Rich or Lean - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

MazzyMan · 10-27-2003, 07:33 AM

Dun mean to start a new thread but got some questions:

1. Will the engine run lean when using a much more free flow exhaust compared to the one that is used during tuning of the ECU? The exhaust used during tuning is a straight through unit but not as free flowing as the other unit.

2. Jap mufflers like N1 etc have connectors or link point pipe measurement as 2.5"...why is this so? Why shouldn't it be 3"? Will connecting a 3" piping system to these sort of muffler create any effects?

3. Increasing the intercooler piping diameter...what will this do? Good and bad.

MazzyMan · 10-29-2003, 06:17 AM

Anyone?

docrice · 10-29-2003, 10:41 AM

1. The engine should not run lean, it should be fine once the ECU adjusts...thats why Fuel Injection is superior to carburetion, it adjusts itself (one reason why we have oxygen sensors)

2. i'm not sure exactly what you mean, mind rephrasing that?

3. not an expert here, but there are certainly negative effects to having too small or too large a diameter pipe, same as with exhaust systems...talk to some experts to find out a bit more, i'm not really turbo-savvy yet.

96twofourty · 10-29-2003, 01:07 PM

If you run a 3" exhaust on a na engine you will loose horsepower because you have no brackpressure, the inverse is true about turbo

BeteNoir · 10-29-2003, 07:44 PM

1. As long as the car is not overheating, and your MAFS and O2 sensors are working, you will not run rich.

2. Yes a 3" pipe with a straight through muffler may actually lose low end power due to reduced velocity of the exhaust gases. Not a rule though and some well designed systems retain useable power curve.

3. Same is true with intercooler tubing. You want to maintain as much velocity and volume as you can. It depends on the size of the turbo and how much psi you're running and the size of the downpipe and the size of the intercooler and.... Basically use what you need. More only slows down the air. An engine is just an air pump when you simplify it.

MazzyMan · 10-29-2003, 08:57 PM

Thanks for all the replies!

As for the second question, as we all know...mufflers like N1 have something like a 4" tip but what i am referring to is the other end which is connected to the rest of the exhaust piping...why is it 2.5"?

I am running a full 3" piping and just wondering why they have it this way instead. Should we be running 2.5" instead of 3"?

MazzyMan · 10-29-2003, 09:00 PM

Quote:

Originally posted by BeteNoir
1. As long as the car is not overheating, and your MAFS and O2 sensors are working, you will not run rich.

Funny thing is that when i used the Monster muffler (as shown in my pictures) which has twin 3" chambers...i registered leaner readings on my A/F meter. I know the A/F meter ain't accurate but guess its a concern.

My regular muffler is a 3" single muffler.

rrobe99999 · 11-04-2003, 01:47 PM

3" exhaust piping is good on your turbo car. The exhaust flow through the system is equal to the flow through the most restrictive part, so having a tip larger than your pipe isn't going to do anything. Use muffler with 3" inlet and 3" tip.

MazzyMan · 11-04-2003, 07:32 PM

Quote:

Originally posted by rrobe99999
3" exhaust piping is good on your turbo car. The exhaust flow through the system is equal to the flow through the most restrictive part, so having a tip larger than your pipe isn't going to do anything. Use muffler with 3" inlet and 3" tip.

How about the part when i mentioned about certain muffler brands having the link pipe as 2.5" instead of 3"?

Sorry to be a pest but really wanna know why it is such.

docrice · 11-05-2003, 05:05 AM

most of "those mufflers" were designed either for looks and noise, and not as much for performance, or were designed for N/A cars, where a 2.5" pipe is better suited.

h3x11 · 11-05-2003, 09:39 AM

Quote:

Originally posted by MazzyMan
Dun mean to start a new thread but got some questions:
2. Jap mufflers like N1 etc have connectors or link point pipe measurement as 2.5"...why is this so? Why shouldn't it be 3"? Will connecting a 3" piping system to these sort of muffler create any effects?

i'm not sure what your question is, but....

edit: if the muffler has 2.5" inlet then you should use 2.5" pipings. otherwise don't cross match the pipe and muffler.

MazzyMan · 11-05-2003, 06:53 PM

Quote:

Originally posted by h3x11
i'm not sure what your question is, but....

edit: if the muffler has 2.5" inlet then you should use 2.5" pipings. otherwise don't cross match the pipe and muffler.

