Exhaust Size!! Is bigger really better?

[JOAO82]

I own a 96 Mitsu Eclise GS Non-Turbo 2.0 DOCH with Moderate Engine Mods:

AEM Cold Air V2 Intake
Greddy 4-2-1 Headers
Tanabe 2.5" Cat-Back Exhaust
High Flow Cat


My Exhaust is finally on its way out with some rust holes in it, and it's very loud and annoying.

I am now really set on Magnaflow's 2.25" Cat-Back System.

I know Backpressure is needed and important.

Is it a mistake going smaller? No big difference? Good exhaust to go with?
Any thoughts????



Much appreciated

Joao

 

[andymoraitis]

On a non-turbo motor it's not so much an issue of needing backpressure but of maintaining proper scavenging through the system. A 2.5" is the max size you'd want to go and is the right choice for your setup. Anything larger would result in poor scavenging since the exhaust will cool too much and not maintain proper velocity throughout the system. I also like the choice of a 4-2-1 header instead of a 4-1.

Hope that helps,

Andy

 

[Blitzeclips]

No, in this case, bigger is not better.

With exhausts, it's all about velocity and efficiency. If you're non-turbo stick with a 2.5 inch exhaust. You do not need the extra .5" because it will hinder your flow. Hahn's record breaking sunfire runs a 21/4" exhaust because thats the most efficient exhaust for the car. It's alays different depending on the set-up, and car.

But in your case, you should stick with a 2.5". I had a 2.5" until I converted to turbo. Then, I upgraded to 3" for more air and quicker spool.

I'm sure others will chip in wiuth their experiences and advice. But I'm telling you, unless you go turbo, stick with 2.5. Although I doubt 3" will make a noticeable difference...

 

[talon749]

magna-flo makes a geat unit, it was my fist mod, we there it on the dyno with a tune up (oil, pulgs..ect) and got 147 crank hp, which is nice, i think it was 119 wheels

 

[dr1665]

Considering your current mods, I'd say you'll be fine with 2.25"ID. You're not really flowing much more air with what you've got going on in the engine bay at this time. I honestly doubt you will see any difference between the two.

 

[SnoopySLR]

2.25 is fine for you, but look towards the future. Do you expect to have cams or a turbo in your future? If so, I'd recomend getting a 2.5 mandrel bent system. 2.5 isn't the best for a turbo setup, but it sure as hell is better than 2.25

 

[4g64GST]

I'd go 2.25 and I say this from experiance. I stepped up to 2.5 on the wifes car and it slowed down through the 1/4. (auto, needs good torque off the line)
If you go with a 2.25 I think you will notice a little more torque down low, which is always go for a daily driver.

 

[JOAO82]

Cool guys thanks for all the advice


I finally took all your advice and went with 2.25" Magnaflow Full CatBack system (part#15691)

I am 110% satisfied not only with the sweet purr "SHE MAKES" but also with the torque I picked up.


One thing though I'm getting a weird smell from it and some visible smoke. I started a new Thread just two below this one.

Any advice you guys have I would be greatly appreciated

Joao M

 

[SnoopySLR]

probably just the oils that are in the system from it being new. My mustangs exhaust smoked and smelled really bad for about 200 miles. Its a Magnaflow