Merge collectors
 

Looking for experienced comparisons between Stainless Works MCL line against Burns B-Tec and Kooks Shootout merge collectors...pros-cons vs cost.. working with 2" ID primaries.

Re: Merge collectors
 

Merge collectors are completely application specific. What you're looking for is who knows what dimensions you need for your application. Primary size is one small aspect, and it has to be correct in both diameter and length for your application before you can design a merge collector with most formulas or software.

Re: Merge collectors
 

The ones I'm looking at are off-the-shelf part numbers, and there aren't really any specified dimension differences between these brands except primary/reduction/collector diameters. I know Burns has the most options with length and collector design (including the different outlet shapes etc.).

Re: Merge collectors
 

I am not at all a fan of merely grabbing a shelf stock merge collector, especially not just because the primary size matches. It is entirely possible, maybe even very likely, that you'll end up with something that does not work with your combination at all. It may do much more harm than good.

The length, minor and major diameters, and even the taper of the megaphone are very critical to tuning.

Re: Merge collectors
 

Gary: I have to agree with Alan as usual.

Talk to Perf. Welding about your engine combo as he is pretty
up what everyone is running and will work with you to get you
in the ballpark. Find out what people with the same combo have figured out.

Next time I see you we can chat about your combo and I will give you my opinion in private.

Re: Merge collectors
 

Has everybody else found those to be faster?

So far, my car is faster with straight collectors. Tried two sets built for a friend's LT1, best set made no difference, he found the same. Other set also slowed mine down. I was told that was because I had too much exhaust lobe, I only have 4 degrees more than the intake @ .050", less than 4 at .200" lift.

Ditto step headers. Mine likes straight 1 7/8" primaries, straight 3 1/2" collectors. I am doing something wrong. Seems like I have wasted a lot of money on trick parts. I must be doing something wrong. When looking at Cour's & Decker's times, something very wrong. smh

Re: Merge collectors
 

Ed,
Step headers and merge collectors are similar to 4-2-1 headers, you need to do a serious amount of tuning and probably cam testing. When you use either, or both, you significantly alter your exhaust tuning, with an exhaust lobe that is large enough for a set of single diameter headers and a merge collector, it is very likely that you can create a serious "over scavenge" condition. If that is the case, you can see what happened with the right dyno data. The solution most often is a smaller exhaust lobe, as much as 4-6 degrees. You may also need to spread the LSA a degree or two. But what you may gain from all of that is the ability to run a large(r) intake lobe.

The short version of that is: if you have a correctly matched and tuned set of basic headers and collectors and cam, it is likely you will find no power gain, or a power loss with a set of stepped headers and merge collectors.

So, when/if you buy a set of stepped headers and merge collectors, and you spend $1500+, expect to buy at least one cam, and maybe spend money on a couple of dyno sessions and a track rental, so another $2000 is easily possible. It's just another example of "HP cost money, how fast do you want to go?"

Re: Merge collectors
 

Alan, I've been telling the same story for years but nobody seems to want to listen. There are advantages to being able to take exhaust lobe away from the engine though. If a conventional header is "properly" sized to a combination, the average Racer should be satisfied. IMHO, most Racers buying off-the-shelf headers are buying too large a primary tube for their application and then being sold the merge collectors as the fix.

Re: Merge collectors
 

Billy, that's what I'm seeing as well. If your headers are too big, you can "crutch" them by using a merge collector with a small minor diameter, and even better, the longer of the two common correct tuned lengths. For example, if you had 2" primaries, and you should be running 1-7/8" or 1-3/4" primaries, you could use a merge collector that had a 1/4" smaller than normal minor diameter ( say 2-5/8" instead of 2-7/8"), and if the first tuned length was 7", you could go with 14".

Unless you buy your headers from someone who really knows what they're doing (there are not too many guys like Jere Stahl selling headers these days) or you have good header software (PipeMax is what I use) most people end up with 1/8" or more larger primaries than they need. In order to compensate for that, they need to add 3-4 degrees at 0.050" to the exhaust lobe. If you can't or don't spread the LSA out, that really limits you on the intake lobe and/or the ICL.

