Darrell,
I think you'd get some improvement with headers vs stock 4into2itno1 TR4A
exhaust manifold but I don't think the small gain would be worth it unless
you are going 'all out' race car.
I am wondering if you have the early version 4A muffler system? - it might be
more productive to rid the front muffler if you have the one that resides in
front of the tranny mount (very congestive) - even the factory did away with
that design and make sure you have good a 'flow-through' system. A good
place to look at headers by the way is Cambridge Motorsports <A
HREF="http://www.cambridgemotorsport.com/splash.htm";>Cambridge Motorsport</A>
(www.cambridgemotorsport.com/splash.htm)
To me the TR4-A stock exhaust manifold is the best in most regards; quieter
than thin tubings, retains heat transfer points to intakes, and it's free
flowing! The last major official factory engineered upgrade for our 4-bangers
before they went to a 6 pot.
Carl
'63 TR4 .. now with 4A manifold
______
I'm still undecided on whether or not to stick with the stock exhaust
manifold on my 4A, or go to a header. Kaster (in the Comp Prep Manual) says
the header is good for a 6 HP increase on a hot street engine, throughout
the power range. However I believe he is talking about the pre-4A manifold,
and the doesn't say anything either way in the 4A update section. I've
heard that the 4A manifold is supposed to be superior to the previous ones,
but is the header still better? The one downside I've also heard with
regards to headers is that they increase the temp under the hood (and being
directly under the carbs and intake manifold probably makes it worse). Do
ceramic coating help? I don't really like the looks of header wraps, so I
probably wouldn't do that.
Darrell Walker
66 TR4A IRS
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