Yea, but you're more open minded than some that I see on the internet, and (obviously, from this post) willing to learn and accept new ideas. There will be some that will see this test and only try to poke holes in the logic and ignore the results.
I believe that questioning and testing ideas (and parts) is a way to learn and accept or no longer accept ideas. You say, poking holes in logic, but I see trying to understand why "it is, what it is." In fact, this open mindedness led me to go a bit crazy with my 306 with the "bigger is better theory". I have an AFR 185 comp with a custom camshaft that mirrors and exceeds many 347^3+ camshaft specs, with a heavily ported SMII that dwarfs the Performer that was on it, to the tune of 30-40% larger runner area dimensions (measured myself), but guess what, the runner length is near identical. Ed must have got this one wrong
The problem is that we all contradict ourselves on a regular basis. We preach, "it is the combination", but then pick out the POSITIVES when we see fit, but neglect to mention that the combination probably played a large part in the results that you believe we ignore. Luckily Tom Moss reminded us of this.
This is what I always try to tell people when the discussion turns to TB/MAF sizing. In a high performance motor, there is no "sizing" of these parts. There's no magic formula that helps you pick a TB size. You just select one that is big enough (within reason) to minimize manifold vacuum as much as possible at WOT. (...And this pretty much comes down to the size of the intake opening, or how much you can hog it out.) ANY vacuum at WOT is an indication of flow inefficiency upstream of the intake, and it is GIVING UP POWER.
I agree with this completely, but it seems to be out of context of this test. I did not see anyone stating a magic formula to pick a TB size. In fact, this should show that it entirely depends on the engine combination, otherwise we would be guilty of the very thing we preach against (i.e. We see dyno results on ONE engine combination and believe it is the answer. In other words, we see a TFS-R vs. TFS-R Box comparison and assume that a shorter runner with a large box style plenum is the answer for all 331's.) This is a post hoc fallacy.
Assuming you are speaking of pressure drops behind the TB (or whatever intake piece you want), there is diminishing returns with this method of vaccum. Say you have a 331 @ 6,000 RPM sitting at 100% VE, this equals 575 cubic feet a minute. Place a TB that can flow 1000 CFM and then add 200 more potential cfm and you just get a .209 value drop in vacuum, but if you move from a 800 cfm TB and move up 200 more potential CFM, you get a .384 value drop in vacuum. So I am with you here.
The OEM has a pretty good handle on this thinking; the Coyote has an 80mm TB and the LS junk has had "huge" TBs for years. Why 5.0 guys are still limiting themselves to 75mm, I have no idea.
There are two large factors for TB sizing from the factory.
1. Packaging (Go delete your EGR plate, then start bolting up the TB - you will see where packaging comes into play on more than just a TB)
2. Modular use (using them on different engines to keep R&D, cost, etc. down)
Unfortunately, in third is power.
It is all a complete package (literally).
Speaking of LS engines, I am not sure I would consider a 71.5 mm wide circular TB is "huge." An Ls1 has a 71.5mm (75mm opening) TB from the factory, and include a throttle cam. Take the '98-'99 pulley system for opening the throttle, which has very close to the same cable pull to the angle of the blade. Now, what did GM do for the later years following 1999? They created a nautilus shell style throttle cam, where the part throttle portion of the cam requires more pull on the cable, with less degree angle actually being applied to the throttle body. As the blade gets closer to WOT, the radius of the cam shrinks and allows the blade to open up completely to WOT. So why would GM, do this?
Easy answer; it is to help with part throttle touchiness.
The minimum area I measured in my ls1 intake TB track was 73.14.
I am not sure who you are referring to on limiting their engines to 75 mm TB's. Most engines out there do not need the extra 3^inches from a 75 mm TB to a 90 mm TB.
Mo air is mo powa.
This is true, IF the other induction parameters (valve events + intake system + exhaust system) is matched.
Slapping on a large intake on an already good performing engine could hurt as well as help it. The volume of a larger intake (or smaller intake) may be productive (or counterproductive) to the efficiency of the engine.
Now, I have *heard* that the bigger TBs (like the Accufab 90) have different geometry on the butterfly valve lever that is supposed to modulate the blade slower at lower openings to help with this issue. I do not know if that is true or not, just what I've heard. Either way, I know of guys running 90s on STREET driven 302s with no problems.
