I'm seeking ideas on an efficient sleeper iron manifold exhaust system. Any ideas or photo's on welding a 3" flange to cast iron manifolds (67 variety) and building a 3" X system. Otherwise, how about using stock manifolds with only 6" of 2 1/2" pipe, then sliding on a 3" pipe adaptor (and downpipe) leaving about 4" of the small pipe extending into the large pipe area to reduce reversion. For additional power, I was told to reduce a 3" X pipe to 2 1/2 immediately after the X to speed up the gasses and create a scavinging effect . From that point on 2 1/2" pipes and good mufflers are sufficient due to cooling/shrinking gasses. Finally, Is a 3" really better than a 2 1/2" with iron manifolds? Give me your ideas, opinions, photos, etc; please.
I don't think 3" is necessary. Most people say from 2.5" to open exhaust is only a 0.10 reduction in ET, so what's 3" worth? I run a stock appearing car with 2.5" exhaust w/an X pipe from the manifolds back, two Walker 17749 mufflers and two Walker bullets 24215. Car is quiet and runs 11.7x's. I also can tell you that 2.5" outlet exhaust manifold does not work, the 67 manifold is worth at best 5 hp, I ran this on the dyno several years ago. Hope that helps. Rob
sleeper exhaust Hey Mr. 'B', Glad to see you made it to v8 buick. I have a home-made system, 3" from the manifold and through the 'X' and then to 2 1/2" on out. I did have 2 1/4" dynomax on the car, but I took the 2 1/2" flow masters off of my truck and put them on there. I have not been to the track with the flow masters yet. The car seems faster, but you don't really know until you get on the clock. Thanks Kirk
