bigjoe1 wrote:All of my experience has been bad. On several occasions a jet boat racer has come to test headers on my dyno . He always brings several sets of Burns headers/collectors. They never show any gains- this is the same Burns guy who sells these very high dollar merge collectors. So far, no good. I still get emails and phone calls about them though
JOE SHERMAN RACING
exhausted wrote:bigjoe1 wrote:I have had lots of guys come to test headers on the dyno, and some want to try the merge collectors. I never seen anything even cose to what they cost as a result. Usually they are a little better way down in the RPM range, never at high RPM though. A few HP for sat 400 dollars is not a good deal. Pretty much a waste of time and money.
JOE SHERMAN RACING
The principle that is at work in a merged collector is this. The smaller the choke the longer it takes for atmospheric pressure to equalize into the back door of a given engine. It protects your power curve the same way as shorter cam timing and longer primary tubes. Just slipping a collector on with a smaller choke will usually show more power at the bottom of the curve. (which Joe points out)..
The secret is that you can now shorten your header which is how you can make more power upstairs.
Header length is always relative to rpm band but also the size of the choke. Most headers have to be long because the collectors are so large. The longer tubes keep the reflected wave "back" at the lowest point on the power band that the engine has to pull from. Change the collector choke and shorten the tubes and you will see the power. If you can't shorten the tubes, do not blame the collector, and if you need shorter headers, call me...
I am using Joe Sherman's example as what will happen just installing on a existing header. If you can not shorten your header or get one shorter for your application, Joe is absolutely correct, they are expensive and are not a solution in themselves.
Strange Magic wrote:If you take two identical engines and where only allowed to work with 2 changes (intake manifold, camshaft) over a long period of time, but one of the engines must have a merge and the other a scavange. I truely believe that the scavange engine would dominate after all testing was done over a long period of time.
I really believe that a merge is just a band aid for incorrect manifold and camshaft events, and there is so much wrong out there that it's no reason why the merge has become a hit. You will not find a merge on anything I build.
P.S. I am a big believer in primary length and 95 percent of the applications out there do not have enough primary, and that will cause signal loss in the intake and poor exhaust speed with a weak ability to scavange.
77cruiser wrote:Would the PS guys use em if they did nothing, or the cup guys?
hoffman900 wrote:77cruiser wrote:Would the PS guys use em if they did nothing, or the cup guys?
Most serious circuit racers (road race and oval track) use them. I've seen top Super Stock, Comp Eliminator, and Stock Eliminator engines with them. It's part of the entire package and if you talk to people who have done the work, they don't make horsepower by themselves, but allow you to change other things which is where you see the benefit. There are many guys who build good, strong 'bracket' engines, but I don't think there are very many serious top level circuit or heads up builders posting and sharing information here. Those who do or are involved with those who do, you listen to them very closely and while sometimes vague, you can read between the lines and get what they're saying. Ymmv and all of that..
Looking at something like EMC, I think you're going to see more and more effort being put into the exhaust side as the competition matures and becomes 'stouter'.