My decision was relatively simple. After years of working on, building, tuning, porting heads, etc, etc, the Ford modular engines I had a choice to make for my next race car. I could do one of two things:
A: Single turbo 4.6 or 5.4 four valve engine.
B: Nitrous equipped 572-598" big block.
The pro's of the small four valve are: excellent airflow, very responsive to turbocharging, lightweight packaging, a good weight break, and I have an excellent knowledge base from working with them for so long. The con's: limited bore spacing, expensive, puny torque, sky-high rpm's necessary to make power, limited quantities (aluminum 5.4 blocks), not enough weight breaks in enough organizations (most lump them in with small blocks at 3000#).
The pro's of the big block: Readily available parts, proven packages, they like nitrous, great weight break at the right cubic inch, TORQUE, I have a fair amount of knowledge of them, TORQUE, people don't suspect them to be really fast compared to twin turbo small blocks, TORQUE. The con's of a big block: iron blocks are heavy, aluminum blocks are high dollar.
So...I can run a turbo 4.6 @ 2600# OR
I can run a nitrous equipped big block (under 600") at 2700#. :shock:
Did I mention torque?
It finally came down to a decision based on overall cost. My father has been running a big block bracket Thunderbird for around four years. Simple 512" with Blue Thunder heads and a glide. The car has no problems clicking off 9.40's at 145 and does it all year long without a hitch. Car was 3050# before this latest revision we've done over the winter. I've seen tons of nitrous, supercharged and even turbocharged small blocks running against him at various bracket races and Fun Ford Weekend series races. They will be working their butts off maintaining their high-tech combo's and Dad will be cooling the car off and having a Coke. No problems. A big block Ford is a well thought out package that makes tons of torque without breaking the bank. We can build his 512" shortblock with simple, off the shelf rods & pistons, a stock block, and an offset ground cast steel stock crankshaft for around $2200. It'll take 7400 rpm shift points and run for over three seasons. About all we do during the bracket season is change valvesprings once. Maybe. It'll go over 150 runs before it needs springs.
Power, torque, cost. Simple choice.