Header Theory Dyno Test

everybody Johnny hook ends with popular hot rodding magazine today we're at West tech performance group and we're going to test a whole bunch of headers today on a big-block Chevy and we're here with Steve dulcich who is going to head up the project for us today Steve Archie toast a little bit about what we're going to be doing today we got a different path we took our headers basically from very small to very big areas in my house and itchy food coordinates primarykey diameter we're going to step that up to the inch and 7/8 some very popular size we got that encoded and uncoated version so we compare the difference of the coating Mike made to the performance of the header then we've done two inch which gave the terms of our primary key binder and issues without inviting a few minutes primary header - for a brief file header a collector but music the right choice who are very powerful engine now we also have some collector extensions here we're going to test those and see if they make a difference - well the clicker extensions will help simulate the Marshall exhaust system to human organization how much of an effect they have by running or 1 and 7/8 Center combination with and without the collector it fits in place we're going to be testing these headers on a really nice 427 cubic inch big block Chevy but tell us a little bit about this engine Steve well this is originally a Corvette engine the 427 displacement of very popular in this 1960s is most partisan for that the AFR cylinder heads these are the 305 as caps so very high flowing head you can go it's not and supported we have a big manifold and the Holly open HP carburetor it's going to be a pretty stout foundation temp.1 actually a bit makes you wonder 600 horsepower mask mode you well we just stepped up from our baseline test the one and three-quarter inch long tube header to the one and 7/8 inch header and boy what a huge difference it looks like we got better than a 24 20 horsepower increase there Steve if you look at the graph over here the the bigger header actually started making up more power from about 4,500 rpm and then just ran away at the top 10 so it's a big advantage now what's even more interesting is a lot of guys will think well I'm going to put the small header on there and pick up a whole bunch of torque down at the bottom didn't work that way so much if you look at the results right here the bigger header actually made better torque down low and yeah that's the red one there now I've seen that kind of result before with higher power motors where you just don't have enough header on it so that may not be what everyone would expect but it's not an atypical result the bigger header is definitely more correct for this engine wow that's cool well I'm very curious to see what happens when we start experimenting around with the header coatings and the collector extensions well we'll just have to wait and see it's only a few diner pulls away 185 a 95 degree cooldown in heaven about one minute you 873 Wow that's 500 degrees apart it I can tell you we can feel the extra heat here in the dyno so yeah it is smoking hot I mean when we had to connect headers in here it was you know almost comfortable it's just not yet this is smoking hot well Steve we have our results from the dyno on the coded versus the uncoated and you know I'd say that the jury's still out looks like we got a little bit of an improvement on the power but maybe not enough to really say it's statistically significant but we do have some other surprising results why don't you lay them out for us well never mind this is exactly the same set of headers the only difference is coded versus uncoated if you look at the ground there's just a little bit of a bump right here with the coating in torque and horsepower tiny bits showing a top it's very close to this distal variation of the dynamic it's like four horsepower 4 pound-feet of torque on a motor that's making you know not even almost 600 horsepower you know every little bit counts boat where we really found that an advantage of right here proving the temperatures in this case I mean the results were just night and day we saw an average temperature in the mid 200s with the coated headers jumping to 870 degrees with the black hand wow that's huge and think of all that heat pumping into your engine bay or a passenger compartment in your running car that makes a real difference to how your street car performs you know that in a daily basis well I remember when I was in there with you shooting the video it just was hugely different I mean there was unbelievably hot when we didn't have the coating on there so ceramic coated headers big thumbs up not necessarily for the horsepower increase but man when you consider all the other components and stuff under the hood you know fuel and float bowls and heat soak and batteries and electrical wiring and stuff it is a huge thing I would not have an engine without a set of coated headers that's my personal it was just a furnace in there with the regular headers so absolutely on party well we just did it before and after comparison of a collector extension which is a very interesting test Steve tell us about the collector extension test well if you look at the graph over here what you'll see is we we've changed our test RPM range basically focusing on a range below peak target because this is where the effect is going to be the most dramatic now if you look at the black trace here that's a plain header exiting without a collector extension you notice this big hole in the torque curve over a pretty significant rpm range especially evident right here at about 3500 rpm which is a pretty important engine speed now the red trace is with the collector extensions added in and you can see all the added torque within this whole range well I think it was a 57 pound-feet of torque at one point probably 3700 rpm or so right in there I mean it's closing in on 60 foot-pounds right about at the torque converter hit on most street cars so that's huge you're taking your street strip car down to the track and you uncork it probably be a good idea to take some collector extensions along