Here's a good example. On a Stock Eliminator engine, we did the preliminary dyno testing with a set of 2-1/4" dyno headers. Then we swapped to the 2" - 2-1/8" Stahl headers with Jere's semi merge collectors. We immediately gained well over 25 ft/lb of torque, but we also lost well over 10HP at the top over a 600 RPM spread. Then I looked at the dyno data closer, and realized that at the same place I lost over 10HP, the engine flowed almost 20 cfm more! Guess where the 10+HP went. Right out the exhaust as an "over scavenge" condition. The correct fix for that is around 4 degrees off the exhaust lobe, and 1-2 degrees more LSA. The reason for the whole thing was the engine previously had a set of Hooker headers that should have been on a Super Stock engine, the primaries were too big and too short. A set of Mark Lelchook's merge collectors were used to help "crutch" that. But even that was not enough. What we know about that, is that this particular car, with that cam and Stahl headers is a killer in the 1/8 mile, but a little off in ET in the 1/4, and down around 2MPH at the top. It's getting a different combination, but Jimmy Bridges and I had decided that, if we kept running that one, it would get 4 degrees less exhaust lobe, and 2 degrees more LSA. I'm pretty sure Jimmy is ten times smarter than I am.

Re: Merge collectors
 

Interesting read. What would be the tell tale signs that a engine may be over scavenging? Anything noticeable in the tune up that would be an indicator of this condition?

Re: Merge collectors
 

Pretty much an over-simplification but the car won't be responsive to timing or jet changes.
If the combo can handle it, open up the exhaust lash and make a run.

Re: Merge collectors
 

Been out of racing for about 15 yrs but I can remember when we changed from our Stahl headers (2 inch) to a Davis step header (2,1 7/8,1 3/4). Didn't see much gain until we added an 18 inch extension on the collector. Really brought it to life.

What was it trying to tell me???

Re: Merge collectors
 

Billy is dead on,you can't seem to get it rich enough. You'll be putting jet in that makes no sense, loosening the exhaust lash and picking up shows the exhaust is pulling unburn
,ed fuel out on overlap,

Re: Merge collectors
 

The topic of lean rear cylinders is what drove my question. We haven't even run the motor yet, not looking for gains, just don't want to go backwards. Headers are nothing special...straight 2" primaries about 40" length. Last year we made some fixes (new fuel pump) and added 13" to the collectors and picked up 2 tenths. I suspect much was from the exhaust. But everything is bigger now, with lots of other changes with same basic induction. We'll probably put straight 4" collectors on to start. FYI this is not for my stocker. It's a bracket motor built with a lot of S/S technology.

Re: Merge collectors
 

Mine is very responsive to timing changes, likes to run richer than some others. I talked to Jere Stahl quite a while, twice when I ordered mine. Always used his stuff on my old "Jr Stockers". Tried to order a set from him when I make it a race car. At that time they had no jig for the LT1 Camaro/Firebird. Whoever I talked to then told me they could build a set for me if I wanted to bring my car there. York, PA is a long drive from Oklahoma. Talking to Bobby Warren a couple years later, I learned he had taken his there to have a set built, so they now had a jig.
Jere had me fax him my dyno data (both steped & straight 1 7/8" headers) and engine specs. I told him I had tried my friend's merge collectors at the track, and what I found.
Jere told me he saw no way it would like the 1 3/4" to 1 7/8" steps, he said the non-step 1 7/8" should be right, and it MAY like 1 7/8" to 2" steps. He didn't see it liking merge collectors, either.
I tried backing the ex lash off with both styles collectors, didn't like it. I have not tried less than 4 degree int/ex duration split @.050". Less than 3 at .200" lift. Tried wider lobe centers, even with more gear. Dyno liked it, short times suffered. Back half about the same. May need a 7" converter with that cam? Don't know. The normal cam did not like one at all.

Re: Merge collectors
 

Quick question, and I know this may be more complicated than this, but as a generic rule of thumb would you need a better scavenging header setup for a cam with more or less overlap?

assume generally the same cam specs for a cam with 80 degrees overlap compared to one with say 70 degrees. only change being lobe separation. you you need more scavenging going to the smaller overlap to be as efficient?