No need to hear any longer, this is true for many aftermarket TB's. Refer back to the nautilus cam talk (which is like MOST OEM's now) + many are going to drive by wire set-ups, so touchiness or sensitive pedals are no longer an issue. The computer controls tip-in; no longer the other way around. I do not see any problems with a 90 mm TB on a 302, in fact, if we looked at just driveability (for the sake of healthy debate), I would prefer a larger style TB on a lower powered engine actually (302 vs. 427).
Joking? Here we have a legitimate test where switching to the 90mm TB proved significant gains over the 75. It doesn't get any more clear cut than this: the 75mm WAS NOT "plenty" for that combination.
Serious - do you not believe that the pressure drop from the 3"^2 area from the 75mm TB to 90mm opening could cause an issue? Bernoulli principle at work. Do you think the box style could attribute more to a larger TB? I do. After all, when does the "plenum" begin, when the throttle is WOT?
Not sure what you're asking...? See below.
Thank you, FastDriver already answered it for me, you just missed it I believe-no biggie.
Keep in mind, Chris, that the cam does not dictate the rpm band of the engine alone. It is the combo of parts that does, and I think that is part of what Tom was getting at above.
Yes, you are correct, which is why your comments seem to contradict themselves. You are speaking about the TFS-R Box as how "bigger is better" prevails, but it is the combination of engine parts/tune that make this happen.
It would be my guess that a more aggressive cam might help the long runner intake shine a bit more, but maybe at the cost of some drivability. Of course, put that more aggressive cam in the box intake engine, and it will likely rev even higher and make even more power, so I'm not sure that camming the long runner intake engine would necessarily help it outperform the box intake engine, but maybe just help it do better than it did in that test.
By more aggressive, what do you mean? Ramp rate, increase in durations @.006", .100", .200", etc.? Lift over the lobe? The intake system is not a cut and dry as many believe. Go read some Gordon Blair stuff, in particular Design and Simulation of Four Stroke Engines. He literally has a couple hundred pages of research in intake designs. I own it and have read through it a couple years ago and the more I read it, the more questions I had.
Your comments about adding a more aggressive camshaft to the TFS-R (non-box) seems to imply the "big head/small camshaft" theory. Well, Ed decided to go bigger on all parts of my new combo, but it works because it is matched - so I take it there are more ways to skin a cat. It is all in the combination! If you go with a large cylinder head (relative to cylinder volume), ensure that you have a matching large volume intake and tuned length with the 3rd or 4th harmonic. This is where the camshaft comes into play.
A large cylinder head + intake system may like a delayed intake opening (or at least slow beginning ramp rate) so when the piston speed increases on the intake stroke towards its peak speed, the draw on the intake runner (head + intake) is greater. This is when the curtain area should be maximized in a timely manner. The change in air pressure will increase the air speed (some call it velocity) and will bring inertia with it. You need less duration. Matched parts become crucial when you go with various parts, like small or larger intakes.
With a large port velocity profile (relative to the cylinder volume), you need to "limit" the camshaft valve activity, not try to feed the cylinder more air with longer/larger durations. Thinking about how a basic 4-stroke engine works, you also will benefit with larger exhaust parameters with a large induction system.
There is no perfect set-up (large induction + small cam or small induction + larger camshaft). They just need to be matched, as this dyno session was matched better and it had some strong results to back it up.
Anyways, back on topic. For sake of argument - let's take the aforementioned XE274HR on this 331. Given the specs of that camshaft, the TFS 185 heads, I get a optimized 3rd tuned harmonic of ~12.9". Well, low and behold, the TFS-R BOX (9.0") + TFS 185 (4.75") length equals 13.75". This is less than an inch from ideal. However, add the extra 2.00" on to create the TFS-R runner length + same cylinder head, you get 15.75" - even further from ideal. The TFS-R BOX fits much closer, compared to the previous dyno run using a tuned length an entire two inches off near optimal. I wonder why the power went up?
Factor in the assumed increase in taper from the BOX upper to lower, and you get even closer to the needed harmonic for a 12.9" length runner.
It was not a coincidence that at those funny RPM's (3700 and 3200) that we saw variations in HP/FT LB numbers at the wheels - tuned length and other intake parameters played a big part in this.
Of course I'm generalizing here a little bit. I know cam guys will do different things with valve events given the style of intake used. That said, if a GOOD cam guy were given the opportunity to create a cam tailored to each intake, my hunch is that the Box might still have the edge. Who knows.
