Well if you read the article Gary posted you will see that the avg. numbers tell the story. The avg. numbers will give you the best times at the track. 1 1/2" 437tq 371hp avg. 1 5/8" 436tq 372hp avg 1 3/4" 438tq 375hp avg 1 7/8" 438tq 374hp avg You think this person that built that Chevy motor is going to worry about what happens under 3500 rpm? Soon as you stomp on it you are going to be at 4 grand the bigger headers take over at that point. You have a Buick 350 not a Chebby. So take your pick. The 1 3/4 headers did the best job. Why are we comparing a Chevy engine to a Buick engine again. Everyone knows you cannot use the same ideas. We use bigger carbs, the cams are not the same, so why would the headers be the same on a Buick as a Chevy. You have a 1 5/8 and a 1 3/4 for a Buick 350 I think we do not have to worry about the velocity problem We probably really need a 1 7/8 header for the bigger cam cars. With the Aluminum heads I know we will need this I can't help it Chevy's suck. Oh snap, I forgot we only race STOCK 350's on this forum. Darn, I am at the wrong website again. Which one of those headers do you think will make your car go faster.
Have the same size min choke on my car I built from the Cone kit as well Times in sig They do work for sure
Avoiding overly technical posting here... (walking on eggshells, lol) Diameter changes tend to be forgiving with power level and rpm range. You have to really overkill to hurt the engine. LENGTH is what tunes that amplitude around an rpm range. Good point on carbs rated for flow on a linear scale not comparing equally when different engines don't even breathe in a linear fashion throughout the intake cycle, and cannot broadly be compared based on what the characteristics are of what's in between the venturii and the cylinder (intake tract). They don't fill the same! Techy people wanting to play with formulas against the parameters in a magazine article have a great opportunity to manipulate #'s to see the effect of things. A broad range of calcs are on the Wallace racing site.
Been away from the computer for a while. Figured I'd let this simmer a while and see what came up. What I see here is very interesting. We know Buick and Chevy are different, but is the atmosphere and fuel they burn also different? The point of that post wasn't which made the best horsepower (woo, 4 more, really going to break some records with that!), but which one gave the best powerband and most torque, which isn't necessarily the best thing at the track, but is best for street use and milder gearing. I have said before that the numbers aren't as important as where they occur (and powerband width), dependent on what you intend on using the engine for. To the text in bold: it depends--on gearing, cam, and intended usage of the engine.
Wow, who's the one going off the deep end here? Embarrassed and butthurt? Clearly it is not me. Show me where I said half of what you claim I did. Now you say you don't judge, but you label everything I wish to contribute with judgmental, errant assumptions, and borderline on a personal attack, bringing up everything you can think of and presenting in the most sarcastic manner possible. I'm noticing a trend here. Come on Derek, you can do better than this (notice how I'm tempering my responses--I'm trying to do better--trying to encourage a peaceful resolve). I was simply showing how smaller tubing and higher velocity does well for street engine applications. That's it. The engine used in the article comparison was a baseline engine, simply used as a workmule to demonstrate what different sized headers will do. Each could have been tuned for optimal performance, but that wasn't the point of the article (or my post). Mostly, it was to demonstrate that shorty headers aren't as 'lame' as you guys are carrying on about. Everything is relative, and obviously you need larger for more air flow to match the velocity with air volume and tube diameter. I thought I had already made this clear? What theories? All this is documented with real evidence. Even the things I talk about in other threads. Heck, even the dyno software uses math to figure things out. It may not be 100% spot-on, but it gives a good general idea on power output and bandwidth. It's certainly cheaper than going through 100's of dyno sessions to sort it all out through trial and error. You think I just pull all this out of thin air? I'm trying to help people understand why/how things work. If someone already knows, then that's fine; however, it has become abundantly clear just how many of you do not understand some things. You don't have to be ashamed. You don't even have to comment. Just learn from it and you and your customers will be all the better for it. There is no such thing as wasted time doing research, investigating, using knowledge accumulated by yourself and others (dyno and track results), as well as other sources of information. It's all important. All of it. What are you so bitter about anyway? Something I said happened to turn out to be true after it was investigated? I don't get it. I WANT someone to prove me wrong. It's one of the ways I learn (not like it would be the first time!). But if you show someone else's error, they blow up in your face, clearly not interested in learning, but wanting instead to simply be right. I'm not that petty. The post wasn't even directed at you personally. I try to make my posts in a general sense so that everyone can see it in themselves, should it apply. Just to reiterate, scavenging and velocity are key, and are size relative to air volume. Bigger=bigger; smaller=smaller. Mix and match in accordance to what works best for your application, based on fitment, budget, and efficacy. Gary
