jeffer949 Posted May 28, 2008 Share Posted May 28, 2008 It was a stock usdm exhaust manifold. i bought it off of someone on here and then ssac sent a call tag for it to save me shipping. It sounds like we are starting to get somewhere now. Lets keep it going!!!!! Jeff Quote Link to comment Share on other sites More sharing options...
rwdawg2 Posted May 28, 2008 Share Posted May 28, 2008 let me know. I would like to see some kind of prototype or finished product. I am very interested to see what you guys come up with. Quote Link to comment Share on other sites More sharing options...
78280z Posted May 28, 2008 Share Posted May 28, 2008 I think there is an interference problem with the downloadable header flange and 1 5/8 tubing with a 1/8" wall.Here is what I mean (#1 cylinder looking from cylinder head side): The overlap inside is fine as it can be ground down and such, but look at the top left at the bolt hole. The tubing actually overlaps the flange cutout. Don't mind the angle of the tubing bend, but the actual part of the tubing that is overlapping the hole for the bolt. There isn't much room for a weld either on that flange. I'll check my turbo manifold when I get home to see if it is like this and what can be done. OTM, I see what you mean, however, that bolt hole may not have to be used. If we make a solid one piece flange(http://forums.hybridz.org/attachment.php?attachmentid=6672&d=1208626726), or even a three piece flange (made by Trust: http://forums.hybridz.org/attachment.php?attachmentid=6739&d=1208934766), those bolt holes are not used. As for the overlapping of the tube inside the port shape as OTM and Slow Old Car mentioned, here is the thread about shaping the tubing to match port shape: http://forums.hybridz.org/showthread.php?t=123881. One of the most important things to mention about that issue is that the two center ports have a different shape than the others. I'm sure that the manufacturer has methods they could use to shape the tubing to match port shape. Quote Link to comment Share on other sites More sharing options...
78280z Posted May 28, 2008 Share Posted May 28, 2008 Does anyone know the actual diameter for the bolt holes in the flange? (I am going to use SketchUp to help design some stuff, so I need that information in order to properly scale my drawing.) Thanks! Quote Link to comment Share on other sites More sharing options...
78280z Posted May 29, 2008 Share Posted May 29, 2008 Heres what I have so far (based on the file from the downloads section): Both are 1/2" thick. The one-piece may not be ideal because of thermal expansion issues, but there are arguments that the effects may be negligible (see thread http://forums.hybridz.org/showthread.php?t=118387). Which design do you guys prefer? Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted May 29, 2008 Share Posted May 29, 2008 id probably say we should go with the one piece. my reason is that gives them one less thing that can be out of alignments. Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted May 29, 2008 Share Posted May 29, 2008 +1 jimbo Quote Link to comment Share on other sites More sharing options...
78280z Posted May 30, 2008 Share Posted May 30, 2008 Okay so I guess then our First Order of Business is complete. Moving on to our Second Order of Business: Runner Sizing. It has been suggested that we use 1 5/8" tubing with a 1/8" wall. Does this mean that 1 5/8" is the outer diameter? If so, this sounds good to me. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted May 30, 2008 Share Posted May 30, 2008 Okay so I guess then our First Order of Business is complete. Moving on to our Second Order of Business: Runner Sizing. It has been suggested that we use 1 5/8" tubing with a 1/8" wall. Does this mean that 1 5/8" is the outer diameter? If so, this sounds good to me. I recommended the 1 5/8 OD primary with a 1/8" wall. This size will support 700+ bhp and is small enough that bolts will clear properly. This size should also allow us more flexibility to get closer to equal length. I'm in favor of larger primaries if it's possible but it will likely result in a header more like a log manifold. I vote for the second order of business to be complete. Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted May 30, 2008 Share Posted May 30, 2008 Second the motion... motion sustained... Quote Link to comment Share on other sites More sharing options...