Re: Merge collectors
 

If you measure the port on the LT1 head, last time I checked, 1 5/8 tube covered the port. The reason you see no change is the header isnt even working at this point....13/4 and 1 7/8 are way too big... proven many times over... you guys are not talking to Calvin Elston obviously....

my proven $.02... race track and dyno

Re: Merge collectors
 

Two header gurus told me steps are what I need, one even talking three steps, (with a 1 5/8" first step) but THE master header builder, (IMHO), Jere Stahl, (knew Jere from Jr Stocker days. Happily he remembered me) told me what it should like after I sent him all the data he asked for, and it agreed what I had found on Patterson's dyno, and (since we don't race Dynos) A-B-A testing during a track rental test session.
More to header fabrication & layout than I realized. My 1 7/8" Stahl headers (one of the very last set they built) are a full MPH faster than my old 1 7/8" Hedman Hustlers, which were on the dyno. And, I can get all my spark plugs out. Haven't been back on the dyno with the Stahl headers.
I just went back and looked, I typed the correct numbers in: 1 3/4" to 1 7/8". I cut a pattern, like cutting a gasket, and sent it to Jere, he had his guys water jet (I think) cut a set of flanges for the 1 3/4" tubes, for my Stahl bolt pattern on my aluminum adaptor plates. So they were centered correctly.
Elston is one I have not talked to.
Btw, Sir, who are you?

Re: Merge collectors
 

http://www.speedtalk.com/forum/viewtopic.php?p=75639

start reading here. lots to learn about the correct header before any of you should consider merge collectors....every winter there is a new thread it and it dies the same way.... this winter, lets start with Calvin and maybe we can convince him to swing in the forum and educate people....

Re: Merge collectors
 

I tested what Jere Stahl recommended. It was faster. Good enough for me.
Thanks.

Re: Merge collectors
 

I went the fastest in B/A and C/A with merge collectors from the same guy that was building them for Glidden. David ran them as well.

Re: Merge collectors
 

Much as I like and respect Jere, I'm not at all convinced his opinions on steps and merge collectors are completely correct.

In fact, when I pressed Jere a little further, he admitted that step headers were worth some power. Ours are one step, 2" to 2-1/8". They were in fact quicker and faster than the Hooker 2-1/8" headers. Even when the Hookers, which were too big and too short, had a set of Mark's merge collectors on them. Later, after some testing and data crunching, Jere and I discussed a set of two step headers, 1-7/8" to 2" to 2-1/8", and a set of merge collectors. Development on that combination stopped before they were built.

Jere's main thoughts on stepped headers, and merge collectors, were for the most part along the lines that few would ever do what was necessary to see what he told me he felt were possible 2-3% gains. As such, he felt for 95% of his customers they were not worth the extra money. The truth is, Jere is probably right. As Billy said, and I agree, for the vast majority of racers, a basic set of single diameter headers with regular collectors, properly sized, will be all they can ever use. They will never do the development necessary to take advantage of anything else.

Now, the flip side of that is that 3% on a 650HP engine is almost 20HP. Well worth the upcharge Jere was asking for two step (three diameter) 4 into 1 headers.

I spoke at length with Jere's head fabricator, who actually runs the new business, and makes genuine Jere Stahl pattern headers. He told me that he would not make single diameter headers anymore, they would at least be one step, for both performance and ease of fabrication. Odds are, my next set will be built there, and they will be two step, or three diameter headers. They will get a set of merge collectors.

I've also talked to Larry Meaux (mostly by email and private message), who developed the PipeMax software that many of us use. Larry said that even some of the most well funded racers, even after seeing what the right size and lengths of primaries and collectors did for their expensive race engines would not spend much more time and money testing cams, and especially not on merge collectors. Larry has in fact expressed the same thing Jere, Billy and I have said. Most racers either cannot or will not do what is necessary to make the higher end headers and collectors work, and will see no gains. Larry has spent a couple of decades on the dyno and the track learning about this stuff, and then writing software to quantify it.

I've spoken with Calvin Elston many times, He is a very sharp individual, and a great fabricator who makes a top shelf product. They are absolute automotive artwork, no doubt. That said, his headers are more than twice what Jere was getting for his, and few people would make the effort and spend the money to see the gains they potentially have. A set of 4-2-1 headers requires even more camshaft development than a set of step headers with merge collectors. Calvin quoted me over $3500 for a set 4-5 years ago, and I know it might take 3-4 cams to take full advantage of them. At a bare minimum, that's $1400-$1600 worth of cams, and 2-3 days ($1800) worth of dyno time. For the vast majority of racers, that's just plain out of reach, and out of the question.

