inline6 Posted August 4, 2012 Share Posted August 4, 2012 (edited) So, I have my engine back from the builder, and now am working on getting it back in the car. I bought this Nissan Motorsport header off of ebay for it. It has the 1.75" primaries. I'm looking at the outlets and wondering what the best way to go from there is. They are 2.5" OD. I've been searching the forums and reading about merge collectors... I guess my question is how do you incorporate merge collector(s) with this header? The outlets are offset from each other so that the exit for one is quite a bit further back than the exit for the other. Do I run some 2.5" pipe off of the one to get to the same location as the other, and then "y" down to a single pipe? I was running a Clifford Research header and two completely separate 2" pipes - and those pipes are still in the car. I've read many of the posts comparing one exhaust vs. two... I guess, going with an all new exhaust is an option, but I like the existing 2" pipes quite a bit. If I want to stay with two, 2" pipes for now, should I just skip the merge collector? Having owned one of these chrome plated headers for my 510 years ago, I know the chrome isn't going to last. In fact, there are a couple of tiny rust spots on the back of this one already. I'm going to ship it off to Jet Hot, where they will strip the chrome and ceramic coat it. In preparation for that, I bolted it on the motor today to check fit. I'm glad I did, as I needed to grind on the flange reinforcement bar that goes under the primary inlets so it would clear the block where the vent is. I also need to determine what kind of hook up I am going to use from the collector to the next piece. And I need to weld in some oxygen sensor bungs before shipping the header off to be coated... Garrett Edited August 5, 2012 by inline6 Quote Link to comment Share on other sites More sharing options...
johnc Posted August 6, 2012 Share Posted August 6, 2012 Do I run some 2.5" pipe off of the one to get to the same location as the other, and then "y" down to a single pipe? Yes. And I suggest Swain over Jet Hot. Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 8, 2012 Author Share Posted August 8, 2012 Yes. And I suggest Swain over Jet Hot. John, I'm struggling a bit with the thought of extending 3 cylinders about 6 inches more than the other three... I mean, if equal length primaries are important, it can't be good to run one half of the header an extra 6 inches or so than the other and then merge... What is the best way to deal with this? It's probably really tight in that area of the tunnel, so running some kind of S pipe off of the one collector and a laser straight one off of the other and then trying to merge where they become equal distance is not looking possible... plus the distance to the merge is then lengthened considerably... Thoughts? Quote Link to comment Share on other sites More sharing options...
johnc Posted August 8, 2012 Share Posted August 8, 2012 Its not ideal but most of the performance from from the header comes from the two merge collectors. I don't know the specific thoughts from the designers but it appears they felt equal length primaries were more important then outlets at the same point. They may have also made the outlet difference enough so that the exhaust pulses merge correctly at whatever final point the system is merged into one. Or maybe they designed it for two exhaust pipes all the way out the back. But... even with the different outlet positions this header made more power on my racing 3L with a single 3" exhaust then any other header tested - although we didn't test the Stahl header. Quote Link to comment Share on other sites More sharing options...
Leon Posted August 8, 2012 Share Posted August 8, 2012 Its not ideal but most of the performance from from the header comes from the two merge collectors. I don't know the specific thoughts from the designers but it appears they felt equal length primaries were more important then outlets at the same point. They may have also made the outlet difference enough so that the exhaust pulses merge correctly at whatever final point the system is merged into one. Or maybe they designed it for two exhaust pipes all the way out the back. But... even with the different outlet positions this header made more power on my racing 3L with a single 3" exhaust then any other header tested - although we didn't test the Stahl header. John, I'm running two 2" pipes off a Nissan Motorsports header and have been considering going to a single 3". I don't trust an exhaust shop to make a "proper" secondary collector and I know that Nissan used to make them to go along with the header. Do you know if there is still a way to get those 2-1 collectors or must it be custom fabbed? Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 9, 2012 Author Share Posted August 9, 2012 (edited) John, I'm running two 2" pipes off a Nissan Motorsports header and have been considering going to a single 3". I don't trust an exhaust shop to make a "proper" secondary collector and I know that Nissan used to make them to go along with the header. Do you know if there is still a way to get those 2-1 collectors or must it be custom fabbed? Hi Leon, I see from previous posts, John has mentioned "SPD, Burns, and others"... You might want to look at this: SPD PDF Is your car race only or on the street? I have a nice dual 2" system on the car right now... What is the reason you are thinking about going to 3" from your dual 2's? Edited August 9, 2012 by inline6 Quote Link to comment Share on other sites More sharing options...
