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Traitor
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249 Posts
Discussion Starter #1
I was reading over at sentra.net about engine modifications.

Exhaust:

"If your engine is naturally aspirated, limit your pipe diameter to no more than 2" or you will lose some bottom end with no applicable gain on top."

That is saying that I shouldnt go any bigger than 2" on my stock GA16. From what I gather from this forum most people use 2.5". Whats up with that?

"Straight through mufflers are by far the lowest backpressure. The Walker UltraFlow, Apex'i, or Magnaflow are some common ones."

I cant seem to find these mufflers with any size smaller than 2.25".

Air Intake:

"The cheapest thing that gives a little more power is the infamous ghetto airbox trick, which involves removing the lower part of your airbox and ziptieing or tapping the filter to the upper part of the airbox. Just for laughs we dynoed this combo and found that we got about 1-1.5 hp out of it! Not bad for free although filtering probably suffers and it looks, well, ghetto!"

Anyone have any pictures of this? I would like to give it a try. How does the filtering suffer?

"If you live in areas of high rainfall, then these should be considered because CAI’s don’t like deep water!"

What exactly is meant by heavy rain fall? Flooding? Is rain of any kind an issue or just flooding? It usually rains for a week straight during season changes around here.


Thats all for now :D
 

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freakish poster
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1,236 Posts
The problem with the air filter is that you have to wire tie it very tight to the air box top. Think of how tight the air box (stock) seals in the filter with those clips and you know what I mean.
 

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Registered
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553 Posts
The 2" exhaust is reccomended b/ cthat will give you the most power without sacrificing much low-end power. Sure you can put a 2.5" on there, but your bottom end would not be as good as it could be. And bottom end is what Nissan is known for.

As for CAIs I would avoid puddles. Also when driving through puddles (the ones you can't avoid), dont hit the gas. This way your engine won't try and suck in any air and water with it. If there a lot of water on the ground, I would temporarily turn your intake piping back to a WAI. Just mount the filter directly onto the MAF sensor.
 

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Sentra Specialist
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1,902 Posts
Honest Bob said:


That is saying that I shouldnt go any bigger than 2" on my stock GA16. From what I gather from this forum most people use 2.5". Whats up with that?
***** Most people think bigger is better. Believe the Sentra.net article. It is the best and most accurate info. We are all lucky to have Mike Kojima sharing his knowledge with us!


Originall posted by Bob "Straight through mufflers are by far the lowest backpressure. The Walker UltraFlow, Apex'i, or Magnaflow are some common ones."

I cant seem to find these mufflers with any size smaller than 2.25".
***** I got my 2" Dynomax [Walker] Ultra-Flo muffler through the Jegs catalog. They list two of them in there, part# 289-17514 and # 289-17516. They are not round mufflers like O.E. They are 4 1/2" tall, by 9 3/4" wide, by 14" long. I welded on my own hangers, and got mine to fit nicely on my B12. They are $61.99 and are guaranteed for life.
 

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S12 Fanatic
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211 Posts
These guys are right on the exhaust. Too large a diameter will lead to not enought backpressure, which will reduce low-end torque. 2.5" was the maximum that the performance garage that did my exhaust recommended for my car, but it's a 3 liter V6, so 2" sounds good for a 1.6 or 2.0. I have a Magnaflow muffler and it's great.
As for zip-tying the air filter, I would not recommend it for the reasons stated in this thread. I would not trust the seal around the filter, and 1-1.5 hp is not worth the risk of sucking particles into your engine.
 

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Traitor
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249 Posts
Discussion Starter #8
Thanks guys! When my stock exhaust finishes rusting through I will go with the mandrel bent 2". As for the muffler, I thought I read that the dynomax mufflers werent the best somewhere in sentra.net? Are dynomax and Walker the same?

As for the CAI, I dont think I want one sucking up the water. How about WAI? Do they make them or will I have to fabricate my own?
 

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Pastor of Muppets
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153 Posts
As for the WAI, be sure to get a METAL adapter plate. The WAI does basically the same thing as the ghetto airbox mod, but with proper filtration. I'm using an aluminum plate on mine, with a K&N cone filter.

For the exhaust- 2" piping is what you need. It's OK to use a 2.5" muffler- in the last foot and a half or so of the exhaust you won't lose the back pressure.
 

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Traitor
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249 Posts
Discussion Starter #10
As for the WAI, be sure to get a METAL adapter plate. The WAI does basically the same thing as the ghetto airbox mod, but with proper filtration. I'm using an aluminum plate on mine, with a K&N cone filter.
Where would I get one of those metal adapters from?
 
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