KA 3" exhaust before/after dyno

[anyotherone]

A few days ago I threw my stock KA24de 240sx on the dyno, bolted on a 3" catback exhaust system and ran it again... here are the results.



This is on my completely stock (intake and all) 100,000 mile 5spd '98 240sx.

[Ritz S14]

How about a larger graph.

[anyotherone]

Yeah, I just noticed how small photobucket re-sized it too.

[anyotherone]

Ok, that's better. I'm not sure what's causing the weirdness at 4k rpms... but the graph is what it is... the only change is the catback.

Now that I own a dyno I intend to map every change I make to the car... I just thought that making an easy to find post with a comparison might help somebody making a decision on what exhaust system to buy for their stock(ish) 240sx.

[sil80forme]

are u kidding me? those numbers are rediculously low. I got 143hp and and 147 tq with just a 3in exhaust and intake, i got the vid to prove just gotta upload the sucker, i think i would look into ur motor cause that seems a lil low lo me.

[anyotherone]

A dyno is only good for comparison. Unless you drove down here to TX and dynoed back to back with me, comparing your numbers to mine is completely pointless.

The point is that I didn't loose any power down low. Everywhere across the curve I gained power.

[OdessaS13]

what catback did you use?

[anyotherone]

Blitz Realize TT... it's almost as quiet as stock.

[aznpoopy]

yeah there was a freshalloy dyno that pretty much confirmed the same thing many years ago.

80mm piping on a ka n/a = no losses anywhere in the power band.

[punxva]

he proved that putting a 3 in exhaust on a stock ka will not take away power down low... and its as quite as stock, almost. Sweet next, get an intake, and dyno it again, and it'll be alot higher, because more flow in and out of the engine.

[sil80forme]

ok sorry i just never had a stock 240 ever show under 130hp on a dyno

[anyotherone]

No problem sil80 - to be honest I was thinking the same thing at first. Our dynojet tends to read a little lower than average, just based on what I usually see on forums and such.

I'm going to test it again with an intake, then S13 cams, then possibly a custom intake manifold, tuned with my AEM EMS.

I'm basically just having some fun before a built KA goes in along with a custom turbo setup.

[trsilvias13]

Originally Posted by sil80forme

ok sorry i just never had a stock 240 ever show under 130hp on a dyno

what if he is using a mustang dyno and you always use a dynojet.

Like the original poster said, do compare unless you are willing to drive down to him and use the same dyno. otherwise saying you got XXXRWHP is sort of pointless.

[Neejay]

Do you think that the 3" yields more gains than 2.5"? (I know they both have gains, just curious. I have a 2.5" right now)

[anyotherone]

I can't say for certain, but I would speculate that 2.5" would make less power, especially at higher rpms. I can't say for sure, and the difference could be very small.

No way to know for sure unless you test them back to back.

[Irukandji]

2.5 inch would probably have better low end torque while the 3 inch has better high-rpm power.

8whp is pretty good for an otherwise stock Ka. Thanks for the dyno info.

[Nan Desu Ka?!]

yay. I was like 95% sure my 3" was perfect for my NA KADE, but this just confirms it. I wonder what im putting out with my intake + exhuast +rebuilt motor with around 15k and full synthetic fluids??? makes me more confident when i go to replace my exhuast (canister is too big and preventing me from going as low as I want in the rear... can we say raked as hell? lol) that i will definatly go 3" again.

Thanks and +1 for you sir.

[fatalfury64]

is this including a straight pipe in the dyno? i was thinking of getting the tanabe medallion concept g blue. its made for turbo applications, but wondering if you'll get results like yours or more without turbo.

[BigVinnie]

Originally Posted by Neejay

Do you think that the 3" yields more gains than 2.5"? (I know they both have gains, just curious. I have a 2.5" right now)

Slipnfall of NICO just dynoed his 2.5" BRM exhaust. Peak HP was 7.2 gained, and torque was I believe 6.8FT/LB.s gained if I remember correctly.
http://forums.nicoclub.com/zerothread?id=147604
His exhaust uses a resonator which cut's back on exhaust flow and increases back pressure. I've also seen dyno's with 2.5" making almost 8HP without a resonator, and a canister type instead of muffler type.
Dyno dipping on the KA is typical at 4000RPM....

