KA 3" exhaust before/after dyno

[Ricks15]

How do you know this?

Thats becasue I drive my car around and I doesnt have that tourqe that it did when I had the stock exhaust, For example when I launch the car to go fast I bearly feel that small pull of tourque. I dont know its wierd becasue maybe my clutch is screwed or someting cuz thats how I noticed that differnce to make the tires skid it takes some extra effort by pressing the gas before it was just rev it up a little and take the foot off the clutch and it would skid OK cuz it had tourqe.

[S14DB]

ah, the almighty ass dyno.

[BigVinnie]

Originally Posted by 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.

I don't see at all how you are sacrificing, or what you claim as "losing torque".
Back pressure in effect prevents momentum, and flow by building pressure. Hence it's term back pressure, kind of like taking a constopated crap (you get all backed up). Pressure is defined as a form of resistance, I don't understand how resistance helps a crank that is moving more towards free inertia as RPM's and fuel dumping increase. In all reality opening up the exhaust, torque is freed up, when you free up torque you get momentum that increases the force of inertia at the crank which causes HP numbers to multiply as RPM's increase.
So if you add resistance to an exhaust, you are preventing inlet air (from the intake) from compressing, there fore decreasing HP and LOW END torque.
Of course a slight amount of back pressure is needed to aid the EGR valve, but that was part of the design of the CATYLITIC converter to aid in what ever back pressure was needed.
I mean if you are into gas mileage, shure a bit of backpressure is needed to feed exhaust gasses back into the intake through the egr, consuming room that air would of taken to decrease the amount of fuel dumping that could of been used to a full intake charge of air. But then again backpressure deals with EPA regulations, not performance.
If you would rather discuss scavaging and exhaust pulses that is a whole other can of worms....

[anyotherone]

hmm... looks like I sparked a bit of debate here.

For the person who asked, the stock cat is still installed on both of these runs.

I'm going to install a header tomorrow and re-dyno to see what I gain. Then on Saturday I'm planning on installing a set of s13 cams to see what kind of power they pick up.

[jdm538]

i dont know but i had 2.5in piping and recently switched to 3in and it made a big difference.

[Dopefish]

To explain the butt-dyno.. as I use to have a huge misconception of backpressure as well.... the feeling of torque upon launch was lost due to the engine not having to fight as much to get the exhaust out of the way. Thus the powerband has smoothed out a little bit in key areas. With less restriction always comes more power as proven by this dyno and many others. You arent feeling the gains but the gains are indeed there, just delivered much more smoothly which is yet another improvement.

I cant wait to see the cams and header gains, I am doing the cams this weekend hopefully. I'll be using 240/248, stock configuration instead of the 248/248 combo. Are you going to dyno headers, then dyno a test-pipe in place of the cat as well? I dont think an intake will yield too many gains as the stocker flows pretty well already, the filter itself may be an improvement due to surface area though.

~Kris

[sideview_180sx]

the 4K rpm difference I thought were butterflies opening up in the intake mani.

[anyotherone]

I'm going to dyno the header with the cat in first, then I'll see about adding a test pipe to see what it gains. I'm going to dyno it tomorrow with the header and see what it does.

Hopefully on Saturday I'll swap the cams in... I can't decide if I'm going to put in the stock 240/248 first or just go straight for the 248/248 since I have the extra cam to do it. I'll leave it up to you guys - which would you rather see?

[s13pignose]

Originally Posted by anyotherone

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

Hold on let me get this straight. It's 3" and sounds almost as quiet is stock. Sounds like a dumb question, but how? On all other boards I read, you will be horribly loud?

Will you post on loudness with header, cause I know they rid of the cat, which usually always = louder.

Thanks

[SochBAT]

2.25" piping with a raptor exhaust.

I win with throttle response!!

[Dopefish]

Thats excellant that you will be testing the exhaust the way you are so each peice will show gains, that way we can see which part offers the most improvement.

I'd rather see the 240/248 combo since I plan to run them that way. Then possibly 248/248 if you still feel the nead for them so that we could see a graphed differance in the powerband and how it is changed between the differant cam configurations.

~Kris

[BigVinnie]

It would also be nice to see what gains an SAFC can make on an already 7% rich KA24de ecu, with the cams and exhaust system.

[S14DB]

I know I was running Hella lean on those runs.

This should help with those looking for back pressure: http://kalecoauto.com/index.php?main...&products_id=3

[waynehead05]

^how does that thing work?

[Neejay]

Originally Posted by waynehead05

^how does that thing work?

LOL Are you serious? Just read the description...its a joke. Come on, 100% back pressure? Read any other product review on the site.

[anyotherone]

Ok, so here it is... First off, let me say that the pacesetter ka24 header completely sucks. The fit and finish, the install, no hardware, etc... sometimes you just get what you pay for.

That said... I am very pleased with gains. Here's a graph mapping the gains from all three mods, and the AFR using the stock ECU.



Run 1 = Stock
Run 5 = 3" Blitz Realize exhaust
Run 9 = 3" exhaust and Pacesetter 4-1 header

[anyotherone]

By the way, this header removes the primary cat, but I left the second one in. The exhaust note is now VERY loud and pretty raspy and sort of "hollow" sounding, similar to the effect that longtube headers have on the sound of V8's.

[someguy_240]

the second cat? you talking about the s14 right? The s14's dont have a second cat. Its hollow! have you never took that thing out and see what it really is? somekind of hollow resonator or cat look a like

and lastly are those dyno runs with or without any tuning during the dyno

[TheTimanator]

Originally Posted by s13pignose

Hold on let me get this straight. It's 3" and sounds almost as quiet is stock. Sounds like a dumb question, but how? On all other boards I read, you will be horribly loud?