Re: Merge collectors
 

I worked with/at Kromerkraft in the late 90's & early 00's. Everything we built in that era was merge collectors with the tower in the middle to make the flow path more streamlined, occasionally megaphone collectors. Our experience from customer to customer was maybe a max of 0.05 seconds improvement. Generally, 0.02 or 0.03 made for a happy customer. Sometimes what the car wants on the track is not exactly the same as what the dyno wants. One occasion, we had a Super Stock engine builder request two sets of headers, one with 2 steps and one with 3 steps. The dyno liked the 3 step and track liked the 2 step. My guess for the merge collectors is that won't hurt, but may not help. Generally, we found that each customer had to be treated individually for his particular setup.

Re: Merge collectors
 

What you'll see on the dyno data, if the headers are over scavenging, is the torque and hp numbers drop while the V/E numbers go up. inconsistent EGT's and BSFC numbers jumping. SS engines are to many different breeds to say if a merge is better, certainly not without the proper cam timing. The PS guys get away with them because their exhaust valves are so small and their ports are fast and efficient.
Frank.

Re: Merge collectors
 

Jere told me mine might like a 2" step on mine.
No more int/ex split than my cam has ( 4 @ .050"), and I backed the ex lash way off, still nothing. Some run single pattern cams, or "reverse split" cams to make merge collectors work? My heads do have very good exhaust ports. Best I have seen for an SS LT1. I have seen, owned and flowed LT1 heads from a few shops. Was no huge difference between the two most popular. (Have not seen Gulius heads) I have tested all five of my cams. I have bigger & wider, smaller & closer, more split, and the one I keep going back to. Done fuel loops & timing loops on the dyno. So far found nothing. May just be too stinking dumb. Likely so.
Got two more races till I'm done anyway. Through looking for more. Trying to watch the average for the other guys these last two.

Re: Merge collectors
 

We set a national record with a set of Hedman step headers on 302 ford. The pipes were 1 1/2 to 1 5/8 step. You can't use there collectors as they are no good for a race car. The collectors we used were made by Headers by ED of Minneapolis MN. He doesn't use a merge type of collector but uses his own style that seems to work just as well. And it is a lot easier to make. Ed no longer makes complete pieces, but has every thing you need to make your own. Now day there is a lot of satisfaction in doing your own stuff. Eds collectors when we finished them were 2 3/8 minor od 2 1/2 major od. One last thing. I talked at length with the late great Jack Davis of Hooker and Davis headers about design. Of all the information he shared with me, one thing he said was about testing. He felt headers had to be tested at the track not on a dyno. Hope this helps and happy motoring.

Re: Merge collectors
 

A friend told me that this thread was getting some attention so I thought I might put in my 2 cents.

IMO, I have never seen a exhaust port that was smaller than it needed to be.
If you can change say header tube size or step length, or no-step to two step, or collector diameter or length or 421 to 4into1, and not see any difference your motor is not sensitive to what kind of a header it has on it. Another way of saying that is your header is not working to add anything to the way the engine runs, is it?

It is certainly possible that whether you buy headers that come in a box or made for you custom, if the above is the case, it is not simply the fault of the header, ok?

If you do not want to change things in the motor so you can gain the extra power available from the exhaust system, then keep bracket racing and praying you don't have to run heads up with someone who does.

Re: Merge collectors
 

Although I won't disagree one bit with what you're saying, I think that you'll find that a good number(I won't say majority) of Stock and SS Racers today are buying an "engine package" because of the lack of time they have to test these days. I don't believe that they have gotten lazy or stupid. They have their stuff dynoed and put it in the car for lack of time. Now, more than ever, they're counting on us to have done the work.

Re: Merge collectors
 

Ya know your absolutely right.

Every once in a while I will get a spec on how a builder wants a header for his engine. All I have to do is ask a few questions and they will admit they really have no idea outside of their dyno header.

So I am asked to figure it out for him or "whatever" I think. So now I am responsible for making his engine run better. Seems most racers know there is something there but few answers...

Re: Merge collectors
 

Yeah, Billy, I agree. Given the amount of time it takes to actually go racing on a reasonably regular basis, and the amount of money required, it is no surprise that so many of the people who actually can afford to race have little or no time to spend on testing. Most of them don't have the money, either.

Re: Merge collectors
 

Calvin, a couple of questions. I've got a set of your 4-2-1 headers on my 327/275 stocker motor and want to spend some time on the dyno this winter doing some camshaft work.

- Is backing up the exhaust duration by 4 degrees is a good place to start. Your thoughts?