[1Via!]

I just got a 5zigen rocket exhaust(3", straight, no resonator) and expereinced a lot less power than I did with a custom 2.5" with a big resonator and a high flow cat. So, i bought a 2.5" cat which gave me the back pressure that I was lacking. I estimate I'm at around 145hp and roughly the same torque.
This is in my s13 with a 1998 KA24DE, 65k miles with an ebay underdrive pulley and stripped emissions. I have no problem pulling on my friends KAs throughout the powerband.

Hopefully I will dyno the car soon.

Anyways, I got a bit off topic. I think that if you do get a 3" on a NA KA you need a resonator or cat to provide sufficient horsepower and torque.

[AllenRPS13]

Originally Posted by n1sm0r

2.5 inch would probably have better low end torque while the 3 inch has better high-rpm power.

8whp is pretty good for an otherwise stock Ka. Thanks for the dyno info.

i totally agree with u!!!

[Ricks15]

2.5in wont loose low end tourqe but if you bolt on a big ol Turbo size N1 muffler to that pipeing then you loose backpreasure,

[S14DB]

Back-pressure rumor is bullshit and has been disproved many times including by me:

Oh, that was on an auto tranny too.

[infinitexsound]

daymn i love how u ladies always get disgruntled about the KA topics...

all good, maybe i should throw my 208k 16v to see where its numbers are...

[EchoOfSilence]

dooooo iiiiiit.

[BigVinnie]

Originally Posted by Ricks15

2.5in wont loose low end tourqe but if you bolt on a big ol Turbo size N1 muffler to that pipeing then you loose backpreasure,

You want to lose back pressure. Back pressure is a sound deadening effect that prevents your exhaust from getting to loud. All it does is send pulses back up the exhaust sooner than later, which isn't all that good either, unless you like lots of scavaging, or hot exhaust gasses sent back up the EGR into the mani.
Back pressure does serve to maintain good smog emissions, and is no way a performance enhancer to have it. This is true and has always been determined by increased piping diameter as a performance enhancer, or doing to the effect of what is called header out, or cutting pipe where it goes cold.
The fact is I live in Cali so I selected a 2.5" pipe to deaden a little bit of noise, and to keep it lower than 95dB. I understand that perferatted pipe is a sound deadener (resonators) and is associated with back pressure, and pulses to run back up my header and cause flow issues. So I selected a cat back exhaust with no resonators. I just didn't want a 3" horn blaring out the rear of my car, weither it had a resonator or not, i just wanted constant, uninterupted FLOW.
The 2.5" over 3" debate is stupid, bigger is better. It's just the crap added to the CAT back that can make or break a CAT back as a performance enhancer. It's just a matter of what works with purpose over function.

For purpose and function I have selected a 2.5".
But if I didn't need a purpose, and just to serve for function, I would use a 3"....

[Ricks15]

Hey man I was wondering with my custom Exhaust setup I got its 2.5in but no straight pipe its bent and routed just like the stock exhaust that was on the car originally, So you're saying backpreasure is worthless if you're trying to make HP, But tourqe is also sacraficed becasue with my set up I have very little tourqe like I used to when I had the stock exhaust on my car.

[S14DB]

Originally Posted by Ricks15

But tourqe is also sacraficed becasue with my set up I have very little tourqe like I used to when I had the stock exhaust on my car.

How do you know this?

[infinitexsound]

Originally Posted by EchoOfSilence

dooooo iiiiiit.

LOL, maybe after i change out the 10k old oil.... with the walmart spacial.. $1.25 son

[Cashizslick]

These are pretty nice numbers for gains on a KA.

Its know that you can bolt on a 3in exhaust on a stock KA and not see a power loss. That way, if you go the usual route with a 240 (turbocharge via swap or KAT) you dont have to upgrade the exhaust again to get the most out of it.

With hondas that was always the problem. You would lose power on a 3ich exhaust regardless of the motor - 2&1/4inch piping was a must. The thing that sucked was that you'd have to upgrade to a 3inch system if you went turbo . . .


BUMP for good gains on the KA