Test Pipe for KA24DE?! Yes I said it.

[costa_rican13]

back pressure is a lie. the computer cannot compensate for the more free flow of exhaust there fore makes slower, or not as much power.


EDIT: PAGE 2!!!!!

[The_caveman]

People still believe that back pressure myth?

So I just got owned On this one read that post and ended up googling back pressure and n/a motors, "learnt me sumthin new" that old redneck a$$ always explained diffrently.


Either way now I kinda want a wide band just to know if my header and exhaust causes my car to run lean lmao..

[costa_rican13]

it leans it out abit. but not much at all. i have a wideband on my n/a ka. its the aem uego.

[IanS]

People still believe that back pressure myth?

Its just easier.

Try explaining to people that their big header and monster 3" exhaust makes less power then a more sanely sized system.

Let them believe that a lack of any back pressure is bad. 90% will never understand that the allowed expansion and cooling in that giant pipe slow down the flow, and allow pulses to bunch up. Or that a properly designed header can actually help with scavenging over an open port, by allowing the pulses to mix evenly. This isn't as important for you turbo guys, but for us gaspers it is. Backpressure = bad. Turbulence = worse. Catalytic converter does NOT = Backpresssure.

A gutted cat, or a cheapo test pipe DOES = Turbulence.

Turbulence = less flow, and less flow = less power.

Like what? I'd like to try those out, cuz test pipes are pretty cheap...

Well considering a test pipe will net you arguably 0 power increase over a properly working cat. Dollar for dollar, almost anything that truly increases power would be a better choice.

If we are talking about a bone stock beat up 100,000 mile KA. A set of spark plugs would likely net you decent power gains. Not to mention the distributor cap, rotor, and wires.

On the more work side of things, but still cheaper, a cam swap would be beneficial even on a stock motor.

A high flow panel filter in the stock airbox can net impressive gains. It just so happens the 240SX uses the same filter as a Subaru WRX, so the options are vast. With some modifications to the lower portion of the airbox flow can be increased further.

Depending on goals. Swapping the ring and pinion for something better fitted to your power band makes for a huge improvement in torque delivery. If staying NA, going with a 4.69 final drive would make even a bone stock car darn quick.

Any of these mods could be had for around $100 or less, which makes them far more worth it, then some stupid piece of pipe with flanges.

Test pipes are for just that, testing, and dyno tuning. Running them on the street is for fanbois, and wannabes.

[The_caveman]

Good reading^^ defenitely true though,I've replaced all those on the single slammer,except I have a retard cone filter that came with the motor and I never plan on touching the cam. It feels like it has a little more power since I fixed all my exhaust leaks and installed the header,but its still only a single cam and only so quick.

At the end of the day all simple bolt ons and basic maintenance aside..
It's still a single cam and it is still slow

[thomasjamal]

Swapping the ring and pinion for something better fitted to your power band makes for a huge improvement in torque delivery. If staying NA, going with a 4.69 final drive would make even a bone stock car darn quick.

Any of these mods could be had for around $100 or less, which makes them far more worth it, then some stupid piece of pipe with flanges.

Test pipes are for just that, testing, and dyno tuning. Running them on the street is for fanbois, and wannabes.

Yeah, I'm not defending test pipes at all. I was seriously asking what cheap upgrades you had in mind that would make an actual difference (since most "budget" upgrades turn out to be fairly worthless). I've been thinking about the cam swap for a long time and have read about the various options but last time I checked there did seem to be a consensus on which upgrade was the best.

I'm curious about the diff swap as that's something I haven't really considered (other than getting a LSD at some point). The options that seem most common are teh Q45 & J30 swaps but where does the 4.69 come from? Is that aftermarket or do you have a specific one in mind?

[IanS]

I'm curious about the diff swap as that's something I haven't really considered (other than getting a LSD at some point). The options that seem most common are teh Q45 & J30 swaps but where does the 4.69 come from? Is that aftermarket or do you have a specific one in mind?

The problem with the Q45 and J30 diffs, is they are both 3.9 : 1. Its a great ratio for turbo cars, or V8s, but for an NA 4 cylinder it is too long. The stock 240 uses a 4.08, which is better then the 3.9, but still long. Some of the CA18 powered 180SX used a 4.36 which I hear can be decent for a stock 240 on the street. Those are the easiest swaps, as you can just swap the whole diff, and many of the 4.36 rear ends can be had with LSD.

To get some real scoot, the Nissan Xterras and Frontiers used an R200 differential in the front, and the ring and pinions can in most cases be swapped to the case of an S chassis. That is where the 4.69 comes from. If you really wanted to go crazy, it is theoretically possible to get a 4.9 rear end set up, and Nismo even used to make a ring/pinion kit, but I have yet to actually find one. The 4.9 would be wicked short, like 130 mph gearing limited top speed.

If you do the 4.69, you better be able to delete the speed limited, or you are going to run into it in a hurry.

[thomasjamal]

Some of the CA18 powered 180SX used a 4.36 which I hear can be decent for a stock 240 on the street. Those are the easiest swaps, as you can just swap the whole diff, and many of the 4.36 rear ends can be had with LSD.

To get some real scoot, the Nissan Xterras and Frontiers used an R200 differential in the front, and the ring and pinions can in most cases be swapped to the case of an S chassis. That is where the 4.69 comes from. If you really wanted to go crazy, it is theoretically possible to get a 4.9 rear end set up, and Nismo even used to make a ring/pinion kit, but I have yet to actually find one. The 4.9 would be wicked short, like 130 mph gearing limited top speed.

If you do the 4.69, you better be able to delete the speed limited, or you are going to run into it in a hurry.

Well that's an interesting option. Since I don't do over 130 very often I'm not worried about the speed limit but I do like being able to drive on the interstate without cruising at 5k rpm (and I'd like to go ka-t some day in the future) so I might look into the 180 diff. If I ever really do turbo I could always swap the j30 internals in, right?

That's enough threadjacking, back to testpipes!

[Lobo240sx]

A few years ago, I needed a new cat for my Corolla. So I gutted the old one and drove around. Yes I know it isn't good but "tried" the myth. Believe it or not, the car actually ran better with a regular cat on than the gutted one.

So FlatBlackIan is correct on this one.

A gutted cat or test pipe on a turbo will give you better boost response and increase flow. I tried it on my 1st SR20DET before changing the full exhaust. When I put the 3 inch Blitz Nurspec R on, I hit the rev limiter faster than I wanted to lol. My friends eyes lit up when he saw the before and after effects of it.

[Dittoz7]

Why no cat?

Because Buddyclub spec II...