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MG MGB Technical - Exhaust systems

My 74B has standard front muffler and glaspac on the rear. I see many sets of headers and flow thru systems available. Do headers make a difference in power? Do flow thru systems make a difference in power? My engine is completely standard. Any help on this question would be most appreciated. Bob
Bob Ekstrand

Even with a stage 2 head and cam, it would not give any increase, but it will make it sound much better. An MGB with a straight through exhaust has been the envy of many exotic car owner.
c cummins

Bob-
The whole idea of a performance exhaust system is to enable the engine to exhale combustion gases at a fast enough rate to create a partial vacuum inside of the combustion chamber. This partial vacuum then causes ambient pressure to force the incoming fuel/air charge into the cylinder at a higher velocity. The higher velocity then creates greater inertia, causing more fuel/air charge to continue entering the cylinder as the valve closes. However, unless the induction system has been modified to increase its flow capacity, the effects are minor.
Steve S.

i think moss are the best for exhausts, i went for a falcon ,standard bore one silencer and a bullit box in the middle .it sounds fantastic and i can cruise at 70mph with out that drone at the rear .i allso fitted the ss manifolds .folcon are cheap and good quality.
daz

I would say get rid of any restrictions. I haven't seen any systems without the resonator or first muffler thing. I'd just get a muffler and or header and plumb up the rest yourself and save a lot of money.
S.L. LaPaugh

My LE runs a Peco system and I don't like it as well as the Ansa system that I had on my '70 B long ago. The sound of the Ansa wasn't as "Civic-like" as the Peco exhaust. I can't make a performance judgement between the 2 brands since they were on different cars. I noted that Moss now offers Ansa (couldn't find one when I opted for the Peco 2 or 3 years ago). Regarding headers, I've read some threads from fairly knowledgeable fellows that think the earlier factory dual collector headers from about '74 back are as good as any performance header, especially when ceramic coated. The later B headers are another matter.
Rick Penland

Bob,

engine building considers the exhaust manifold as part of the head. Many tests have been made to find something better than the stock carst iron manifold but all this nice tubular constructions did not show any advantage, although they are lighter than the oem part.
Matching the carst manifold to the ports does give a noticable advantage, although it is a lot of work and very time consuming.
Many drivers say that the Peco big bore is an advantage over other exhaust systems and they seem to be on the right side within a few HP, although any comparable big bore pipes and straight through single pot glas pack mufflers can be combined to give a comparable result, as long as the over all lenght is the same and the connector at the downpipe is modified to acept the big bore tube of the new system.

With a stock engine it might be worth 2 to 3% of HP increase, not that much but the sound is phantastic and gives you a feeling of much more to be achieved.

Ralph
Ralph

you don
daz

you dont need a large bore exhaust on these engines, ive had a peko, i find the standard steal does not give a nice tone,have a look at the falcon bomb box system fsmgbcb BOMB system .its fantastic from moss .the center box is just a wide tube .think they are not charging vat at the moment and even cheaper for over seas .
daz

This thread was discussed between 09/10/2008 and 13/10/2008

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