Realistic Hp/tq Expectations...

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Here's what Pro-M's website has to say about the 75mm bullet:
The Chrome Bullet is built in a beautiful polished chrome housing and is available in calibrations for use with up to 42# injectors, supporting as much as 550 flywheel horsepower.

A general search indicates that a Lightning MAF quits somewhere around 450-500rwhp. Pretty close. I learned something here, but the point in the upgrade would be to reduce the restriction in flow. I agree with your assertion that it's not going to be worth the cost or effort, but I think it would definitely pick up something.
 
calculation is VE*RPM/2*cubic inch displacement/1728 = volume in CFM (cubic feet per minute)

A 75mm is no restriction to flow whatsoever. I'm still running the 75mm Pro-M I bought 14 years ago.

Kurt

Why do you believe that? When will it become a restriction to flow? Do you have any evidence that indicates that increasing the MAF size on an H/C/I 302 results in no power gain?

Hell, what do I know. Maybe you're right. I don't bother with MAFs these days, anyway.
 
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I'm not sure what you're trying to do.

Ok, for :poo:s and giggles a 347 turning 6500 rpm at 95% volumetric efficiency, which is pretty good at that RPM, would be moving 620 CFM. This motor is going to make over 400rwhp at sea level under standard conditions.
 
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If 5spdGT posted it, it probably was well researched.... sounds like something he's done here. Consider the fact that's airflow at a given pressure differential on a flow bench. Likely, it's at 26-28" vacuum. Just because they will flow that at around a 1 bar pressure differential doesn't mean they won't still cost power. Ultimately, what you're shooting for is minimal vacuum in the intake at WOT. If you have a way to read the factory MAP sensor or if you have a boost gauge, it's a pretty easy measurement.

In one test I saw, a 90mm TB picked up 14hp on a 331 and made extra power throughout the ENTIRE power band. I expected the 75mm TB to make just as much power until maybe the very top of the powerband. Here's the article from dyno proven small block ford performance:
To test the flow limits of a 90-mm throttle body, the first thing you need is a powerful test engine, something considerably stronger than a stock 5.0L. The reason for this is that a 75-mm throttle body flows well enough to support somewhere over 400 hp. Were we to test the throttle bodies on a stock engine, there might be very little power gain because the engine would not take advantage of the larger throttle body’s extra capacity. On the other hand, if we were to perform the test on a radical EFI race engine, something capable of producing 600-plus hp, the power gains might be huge, on the order of 30 hp or more. Then everyone reading this test might jump to the conclusion that throttle-body upgrades are all worth 30 hp. The reality is that no throttle body test is an absolute. The gains experienced on this test are indicative of what will happen at this power level, but results will most definitely change with milder or wilder combinations. The same can be said of supercharged, especially with positive-displacement blowers, and turbocharged engines, as these applications have specific throttle-body needs.

Our 331 test engine was the same CHP stroker used in test 4. The 331 was comprised of a 3.25-inch stroker crank, forged rods and pistons and topped off with a set of TFS CNC-ported Twisted Wedge heads with 185-cc ports. Though designed with forced induction in mind, and as such equipped with 9.0:1 compression, the 331 stroker was nonetheless powerful even in naturally aspirated trim thanks to the free-flowing TFS heads, XE274HR cam, and TFS Box R intake. Whether on the dyno or in the car, a good indication that the throttle body sizing is too small is the presence of vacuum at wide-open throttle. During our dyno session, the data logging indicated a solid 1 inch of vacuum present at wide-open throttle with the 75-mm throttle body. Installation of the larger 90-mm throttle body dropped the vacuum present down to just 3/10 inch. Vaccuum is measured in 10ths/inch. It’s the way the dyno provides the information. Naturally, removing the inherent air flow restriction had a positive effect on power as well, with the larger throttle body moving peak power output from 441 hp to 454 hp. As expected of this type of change, the power gains increased with engine speed. That the Box R upper intake was designed with a 90-mm opening to accept the larger throttle body was the deciding factor—this 331 combination needs the 90-mm.
 
Kinky is the way I go. I have a 70mm tb, and I think it's actually a 77mm maf. Vacuum is 0 in the intake all the way to the red line with 192cc heads. I'm sure it would be 0 with 205cc heads.

Kurt
 
My understanding is that I'm limiting my ultimate HP/TQ potential with the Ecam and the tubular GT40. The intake will stay, but the cam might find it's way back on my shelf if picking a new custom/off the shelf cam is worth the $$$. What cams would work best with my set up, and what kind of improvement could be expected?
Thanks again,
-Jeff