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short vs long tube?

46K views 51 replies 20 participants last post by  Jtmattel05  
by the pic tha sublime showed ,the LX`s LT`s arent as long as on my G body cutlass

on my cutlass the LT`s go as long as the tranny crossmember.......

I tought that even on a LX body ,the LT`s would end up paralllel to the road ! not in LX`s case as i see!
most of the LT's out there have the collector tube parallel to the ground. That's first set of LT's I've seen that doesnt do that actually.

borrowing some pics from marylandspeed.com :
SLP LT's
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Kook's
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Borla:
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1.5" outside pipe diameter for the runners though? Aren't most LT's running 1 3/4" or 1 7/8"? How would an increased runner pipe diameter figure into those results?
 
Yea, and that somewhat leads to what I'm getting at, with a larger diameter runner, how will that affect the length of the pipes? Will they need to be shorter or longer? I bring this up because I don't think you will find any LX longtube headers out there that run 1.5" pipes. Kook's and a couple other makers have LT headers that use 1 7/8" runners, which would greatly affect the calculations of that Pipemax program I think, moving the range of optimal runner lengths.
 
I've never measured exhaust temps myself, but the reason I'm concerned and very interested in your input about this subject is that I have a full SRT exhaust in my RT, and my exhaust ports are matched to the 6.1 exhaust manifolds (not exactly port-matched to this specific combo, but rather they are opened up to be the same shape and size as the SRT manifolds). Given the larger diameter tubes from midpipe to catback, and what I believe to be a more efficient setup than having RT shorty headers, would it make a big diff to go with longtubes at this point? Headwork & cam swap has been done too.
 
Well, I believe my setup to be more efficient than having aftermarket 5.7 shorty headers because:
a) my exhaust ports are matched to the 6.1 manifolds,
b) I'm using a freer-flowing midpipe setup by using the SRT mids.

I just wanted to know if the lengthened runners of longtubes will make a significant difference over my current setup (I would be getting 6.1 LTs, if I switched over).