78280z Posted May 30, 2008 Share Posted May 30, 2008 Alright, Second Order of Business complete. So now we move on to the Third Order of Business: The Equal Length / Pulse Tuning Dilemma. Here's some info from Nigel's post to refresh our memories: TUBULAR MANIFOLDS When designing a tubular manifold, the goal is to keep as much thermal and kinetic energy in each exhaust stream as possible. Short tube lengths are better than long ones. A minimal number of bends is also preferred. Where bends and turns in the tubes are required, keep them gradual and smooth. Large radii are better than small radius bends. It's also important to keep the individual tubes as equal in length as possible. The closer they are to each other, the faster the turbine spool-up will be. It's better to group cylinders that are far apart in the firing order together in the collector. So, we need to decide on the grouping in the collector and the desired length of each runner. As for the grouping in the collector, the L28's firing order is 1-5-3-6-2-4. So, the grouping should be 1-6, 5-2, and 3-4. As for the runner length, the reference that Nigel used suggests short lengths are best. However, I've read that runner length is dependent on where you want your torque delivery in the RPM range, with short runners favoring high RPMs and longer runners favoring lower RPMs. But, this train of thought may only apply to N/A applications. So, which is the correct theory and based on that, what is the desired linear length of each runner? Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted May 30, 2008 Share Posted May 30, 2008 i have seen that 26" is the correct length fro the primaries. here is a link to another thread that talks about it. http://forums.hybridz.org/showthread.php?t=116979 monzters is awsome but will not work for most. if we kept the length as close as possible, it would be a plus. what that is i have no idea but i know i do not have that much room and it is a race car. let alone having an ac and other stuff in the way. 18"-24" i think would be doable. 18" of curly tubing is not tha much space. as far as flanges are concerned, i will cut off and add my own if ness. jimbo Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted May 30, 2008 Share Posted May 30, 2008 Hey 78280z id just like to say thank you for taking point on the design of the manifold. Looks like your doing awesome so far. Ill keep things going on my end and i hope we can get this going soon. Quote Link to comment Share on other sites More sharing options...
78280z Posted May 30, 2008 Share Posted May 30, 2008 Hey 78280z id just like to say thank you for taking point on the design of the manifold. Looks like your doing awesome so far. Ill keep things going on my end and i hope we can get this going soon. No problem, it's coming together well! i have seen that 26" is the correct length fro the primaries. here is a link to another thread that talks about it. http://forums.hybridz.org/showthread.php?t=116979 monzters is awsome but will not work for most. if we kept the length as close as possible, it would be a plus. what that is i have no idea but i know i do not have that much room and it is a race car. let alone having an ac and other stuff in the way. 18"-24" i think would be doable. 18" of curly tubing is not tha much space. jimbo Okay so we know the desired runner length. Now to accommodate the widest variety of applications, we should probably keep the turbo flange close to its position on the stock manifold, correct? To ensure that this is all drawn up correctly and clearance issues are avoided, I need some measurements. First, I need to know the approximate position of the turbo flange relative to the manifold flange. Maybe pick a point on the manifold flange and then give me X,Y, and Z measurements to the four corners of the turbo flange? Whatever you think will give me the best idea of the location of the stock turbo flange. Second, I will need to know the limits of the overall size of the complete header. Perhaps give me the X,Y,and Z dimensions of a 3D rectangle that the header must fit inside. Once I have that information, I can start looking at ways to route the runners. Quote Link to comment Share on other sites More sharing options...
Slow_Old_Car Posted May 30, 2008 Share Posted May 30, 2008 i disagree on flange placement, i belive a centered out design would be more ideal as it clears a path for downpipes alot easier. only downside is the iffy nature of which guys have AC and which do not. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted May 30, 2008 Share Posted May 30, 2008 i disagree on flange placement, i belive a centered out design would be more ideal as it clears a path for downpipes alot easier. only downside is the iffy nature of which guys have AC and which do not. We definitely need to consider folks with A/C. I'm one of them... I vote for a flange that's aft of center but not nearly as far back as the old BRE manifold. It probably could be a bit forward of the OEM L28ET manifold. Quote Link to comment Share on other sites More sharing options...
78280z Posted May 31, 2008 Share Posted May 31, 2008 Okay so it sounds like we know where we want the flange: somewhere aft of center, but forward of the stock manifold. So, if someone could take some measurements and post them here, I will be able to start drafting! Thanks! Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted May 31, 2008 Share Posted May 31, 2008 from what i have measured before i think we could move the flange about an inch closer to the fender well and probably forward about inch and still be ok. This would give us alot more room also i believe. Does someone have an extra manifold laying around to where they can get the measurements? my extra one is at SSAC Quote Link to comment Share on other sites More sharing options...
Guest explodethepa Posted June 1, 2008 Share Posted June 1, 2008 I would like to join the voice of warning with someone before me. SSAC might not be the good choice for manufacturing those manifolds, they have a rather bad reputation with other makers enthusiasts. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted June 1, 2008 Share Posted June 1, 2008 i have seen many of the there manifolds and they are beautiful. at first they where cracking when they wherent braced. But they have since then started bracing the manifolds and they havent had a problem since. Quote Link to comment Share on other sites More sharing options...
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