Yes, you are generalizing, but it makes discussion better. I am not sure I agree with your assessment by looking at the "all else equal" situation you are creating for the cam pro. It depends on the combination entirely. Of course, one could have the exact same heads, cam, and intake, but yet run entirely different times or drive completely different. I would estimate there are 100 different reasons for this that are obvious, so I believe it is incorrect to look at this dyno run that FastDriver showed us from back in late '05 (put in MM&FF in March '06, then published in the book in '08) and assume that a TFS-R Box is better for all engines "all else being equal."
In fact, here is the results of a 30 second google fest showing how a TFS-R Box did not work for some. I hope this reaffirms that the combination and goals are what matter, not just the intake:
"Well im gonna try to help clear up some of this & this is from real world testing. i have 331ci motor with a ysi on it & afrs 205s & a small hyd roller cam when i first started going to the track i was running a fully ported edlebrock peformer rpm 1 intake & my best run was 8.98 & 150. The next race season i switched to the box r intake had the car tuned & the best that i could get out of it was a 9.1 @ 151 thats after many many tries the car seemed to be down on mid range power. So i got pissed because i spent 650$$ & was running slower, so i switch back to the rpm intake & the car was leaving alot harder so i ended up running 8.96 @ 155 mph this was in 09'. Now 2010 after talking to a few other guys i decided to switch back to the box & have Kurgun tune the car, so in apirl 2010 i had Kurgun tune the car & she made 920 rwhp that same day i took the car to byron dragway & clicked off a 8.99 @ 155.70 with a 1.40 60' i was happy got a 8sec timeslip with the box. So as the race season goes on the car is running low 9.0s & 152 with 60' times from 1.29 to 1.35 i also made a few more 8 sec passes with best of 8.92 & 153 i was happy but i could tell the car had more in it. so... i switch back to the rpm & went testing & i started to run 8.80s @ 155 to 156 & then i got the car to run 8.70s @ 158 with some more testing. I think the cam has alot to do with it as i was trying to shift @ 7200 with the box @ i was shifting @ 6800 with the rpm all i can tell u is that my car is faster with the rpm. i think the rpm had a little bit more mid range power than the box, my best mph in the 1/8 with the box was 122 & with the rpm was 125. the box is a bad ass intake if ur shifting @ high rpms. i will switch back to the box whenever i change my cam to a solid roller, my cam was made to shift @ 6800 rpm"
"
My buddy's 418W made 435hp/450lbft with the R intake and then made 435hp/400lbft with the Box R. Basically, he lost 50lbft and gained nothing for hp. On the same dyno, no other changes...all numbers at the wheels of course.
He now used the Box R on a 427 and made 505hp/503lbft...with different heads and a different cam. "
Now, did reading those two real world reviews (among others that I did not include) lead me to believe that the TFS-R Box is an ill-equipped intake? Absolutely not! It just tells me that it was not good for the particular combination, just as it can also play in a positive light, as the test that Fast Driver posted. It worked for that combo, no doubt! There is no logic I have to make-up, it just worked, but for a host of reasons (some mentioned above). Along those same lines, the dyno graph of the Boss 302 and GT above with two different intake styles are a stroke of engineering genius. Those engines have different components, goals, and design factors that allow the engine to work optimally to what it's intended goal was. The same reason why a "short runner" intake on an LT1 @ 2.875" gets out powered by a 10.375" ls1 intake (measured these myself). It is the combination - not the intake.
It's all about the combo, hell, I've seen guys with iron GT40 junk make 350 to the tire and run 11s. There are just obviously better parts to help you make more power when put together right, and I think this article is good argument that the Box R is a serious piece.
Combination plays a major role, but also the goals of the car along with weight, daily driver vs. street car vs. track car, etc.
Yea, I've thought about this before. The runners in the lower intake alone are longer than those in a single plane intake. Runners in a single plane intake are shooooort.
Tuned harmonics, packaging (think large carb/air filter sitting under a stock hood), dry vs. wet flow are major reasons for the differences. Most of the EFI lowers are like you are alluding to are in the 5.5" to 6.5" range. But, the cross sectional differences, taper, harmonic wave tuning, etc. all keep similar powerbands and potential. In fact the LT1 intake is shorter than 95% of the old school single/dual plane intakes, and it was EFI. Hmmm...
In short, one dyno or a couple test can not conclude that a 90 mm TB is needed or that a box intake is best for all engine combinations. Those famous words we hate to hear so much:
It Depends!
I just wasted 30+ minutes and just scratched the surface.