Citazione:The F series engine is Mazda's big block and the B series is the small block.
51 mm rod journals vs 45mm rod journals
34,29mm valves vs 33,28mm valves
head ports approx 20-30% larger
86mm bore vs 83mm bore
86mm stroke vs 85mm stroke
physical block constraints: BP = 86mm bore and 88mm stroke, FE3 = 89mm bore and 94mm stroke
22mm wrist pin vs 20 mm
The DOHC BP does come with a forged crank (SOHC is cast) and most FE3's is cast. That is true only because the BP desparately needs it. With the power level it is tuned to and the smallish 45mm journals a cast crank would not last long. note: the rod bearings are always the first to go out on a BP and typically show signes of wear around the 40-60K mark, a FE3 has no such issues with the phyisically larger hard-parts.
In the world of reliable street engines (not one-run wonders or dyno queens but 50K mile daily drivers), the BP can be boosted to about 250-275 rwhp before aftermarket rods are needed. That same formula for a FE3 would be around 400 rwhp for a stock long block.
If you are not doing anything to a junkyard engine and just bolting it in then a current generation BP would be as strong as a FE3. If you plan to pump up the power beyond, say 250 to 300, then a FE3 is the better bet.
Tratto da https://fixjunk.com/solomiata/solomiata/FE3.html
Altre info:
https://www.miataturbo.net/build-threads...rbo-49372/
