Dual exhaust overkill?
 

I've been reading the forum a bit and came up with this as a basic plan for what I want to do, as I would rather rebuild the whole exhaust now than fix the bits that need it and have to rebuild anyway next spring.

From the existing headers, 2" pipe to Hi Flow pre-cats, more 2" pipe to Aero AR20 resonators or Thrush glasspacks, then I have to figure how I am going to connect the 2" out to the 2.25" (or larger) on the input end of Thrush Type 304 stainless steel welded mufflers.

Is this overkill, or do I need all of it? Should the resonators go before the pre-cats? I've never done anything like this, the only car I've worked on myself was an X1/9 and not on the exhaust.

Re: Dual exhaust overkill?
 

Pre cats before the resonators

Just get a 2" to 2.25" exhaust adapter(or whatever its called)-can be found at autozone or any other local parts shop

And to be honest, unless you're really looking at getting more power out of the motor, true dual exhaust seems to be a waste and just added weight on a stock SVX motor

Re: Dual exhaust overkill?
 

I need to replace the exhaust anyway, and I want to open it up to take as much air out of the cylinders as I will be ramming into them when I upgrade the intake (when I can afford some kind of TC/SC system). I was just wondering if there's too much in each line, or if all of it is necessary to get quiet in the low end but a nice tone when I push it. I also want this to last another 15 years like the stock one did, or at least as long as I can keep this car on the road (94 SVX, no idea what 'type' it is, other than 'teal' :D ).

Edit: Ouch, that second SVX in your sig makes me want to cry.

Re: Dual exhaust overkill?
 

keep the precats or replace them with stanless steel resonators (you don't want to use fg-filled resonators, as they'll foul the primary cat) - this will prevent the dreaded "3k resonance". Go with a single 2.5" pipe aft the primary cat. This will get you all the flow you need and keep the weight of the system down vs a dual system.
-Bill

Re: Dual exhaust overkill?
 

2 into 1 is going to be a bottleneck when I increase the air intake later.

Re: Dual exhaust overkill?
 

Mr. SVXRide is correct....you can always increase the ID of the "Y" fitting. Do the math regarding fluid flow - anything over 3" is going to start killing your bottom end.

Re: Dual exhaust overkill?
 

Fixed it for you fella!;)

Re: Dual exhaust overkill?
 

I'm not proposing anything over 3" on a 2:1, just a continuation of each 2" through to its own separate outlet. I know enough to figure that two 2" into one would need something more like 2.8, which I won't be able to find and wouldn't want to anyway, so taking the two straight through will do the job without having to merge then split them again at the back end.

Re: Dual exhaust overkill?
 

If you do build a true dual exhaust for your 3.3 SVX,
do not go over 2" per bank,
do not merge them with an X pipe or an X muffler,
expect to need four mufflers or resonators to have a nice sounding car, at all RPMs.:)

Re: Dual exhaust overkill?
 

It's not like I am asking whether to go 2:1 or not, I never asked that. I am only asking whether I absolutely need mufflers, resonators *and* pre-cats on each pipe. I only ever had a cat and muffler on my X1/9, and you can bet your sweet posterior it benefitted from a dual exhaust conversion when I had the boost pressure jacked up to 17:1 (with a lot of intake changes). There was never any question about whether I would or would not have a complete dual exhaust or why, just what I really, absolutely need, now that I don't have the help of a crazy Renault mechanic.

Re: Dual exhaust overkill?
 

Thanks, what do you mean by "nice sounding"?

Quiet at low revs, and "What was that?!?!?" at full throttle?

I don't know what jokethis89's performs like, or even sounds like, he hasn't posted a clip yet.

P.S.: What do you mean by 4 mufflers or resonators, two on each pipe in series?

Re: Dual exhaust overkill?
 

1)Something that does not sound like crap below 3000RPM.
And sounds FANTASTIC above 3000RPM!:cool:

2)Acceptable at low RPM, and exotic at higher RPMs.

3)Two mufflers or resonators per side.

Re: Dual exhaust overkill?
 

I changed my stock exhaust, which by the way was silent as a grave, I went this route^ dual 2" piping no third cat. There is very little room for good mufflers so I have 2 long glasspacks, I think 24" about midway under the car and right behind the rear diff I am putting 2 more short glass packs as resonators. I am adding those last 2 because of the drone. Right now it sounds absolutely great at idle, and reasonably quiet but hit 2k and it screams and driving at highway speeds is almost enough to give you a headache. So far I have spent $260 on my exhaust, I wish I had seen this post first though because I will be spending about $90 more for the additional glasspacks if I had done it all at one time I would probably only be spending 50 more. I also got factory looking, but bigger chrome tips they look perfect on here.

Re: Dual exhaust overkill?
 

You have in effect halved the number of pulses of gas normally travelling down a single pipe. On the basis of tuned effect, it is essential that the cross section of each pipe comprising a dual system, equates logically with the original single pipe and is of a reduced area.

In my opinion a dual pipe system is ideal. The original OEM design constraints would have involved cost, space and ground clearance.

Re: Dual exhaust overkill?
 

I am making a topic with a couple of pics of the way mine is set up, though as mentioned at the current time it does not include the resonators.