Wardy,
From all I have read the important part is the dump
pipe off the turbo. I have gone 3" off the turbo down to about the gearbox
cross member, then 2 1/2" from there back. I am currently using just a
single custom made semi-straight-through glass packed muffler and it is nice and
quiet. No cat at this stage, but I will need to get one sooner or later
:-( I have a fitting brazed on just after the dump pipe to measure back
pressure - it is difficult to measure any at all!!
3" systems are more difficult to
silence too. They tend to sound like a drainpipe (you might like this sound - I
don't). Even on a turbo engine. I've heard some shockers! The guys with the
later model cars (200SX's etc.) are better off in this regard because they have
a lot more room underneath for a big muffler, so they can realistically run
3" systems and still have them nice and quiet. Because our 1600s have
bugger all room for mufflers it is difficult to run a large diameter exhaust and
get them quiet. Depends what you call quiet too!
The old Dattos
only came with a very small dia exhaust, so there is not a lot of room under
there to neatly tuck in a large dia exhaust. They tend to hang out and stuff up
ground clearance. To get a 3" through the rear cross member is pushing it
too. To remove enough material to fit the 3" pipe through with reasonable
clearance you end up with all hole and very little cross
member.
It is very fasionable to run a big exhaust, and with
turbo engines any back pressure is obviously bad, but I think a lot of people
tend to run them just because everyone reckons 3" is where it's at! I doubt
many of them have actually measured the back pressure. You are probably better
off getting a good cat (I have two good cats, but I don't intend to fit them to
my car, although they do run well) and quality muffler - unless you are going
for really high horsepower with a huge turbo etc.
You
asked...
'later
PL
-----Original Message-----Wardy
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of John Evans
Sent: Wednesday, 12 April 2000 8:14
To: [EMAIL PROTECTED]
Subject: Re: exhaust systems for turbo's
The amount of restriction caused by a 2.5" when compared to a 3" is minimal compared to the potential restriction caused by a cheap or poor flowing muffler and even more so cat converter. A good 2.5" exhaust should be able to flow over 400hp on a turbo engine so if you have some extra cash invest it in the best 2.5" cat and muffler you can get IMHO.
Cheers
John
At 07:06 11/04/00 +1000, you wrote:
G'day listers, hey I just wanted a little feedback on what exhaust systems ppl are using on their turbo motors. I went to the exhaust shop today (from what I hear, a pretty respected one in the area) to organise for a system on the 1600 when the FJ20T goes in. They reckoned using a highflow cat converter & muffler, and use 2 and a half inch system all the way back. I was thinking of a 3 " system but they reckoned it was un-necessary. Experiences/thoughts ?
Wardy
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