flclsteve

Just installed my exhaust and it feels very slow not saying my car was fast before but it just seems to take alot long to climb the rev's when driving any ideas why? its a catback with 3 inch piping on a na ka i know 3 inch is big just didnt think it would affect any thing.
ka24e
cold air intake
cat-back 3 inch pipe

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wickedS14

And your wondering why it takes long to get up to rev. 3inch on a 24e, thats overkill. You sir need all the back pressure you can get. It's like blowing through a mcdonalds straw to then blowing through a papertowel roll. Put back on your other exhaust and save the 3 inch for a higher hp motor. Just my 2cents!

apex

do a tune up

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Red Rocket

dino6192

for what? he needs backpressure! 2.5 is the largest I would have gone on your car. nice exhaust though.

apex

shut the f up i got a sohc with headers 3'test pipe and 3' catback
here me gettin sideways

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Red Rocket

flclsteve

still learning makes sense like a dual cam or sr?

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BigVinnie

Correction.. It's called pulse scavaging. Back pressure is for emissions only and has nothing to do with increasing performance. The least amount of back pressure the faster the car will accelerate. The larger the pipe diameter being to big the more the pulse scavging becomes disrupted. Pulse scavaging is what draws in a positive vacuum to allow flow to increase at a faster velocity though pipe. During valve overlap in high rev this helps increase the intake velocity as well.
Basically there is a lower velocity travelling through the exhaust which is disrupting intake velocity in the higher RPM range.

In refrence o KA's using a 3" exhaust pipe. It would be more for KA24de's rather than KA24e's. KA24e's have one less exhaust valve per cylinder and the CFM rating on the SOHC head is about a 1/5th less in flow to the DOHC head. Timing on the KA24e is slow too, you negate power losses with a large pipe and that kind of timing, with CFM rate.

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luftrofl

Your analogy disproves your point. It's easier to blow through a paper towel roll than a straw.

edit: just for fun, explain why you need more backpressure

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Engrish is funny in Japan. In America, it's for stupid fanboys.

ALEXTHESUS*PECT

for ka's i would say 2.5" is max for na. sr or turbo ka would be 3". you got no torque, and we all know with that sohc, you got no real top end either. but i'm sure you got a loud fucken car!

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TEAM SUS*PECT

flclsteve

seriously it sounds fucking crazy i need to post the video

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jinesz32

i had a 3" BC exhaust on my na ka24de, feels like it ran better.

then again yours is 24e, not really sure about those. i just heard the ka24de's like to breathe.

MTalon

if he still has the stock dp, hes got back pressure. If he installed headers, and a test pipe and the exhaust then I would say theres not enough back pressure

S14DB

WTF are you people talking about back pressure like it's a good thing?

Check for exhaust leaks.

Are we talking ass dyno here? Cause sure it will feel different. Doesn't mean you're loosing power.

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Comments should be taken as Opinions not as Statements of Fact

flclsteve

No we are not talking dyno but ya driving with it its pretty noticable doesnt seem to be any exhaust leaks but i can live i guess

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apex

u need a tune up of sumthing
there r even dyno sheets posted on here if u search that shows
3" only has gains no loses might feel like it but u gained more topend with 3"

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Red Rocket

wickedS14

What were you running before that? stock? I got a custom 2.5 straight piping w/ a glass pack resonator angled out to apexi n1 tip for my bone stock kade. I chirp through 2nd whenever and spin through 3rd if raining "bald tires".

flclsteve

[ame]http://www.youtube.com/watch?v=amAA-rJhH8A[/ame]
so heres the vid just in case ur wondering so i guess i should just go do a swap now =P or get smaller pipeing

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MTalon

couldn't even wait to get the car off the jack before starting it.. sheesh.

Felipe

hahaha... nice...


just put a silensarrrrrrrr

sunnys14

For KA's, 3" ftmfw.

Big engines like to breathe, the end.

Jeezy240

i feel that 3 inch is too big. your loosing power. theres not enough backpressure. if you were to put a cat in there and a silencer then i think it might help some.

flclsteve

there is a cat its a cat back system I'm sure I can ghetto fab some silencers or somthing

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airforceone451

Obviously with a bigger diameter aftermarket exhaust system you will lose power in the lower powerband, but you also free up space so you gain power in the upper rpms...I don't think 3 inches is overkill for an n/a ka

5t341tH

try putting a highflow cat in. i was recommended to do so by a muffler shop.

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lexus baby

bigjacsoc

if u have a test pipe downgrade to a cat or a resonated test pipe to get ur backpressure back. u can get resonated from www.projectnissan.com

Mikey213

im not sure, but i think those dynos are only for the DOHC...

cornercarver240

why does everyone keep saying he needs backpressure. no he doesn't, backpressure is bad for performance. the reason it feels slower is because the exhaust is too big, it flows a very large amount of air but the velocity has been reduced a great amount, which reduces scavenging thus lowering torque. it can no longer expel the air out efficiently, and on a car that already doesn't have great volumetric effieciency this will be much more obvious. bigger is not always better, you need to find what's best for your application.

BoostedCoupe

wow backpressure this backpressure that. I have 3" headers 3" cat and catback and it fills alot better than stock or anything else. ka's love to breath dont believe me? look at this then
http://www.zilvia.net/f/showthread.php?t=177055&highlight=ka%27s+love

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92 vert converted 5speed and other little things

DohcKA

sell your exhaust.... dump it into something more worth your money at the time.... stop fart canning down the street

projectRDM

What a whole thread of fail.

Backpressure is something some fool made up 60 years ago and people still swear by it. An engine does NOT need backpressure, period. You want to get all the exhaust air out as quick as possible to avoid creating backpressure, which chokes down the engine. A very small amount of lowend torque is lost due to the added flow, but it's hardly noticeable even on paper. There has been TONS of dyno graphs shown for nearly 20 years proving that the bigger the exhaust you have on a KA, the more power you make. Done.

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FORMERLY R240NA

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