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First: I am not trying to be argumentative here or convince anyone that I am right and they are wrong, or that the allowed header mods are worthless. This topic was started purely for the purpose of comparing results after having asked a number of people privately in the weeks since my tests.
A bit more explanation of the placebo remark. During the debates about possible 1.6 allowances my position against lightening the stock flywheel was that while not a zero net gain and I would absolutely do it if allowed, the benefits would be so small as to be negligible above 2nd gear and far, far below what "conventional wisdom" suggests. I was asked by an SMAC member to back that up with the math and did so, and several others followed with comparable results using various methods. BTW, this is just one of countless examples of people doing something for years with (very nearly) zero net gain. An even better example is a cheater alloy driveshaft. Do the math on dropping a couple pounds from something only a few inches in diameter, but be sure to work with plenty of significant digits to the right of the decimal. As I said all through that debate, not absolutely zero, of course, but far below what most seemed to believe, and my oft stated concern was that the value of such an allowance would be misunderstood so when it didn't seem to help we would get something like "we gave you the flywheel, now you want more." And we would have only ourselves to blame. BTW, I never claimed that the 1.6 needed help but wanted to be sure that if it was so deemed that the help was actually material. And THAT was when I started referring to placebos in this context. Not to suggest intent, so a poor choice of word, but otherwise it conveys the potential problem. My vocabulary lacks, give me a better word so it doesn't require a paragraph to explain next time.
Sean, I get your irritation given that I was not adequately clear in my post, but setting aside this instance for a moment can you point to even a single case in the past when I spoke in unsupported absolutes or put myself forth as the sole arbiter of what is best for anything? I will gladly reconsider and rephrase if I gave that impression. In the recent discussion of SMSE others were slamming it as if they alone know what's "best", and the most vocal was positively offended to have been left out of the decision process. It wasn't me.
Meanwhile I repeatedly examined the subject from all sides, asked questions to learn more and voiced skepticism of anyone who was adamant that they had all the answers. Anyway, because I value your respect please go back and reread my posts with a new understanding of what I was really trying to say and ask.As for your dyno numbers, "wow" doesn't really cover it. But please allow me to ask some questions and make some points for your consideration. Again, non-confrontational.
- Without giving up any secrets, did you use a flow bench or other special knowledge to do a "better" job of grinding away the welds than joe-average might do? At the ports it would appear that the answer is No. Is that correct? What about at the collector?
- What relevant temperatures did you monitor and control? Did you simulate real-world conditions on those? For example, IATs on the engine dyno are likely to be quite different than we see on track, though the new turn indicator delete will reduce that significantly. Still, the unobstructed availability of cooler air inherently means more power potential which in turn requires more flow and so more potential benefit from the improved header. Would you agree?
- Did it require any re-tuning after the modifications, and if so what and about how much?
- You stated that this was already an A+ engine on the chassis dyno, that too would be consistent with the notion that an already strong engine (for whatever reason) is more likely to benefit from improved flow capacity. True?
Again referring back to my original posts, it may be that OUR engines/cars are unable to take advantage of the theoretical benefits. That is a possibility I was hoping to explore. To quote myself from the controversial post "Perhaps if we were making better power then this would show benefits, but first we need to figure out where our engines are weak." For example, one of our cars has at times had what was sold as a "good" intake manifold but never made more power than the others. Because we never observed any difference we haven't done controlled comparison tests. I have no idea how much of a variable they really are or how many have been tweaked, but that is potentially a more limiting factor which reduces the benefits of the header mods. After all, the pump is a system and its efficiency depends on all the parts working together. Improving efficiency of the output is of limited value if the intake is choked down.
Regarding engine dyno vs chassis dyno, as my questions above already telegraphed I'm not certain that either one is clearly the "most accurate" for these tests. Neither simulates the real-world but in some ways the chassis dyno is a little closer IF used properly. In my case I can simulate the functionality of a computer-controlled engine dyno with fixed-load at variable RPM, fixed RPM at variable loads, ramped runs in steps of x RPM for a number of seconds per step, etc. True there are the additional variables of the drivetrain, but once up to temperature and kept there they are pretty much constants and have the benefit of being "real world". I think it could be argued that the chassis dyno presents the engine with a more realistic load as well, though I don't know if that's at all relevant.
I would love to have an engine dyno, no doubt, and I am pleased that you are able to share those results. That is valuable data to be sure. However, assuming I have even a slight clue using my dyno I don't think your results invalidate mine just because of the equipment used,or vise-versa. Which leaves me with more questions than answers so far.
Consider my results from my perspective for a moment taking in to account more than just this isolated test data.
We have been using the same dyno for years and have continuously refined our testing process to get repeatable results. The two engines we built last year are nearly indistinguishable when tuned the best we know how and under identical conditions, yet we can identify small variances when conditions or tuning variables change. The headers I tested had welds at least as big as those in your pictures, I'd say bigger. It seems highly probable that if those welds represented a meaningful flow restriction for that engine, then simply removing them should show up as some kind of change in my tests. It is all but impossible that the two just coincidentally became "equal" only after one was modified so dramatically, which means it is far more likely that the modification made no measurable difference on THIS engine in this car. Does that seem like a reasonable hypothesis? [noun. A supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation. A proposition made as a basis for reasoning, without any assumption of its truth.]
And that lead me to start inquiring. But for one careless word I might have kept things on topic and avoided my longest ever post from a phone.
Todd, feel free to count me among those who don't know what they're doing because I certainly still learn something new each time I experiment or read about someone else's endeavors. Hopefully I'm not alone. In this case I at least am working from first-hand collection of data under carefully controlled conditions, yet I doubted my own results so rather than jumping on here and declaring anything as fact, I started asking people. The responses, from people who theoretically do know what they are doing, were mixed, so I came here to ask the broader community. Read the first post again and I think you will agree that I did it politely, being clear that it was our "first attempt" and the limits of the test. If your only real complaint is about my later use of the word placebo then fine, my mistake, I'll write off the personal insults as provoked. If you have some constructive questions or suggestions regarding my data and testing, I am eager to engage.
Ralph, thanks for the kind words. Please accept my explanation of the placebo issue, absolutely no intent to imply conspiracy of any kind. To even suggest that you must think I'm pretty loopy. Look back over the years and count the number of times I was not proved correct about things I said that then drew derisive black helicopter posts from some people. Seriously, try it. I could create a post longer than this of examples where I was proved right. That's not braggadocio or exaggeration, my name is not Trump, but I think your recounting of the past is casting an undeserved shadow on me (maybe from a white helicopter
).
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seriously, I get why they might have been a little bit tweaked given how my words were interpreted, though that could be seen as either a compliment or a sign of pre-disposition to expecting crap from me. Whatever, let's move on!
