Question

[mikeroy420]

Why do you need a different exhaust for a turbo engine, than a NA engine? Thanks.

[ca18guy]

You don't really.

[mikeroy420]

OK, so I can get a dual N1 for my ka engine, and use the same exhaust for an sr engine?

[Dousan_PG]

yes

[Steeles]

Originally posted by mikeroy420
OK, so I can get a dual N1 for my ka engine, and use the same exhaust for an sr engine?

thats what I did

[Foxcolt]

Originally posted by mikeroy420
Why do you need a different exhaust for a turbo engine, than a NA engine? Thanks.

NA engines run best on 2.5 inch piping due to the "supposed" need for a little back pressure (I've never been able to figure out why though)

With a turbo car the free'er(??) the exhaust flows the more power it will make. So a 3 inch pipe is often a standered when getting an exhaust.

However putting a 3 inch pipe on an NA often causes some loss in low end torque and a very load and obnoxious sound.

[Steeles]

its all about velocity :D (as was explained to me) the benefits are all about escape gas velocity. backpressure is a by product of a almost properly sized system (hence the backpressusre = good myth) too big and not enough velocity makes you slower (ie big exhaust on NA motor) losses HP too small losses power due to backpressure, the gas is getting caught up in the exhaust cause it cant move fast enough results in pushing back into engine = bad. I think thats about right... I need to just copy D240t's explination of this and keep it on file lol

[AKADriver]

Steeles got it.

A real hot N/A engine could use a 3" exhaust though, for the same reason a turbo car could. But at that point you're reaching the upper limit of streetability from an N/A KA.

[mikeroy420]

why then can you buy exhausts that are specifaclly made for either na engines or turbo engines. i always thought that you needed to buy a different exhaust depending on your set-up. for example on APA it says " The N-1 Series Mufflers are available for both NA (naturally aspirated) and turbo-charged cars." that seems like it refers to two different exhaust systems. Just courious b/c i don't want to spend $1000.00 on it now then not be able to use it when my sr goes in. And if they are the same what size would be best considering i want to use for na until i get my sr then use it on that. thanks

[ca18guy]

Most of the exhaust for the 240 seem to say either turbo or n/a when refering to the size of the piping. Most of the "turbo" exhausts are 3" and the "n/a" exhausts are ussually 2 1/2 inches in diameter. In reality 2 1/2 inch diameter is enough for most turbo 4 cylinders. I believe Boosted S14 here has close to 400 RWHP and actually went back to using a 2.5 inch exhaust to gain a better powerband (I wish he would have dynoed with a 3" but I don't believe he ever did?) So you can't go wrong with a 3" or 2.5" exhaust.

[sykikchimp]

actually I think boosted did it to quiet down the beast...