I love your advice, pmuller9. Anyone who doesn't consider everything you say is gonna be sad when it comes time to bolt together any Ford Six.
My personal opinions follow.
The five methods of assessing the adequacy of cam and port requirements I like are
1. Stan Weiss's peak Power RPM verses cfm flow at 400/450/500/550 lift charts.
2. Eduardo Webbers idealised Venturi area verses peak power rev range calculation. You have to calcualte the ideal sizes by removing the venturi verses throttle diameter, and its kid of restricted to Independent Runner systems, but its perfect for optimizing EFi or a 6-bbl carb system (two 4bbls with one venturi each blocked off, six 1-bbls carbs, two 3-bbl IDFC3's, three 2-bbls Holleys or DCOE's etc.
3. Flow Net analysis (Civil and Mechanical Engineering process, which creates a sectional number of 90 degree flow paths verses flow drops)
4. PipeMax
5. Any of the six common Hp and Torque programs which generally use five general kinds of estimation.
I ignore the simulations because they tend to push into the earth bound idea of increasing air velocity, of down grading a cam duration and lift to get out of a potential turbo chart hole.
Oversizing turbos is okay if you use upper turbo intake boost modulation, or by pulling the timing out and adding fuel to operate the turbo as a giant gas turbine engine. Ak Miller did the former (TC-1 contoller) , Anthoony Rodregiaz did the later (treation the turbo as an auxilar engine), each is an easy solution to avoid the dreaded over conservative V8 derived strictures, which are essentially Air Restricted ideas based on US air restriction rules for cost reduction in all forms of motorsport. Its simply that if everything used Indpebdent runner philosphies in each class of racing, then NASCAR's would use 8 S&S D type carbs with 1.875" venturis and bigger than that throotles, and the perforamce landscape would then have a lot of lead ignots in the chassis to stop them over-performing
The Lambda ratio/L/R ratio of the little 200 is just the same as the Aussie 221, and US/Australia 250, and the same as the Australian 215/245/265 in line sixes...pretty poor, and it likes nice wide lobe separtion angles, and any time you turbo, the engine is suddenly behaving more like an engine 100 cubic inches bigger, and so you just add another 5 degrees on you stock 108, 110, or 112 figure, and pump up the 50 thou and at lash durations, and look at how you migh best optimise the valves to suit the area of the ports.
fast64ranchero Your old sawn off 250 log had upside down cathederal ports, and the average area after savage porting was still less than the Round Port M code 170HP 250 Aussie Ford engine the Classic and Vintage Inlines head was copied on. The VI head de-dagged flows well over 230 cfm at 25"Hg, and its got all the good points of the best HFII casting Aussie 200/250 X-flow heads, with better mixture motion, and the only ratty part is the shallow legth valves and that was only becasue its taken 10 years for people to get gready enough to go straight for 330 hp plus packages.
It really wasn't helpfull for people to say that a natuarlly aspirated 200 or 250 will never match an M3 BMW in line six for power out put when in 2005, little Holden 202's with 30 year old aluminum Phil Irving Heads were making 370 hp on pump gas with triple Weber DCOE's at less than 7500, and tiny four bearing 170's with cut off logs, 280 hp net at 6500 rpm with triple 45 DCOE carbs.
Adding a 1.7 to 2.0 boost ratio to those non cross flow 170 and 202 engines takes us right up to at least 486 or 666 hp (oops, did I say that).
Yes, off idle performance is really important, and yes, an engine has to meet its target requirements on the street if its going to be used that way, but plenty of V8's are over built with too much exhaust and no suitable attention to toning it down for use on the street. People love rumpity rumpity cams, but on an in line six, they hate noisy cams with tappetty ramps, and this is ture of side plate engines and engines with converted rocker gear which aren't masked by the tradiational V8 exhaust, or the intake that covers the lifter valley of a V8. The way modern people just go to big, droning single exhausts with massive fart can exhausts is a function of the ricer crowed, and for turbo engines, people need to get a lot more creative to avoid the awfull IHI Red Seal Six drone so it doesn't sound like a garbage truck. Cam timing should be a lot more aggressive, IMHO, and the turbo should be sized larger, as the six cylinder ports and active rev ranges on the street won't cause holes in the delivery. There are no jump into top at first chance automatics for Fords like there are with Ford V8's. The AOD in stock form is a pefect boat anchor for making a V8 a dog unless some attention is given to making the stall ratio and axle ratios suit the 3rd and 4th gears. IF manual, it'll be a 3 speed 3.03, T5, and top loader 4 speeds and SROD's or wrong ratio 4 cylinder T5's are a lot more rare, so generally, a C4, T5 or 3 speed 3.03 will be awesome with a really big turbo. Pinto and higher stall spinners are around, and so are reaaly good 7.5 and 8.8" live axles from Rangers and Exploders to raid the 3.73's that work so well with autos, 3 speeds and T5's.
