Guest Anonymous Posted July 4, 2001 Share Posted July 4, 2001 I have just acquired a V8 Z with a Scarab placement Chevy 350 (Please see my post in "Non-Tech") I need to fix the exhaust. The flange between the header and pipe on the driver's side is bent from striking something on the ground. Can the header and pipe flanges be straightened (if so, what is the best method for this?), or am I better off replacing the header & pipe? I have no ideas what kind of headers are on the car, so a replacement would mean both sides (and maybe part of both pipes as well?) Question 1: If I need to replace the headers, what headers should I use? The JTR book mentions the 'ramshorn' manifolds. Should I find some of these or get new headers? I know there is a performance and cooling benifit to tubular headers, but how significant is this? Question 2: If I have to replace the rest of the exhaust system, is there a good sytem to use in a V8 Z, or should I just have a shop custom-make one? The car currently has full dual exhaust with no crossover pipe, and glasspack mufflers. Would I be better off with a single larger pipe (due to space considerations) or a set of duals with an "H" pipe? Last, Does anyone havs any favorite mufflers to recommend? Thanks very much for any help! Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 4, 2001 Share Posted July 4, 2001 Brian, I'm almost sure that the flange can be straightened out--maybe a vise and a hammer would work? I'd try that first. Otherwise if you have to buy new, don't get the ramshorn mufflers if you want the best performance--nothing wrong with them, and you can get them from a wrecker for about $20 each. I bought headers from Summit racing. I'll have to get them coated though. As far as exhaust is concerned, you can do a single 3" which is very efficient and hardly gives up any power to a dual system, but I think that's up to 400-450hp--beyond that duals will help. I have a 3" single and have a Dynomax Superturbo in back and a Borla stainless stright thru design muffler coming off of the Y-pipe under the car. If you go duals, the crossover pipe or "H" pipe will help to smooth out the idle and supposedly give a little bit more power. A good muffler shop can set you up nicely. You'll do really well if you can find a place that will do mandrel bent systems, but they cost a bit more. HTH. Davy Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 5, 2001 Share Posted July 5, 2001 A single 3inch flows as much as two pipes at 2.5 inches. We've gone over this before and it comes down to friction in the pipes making the difference. Anyone at a muffler shop that tells you that two 2.5inch pipes flows like a single 5inch pipe is an idiot - run away! Sia Davy - you've got a muffler up towards the front and one towards the back? I'm getting close to "muffler day" and think I'm going to end up with an exhaust like yours. I want something shiny in back but am pretty sure it would be too loud. I wasn't sure there was enough room up front to do this Is the Flowmaster Y pipe worth getting? Anyone using it? Quote Link to comment Share on other sites More sharing options...
jeromio Posted July 5, 2001 Share Posted July 5, 2001 This could be an interesting topic - I don't recall seeing it before (at least in any technical detail). I could see the "pulse" factor (the gush of the other cylinders exhaust flow creating a kind of suction that ends up pulling the exhaust from the rest along) playing heavily in this - you have 8 pulses versus just 4. And the friction would certainly be a factor along with some other nuances of flow in tighter spaces and such. But dual 2.5's against a single 3 - that's 40% more cross sectional area. Hard to believe that they could even be equivalent - much less the single 3 being superior....? Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 5, 2001 Share Posted July 5, 2001 I agree - 2 2.5" pipes are 9.8 sq.in. in cross section, versus one 3" pipe at 7.1 sq.in. I have a very hard time believing that friction can account for that much reduction in flow. But V8s 400 hp and under, that don't see high rpm use but every once and a while, the 2.5 duals into 3" single seems like a good choice. Quote Link to comment Share on other sites More sharing options...
