exhaust ideas

takotruckin

Registered User
hey guys, i need some advice on how to set up my exhaust. i have a 90 sc motor in a baja bug. so i need my exhaust to be compact, but i dont want to lose any torque, i also want it to sound decent. i dont care if its loud
 
Sounds like a custom exhaust is needed.......

I would think you would want some back pressure and I am assuming that the exhaust will be quite short.....
 
I think you would want to place the O2 sensor so it would run
in about the same tempature range as before in a stock set up.
About the same distance from the heads.

I would think this to be the most important part in your custom
exhaust for tuning later.

The O2 sensor should be setting in the exhaust pipe above the
3 & 9 o-clock .You need this position to keep moisture away
from the O2 sensor.helps make it last longer and run cleaner.

RANDY
 
Your conversion has gotten my interest up. I'll assume a few things to bring you my thoughts. If the engine is adapted to a VW transaxle I would bring custom 2 1/4" downtubes off the stock manifolds, Y them into a single 3" pipe then use a single 3" in/out muffler. The configuration could be several ways. Easiest may be to route the single pipe up one side and then 90* bend to mount the muffler crossways across the top rear. Possibly mount the manifolds upside down and run the pipes topside and then down to a muffler at a good location. The point is I don't think you'd lose enough torque to notice in a car half the SC weight. You could overdrive the blower to gain back lost torque. Another assumption is a custom intercooler. Just keep the exhaust pipes as far away from i/c as practical. The exhaust may be a bit loud, but droning shouldn't be an issue since everything is out in the open and not running down the length of the car. At least I'm interested in keeping informed so feel free to IM or email me with info or questions. Good luck, John
 
the oe manifolds wont mount upside down and i am keeping the o2 sensors in the stock place. i am currently trying to figure out how to run intercooler plumbing, i have it in the stock location for testing.. im trying to get the radiator lines run and get it wired, then its going to the muffler shop. i might have him do my intercooler plumbing as well. will a small turbo muffler work or would i need two of them? CB performance sells them for vw motors which are up to about 2.2 liters.

ps. im sorry for bringing up the exhaust topic, i know its a little overused around here, but i need some advice from people who really know these motors before i go to the muffler shop. thanks for the help
 
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Why do you say the oe manifolds don't mount upside down? I have checked the spare heads and manifolds in my garage and they fit just fine upside down. Is there an issue I'm not seeing? The only issue I can see is you'll need to port the manifolds slightly to match the lower shape of the port at the head. The O2 sensor is in the driver side manifold already, passenger side I would put the bung anywhere within 12" or so from the manifold exit. John

P.S.: I think a single turbo muffler would work fine if designed for 3" in/out. Also, your exhaust questions are exploring uncharted territory and I, for one, welcome your questions.
 
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i think i tried mounting then manifolds upside down but they hit the intake and intercooler tubes. i'll try to check it out tomorrow at work. the turbo muffler does have a 3 inch inlet, so it should work. or would two 2 inch mufflers be better? thanks for your help
 
A Supertrap muffler would be tunable. With the addition or deletion
of disc on the end of the muffler exit.So you can tune for back pressures.
I don't know about the costs.You may be able to fab something
along this line,to save money.

Weld a bolt sticking out from the exit end of your collector.Then stack
a disc the diametter of exhaust collector then a small washer then
another disc,another washer,another disc,ect.Then a nut to hold
together on the weld in bolt sticking out the center of collector
or muffler tube.

use a Y PIPE to tie your headers into one collector.Then build the
supertrap disc part.

Randy
 
OK, I'm sure you're right, upside-down mani's would undoubtedly interfere with stock intake tube and upper i/c tube. I just figured that as custom as this install is that re-routed intake and custom i/c tubes would be needed anyway. I was thinking possibly roof mount i/c with a fan, but not sure how it would all fit together with the rad and exhaust. BTW, is this going to be mid engine or is the engine hanging off the back?
Randy, I like your Supertrapp idea. Very tunable, probably loud, but nice and small. Whatever you use, personally I think one muffler is better than two as long as it's big enough to flow. John
 
it has got the engine hanging off the back. i have the radiator mounted in the trunk, and i am planning on mounting the IC on the roof or under the back window. i am probably going to wait until a move the ic before making my exhaust, i may also move the intake to inside of the car or something. im probably just going to use a small turbo muffler, but i might try and play with the supertrap idea
 
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