Hi John,
Forgot to answer your real question.
This is my understanding from others on the list. If others disagree,
please chime in.
The stock exhaust manifold is good enough up to 150 hp or so. Rationale
is that that's what the TR5 used.
Long single exhaust runners (headers) are the only way to improve the
scavaging of the exhaust gases. You need a long single pipe on each
exhaust port.
Headers are noisy, and introduce lots more heat into the engine
compartment. Some have had trouble with the heat and some have not. Some
have devised heat shields between the headers and carbs. Not sure what I
think of all this. Seems to be mixed opinions I guess. I'm hoping the
ceramic coating will help this.
You can expect either a 10% or 10 hp gain with them -- can't remember
which -- both are about the same I guess at 120hp or so.
Seems to be of most benefit if you increase the carburation, and a
"hotter" cam. I would like to go with Richard Good's triple ZS set up at
some point, but no one seems to know how well they work because they
always change something else at the same time -- like the cam or the
headers. So I thought I would change everything else but the carbs the
first time around and then go with the triples later as a second pass
kind of thing.
Don Malling
John Mitchell wrote:
> Anyone have experience with the header kit that TRF is listing in their
> web specials?
> https://secure.zeni.net/trf/specials/index.php?show=17
>
> I was just wondering if a header is a big improvement over the stock
> manifold?
>
>
> John Mitchell 76 TR6
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