does anyone elses na lancer pop or crackle when u downshift

[SAM-24A]

I did a fair bit of research at various exhaust places. A lot suggested stay at 2 and no larger than 2 1/4

I cant confirm or validate any of the research that LZY_EYE performed .... however the exhaust places that suggested stay at 2" were wrong and/or dont know what they're advising about.

The mid-pipe on a stock Lancer exhaust system is 2 1/8" ..... NOT 2"

Refer to this thread: Genuine OEM Exhaust System.


This was my original exhaust measured at 2 1/8", I also measrured MiztaB's (both 2.4L)
Hoges 2.0L was also exactly the same at 2 1/8"

Note: Exhaust Piping is measured on the outside.

Max Mid-Pipe Recommendation:
2 1/2" for 2.4L
2 1/4" for 2.0L
These sizes are recommended providing that your exhaust system is supported via the use of Performance Components such as Headers, Free Flow Mufflers & Cats.
Anything larger will cause a slight loss in Back Pressure which will effect Low & Mid range Torgue.
Consequently diminishing the advantage of those Performance Components included in your exhaust system.



Regards: Sam

[ofey]

I am out of my depth here but would like to know :

Why would exhaust and mid pipe manufacturers quote in OD (or Outer Diameter)?

Surely the sensible way would be to measure inner diameter (ID), thus removing the thickness of the material used to form the pipe.

The real throughput is the diameter of the orifice through the middle of the pipe right?

*scratch head*

I design vacuum chambers to do scientific stuff and often we have to specify ID and OD as the thickness of the chamber material plays a huge part in how fast it cools or what temperatures its able to sustain.

[lancerdarryl]

Wise advice as usual Sam

[debonaire]

Another cause of running rich is the O2 (or lambda) sensor. The O2 sensor in the exhaust is what tells the ECU whether is is giving the right amount of fuel to the engine, by analysing the composition of the exhaust gas. (Aside: It does this when in normal driving, but when you plant your foot the ECU actually runs in 'open-loop' and pays no attention to the O2 sensor and just squirts as much in as it can to be safe).

Once the O2 sensor packs in, the ECU does not get a recognisable signal so to be safe it just runs rich all the time. You should be able to test whether its broken with a multimeter - if you get a constantly changing voltage that shows it is reading and constantly adjusting as it should - if it is 0 or unchanging its probably busted. Or, if you just pull it out and give it a shake and hear pieces rattling about like I once did, that's another sign its probably the cause of all that black soot on the back of your car

[whitenight]

I am out of my depth here but would like to know : Why would exhaust and mid pipe manufacturers quote in OD (or Outer Diameter)? Surely the sensible way would be to measure inner diameter (ID), thus removing the thickness of the material used to form the pipe. The real throughput is the diameter of the orifice through the middle of the pipe right? *scratch head* I design vacuum chambers to do scientific stuff and often we have to specify ID and OD as the thickness of the chamber material plays a huge part in how fast it cools or what temperatures its able to sustain.

tube is always messured as od (outside diameter)

pipe is messured inside as nb (nominal bore)

pipe usually has a wall thinkness of 2mm +

tube has a wall thickness of 2mm or less

[SAM-24A]

Another cause of running rich is the O2 (or lambda) sensor. The O2 sensor in the exhaust is what tells the ECU whether is is giving the right amount of fuel to the engine, by analysing the composition of the exhaust gas.

Good Point Vaughan ....
Your absolutely correct about the 02 Sensor and its roll with reading and reporting AFR's in the expelled exhaust gases to the ECU.



Sam .....
Merlinised AspiRe 2.4L

[SAM-24A]

I am out of my depth here but would like to know :
Why would exhaust and mid pipe manufacturers quote in OD (or Outer Diameter)?

I agree it sounds wrong to quote an outside diameter rather than the inside .... since the inside diameter is the "Actual & Operative Diameter" which governs / determines and influences exhaust gas flow.

However, Think of it this way: The outside diameter is always going to be constant/correct as measured.

Explained:
If you measure a pipe as 2 1/4" outside .... then it is correctly stated as 2 1/4" outside .... irregardless of wall thickness.

If you measure a pipe as 2 1/4" inside ..... then the outside diameter will need to be re-calculated by adding the wall thickness of the pipe (generally 1/16" x 2) = 2 3/8".

You could argue that if all manufacturers agreed and adhered to a worldwide standard .... then it would be OK to use the inside diameter as the "Identifying Size"

Not Really .....
Firstly: Exhaust Pipe sizes are standardized in Easy 1/4" increments.
Secondly: Exhaust Pipe Manufacturers make exhaust pipe from many different metals such as Mild Steel, Iron, Cast Steel, Stainless Steel, Titanium etc etc.
Since some metals are either weaker or stronger than others .... the thickness's (gauge) needs to be considered and applied in the manufacturing process in order to achieve the equal/desired Tensile strength suitable for the exhaust application.

A Common Automotive Exhaust Scenario:
A 2 1/4" (outside) Mild Steel Pipe with a wall thickness of 16 gauge (1.65mm) (weaker metal --- is thicker)
A 2 1/4" (outside) Stainless Steel with a wall thickness of 16 gauge (1.59mm) (stronger metal --- can be thinner)
Difference = .06mm x 2 for both sides of the pipe = .12mm

You can clearly see that using the "Inside" pipe size & applying this minor ".mm" difference to all exhaust pipe "Outside" sizes would complicate and confuse the entire "Identity Size" Issue, and the Easy 1/4" Standard could not apply.

Furthermore: Size complications would occur when Pipe/Component Connection situations are encountered such as .... one pipe inside another or when fitting the mid-pipe into a muffler, reducer, y-piece or exhaust tip.

Note to Remember: Although Exhaust Pipe is Manufactured and Measured at the Outside Diameter ....
All and/or Most other Exhaust Components such as Mufflers, Cats, Reducers/Extenders, Collectors, Y-Pieces are made and measured on the inside diameter,
since they all and/or in most cases fit over the outside of Exhaust Pipe.

Conclusion ... as per the Automotive Exhaust Industry Standard.
It's far more Simple, Easy, Less Mistaking & Accurate to use the "Outside" size as the "Identifying Size" .....
since the wall thickness (gauge) of the pipe "does not" have any influence over the outside size .... and Inside size for Exhaust Components.


I hope this clears-up and explains why the Automotive Exhaust Industry designates the:
"Outside Dimension for Exhaust Pipe"
"Inside Dimension for Components"
as the Correct Method for Size Identity.



Sam .....
Merlinised AspiRe 2.4L

[ofey]

I could have sworn there were posts after these?
Why were they deleted?

[SAM-24A]

No deleted posts Irving ..... So put your suspicions to rest.

I only added the yellow type & the last paragraph at the bottom to further answer your question and thought it more appropriate that my answer to Vaughan aka "debonaire" appear before so as not to confuse 02 sensors post with the pipe size post.

So I copied, deleted & re-posted .... that's all.
Besides... I'm sure an Admin can check the page logs for you to allay your suspicions.

Sam.