johnc Posted August 9, 2012 Share Posted August 9, 2012 I prefer a single exhaust for engines under 4L. In many cases a single exhaust can help engines over 4L if the tubing diameters are increased. Trans Am race cars that had a 180 degree header setup ran a single 5.5" exhaust through the passenger seat area and out the passenger door. I order merge collectors from SPD all the time. I have a couple different variations depending on your horsepower and torque goals and what you're intended use is. Quote Link to comment Share on other sites More sharing options...
240zip Posted August 9, 2012 Share Posted August 9, 2012 So, I had the same issue for my build. I'm sure John C will have something to say with my approach. First we made them even. We then added a two into one and a flange. Then we created a flange with a stainless flex coupler which went to the rest of the exhaust. Sorry the pictures stink. Quote Link to comment Share on other sites More sharing options...
240zip Posted August 9, 2012 Share Posted August 9, 2012 note ... mine was an MSA header, not NISMO Quote Link to comment Share on other sites More sharing options...
Leon Posted August 9, 2012 Share Posted August 9, 2012 Hi Leon, I see from previous posts, John has mentioned "SPD, Burns, and others"... You might want to look at this: SPD PDF Is your car race only or on the street? I have a nice dual 2" system on the car right now... What is the reason you are thinking about going to 3" from your dual 2's? Thanks for the link! The duals on my car right now are okay, but a bit loud and raspy for my taste. If I were to build another exhaust system it would be a single 3" with a nice muffler and resonator. With that said, I always wanted twice pipes and I'm happy I tried them out. The car is mainly used on the street with very occasional autoX use, but I am planning to run it on the track in the future. I prefer a single exhaust for engines under 4L. In many cases a single exhaust can help engines over 4L if the tubing diameters are increased. Trans Am race cars that had a 180 degree header setup ran a single 5.5" exhaust through the passenger seat area and out the passenger door. I order merge collectors from SPD all the time. I have a couple different variations depending on your horsepower and torque goals and what you're intended use is. John, any recommendations on which merge collector you choose for a street/autoX car? I'm thinking a parallel 2-1 Y-collector with a megaphone following when I get to building a single system. I'll have to find good spots for the WBO2 as well. Quote Link to comment Share on other sites More sharing options...
madkaw Posted August 9, 2012 Share Posted August 9, 2012 Duals are a total pain in the a$$, and it is really tight under there. Then there's the extra cost, noise, weight--so my recommendation is hook them babies back up to your duals and run it The sound of my exhaust is in the top things I love about this car. As far as worrying about matching up the primary lengths, not sure if it's going to cost you much HP in the end. The arguments could go on forever as far as what's better, single ,dual, but I vote duals- IMHO Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 10, 2012 Author Share Posted August 10, 2012 (edited) The arguments could go on forever as far as what's better, single ,dual, but I vote duals- IMHO Well, the first exhaust I put on the car was an old Nissan Comp set up and the Clifford Research header. The pipes were dual 1 and 3/4" with 4 glasspacks - 2 small and 2 larger. I absolutely loved the sound especially above 4000 RPM. When the glasspacks had burned up many years lateer, it got too loud, and I was getting pulled by cops too much. Since, I had taken the glasspacks off and put a straight pipe on at a track event once, and noticed how much more power I had, when I redid the exhaust, I went with two 2" pipes. That is about the equivalent of a single 2.75" pipe flow-wise. I put a lot of time and effort into it. It has two stainless Magnaflow 4" round resonators in the driveshaft tunnel and two aluminized Magnaflow 5" X 7" oval mufflers (flipped and staggered) in the back. I put some nice stainless tips on the end. Here are some pics: I didn't like the sound as much, but it wasn't bad. Here is a dyno run... A part of me thinks that pipes that are too big in diameter for a given engine hurts sound quality, and that with the new motor, my existing pipes will sound better. I think what I'll do is go ahead and buy what I need and fab as necessary to hook up to the existing pipes... then dyno it and see how it sounds. If I am thrilled with the sound, I'll probably keep it a while, but if not, I'll move to the three inch and try to get a good merge collector or whatever the terminology is in there too. Edited August 10, 2012 by inline6 Quote Link to comment Share on other sites More sharing options...