In a V8 setting, yeah, its easy to mess up and overload a turbo. In an I6 setting, not easy to mess it up because an in line six is very responsive to aggressive cams than V8's are. This stuff is all right back to the SEFI Buick T types, and the later GN's and GNX''s. The log head six with a multiple V head transplant will just lap up the cam and duration's
My classmate had an SL/T 3300 L34 LH Holden Torana replica, basically a 1973 XU1 Torana engine with a 1978 era AIT twin Zenith Stromberg CDS175 carb TO4 that made 350 hp athe flywheel under boost. The 3.3 Holden was an initial GM disater Area engine with crook valve sizes, low duration and lift cam, and it got worse each year from 1971 to 1980. The only good one was the 3300 Torana XU1 version, A stock cam on the base engine was 256 degree with about 370 thou lift. On the XU1, there were three cam choices, as they were mated with triple carbs, and each of thse cams had huge duration, but only moderate lift because the rocker gear was a disater. With the right turbo, the smallest came was horriable.Each growth in cam fixed up the ineraction bettwen the TO4 and the smallest XU1 3300 cam was over 300 degrees at lash, worked great with the right size T3 60 turbo. Then there was a Speco Thomas 260 degree cam which took the stock 90 hp engine to 160 hp with the right mods, and then a 280 degree hydraulic cam, which made an easy 200. The real cam was the XU1 cam, and too much would have been the 314 or 326 degree mother, but they had really low lift, and would work great on a much wider than stock 110 lobe center.
The little Toran was a four door Fox Mustang in every way, and Jaqui Peck cooked it on the way to school in the 25 miles from her place to my hometown, but it was a piston and vale issue, not really anything except the engine not being clearanced to suit. With an XU1 cam, it was exceptional, even better with the 5 speed Toyota Celica gearbox. Turbo 3.3's are essentially supposed to be like a Porsche Turbo 3.0 or 3.3 911/930 Carreras, full of off turbo docility, and then an all might mid range whoosh like Chris Cornell or Eddie Vedder on hyperdrive. And more like a 3800 231 Buick.
Never loose site of the ability of camshaft to suit the purspose of the build. Down here, our early Turbo Sixes were V8 substitutes with GM 180 THM gearboxes, and they didn't get any support from GM Australia because it was too worried about the Japanese and how it would ace the 2 liter market. It spent money on J cars hwne the public wanted tow cars for its boats, and Holden got out of that market and replaced its big pickups and subframe chassis cars with puny Jap cars and German based unibodies with Nissan engines. It never did anthing for its own stuff untill it was too late. Ford Australia, under corporate orders from Dearborn, didn't even run a Ford developed turbo on ther long stroke in lione OHC six untill 1987 internally with AIT.
Don''t hold back. Your cam machinists and turbo development leads the world, but you all are too conservative in my opinion, and if a little 3.3 liter six with a better L/R ratio of 1.65 and less over square bore to stroke ratio of 3.625 by 3.25 and a lousy 9 port head can take a 314 degree cam, pas emissdions, and win 500 mile races, then you better believe a modern US cam and turbo combination on a less revable engine with a much better VI head can work with more aggressive specs. The port area was set up for revs, hp, and taking the old log 200 kicking and screaming into the 21st century.
The 250 cut off log needed more lift, more duration, and squaring off and high porting of the roof of the intake ports to improve the shot to the short turn radius. Elmo fow benched the Classic inlines head to imporved on the mixture motion, maintan the port areas, but improve efficency and port to port balance. That head needs, cries out for lift, duration, and over rev potential past the power peak so it doesn't suffer power loss at high rpm like every US engine except the SBC, SB Mopar and Cleveland 351. You won't get the "gosh is this thing ever gonna stop" endless elasticaity past the 5800 rpm level the best Hydraulic or solid lifter versions of the early 350 Vette LT1, Mopar 340 4-BBL and 340 Six Pack and 351 4V HO and Pantera Clevelands made.