Something else I wanted to point out about exhaust pulses helping each other out: the closer the pulses are to each other (in both timing and physical distance), the better they will help each other. Very simple concept, and is used in 4-2-1 header technology, which use the engine's firing order and tube merging to combine the pulses in the maximum efficacy possible. This isn't a 'theory' or 'nonsense'--it is science, math, and documented fact. It works. On a manifold design (and even 4-1 headers, to a point), you don't get this same effect within the manifold/header itself; it is therefore important to understand that the individual pulses will then exit the manifold/header one pulse at a time and can be better drawn out with a merge pipe (Y or X) that uses the alternating exhaust pulses from one side of the engine to the other. This gas velocity science is still applicable here, and even though doesn't work as well, is still a better alternative than using divorced pipes. It is also important to note that the hotter you can keep this gas up to the merge pipe, the better the merge pipe will scavenge, so a good coating is highly advised. This is why using merge pipes produces more power even in headers, vs just letting each cylinder have its own tube and letting it blow out into the atmosphere--or separately into one large collector; or divorced pipes on iron manifolds---take your pick, it's all relevant to this concept. Anything used to help draw out the gasses is preferred over simply letting the expanding gas and piston movement to do all the work. Behind each exhaust pulse is a low pressure wave, which when passing by another opening at the proper angle, will create a 'vacuum' to draw out from that side. This aids in scavenging, which aids VE, which produces more power. The hotter the gas is, the more it expands, the faster it moves. Proper sized piping permits this hot gas pulse to move at a speed which aids the engine (in scavenging, which aids VE based on cam overlap) and helps base where the powerband will be. Smaller tubing = faster gas movement with lower RPM or less CID; Larger tubing = more volume which needs higher RPM or more CID to have a similar velocity. This is why larger tubing generally benefits larger engines or higher rev'ing small blocks, and why smaller tubing benefits lower RPM engines. It makes sense then that in order to maximize this effect, a coating over the tubing to retain as much heat as possible would be a wise move, and would also help keep the engine compartment cooler, which will make even more power and give other components a longer life expectancy. This can be applied to any exhaust used, whether it be headers or iron manifolds, and head pipes back to the merge pipe. As the exhaust moves farther from the source of ignition, it begins to cool very quickly, which contracts its volume and slows it down; smaller tubing is then beneficial to ensuring better exhaust evacuation. This is also science, and works. Finding the proper sizes can be trial and error, if you do not do any research or learn anything from others who have done it. Gary
Not disagreeing with your points... I don't think the discussion on long tubes vs. short tubes has as much to do with amplitude of the effect being stronger as a result of the pulses being closer to each other (if I read that right). Although that might be true, the length of the tubes at the merge point influences the rpm range that scavenging centers it's efficiency around.
Why don't you go back and read your own story those were average numbers which means that happens between 3 and 6 grand and the best avg. numbers will win on the street. If cheve is any different in the atmosphere dept then why would you need anything bigger than a 650 carb on a 350 Buick, that is what chubby uses for max carb. I stand behind my previous post statement. Write me another story with bold statements so I can read them correctly. Why I waste my time with this crap is beyond me. :sleep:
Being closer together (both in timing and physical distance) is when two tubes placed adjacent to each other fire sequentially, which brings them closer together in timing due to the firing order, and being right next to each other helps one draw harder on the other. This is what started the debate you and I had a while back about the flat line creating more surface area, permitting maximum surface area for a harder draw. While you seem to disagree on this (or did, I'm not sure where you stand now), it does make a difference. While the difference may be small, we all know that every little thing makes a larger difference when you compound them with other effects that is integral within the entirety of how the machine works as a whole. It's rather like how round vs oval can affect how flow behaves. With round, the distance from one side of the diameter to the other is farther apart (recall that closer is better); where on the oval, the thickness of the narrow part of the oval is brought closer together, while having the width to permit the entire volume to be affected. This is exactly why the Buick 350 intake head runners work so well, and has been misunderstood by so many to be a 'flaw' rather than purposeful engineering incorporated into the head's design. You can flow more while retaining better velocity vs a round port design. Taking all this into consideration, imagine then why a "D" port/tube would flow better than a round port/tube. While not completely oval, the flat side of the "D" brings that side closer to the center of the round part, while also having the benefit of the flat spot creating more surface area for more effect. It's no accident that many manufacturers of more expensive products incorporate this design into their collectors. Opposed to this concept is the round tube, which won't be as effective on physical proximity (even for tubes butted up against each other, side-by-side), and then add the fact that on a 4-1 header you'll have the firing order sometimes creating tubes opposite of each other in the 4 tube cluster (where it enters the collector) fire sequentially, and those tubes are even farther apart. While still much more effective than a log style manifold and does in fact aid scavenging, isn't as effective as it could be--in comes the 4-2-1 header. The 4-2-1 header splits the primaries into 2 groups from the head (each into a merged pair), then those two merge into the final collector (I know you know this, I'm simply writing it out for educational purposes). The primaries are divided up so that the firing order will better time the pulses so that they can offer maximum pulse gathering effect, as opposed to firing too far apart or too closely together (timing wise). It also adds the benefit of an additional scavenging path prior to the secondary scavenging path, where the two middle tubes merge into the final collector. This is also true. Tube length also plays an important role in pulse timing, dependent on the amount of air volume and the space required to expand to optimal distance away from the ignition source. This is also where tube diameter and tube length become more important in their relationship with each other with the amount of gas volume to be moved. It's also the same reason why collector length is important in relation to primary tube diameter and length. It all works in