well we just stepped up from the one and seven-eighths inch header to the two inch header and we've got some very interesting things going on here the person you've been seeing in our video quietly operating the dyno is mr. Steve Brule he's the dyno operator here westtech performance Steve tell us a little bit about what's going on what are we looking at here on this chart well what Steve and I were just discussing is we've got the ancient seven eighths header versus the two inch header this is kind of the step up into the realm of this sort of power level that you would typically expect we slee see a slight tilt in the curve the black line is the two inch header nation 7/8 is the red line we're seeing a slight loss in bottom end power of 3,000 a little crisscrossing in here not much difference but right at the peak you see where the two-inch header really breathes better now with our initial test for the inch and 3/4 header we were so far out of range with that it was just too small for anything about this about this engine it was worse at the top by a lot and also the ancient 3/4 now the redline it's also worse at the bottom so the ancient 3/4 is clearly not the right header for anything about this well we're doing a two-inch header now we're going to try the biggest one to an 1/8 inch header let's see is the same have any more left in it see big tuna to 1/8 inch and well this is our last setup of the day we found so far today was the inch and 3/4 was grossly undersized and lost power pretty much everywhere in the curve stepping up to the 1 to 7 days we have a pretty decently matched header nice power curve throughout 2 inch widths of just a little better at the very top but down lower mid-range it was pretty much a wash my money's on the 2 inch ones that take maybe there's a little nuts in this table I think maybe this might be a little too much words that might not be sure here in a second let's go to the dyno to find out well we just finished testing the two in an eighth inch header and we've got the graphs up of the two inch compared to the two 1/8 inch and it looks like it's too close to call there there's some differences there between the two can you anybody want to get hazard a guess Steve or Steve what's going on I'll take a bite out you look at the very top here you know it's virtually the same power within one horsepower over here the two headers depending on how the pipes are tuning in at different rpm say slop advantage and disadvantage but where the smaller header hasn't very clear advantages it's just going to fit the car a lot better so you're really losing 54 not really any gain in performance from what I can see Steve yeah adding the average numbers are virtually the same if you look at it from 3,000 to 5,000 but the interesting thing is a lot of people are going to state the smaller header would be better at 3,000 and wide-open throttle now I mentioned that when we're testing it wide open throttle a lot of those sorts of thought processes really are calculating some of the things that people are thinking really probably has more to do with throttle response in part throttle but this all has to do with tuning I mean as far as the pipe diameter length versus intake manifold and camshaft and all of those things have to be taken into account when you're looking for the optimum headers so basically these are two are swapping it a little different rpm range which is a clear indication of cylinder filling when the torques higher the cylinders build more efficiently the volumetric efficiency of iron and because of the way that it's tuning it's kind of dropped down here a little bit smaller headers actually a touch better well that's very good we do have one more thing we're going to have to test and that is the shorty header that's the thing that everybody wants to know if I put a shorty header in there is it going to be good is it going to kill my horsepower is it going to be easier to install what are the advantages I say we go in there and swap those headers out and do one more so that shorty header was really something there that was a real eye-opener one in seven eighths inch primary tubes very short and going into a rather small collector flange something like two and a half two and three-quarter but the results not what a lot of enthusiasts would hope for but they're still hope therefore folks if they need that kind of product well if you want to just look at the power out but the graph shows it pretty clearly right from the bottom of the curve here across to the top does it flossing torque corresponding loss in horsepower almost fifty horsepower at the maximum power loss here at the high rpm range now the thing we want to point out to people here is that this is kind of comparison of best-case scenario you picked the perfect Tedder for the engine the header fits in the car everything's hunky-dory versus hey I can't put anything in except for either stock manifold or a shorty header that's really the kind of compromise the trade-off that we're dealing with here the shorty is not going to be your best choice or your first choice if all-out power is what you're after but if you're looking for fit you want to do away with a lot of hassle of getting a set of headers up under your car the shorty is just a nice way to go well we're finally finished with the cornucopia of headers in our big-block Chevy dyno test wow I'm really tired Steve how about you well I don't a we've got through a lot of header tests good about where can you find this stuff Steve somebody wants to read about this all going to be laid out in the October issue of popular hot money max yeah and that will be on the newsstand the third week of August so we'll see you on the newsstand full

Channel: popularhotrodding

Views: 550,697

Keywords: headers, dyno test, big-block Chevy, Hooker headers, long-tube headers, ceramic headers, collector extensions, primary tube diameter, shorty headers, Westech Performance, SuperFlow dyno, headers on dyno, header dyno test, Steve Brule, Steve Dulcich, Johnny Hunkins, Popular Hot Rodding, ceramic coating

Id: O1bXPNy1Yn4

Length: 18min 17sec (1097 seconds)

Published: Tue Jun 11 2013