madkaw Posted August 10, 2012 Share Posted August 10, 2012 Not sure if the sound quality has anything to do with the engine size. I think it's a challenge to get the L6 to sound good with duals. I was told on this site that duals would sound funny because of exhaust pulses -blah blah blah The drone will always be an issue, but manageable . Chambered mufflers are better for quieting the beast, but I went with 10inch magnaflows- turbo type. I also have 12 inch resonators in there, not sure if they do much at all. Your set up doesn't allow the room for the larger mufflers so it will be louder. I posted a video called " music to my ears", that barely does the sound justice, but listen with headphones. I will be making another video now I have my triples on, because the sound got even better. The biggest thing to avoid for me is the cackle sound, but I think you need bigger mufflers to avoid that. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 10, 2012 Share Posted August 10, 2012 So, I had the same issue for my build. I'm sure John C will have something to say with my approach. First we made them even. Looks fine to me. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 10, 2012 Share Posted August 10, 2012 John, any recommendations on which merge collector you choose for a street/autoX car? I'm thinking a parallel 2-1 Y-collector with a megaphone following when I get to building a single system. I'll have to find good spots for the WBO2 as well. A lot depends on where you want to help your power band. I won't post this stuff on forums anymore because other people are making money on the work I did with Sunbelt years ago. Quote Link to comment Share on other sites More sharing options...
Leon Posted August 10, 2012 Share Posted August 10, 2012 Well, the first exhaust I put on the car was an old Nissan Comp set up and the Clifford Research header. The pipes were dual 1 and 3/4" with 4 glasspacks - 2 small and 2 larger. I absolutely loved the sound especially above 4000 RPM. When the glasspacks had burned up many years lateer, it got too loud, and I was getting pulled by cops too much. Since, I had taken the glasspacks off and put a straight pipe on at a track event once, and noticed how much more power I had, when I redid the exhaust, I went with two 2" pipes. That is about the equivalent of a single 2.75" pipe flow-wise. I put a lot of time and effort into it. It has two stainless Magnaflow 4" round resonators in the driveshaft tunnel and two aluminized Magnaflow 5" X 7" oval mufflers (flipped and staggered) in the back. I put some nice stainless tips on the end. Here are some pics: I didn't like the sound as much, but it wasn't bad. Here is a dyno run... A part of me thinks that pipes that are too big in diameter for a given engine hurts sound quality, and that with the new motor, my existing pipes will sound better. I think what I'll do is go ahead and buy what I need and fab as necessary to hook up to the existing pipes... then dyno it and see how it sounds. If I am thrilled with the sound, I'll probably keep it a while, but if not, I'll move to the three inch and try to get a good merge collector or whatever the terminology is in there too. Nice vid, sounds similar to my twin 2" system. I have 2 glasspacks per pipe, turned around so the louvers face the other way. I've yet to dyno it, but will soon. I dynoed with a single and stock manifold so I'll have something to compare to. I agree on the sound, it's good but not exactly what I wanted. A lot depends on where you want to help your power band. I won't post this stuff on forums anymore because other people are making money on the work I did with Sunbelt years ago. No problem, I was more curious in the type of merge collector you use (when browsing through the SPD link). I can handle placement and design. Quote Link to comment Share on other sites More sharing options...
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