mid-pipe

[speedking604]

what size is the size on a stock mid-pipe on 2002 sir???i was confuse if i will get the 2.25" or 2.0". help please???which one is bettr???i have 5 zigen muffler already.

[Lucid Moments]

Originally posted by speedking604
what size is the size on a stock mid-pipe on 2002 sir???i was confuse if i will get the 2.25" or 2.0". help please???which one is bettr???i have 5 zigen muffler already.

I think the stock is like 1 7/8". I think the consensus here is that you go with the 2.25" if you have to get crush bent cause you can't find someone to do a mandrel bent one for you (that is what I have), or you go 2.0" mandrel bent.

[speedking604]

yes , i was asking if which one i need to get. 2.0 or 2.25???which one is better??which one do you have?is it loud?? i like louder ex...as long as not illegal.

[Peking]

Originally posted by speedking604
yes , i was asking if which one i need to get. 2.0 or 2.25???which one is better??which one do you have?is it loud?? i like louder ex...as long as not illegal.

LOL, I have had the 2.25". And loved it, wouldn't go any bigger than that IMO. If you go with 2.00" it is easier to bend and will go better over the rear sway. You gonna keep the stock muffler, or get an aftermarket one?

[speedking604]

i have 5zigen muffler already installed. which one is better???and whats the different in hp???2.0 or 2.25?

[mathman]

Originally posted by speedking604
i have 5zigen muffler already installed. which one is better???and whats the different in hp???2.0 or 2.25?

Typically (i.e. within reasonable sized pipe), larger exhaust will give higher peak hp numbers, but push the rpm at which the max hp occurs out farther, and the hp on the low end of the tach will suffer some. In other words, you will likely sacrifice low-end power for a better rush at high rpm by going to a larger diameter exhaust. Which one is better depends on what you like.

Mathman.

[speedking604]

well, meaning the 2.25 will go faster compare to stock from a dead stop. what about if running top speed? does the 2.25 will still be faster or the stock? just curious coz when i have a 1.7 el with i/h/e/mid pipe, from dead stop the car accelerate faster but when i run the car to top speed it seems slower. need more explaination please.

[mathman]

Originally posted by speedking604
well, meaning the 2.25 will go faster compare to stock from a dead stop. what about if running top speed? does the 2.25 will still be faster or the stock? just curious coz when i have a 1.7 el with i/h/e/mid pipe, from dead stop the car accelerate faster but when i run the car to top speed it seems slower. need more explaination please.

Sure. I'm making up some numbers here, so don't quote me, but hopefully you'll get the idea.

Let's just compare the 2" to the 2.25". From idle to (say) 4,000 rpms the 2" pipe will produce more hp/torque. At 4,000 rpms the hp/torque from both will be equal. Above 4,000 rpms, the hp/torque from the 2.25" pipe will be greater.

Keep in mind that there are other dynamics at play here. When removing/replacing the stock cat, resonator, or muffler, it's possible to see hp/torque gains across all or nearly all of the rpm spectrum. The above is a broad generalization.*

Mathman.
*Individual results may vary.

[speedking604]

thanks for helping me out guys........is there anyone from vancouver that can help me where to buy a 2.25" mid pipe without resonator????

by the way guys, which one do you reccommend??? with resonatore or without?? like i said i have 5zigen muffler already. what is the different anyway?? thanks again.

[Peking]

Originally posted by speedking604
well, meaning the 2.25 will go faster compare to stock from a dead stop. what about if running top speed? does the 2.25 will still be faster or the stock? just curious coz when i have a 1.7 el with i/h/e/mid pipe, from dead stop the car accelerate faster but when i run the car to top speed it seems slower. need more explaination please.

Depends, only way to know is to dyno. You will lose some TQ with a larger pipe, unless you make up for it in another way.


Originally posted by mathman
Sure. I'm making up some numbers here, so don't quote me, but hopefully you'll get the idea.
Let's just compare the 2" to the 2.25". From idle to (say) 4,000 rpms the 2" pipe will produce more hp/torque. At 4,000 rpms the hp/torque from both will be equal. Above 4,000 rpms, the hp/torque from the 2.25" pipe will be greater.
Keep in mind that there are other dynamics at play here. When removing/replacing the stock cat, resonator, or muffler, it's possible to see hp/torque gains across all or nearly all of the rpm spectrum. The above is a broad generalization.*
Mathman.
*Individual results may vary.

From Dyno results I have seen over the years. Exhaust systems, after Intake and header will help produce HP, most dyno's show loss of Tq.


Originally posted by speedking604
thanks for helping me out guys........is there anyone from vancouver that can help me where to buy a 2.25" mid pipe without resonator????
by the way guys, which one do you reccommend??? with resonatore or without?? like i said i have 5zigen muffler already. what is the different anyway?? thanks again.

You can get them from ebay. You do not want a resonator, this frees up the flow. You will sound louder and deeper. Also I have noticed bigger gains in gas mileage.

[SF-SI-02]

better gas milage with or without a resonator? If you want some pick up early in the rev band, and you have to gas it more to compensate for low end losses, then I would expect gas milage to actually decrease...

[Eee Pee]

This dyno graph is from Jack at P1Auto.
Stock is the Zero line.
The differences from stock are what you see.
This is not the HP or TQ curve, only the changes from stock.

The Zero line is a stock B pipe, The blue and green are a 2.25" non resonated pipe.



http://www.p1auto.com/jack/pictures/nobpipebus.jpg


So you are losing ~4.5 ft/lbs of torque @ 2800
And gaining ~6.5 horsepower @ 6525

[mathman]

Originally posted by Eee Pee
This dyno graph is from Jack at P1Auto.
Stock is the Zero line.
The differences from stock are what you see.
This is not the HP or TQ curve, only the changes from stock.

The Zero line is a stock B pipe, The blue and green are a 2.25" non resonated pipe.

So you are losing ~4.5 ft/lbs of torque @ 2800
And gaining ~6.5 horsepower @ 6525

Thanks, Eee Pee. I've been curious about what kind of gains a midpipe would produce. That pretty much answers it.

Notice that peak tq on the base run peaked at 5550rpm, and the tq now peaks at 5800rpm. There was a power loss in the 2500-4000rpm band, which is pretty typical. We've sort of pushed the tq curve out a bit.

So, we've gained both peak tq and peak hp, but at a cost of tq and hp at lower rpms.

Mathman.

[speedking604]

thats really big help......thank you soo much. i wish will have more discussion about this kind of performance. by the ways, it's says on the magazine that quarter mile for si is 16.1 stock. if i have the 2"25 mid-pipe and my 5zigen muffler. what do you think i will come up on quarter mile???remember i have 8 years experience on driving manual. oh and one more thing" i can lunch without spining my tire"