exhaust exhaust exhaust.... *lightbulb*

[chmercer]

is there any advantage to getting a big shiny japanese catback vs just getting a downpipe and a cutout? like i know its not legal and stuff but performance wise, wouldnt a cheapo dump pipe be better than the fanciest jdm type r cusco spec 2 exas n1 exhaust money could buy?

[Silent Drifter]

if you can stand an extremely loud BRAWHHHHHHH at all times then go for it.

[chmercer]

no no i wouldnt always run it open. what i am talking about is like running the stock exhaust with a 3" dp and a cutout where the cat goes, so driving around town i would have stock muffled exhaust, and driving at events i would have 0 backpressure. is there any flaw in my thinking?

[AZhitman]

Unless you're running turbo or S/C, there's no need for a cutout.

Backpressure is your friend, but not to the extent the stock system creates. A nice mandrel-bent catback can give you 10-16 hp on a n/a S14.

[chmercer]

backpressure is your friend? huh?

if a mandrel bent catback gave me 10-16, wouldnt running a 20$ cutout on the stock system give me just as much, if not more?

[AZhitman]

There's gotta be a balance. Try removing your whole exhaust and see what kind of low-nd torque you have...

Otherwise, everyone would just be running straight dumps.

[usdm_180sx]

backpressure is your friend? huh?

if a mandrel bent catback gave me 10-16, wouldnt running a 20$ cutout on the stock system give me just as much, if not more?

On n/a engines backpressure=torque. No backpressure=less torque

[Silent Drifter]

Well I dont have proven results but I had my stock exhaust disconnected befor the cat an it was very sluggish feeling. Then I ran it disconnected after the cat an noticed it was more responsive an it pulled very hard in top end. Also ran a 15.5 with it like that.

[EnzoRWD]

actually, backpressure is bad. but exhaust gas velocity is good. big pipe = low velocity, low flow, low torque. backPRESSURE isnt neccasarily what's good. a big dump pipe out the side would be bad because of no velocity, scavenging, etc-Enzo

[AZhitman]

There we go - Thanks Enzo!

[usdm_180sx]

actually, backpressure is bad. but exhaust gas velocity is good. big pipe = low velocity, low flow, low torque. backPRESSURE isnt neccasarily what's good. a big dump pipe out the side would be bad because of no velocity, scavenging, etc-Enzo

I stand corrected. At 60mm the exhaust gas velocity is optimal for n/a ka engines

[Nismo_Freak]

Actually, a 3" exhaust on a naturally aspirated KA is shown to give substantial gains over even 2.5" systems. The KA has alot of exhaust velocity because of it's long stroke.

Back pressure is bad, velocity good.

And low end torque is kinda a joke on a 4 cyl. ... who drives around flooring the throttle when the revs are under 3000 anyways. If you want low end torque get a truck.

[usdm_180sx]

Actually, a 3" exhaust on a naturally aspirated KA is shown to give substantial gains over even 2.5" systems. The KA has alot of exhaust velocity because of it's long stroke.

Back pressure is bad, velocity good.

And low end torque is kinda a joke on a 4 cyl. ... who drives around flooring the throttle when the revs are under 3000 anyways. If you want low end torque get a truck.

Then why did HKS make their hi power exhaust for the n/a ka 60mm then?

[AZhitman]

Big difference between a full catback where exhaust gas pulses can be managed for full scavenging effect and a straight dump.

There's no comparison.

You can't look at piping diameter alone - There are so many more variables.

[whiterps13]

why do you think big companies spend so much money on exhaust development? if it was as easy as making a dump pipe hks and apexi wouldnt exist. id go with a big name company, because most of them actually dyno and tune the exhaust.

[AZhitman]

Small correction: Not ALL bigname companies dyno and tune. You'd be surprised how many do not. You'd also be surprised at how many of them are not even IN the exhaust biz - Many just buy and slap their logo on it. Often, several companies buy from the same shops!

BRM actually does dyno and sound tuning, and they're a small company cranking out hand-crafted units. Minimal overhead, no advertising budget - it all goes into the product.

[usdm_180sx]

Small correction: Not ALL bigname companies dyno and tune. You'd be surprised how many do not. You'd also be surprised at how many of them are not even IN the exhaust biz - Many just buy and slap their logo on it. Often, several companies buy from the same shops!

BRM actually does dyno and sound tuning, and they're a small company cranking out hand-crafted units. Minimal overhead, no advertising budget - it all goes into the product.

I don't recall him saying that all companies dyno and tune, he said MOST do. I think it's safe to assume that companies like HKS and APEX do their own testing. After all, they only have their own cars competing in the D1. How credible is that?

[MainEvent212]

i'm thinking of gettin one of those electronic cutout thingys and running a side pipe after the driver's side door 8-)

[AZhitman]

I don't recall him saying that all companies dyno and tune, he said MOST do. I think it's safe to assume that companies like HKS and APEX do their own testing. After all, they only have their own cars competing in the D1. How credible is that?

No need to get all bunchy - I'm in the business, and I know for a FACT that some companies do NOT build/test/tune their own stuff (one of them is very near and dear to us Nissan enthusiasts).

Not trying to be a butt, but just don't get misled by who spends more on glossy ads in ricer mags.