unison, and when timed in a precise fashion, will optimize scavenging with tube size and the amount of air to be moved within a specific operating range. Amazing how header size can affect powerband almost (if not more, in some regards) than the camshaft! People get wrapped up in how important the cam is (even though it still is, of course) when it is only one part of the entire package. Air is flowing, and uses many parts to make it all happen as a whole. Change one aspect, and it can offset the effects (beneficial or detrimental) of the rest of the parts. Often the environment cannot be created to manufacture the 'perfect storm' and so there are almost always going to be compromises. While it may come down to 'splitting hairs', small differences can add up quickly and be amplified when working with other components. While not as important on a daily driver or typical street machine, these differences can be what makes you win or lose when you're counting in increments of 1 mph and .1 of a second. When it's as simple as adding in a merge pipe when using manifolds, little extra effort or resources are required to make this small change that can add up to noticeable differences in the engine's efficiency and performance. Please feel free to add in your own thoughts. Gary
You 'waste' your time because you are evidently interested. Pretend you're not, but your posts tell another story. Hey that's ok, don't be ashamed. You want to learn or you wouldn't be bothering at all with it. I find this promising. I know they were average numbers. Don't get too obsessed with the numbers. Where they occur matters more, depending on what you intend on using the engine for, car weight, gearing, etc. Also remember that it's not always about racing. Check out my new post and tell me what you think. Gary
Sooo, what I'm attempting to say is that longer tube headers and tri-Y headers tend to work better in a more usable powerband than shorties because the pulse timing aids cylinder scavenging more effectively than shorties that are paired more closely together, even if there's a theoretically (by your description) stronger influence over the adjacent cylinder's event because of the tubes being joined closer to the adjacent cylinders. You don't have to follow my opinions on that, there are other places to read about header design...even some from the best in the business. They way I read it was that the sound wave and it's reflections (the basis for the header formulas) have more "pull" than the moving mass does on another tube. Remember, we are trying to pull on the opening intake valve during overlap in order to initiate the intake tract, not simply pull on the adjacent cylinder harder. There's more going on than flow and improved flow from merges, they are sound wave tuned. If one accepts the theory of an intake manifold able to be made "tuned" to an rpm range and acknowledges the effect of "intake ramming" via inertia then......understand that the pull from headers can be 9x stronger on the intake tract than the aforementioned inertial ramming. That should say a lot! Tri-Y headers seem like shorties, except that the tubes are paired for 180* firing intervals, making them tuned for both hp and torque peaks (or so), rather than one narrow range. The pairings are usually made with adjacent cylinders merging on one bank and cylinders 2 apart on the other bank of the v-8 (they cross tubes). Long 4-1's have an out of sequence cylinder on each side, but still seem effective enough anyways. There have been 4-1's out there that route the out-of-sequence cylinder to the other side in order to negate that disruption. (I think the one's easiest to Google would be seen on FE fords, where they cross over behind the sump in the oil pan.) I'm guessing they have fallen out of favor due to the hassles (many ways) and the fact that they might not add as much hp a$ they co$t. The effect on powerband related to cylinder size/header dimensions can be seen by creating a sim engine into Pipemax or other available header calcs. These are used by professional builders wanting more than a shelf set of tubes or have a weird combo. I hope this isn't taken as inflammatory, it's just basic tech. [keep in mind that although it sounds like I'm selling headers due to their fantastic influence on the engine...none of it amounts to a hill of beans if the entire system doesn't work well together, ie. the camshaft. this is why I post more questions than answers when people ask "how much hp will (generically described) headers ADD to my xxx"!]
unless you have a big bank account, much of the written stuff is a bunch of crap. you can yadda all day about header theory, but nobody is going out of their way to make the fancy stuff. all you are doing is confusing the 350 crowd. headers by doug, t/a and hooker are the only ones available. that's it. get over it. AND the theorist's don't even run a 350. :blast::blast:
AND to further prove my point about all these crap, ASK the guys who run nhra stock, super stock. bet they don't run any oddball built headers.
Woohoo, look at all the attention and views this thread is getting in such a short time! Even GSJohnny has something to say (who normally remains quiet these days). :grin: Come on Johnny... don't be so grumpy and dismissive. Don't sell the readers short. It's a younger crowd now, and they know a lot more than you think. They can certainly learn! Look at how fast kids are learning nowadays (when given the proper chance). If we can explain how/why things work, then what's available may indeed change, especially with the introduction of newer parts and the opportunity for other new products, whether custom builders step up to the plate or a parts vendor starts offering more off the shelf variety. Don't be so resistant to change, or you'll end up like the dinosaurs who couldn't adapt fast enough. We all know what people use, why they used it, and what was (or wasn't) available in the past, both with physical parts and knowledge. Times they are a changin' Keep stirring the pot though, we need as much input on all this as we can get our hands on, and as always, thank you for your input. Gary
Information well received; thanks for your input. I would add more, but I fear we would be just talking in circles. I'll let the information stand as is and let it be for the record. Thanks again! Gary
I'm tossing around some ideas myself. Keeping them to myself for now, though, since it's still a work in progress. Your suggestion shows me you're on the right track though! :TU: Gary