Guest dankinzle Posted July 5, 2001 Share Posted July 5, 2001 I've got 2.5" into a flowmaster ypipe right before the front diff mount into a single 3.5" into a delta 40 flow. It looks humongous from the back of the car. A motorcyclists behind me actually drove up to my window to ask me what I had cause he could feel the breeze from my exhaust. It sounds really dang mean too. The groundclearance isn't too bad either, it's just tucked really close up. SOrry blkmgk, I haven't been able to get any audio or pics for you yet. I'm trying to finish building my computer, but it should work soon. Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 5, 2001 Share Posted July 5, 2001 Long, I'd bet that exhaust would be too loud for my tastes for MY car, but I sure would love to hear it! My dad thinks the exhaust on his neighbors 427 Cobra kit car (sidepipes with some baffles) is too loud, but if I had a 427 Cobra, it'd be loud too - it was MEANT to be loud . How many big baffles are in the Delta 40? That's the newer Flowmaster design - do you think it's quieter or less resonant than the older regular flows? Let's hear it! Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 5, 2001 Share Posted July 5, 2001 Well, we've debated this before and I've heard from more than one source - 2X2.5 is supposed to be about equal to a single 3 inch pipe. I could be wrong but I know for sure that 2.5 X 2 in this case is NOT equal to 5inches single. Hrm, will have to do a search because I could swear someone whipped some math out on this problem last time! Considering the Camrobirds run 3inch pipe and see plenty o' power I'm thinking a 3inch will be fine for me. Setting up two pipes is just looking like too much hassle this time around. Sweet - UPS guy just showed up with toys Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 5, 2001 Share Posted July 5, 2001 BLKMGK: you are right and we have gone over this before! I believe the consensus was what you just stated (but could it have been dual 2-1/4" pipes that were equal to a single 3" pipe?) I bought my system from Rick Johnson, a motocross racer that used to post here, who replaced his old 3" single with a 3.5" single--he said there was NO hp difference and wished he had not sold me his exhaust system! I think he was running 450 hp(?) Rick told me the single 3" stainless steel Borla is no longer sold in the exact dimensions of the one I currently have (it's about 15" x 3" hrm...have to check). He says the mandrel-bent system is relatively quiet (which is what I wanted) and flows great. The Y-pipe is not a Flowmaster, but was custom made. I would buy a Flowmaster in a heartbeat if I had to do this from scatch. The routing of a single system just makes more sense to me. Sure, the dual is more sexy, and if you have the room like Mike Kelly does, or the engineering skills and patience of Pete Paraska, then by all means go dual! Otherwise, a single system is a little less expensive, fits well, works well, and looks a little more ricey but is more stealthy too Davy Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 6, 2001 Share Posted July 6, 2001 Davy how loud is that Borla? I almost ordered an UltraFlo and pondered the Summit stainless muffler too but held back. I don't know if I need offset inlets or what Heelp! I'm afraid I'll hit the muffler shop and end up with whatever he's got on the shelf and not like it! I'll order the Flo-Y pipe tonight probably. I'm not going anywhere till Jeg's gets me my water pump pulley anyway.... Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 6, 2001 Share Posted July 6, 2001 BLKMGK, you foget it's not hooked up yet! The Borla would be freaky loud if it didn't have the Dynomax Superturbo after it. It (Borla) is a straight thru design and acts as a resonator of sorts. I took Rick Johnson's word for it that the system is "quiet" and fits w/o too much massaging of the underside. The guy is very meticulous and I can tell from just looking at the way this thing was made he was totally telling the truth...plus I got a great deal on an otherwise $500+ system Davy Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 6, 2001 Share Posted July 6, 2001 Here's one of the old posts on this topic: http://www.hybridz.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=8&t=000042 Note that Rick (Fast Frog) did some research that says that for two pipes with the same cross sectional area as one pipe, the wall area increase gives a 7-10% reduction in flow volume. But that might be a steady state flow, not the pulsations exhaust systems have (my theory). Anyway, Two 2.25 pipes have 7.95 sq. inches of cross section, and One 3" pipe has 7.1. Subtract 10% from the 7.95 and you have 7.15, so by the above theory, they'd be about the same. Oh yeah, here's another thread on the exhaust issue (2 vs 1): http://www.hybridz.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=13&t=000089 Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 7, 2001 Share Posted July 7, 2001 Pete, thanks for looking those up, but the thread BLKMGK and I are thinking of was really long and even more informative I at least can remember that because Rick Johnson who I bought the system from posted a bit on that thread. The thread probably started out as one topic and ended up being exhaust! Phooey! Again, thanks for looking. Davy Quote Link to comment Share on other sites More sharing options...
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