1320stang said:
I think the big reason for going away from the BB motors is in many cases, they're not needed due to the diesel motors that are out there. Now a 7.3 is a BB really. A V10 motor is 6.8, but the cylinders are the same size as the 5.4, is the 5.4 a SB?
Alright, well I'm going to keep this to V8s for the most part. The only V10 put in performance cars are the Viper V10 (which, if it wasn't for the fact that the V10 is part of its image, would have lost the V10 already... DC wanted to move it to a smaller V8 with similar power but it did not get good press), and the BMW M5 and Lambo Gallardo (both of which have V10s in the 5-6L range, still small block displacement).
I consider any V8 that was designed with 250-375ish cid to be a small block. It depends more on the engine family than the greatest displacement you can get out of a family. You may point out that there were 400 SBCs and 400 Ponchos... those were just V8s from families meant for smaller displacements stroked out due to the muscle car age. Hell, a lot of people would prefer a 350 SBC to a 400 due to better bore-stroke ratio, etc. The block itself is the same as the small block, hence its a small block. You may also point out that Dodge is coming out with a 6.1L Hemi and rumor has it that the next z06 will get a 7L V8. My thoughts on this are A) its doubtful and B) the block for that LS7, 427 cid, 7L motor would still be derived from a small block still, and it would still be a small block.
I consider the 5.4L a small block (Even thought it is big). It does not fit neatly into conventional categories because it is a OHC motor and inherently has different design constraints, but the closest you can get from its family of engines is a small block.
1320 Stang: The difference between a stock dressed out 351W and a 427FE is about 120#.
I'm planning on doing a Cobra kit in the near future to both drag and autocross, and I am having no second thoughts about my plan to go with a big block.
Well, being that it is a 2000 lb car designed to handle, your car will handle relatively well. Carroll Shelby did, however, prefer his 289 Cobras because they handled better... he actualy referred to the 427 powered ones as "pigs."
Anyway, everyone keeps bringing this up. Alright, that figure is true. But ask anyone who does anythign that requires handling of any sort, and they'll tell you that 120 lbs is HUGE. Our cars, even with aluminum headed 302s don't have great weight distrubitions. With big blocks, its almost impossible to even approach decent.
The main reasons that small blocks are around in performance vehicle are many. Big blocks don't get the gas mileage that small blocks can. Second is driveability... all that torque and weight imbalance of a big block can seriously hamper day to day travels. Third I'd put down the handling issue, being that in a performance car these days, people look at handling every bit as much as straight line power. This isn't the 60s, and big blocks have a huge disadvantage here. Finally though... small blocks, with all the modern bells and whistles, can provide all the power one would need. An LS2 is capable of taking a 3500 lb car into the 12s stock. They still respond well to mods. Same with a Hemi, and in a few years the 4.6L will be there too. They create more usable power, with a lot of science behind their power curves so that the cars can actually utilize most of it (and all of you guys with late 60s mustangs and big blocks know what I mean there... sure, spinning is great, but actually going somewhere is better).
I'm not going to be a ricer and pull up specific output arguments. I know those are BS. I"m not saying that smaller motors are better either. I think small block displacement V8s are an optimal performance configuration for a mid weight car. Everyone knows that huge motors have more power potential. But after a point, that extra size doesn't help until you're trying to run 7s.
Sorry for the book.