acceleration issues

[nismo_race]

i have an 01 sentra with the sr20de in it. i put a aem cold air intake with bypass valve,2 1/4 in catback exhaust with dual tip muffler, 7 mm wires and bosch platinum 4 plugs. after i put the intake on, i started to have accel problems.from idle to 3k it seems like it is struggling, but once it gets to 3k it opens up pretty good. it's fast high, but i want it to be fast from idle to redline. can anybody help me?

[NISTECH]

loose the plugs, go back to the NGK plats , see if you have an improvement.

[nismo_race]

i put in the ngk plugs and i noticed a slight improvement, however i still notgetting the exact response i was looking for. any ideas on what other options i could do?

[nametakennow]

I had an Injen CAI til about 4 days ago... now my car is in pieces on my garage floor.

On purpose. We're turboing it .

Anyway, check out this dyno graph to see why.

As you can see, most of the gains occur after 3k, so the car feels like it's slower down low.

It's not.

Take it on a back road, put it in 4th at about 70mph (should be in close to the 4k rpm range, if I'm thinking correctly), now floor it.

That's what you bought.

You see, a bigger intake pipe isn't going to make a difference until you're pulling enough air to need the extra capacity. You gain less down low because all of the gains are from the shortening of the intake system and the biggest one, of course (which also has more effect when you need more air) is the change in filter element.

Thus, it's normal for it to seem like it's more sluggish, but it's not.

If you really want to test it, get it to 3k rpm in 3rd gear on a straight road with few cops and wind it up to 5500 or so (after that power starts to drop off again, though on up to 6k you probably won't notice the drop off), that's the ticket.

Don't have too much fun .

Also remember that your exhaust system piping (stock) is about 50mm (a nudge under 2in) in diameter. Your stock catalytic converter has a 2.5in diameter. That piping is TINY, then it gets into that HUGE cat, then it's forced into another TINY exit. That's restrictive.

Some guys have seen upwards of 30hp from a header and catback exhaust. I prefer boost, but that's not for the faint of heart.

edit: Yes, that's an Injen graph, it makes the exact same power as the AEM, trust me.

If you want more response you have 2 options.

1. take it off and get a short ram intake. It's basically a filter slammed onto your MAF, then a pipe from MAF to the throttle body.2. Boost it. (Okay, so that may actually reduce response slightly, I'm not sure yet, I'll let you know .

[nismo_race]

should i modify my cai to short ram or should i just spend the money on it?

[nismo_race]

also my friend has an 04 xterra with ka24 engine and cannot seem to find a intake (cai or short ram) for it. he has searched all the websites we could think of but no luck.

[nametakennow]

Check the NICO sponsors (ads on the side, top, and bottom), one of them my have an Xterra intake.

Neither?

A short ram isn't going to increase response enough to warrant spending the money, and you'll lose a pony or two in the sweet spot anyway.

The problem with simply removing the lower pipe and bolting the filter to the MAF is that you lose the temp sensor bung, and cutting a new one in somewhere would make your intake setup completely un-sellable to a lot of people, if/when you choose to ditch it.

In fact, the "response gain" you might see from a short ram might be from the loss of power in the sweet spot, less of a kick in the pants at 3k will make it feel more linear, and thus like it has better response.

Keep what you've got and get a better exhaust setup. The stock mani has a precat that chokes you like nobody's business. The stock cat is 2.5in and appears to be decent-flowing. You'd gain a little from replacing it too, but I wouldn't bother if you've just got a CAI, catback, and header unless you're planning on cams.

BRM makes a great exhaust (I have one), but there are a few other options too.

I'll get a good clip of the sound of the BRM later this week or early next week, if you're worried about sound.

^The point of all that is that to get better response you should increase the performance of other areas of the car. You can pull in all the air you want, but if you can't get it back out you're going to lose power.

If I were you I'd get a good catback and see if the response gets to more what you like. I noticed a decent response gain at 2-2.5k rpms with just a catback. It's nothing drastic, but enough to be worth the money.

Below 2000 there's no point in being at WOT, just downshift or launch at a higher rpm. Heck, I'd say that about 3000 for that matter. If you're going to drive hard, be where it pulls hard or you'll just get bored.

[nismo_race]

i already have a 2 1/2 catback custom exhaust. does it matter that it isn't a brand name company exhaust? i am lookin into the header issue though. as far as the xterrra intake we found one by weapon r, but we'll check out the others cause that one was 300 bones.

[nametakennow]

Mandrel or crush bends?

What kind of muffler and resonator (I hope you got a resonator)?

If it's not a straight-through design, you're losing power. Magnaflow makes mufflers/resonators with a straight through perforated core that are quiet when you want, loud when you stab it, and free-flowing all the time. http://BRMusa.com

A header will also improve things, get a high-flow cat while you're at it to finish it off.

Hotshot makes a good header, but I keep hearing about rust issues. I'd go with the OBX, it's a Hotshot copy, makes very nearly the same power without the rust issues (stainless steel).

[nismo_race]

mandrel and i have a daul 2" tip muffleri'll send a pic when it's light out side but also here is some pics of the intake i took when i was messing with the intake.this was after i shortened it.

[nismo_race]

this was before i shortened it.

[nametakennow]

Is the response any better with it shortened?

Did you relocate the intake temp sensor (next to the battery in pic 2)?

I still think that it's the change in torque curve that made you think it was slower to respond.

[nismo_race]

unfortunately not. my MAF sensor went bad so in the process of trouble shootin i put it back to the long way and put a new sensor on and that seemed to improve the performance and now i'm just goin to have to wait till i have the money to boost.