| In the initial thread, It mentions that his manifolds flow a little less than the MS manifolds and that the turbine housing is the primary restriction. This is what I believe to be the case but I haven't flowtested anything so that is an untested theory. I believe his custom turbo setup uses 4bolt turbine housings, however he did open up the size of the internal wastegate port and make a custom flapper door allow the boost to be controlled more effectively. Ash, If you changed the housings to say.. a true 5bolt setup. Do you think that your turbine housing will no longer be the primary means of restriction, thus pointing it back at the manifold setup? The wastegate size will only affect flow when it is in any position other than closed, however, I do see your point in that when running, say, 18psi of boost, the wastegate is going to have to open up once target boost is reached and this will improve flow volume. Using a 5-bolt housing wont necessarily mean it will have more or less flow - that will depend a lot on the A/R geometry. If you want more flow you will have to give up spool response so there is a balancing act when it comes to changing A/R. If I were to go to a 5-bolt housing with same A/R it isn't going to change anything much at all, but if I go to a larger A/R it will flow more but have less response, of which I will not desire. Also, I see in the other post replying to Dee, you mentioned that by possibly going to MS manifolds that it may not benefit YOUR setup due to your turbine housings (4bolt). However; Do you think that the advantage of the increase of thermal dynamic efficiency (mass) of the MS manifolds and them fabricated of ductile iron and the characteristics of maintaining heat/energy etc will still benefit over the use of SS tubular setup (for your turbine housings) I tend to think that the differences between the MS manifolds and my own will be marginal but until I put a set of the MS manifolds on my car and test I really can't say much. >Since the properties of the ductile iron will increase the scavenging effect of the exhaust gases. Being that your turbine housing is also constructed of ductile iron. If you used the MS manifolds and your modified 4 bolt turbine housings. Being that the properties of both exhaust manifold/turbine housing having the same charateristics. Scavenging effect is dependent on the geometry of the manifold, not the material it is made of. In your opinion, do you believe that this will also create a better flowing setup even through your turbine housing selection? I dont think the material will really make that much difference. On a Eagle Talon Tsi that I built a while back.. I remember switching from the cast iron manifold setup to a SS tubular design and the difference of spool up was in favor of the cast iron.. I do believe of course that the SS tubular would have more high end FLOW... but the characteristics of the cast iron exhaust manifold and its ability to increase the thermal efficiency/heat transfer down through turbo/exhaust (besides the durability) made the car FEEL more powerful. It is nearly impossible to remove sharp edges at merges of pipe with a tubular manifold since the material is so thin whereas cast iron can be made in any shape. Having rounded corners and dynamic turns/transitions will always benefit flow of gases - something that is nearly impossible to match with thin wall tubing in such a compact design as our cars use. Cast iron has a great advantage in this respect. :) I had this bouncing around in my head the other day and figured I would post to get some thoughts. Good to see it stirring up some thoughts. I've heard that if everyone thinks the same thing then someone isn't thinking. So thanks for the post-back... :) I just wish I had more information on this topic - I've got the engine all back together and will be reinstalling her this weekend. So unfortunately I wont be doing a bunch of flowtesting with these parts. Perhaps down the road when I have my hands on some manifolds and some turbos I'll take a trip up to the flowbench to see how things stack up.
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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