Will you post on loudness with header, cause I know they rid of the cat, which usually always = louder.

Thanks

I have the Realize TT on my car as well, 3" from the turbo back with a high flow cat. Still extremely quiet.

Well, technically the TT is not a full 3" exhaust. If you look inside the muffler you can tell it gets a little smaller. It also has a resonator to make it quieter as well.

[S14DB]

Originally Posted by anyotherone

By the way, this header removes the primary cat, but I left the second one in. The exhaust note is now VERY loud and pretty raspy and sort of "hollow" sounding, similar to the effect that longtube headers have on the sound of V8's.

Get a resonated test pipe. That hollow section makes some weird noises. The resonated test pipe should clear it up.

[anyotherone]

Thanks for the comments, I didn't actually look into the secondary "cat", I guess it might be hollow... I intend to replace it with a test-pipe anyway, so thanks for the advice on the resonated one, I'll try that.

Those dyno runs are with the stock ECU, no tuning. You can see that there is a pretty lean spot between 4-5k rpms... I'm tuning right now to take care of that. I'll post a dyno after I finish tuning in a little while... the curve already looks much better.

[Gearhead_42]

Originally Posted by someguy_240

the second cat? you talking about the s14 right? The s14's dont have a second cat. Its hollow! have you never took that thing out

Ummm no. YMMV, but on my 96 auto the primary (smaller on near the manifold) AND the secondary (big flatter one) BOTH are active cats.

Anyway, I've gone with Hotshot headers, Magnaflow 2.5" hiflow cat, and HKS HiPower catback. I welded in the appropriate O2 sensor bungs to keep the OBD happy and use the second Hotshot sensor bung for an AF meter. The intake side has an Injen CAI minus the extension. Butt dyno tells me there a significant HP increase over 3400 RPM, and it runs right up to the rev limiter now (used to tail off about 600 RPM short).

Don Nimi offers a bolt in hiflow cat through his PDM Racing site, if you want to "keep it legal"

l8r
Dan

[sunnys14]

i had the pacesetter 4-1 header and blitz nur spec R exhaust. kinda loud but i felt some gains also. the quality of the pacesetter header was absolute crap. it got rusty 1 day after i drove it. the reason i picked this header over hotshot, OBX, and DC sports was because pacesetter is the only company on the market that makes a 4-1 header. 4-1 is mainly made for top end gains.

[BigVinnie]

ECU tune at this point should show some major gains.

[anyotherone]

I finished tailoring my basemap and the car pulls much smoother now. I eliminated the 4k dip and trimmed up the timing... the curve is definately smooth, but the peak numbers aren't much different. Tomorrow or Monday I'm going to finish up the tune and I'll post my results. After that I'm going to install the S13 240/248 combo and see what it looks like.

From there I might build an intake pipe with an open filter to see if any intake restriction is holding me back. Since I'm tuning the AEM with the MAP sensor I can completely delete the MAF.

I'm curious about intake manifolds and wilder cams, but I'm trying to map out the average 240sx owners options for cheap power in order to help out the community.

[BigVinnie]

Originally Posted by anyotherone

I finished tailoring my basemap and the car pulls much smoother now. I eliminated the 4k dip and trimmed up the timing... the curve is definately smooth, but the peak numbers aren't much different.

I'm curious to know what octane you are using? Why haven't you disabled closed loop (or just knock sensor). You will show larger gains disabling closed loop so that the knock sensor doesn't retard timing on WOT.

[S14DB]

Why is it a good idea to disable the knock sensor?

[boosteds13]

Originally Posted by BigVinnie

I'm curious to know what octane you are using? Why haven't you disabled closed loop (or just knock sensor). You will show larger gains disabling closed loop so that the knock sensor doesn't retard timing on WOT.

Umm.... wtf? "disable" the knock sensor? If the knock sensor is not there, the ecu goes into limp mode. If you use a resistor or whatever to "simulate" a knock sensor, then a bad tank of gas = no more motor. If the car is properly tuned, then the knock sensor shouldn't be an issue. Lastly, there is a knock sensor on there for a reason- you should probably use it...

[BigVinnie]

Originally Posted by boosteds13

Umm.... wtf? "disable" the knock sensor? If the knock sensor is not there, the ecu goes into limp mode. If you use a resistor or whatever to "simulate" a knock sensor, then a bad tank of gas = no more motor. If the car is properly tuned, then the knock sensor shouldn't be an issue. Lastly, there is a knock sensor on there for a reason- you should probably use it...

This is stated from the ECCS forums....
For those that don't know the Juan Willie tune..
http://www.hybridka.com/eccs/viewtopic.php?t=214
You don't need knock sensors for NA applications, only boosted. Adding knock signal to an NA engine only retards timing when trying to climb at higher RPMs and advancing ignition timing during WOT.
Ignition timing and fuel dumping can always be tuned or modified, it gives NA engines alot more room to play with power.

[S14DB]

Originally Posted by BigVinnie

This is stated from the ECCS forums....
For those that don't know the Juan Willie tune..
http://www.hybridka.com/eccs/viewtopic.php?t=214
You don't need knock sensors for NA applications, only boosted. Adding knock signal to an NA engine only retards timing when trying to climb at higher RPMs and advancing ignition timing during WOT.

I don't see how that thread explained your point.

You should have a lower chance for detonation on NA. But, that doesn't mean you don't need a knock sensor. I don't see any reason that you would want to remove something that is supposed to protect your engine. If you are experiencing retard from the knock sensor. You ether need to Adjust your tune or replace your knock sensor.