- If an engine really is over scavenging due to the header design, what are some of the things to look for on the dyno or the track?

Thanks for joining in. -Al

Re: Merge collectors
 

I tied a set of headers together on Line's dyno and picked up five foot pounds of torque with no other changes. A two into one set up. Back to Jack Davis, he told me he made a set of two into one collectors for a NASCAR team. When they ran their car at Michigan the car was so much faster that Nascar banned the two into one set up. Hence they went to the "X" pipe. All we are trying to do is to keep fifteen pounds of atmospheric pressure from running back up the pipes. The fewer openings you have for the exhaust pulses to exit the better headers and collectors will work. Just think of how small that exhaust pulse is at six to eight thousand or more r.p.m.

Re: Merge collectors
 

I'm not understanding what you're trying to say. If X cfm of air and fuel is going in then X cfm of air and fuel must be coming out. The exhaust pulse may be getting faster(and stronger) but it's not getting smaller!

Re: Merge collectors
 

So, we are supposed to buy the trick of the week header, then build an engine combo around that?

Re: Merge collectors
 

Ed you hit the nail on the head! I've been saying that for years. Here's a bit of wisdom from Scott Burton who once told me when we were discussing this subject, "You will never spend more money and get less gain than with headers." Nuff said.

Re: Merge collectors
 

Ed, I know you work more than most people on your combo, you are very innovative, and it shows. I think what is being said is really right up your alley. When you change one thing on a car it affects other areas (Law of Unintended Consequences). For instance if you found 50 hp with a new fuel injection system you may need to work on the chassis/suspension, or even the camshaft to lower the ET or possibly find even more power.

I had a highly, highly respected engine builder tell me, in front of another engine builder, I was stupid for even thinking I knew more than him about headers... the headers he recommended were the best for the combo. Well Calvin's headers were .13 faster than the headers the engine builder recommended, and we did find more. With our small block we went 4 years before we lost a heads up race, and that was totally my fault for taking the competition for granted.

Some who have worked their a$$e$ off refining their combinations with Calvin's headers (as well as others) have found significant HP by keeping all events on the cam the same and only closing the exhaust lobe earlier. Mind you these are people who were already at the top of their game.

When you are already at the top of your game how much money/time would you spend for 15 HP? The exhaust on a Stocker/Super Stocker has not changed much since the classes inception. Yet the engine development has changed radically. Why would you not work on an area most overlook because "it is just a set of pipes."

NASCAR was revolutionized by Calvin's headers. One of NHRA's winningest drivers has used Calvin's headers for numerous wins and speed/ET records. These are teams/engine builders/drivers who are paid to be innovative, or they have no job.

Bill

Re: Merge collectors
 

We've talked a lot about diameter but what about length, is equal length still the standard or is there any experimentation in tuning length to each cylinder?

JimR

Re: Merge collectors
 

You bring up a very good point with this question. Look at the stocker intake manifolds, do they have the same runner length?? NO!! so when the header builder like Calvin ask you to stagger jet, you ask him why?? Well thats why. Different cylinders will appreciate different tube lengths. Especially in a step header, stagger the steps and watch it pick up power!! The easiest way to see this is with your EGTs on the dyno.... well then again, everybody doesnt dyno...

Carry on.....

Re: Merge collectors
 

Maximizing each cylinders potential is what the fastest engines are best at. The dual plane intake and short/long intake runner ports create a real challenge to this goal. We have been stagger jetting, varying the lash and timing to compensate, as well as having multiple pattern cams of late. Cylinder specific tuned headers has been on my mind, and even suggested as a "cure" for the runner issues several years ago to me by a person who's opinion I respect.

Sneaking up on advancing these combos and with all the R&D that has been exhausted (pardon the pun) over the years, I can't begin to imagine the potential curve balls that await header tube per cylinder tuning. Anybody want to spend a month on the dyno with a header fabricator? That's out of my budget.

Re: Merge collectors
 

Don't need a month on the dyno. Did it with Jenkins about 8years ago when I worked with those guys now known as black arrow racing engines. We staggered the steps on certain tubes in an effort to equalize collector pulse timing and it worked!!!

I will jus sit back and let Calvin share his knowledge. He is far ahead of me. Yet some guys won't even listen to him.... I don't think there is a combination he couldn't speed up for any racer who frequents this forum. In the long run,he would save people a bunch of money and testing.... Well we know that story all to well...