that number drops radically. Right around 200-280hp they make pretty awesome vehicles by all accounts, much above that they start verging on overpowered. You can stick a Chevy LS in there and get 400hp instantly but it starts to become a bit of a handful with the short wheelbase and such, go look at videos of people who have swapped them to see what I mean. One swap i'm a fan of is the honda J-series which if it's one of the stock 240hp ones can just bolt right to the 5 speed with decent ratios and be alot of fun, but I don't know if i'd call this outright race car power. The 6 speeds are stronger but not as good of ratios once power climbs to 300hp. Miata rear ends seem to take in the 200-300hp range quite well as street vehicles, upgrades are not too hard, I think the Ford 8.8 is commonly used but I lost interest in specifics of that upgrade when I saw how 350hp plus Miatas behaved on a track/just a bit much to handle. How fast of a Ford small block? You can build one for 300hp or 500hp or 700hp on boost. I'd think it handle the first one just fine without slicks and drag abuse. But at that power i'd almost stick in a J-series, save 100lbs, have more fun revving it up (and better meeting the stock 5 speed ratios) and call it done. At 500hp i'd probably look at chassis with longer wheelbase that wont come around quite as fast when you start to lose traction.
As far as engines, though earlier Miatas often used milder Ford 302's (300hp max) i'd prefer a Chevy LS whenever possible for reliability, and in any other vehicle since even weight and compactness is the same. Ford 302's used to be the lighter option vs the small block chevy, but not vs the LS. LS is about the same weight and better in every way even just basic reliability at 300hp let alone more. The only case I wouldn't swap would be a newer mustang with a modular v8.
However race cars always like to be light. Newer mustangs with that modular v8 are still heavy by most standards like 3500lbs, there are other rear drive vehicles though which aren't that you can put a Chevy LS into to make power. That's pretty much the ticket to budget speed, one of the lighter vehicles is probably like the Toyota 86/Subaru BR-Z chassis vehicles which tend closer to 2700lbs - 500hp in that will be like 650hp in 3500lbs vehicles. I've seen some nicely modded ones of those. If/when I ever get out of my financial poverty hole my plan has always been to first get a Miata and learn to drive, and then get an 86-chassis and stick an LS in that once I want to get faster. (ie 11 second quarter mile and 0-60 in 4.0 seconds or less where the Miata just becomes increasingly hard to handle by what i've heard)