Zac88 Posted June 25, 2012 Share Posted June 25, 2012 So as long as the primaries are the right size with a proper merge collector any aftermarket header would be a gain from stock? Link to comment Share on other sites More sharing options...
mwiener2 Posted June 25, 2012 Share Posted June 25, 2012 An exhaust that most efficiently pipes the exhaust gas from the ports to the turbo in terms of heat, pressure, and flow will yield the best results. That may mean progressively larger pipes running from one cylinder to the next joining in 3 different places. I don't know what the best setup is. In most cases, the best setup will be different for different cars. Even with similar setups. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
turbodog Posted June 25, 2012 Share Posted June 25, 2012 In any gas flow system, a transition (up or down) in pipe diameter or a bend will have more resistance to flow than a straigth section of pipe. Hence the importance of port matching. Link to comment Share on other sites More sharing options...
mwiener2 Posted June 25, 2012 Share Posted June 25, 2012 No. Hence the importance of reducing bends to a minimum. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
m sprank Posted June 25, 2012 Share Posted June 25, 2012 Less bends. A decent set of headers will yield gains (EL or UEL). As to what is "perfect" or "the best" that is a loaded question. As Mr. Weiner has pointed out. Almost no one has exactly the same set up. Manufacturers have to make a product for the masses. A custom made header is out of the price range of most buyers. Port matching your OEM manifold/porting the OEM manifold yields very minimal gains. I have seen 15whp gains from a set of eBay headers that cost $100. Not saying to go buy eBay headers. Just making a point. Link to comment Share on other sites More sharing options...
turbodog Posted June 25, 2012 Share Posted June 25, 2012 No. Hence the importance of reducing bends to a minimum. Cool story bro. As a practical thing, it's much easier correctly port match and polish an existing system than it is to "reduce the number of bends". LOL. Link to comment Share on other sites More sharing options...
turbodog Posted June 25, 2012 Share Posted June 25, 2012 Anyone who's interested in piping bends and transitions vs. flow should check this out: http://www.pipeflowcalculations.com/resistancecoefficientK/ Link to comment Share on other sites More sharing options...
mwiener2 Posted June 25, 2012 Share Posted June 25, 2012 Gee thanks. Port matching has nothing to do with equivalent length. Port matching usually ends up with an increase in diameter around the ports, but no where else. No major gain. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
turbodog Posted June 25, 2012 Share Posted June 25, 2012 Gee thanks. Port matching has nothing to do with equivalent length. Port matching usually ends up with an increase in diameter around the ports, but no where else. No major gain. LOL. What??? Equivalent length is one of the easiest ways for the layman to visualize resistance in a piping system, through bends, transitions, etc. Which is exactly what we are talking about here. Port matching is the process of removing step transitions caused by ports/holes/piping of components not lining up with another, by typically grinding that step transition into an angled transition as needed, which most certainly is a decrease in flow resistance. http://www.circletrack.com/techarticles/general/139_0305_port_matching_engine_porting/viewall.html Link to comment Share on other sites More sharing options...
JMLegacy Posted April 3, 2017 Share Posted April 3, 2017 5 year bump? Why not. Keep all the info one place. I did this over last weekend. I'm on a 5eat JDM 2.0 liter so it's a slightly different feel. The car feels like it is gliding. IDK if it's the wrap but at low RPM the car is a little more silent. Once i start generating some boost it feels like normal and up top actually feels a little more stronger. Once you start some spirited driving then ALL HELL breaks loose. You are gonna believe you are driving a different beast. I'm telling u, early torque like no other mod! Very responsive! This is the best mod i've done since methanol injection. One thing though, you do not necessarily need to port the outlets at each joints, only the inlets. So port the 4 inlet at the flange from the engine, the first flange on the crosspipe, and the inlet on the right manifold. Also doing this adds to the anti reversion effect (less exhaust diluting your intake charge) I'd say 65-70% of this improvement had to do with the wrap and about 30-35% with the porting. Mainly i did this to allow me to brake boost quicker, but that hasn't worked out. The manifold still needs to be hot before i can brake boost to a usable launch RPM Link to comment Share on other sites More sharing options...
JMLegacy Posted April 3, 2017 Share Posted April 3, 2017 Link to comment Share on other sites More sharing options...
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