2G Custom exhaust

[97gsxmod]

I have a side exit exhaust on a car a recently purchased and I’m in the process of designing an exhaust for it. I have looked here and in other forums for the answer to two questions I have but haven’t found anything

1. If you ran an electric valve in a y splitter to a front side exit from a standard full rear exhaust system would the valve create unwanted back pressure and affect the flow when closed by creating a dead end in the y pipe ? If so would it be better for the valve (dead end when closed) to be closer to split from the original system or father away from the original system. ( having a longer tube running to the dead end, or having a shorter tube running to the dead end). And if this is an issue that effects flow would it be helpful to put in a pipe running from the dead end back the main line so when it’s closed the gas can have somewhere to go.

2. If I have a 2.5 diameter side exit

Edit . - 2 if I have a 2.5 inch side exit that’s about 32 inches from the turbo including the bends can I just put a cat and muffler on the side exit ? Or would it be crazy loud still. Maybe a v pipe running to two mufflers than another v back to a single tip?

 

[BLACK'98DSM]

If strictly running side exit, you'll likely only have room for a small catalytic convertor and a low profile straight flow muffler. Which would still be quite loud. Stubby catalytic convertors hardly offer sound deadening qualities, and low profile straight flow mufflers are usually just resonators. Though my setup differs, I've been trying to design a side exit for my 2g that includes a muffler and resonated tip, and that in itself has been a task. I don't expect it to be quiet whatsoever, but having no muffler is illegal. Not that I'm concerned about legality as the car is far from street legal, but at least if I got pulled over I'd have something to point at and say I have a muffler.

On the note of valves... The Y pipe is the most common because they're cheap, easy to install and available everywhere. I personally prefer a cutout valve on the side of the existing pipe. That way you have lesser risk of flow restriction (through primary plumbing) and lesser loss of scavenging, though some. I've never seen a cut out valve that is completely restrictionless (it would need a curved flange to mate perfectly with the pipe), but this works best from my experience. Run a standard exhaust, and plumb the side exit from your cutout valve. Something like this:

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You'd want a circular valve so further pipe can be attached, but you get the idea. Also note that being mounted on the side of the pipe will not allow all gasses to escape through the side exit. Some will still be forced through the rear pipes. This is just to enhance sound, not performance.

Maybe someone who has actually done this will chime in, but I'm sure all of us just stick with one or the other. If you want to ditch the idea of a side exit, just have the valve dump exhaust towards the ground. Loudness will be there but no visible tip on the side if that's what you're trying to keep.

 

[97gsxmod]

Thanks for the advice! I’m not crazy about the idea of a straight pipe to the front side exit but the whole is already in the bumper, and it looks kinda cool. But I’m trying to save money buy not having to replace and repaint the bumper (not to mention paint would never match) . But I also would hate for my main exhaust that’s in everyday use to be poorly effected by back pressure. And then lastly like you mentioned a small cat and muffler system of the side exit might just end up being so loud it’s essentially useless and will need to be redone.

What do you think about a v pipe on the side exit to dual mufflers then another V to the tip?… or maybe just run another tip from the dual muffles?

Or am I just over thinking it and a cut out valve to the side exit will be fine and not effect scavenging to much.

And just to be clear your saying a cut out valve attached straight to the main exhaust pipe will create less negative effect on scavenging then on farther down in the side exit pipe( farther away from the main pipe creating a long dead end tube)?

Thanks again