On Wed, 29 Apr 1998, DLM Assoc wrote:
> Hello all:
Howdy.
> I got my new Stahl header yesteday and it looks great. If it fits
> and works as good as it looks I'll be a happy camper. Before I
> start though, I've got a couple questions for the group...
>
> 1. I've had at least one recommendation that I have it powder
> coated, another says don't do anything. What's the general
> concensus? Is powder coating important? Is high temp paint
> sufficient? Should I leave it "nekkid"?
Don't paint it. The first time you heat cycle it, the paint will break
into tiny flakes and get everywhere.
I don't think powder coating is made for high temp applications, so you
might not want to go that route, although I do not know for sure that
there is not a high temp powder coat
-unless-
Get it "jot hot" coated or other similar ceramic coating - inside and
out. It's around $150 - $200 and the coating actually helps the
"scavanging" effect of the pipe. Maybe the Jet Hot process is a high temp
powder coat??? Note: Swain and Airborn are other vendors of the ceramic
coating process.
> 2. It's got a 2.5" OD collector pipe. Can I continue 2.5" to the rear
> or do I have to do anything else through the frame X member (TR4)?
I don't know about fours... someone else 'll probably chime in. I know on
TR6's that the 2.5 inch pipe to the back is one of the possible good setups.
> 3. Someone recommended a section of flex pipe from the collector
> to the exhaust pipe to absorb vibration. Seems to make sense,
> does it?
I can't tell you for sure, but flex pipe will probably introduce
problems, I would not do this if there are other options.
> 4. This sucker's going to be loud... is that a problem anywhere?
> Noise doesn't seem to bother the local autocross group here, except
> for one RX7 that they comment about but don't take action against.
> Is a "supertrap" or similar a good idea or just not needed?
Any car with no muffler will be loud. Any muffler will reduce your power
somewhat. It's up to you to decide if you want to be a noise source. Some
clubs really frown on noisey cars because they have to deal with noise
ordinances at the various venues... Frankly, the right thing to do is to
use some form of muffling, but it's up to you.
You can use various forms of muffling. The key is to make sure that the
muffler does not restrict flow... for example, some types of "cherry
bomb" mufflers have the pipe perferations pointed towards the exhaust
stream... this is bad.
Supertrapps are kind of kool because you can tune them. Thus, you can be
more or less quiet and you can tune for the best power by adding or
removing discs at then end of the pipe. A lot of Autocrossers use
Supertrapps.
> 5. Does the pipe need to be welded or are muffler clamps good
> enough? Seems that they'd make it easier to remove things later on..
You should probably put a flange on the end of the header where it joins
the rest of the pipe (and one on the pipe itself). This will allow you
take the exhaust system apart if you want to remove the engine.
> 6. Anything else I need to know?
Probably a lot. The way to tune your system is to get some dyno time. If
you can't afford that, you might want to get a G analyst and make several
different length pipes and go to the drags and see where you get the best
power...
Exhaust systems require some black art (pun intended) to get fully optimized.
Good luck, and there are several folks on this list that should provide
you with meaningful suggestions.
> Thanks...
> Don Marshall
> '63 TR4 EP Autocrosser
rml
TR6's
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