Excuse this, here is another wacko crusade from the brotha from down unda...
Switch to the next post if you want peace or no headache!
I haven't been able to load the EA 3.0 program on my computer yet, but I've gone over everything I can find on power calculations.
The thing that gets me is that the accuracy is relative to SAE net installed, and backpressure and engine heat create a difference. There are many variables.
The thing I do is look at what the engine runs stock, and then add the effective boost ratio.
A cam above 270 degrees will always add power on a turbo. ALWAYS. What is critical is that the turbo doesn't surge or overspeed. If you run a big cam, you will hurt low speed torque but could stand to gain a lot of extra power. Because our cars are steet cars, we get forced to run tame cams even if it has a turbo. That's why most everyone says no big cams.
The power in the 200 with 500 cfm and 274 high intensity cam on a wide lobe centre. The 112 lobe centres add low end torque, the stock 110 centres give good all round power with poorer low end torque. Power with this cam is less than on a 280 degree cam with 215 degrees at 50 thou on a 110 centre. Before turbo. After turbo, its likely to be much more.
The power without turbo and a set of headers should be about 175 hp at 5000 rpm with headers, and torque should be 185 to 190 lb-ft at 3700 rpm. The effective rev limit is 5500 rpm. Critical load is the con rod quality and poor rod length. When the turbo is added, it normally has the best iron exhast manifold you can get . The J-tube isn't that good. The effective boost at 10 psi is less than 1.68, minus a heating factor. Peak power is therefore
175 hp *1.68 *(.85) = 250 hp @ 5000 rpm
190 lb-ft *1.68 *(.85) =271 lb-ft @ 3600 rpm.
The cam will not scream as much as you think. The rod ratio, lobe centers and breathing restrictions tame the peak volumtric efficiency. The 200 is actually a great engine to super charge. It's hard to get a VE over 75 % even cammed up with a single carb and log head.
Upping the boost 20% results in less than 8% extra power. That's 268 hp and 290 lb-ft.
I doubt you'll get much higher than that. The carb isn't the restriction to power, its the response time to air fuel mixture changes. More carbs, more response.
What is loosened up in a normally aspirated engined is loosed in a turbo.
If head flow modifications were banned tomorrow, the best bolt on mod is three 2-bbl carbs. The dyno programs do allow for independent runner systems, and the log head can be converted to one with a few Offenhauser plate style tricks. The head may react well to porting, but I'd bet money a proper triple 2-bbl carb withy the stock head is the single best mod, not die grinding or otherwise. The ports are quite a good size, about 1.4", which is bigger than the cross flow.
For bang per buck, get a couple of extra carbs to ride shot gun with the single 500 cfm carb. The peak rev range for them is about 5500 rpm, and the effective improvement in head cfm and total VE is over 91% area.
On a V-8, independent runner systems are worth up to 25% over a properly sized big 4-bbl. On a six, it's likely to be much more than 50%. The 2v head alone is a 25% boost with a stock carb via much better flowing head and mandatory headers. The extra fuel via a 2-bbl is another 15%. Just a full 3 by 2bbl carb is the single biggest boost you can get on a six this site of a turbo, supercharger or nitrous. If the your amazing 200 will do 175 hp with a single 500 cfm Holley, then it will do 225 hp with carbs with six 35 mm chokes and 43 mm throttles.
A 29% power boost unturboed is a 29% boost turboed as well.
At 10 psi with one 500 cfm carb, 250 hp,
At 10 psi with three carbs, that's 323 hp .
The biggest restriction on the log , 2V or ME/SP I6 from giving the power per cube of a big 300 is just the amount of carbs. FrenchTown Flyer is onto something that is even more relevent to turbos than full-on drag cars. I delight in seeing the Argentine racers running 300 hp from a 188 Ford six with one IDF or DCNF Weber. I'd just bet with three of them, you'd get another 90 hp at the same revs!
The other plus is that you only need run 10 pounds boost, and still have a car you can drive everywhere!