Poeple are recommending 3" piping with 3" mufflers...so why are the Jap mufflers using a 2.5" link pipe? I am just curious to know about their R&D issues for them to use 2.5" instead of 3".

And frankly...cat back 3" to a 2.5" muffler isn't wrong yeah?

10-27-2003, 07:33 AM	#1
MazzyMan Leaky Injector Join Date: Oct 2003 Location: Singapore Posts: 56 Trader Rating: (0) Feedback Score: 0 reviews	Rich or Lean Dun mean to start a new thread but got some questions: 1. Will the engine run lean when using a much more free flow exhaust compared to the one that is used during tuning of the ECU? The exhaust used during tuning is a straight through unit but not as free flowing as the other unit. 2. Jap mufflers like N1 etc have connectors or link point pipe measurement as 2.5"...why is this so? Why shouldn't it be 3"? Will connecting a 3" piping system to these sort of muffler create any effects? 3. Increasing the intercooler piping diameter...what will this do? Good and bad.

10-29-2003, 06:17 AM	#2
MazzyMan Leaky Injector Join Date: Oct 2003 Location: Singapore Posts: 56 Trader Rating: (0) Feedback Score: 0 reviews	Anyone? __________________

10-29-2003, 10:41 AM	#3
docrice Zilvia Junkie Join Date: Jan 2003 Location: central PA Age: 40 Posts: 416 Trader Rating: (0) Feedback Score: 0 reviews	1. The engine should not run lean, it should be fine once the ECU adjusts...thats why Fuel Injection is superior to carburetion, it adjusts itself (one reason why we have oxygen sensors) 2. i'm not sure exactly what you mean, mind rephrasing that? 3. not an expert here, but there are certainly negative effects to having too small or too large a diameter pipe, same as with exhaust systems...talk to some experts to find out a bit more, i'm not really turbo-savvy yet. __________________

11-05-2003, 05:05 AM	#10
docrice Zilvia Junkie Join Date: Jan 2003 Location: central PA Age: 40 Posts: 416 Trader Rating: (0) Feedback Score: 0 reviews	most of "those mufflers" were designed either for looks and noise, and not as much for performance, or were designed for N/A cars, where a 2.5" pipe is better suited. __________________

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10-29-2003, 01:07 PM	#4
96twofourty Zilvia Junkie Join Date: Oct 2003 Location: nor*cal Posts: 354 Trader Rating: (0) Feedback Score: 0 reviews	If you run a 3" exhaust on a na engine you will loose horsepower because you have no brackpressure, the inverse is true about turbo

10-29-2003, 07:44 PM	#5
BeteNoir Join Date: Oct 2003 Location: SoFla Posts: 38 Trader Rating: (0) Feedback Score: 0 reviews	1. As long as the car is not overheating, and your MAFS and O2 sensors are working, you will not run rich. 2. Yes a 3" pipe with a straight through muffler may actually lose low end power due to reduced velocity of the exhaust gases. Not a rule though and some well designed systems retain useable power curve. 3. Same is true with intercooler tubing. You want to maintain as much velocity and volume as you can. It depends on the size of the turbo and how much psi you're running and the size of the downpipe and the size of the intercooler and.... Basically use what you need. More only slows down the air. An engine is just an air pump when you simplify it.

10-29-2003, 08:57 PM	#6
MazzyMan Leaky Injector Join Date: Oct 2003 Location: Singapore Posts: 56 Trader Rating: (0) Feedback Score: 0 reviews	Thanks for all the replies! As for the second question, as we all know...mufflers like N1 have something like a 4" tip but what i am referring to is the other end which is connected to the rest of the exhaust piping...why is it 2.5"? I am running a full 3" piping and just wondering why they have it this way instead. Should we be running 2.5" instead of 3"?

11-04-2003, 01:47 PM	#8
rrobe99999 Zilvia Member Join Date: Jul 2003 Location: Destin, Fl Posts: 262 Trader Rating: (0) Feedback Score: 0 reviews	3" exhaust piping is good on your turbo car. The exhaust flow through the system is equal to the flow through the most restrictive part, so having a tip larger than your pipe isn't going to do anything. Use muffler with 3" inlet and 3" tip.