Alex01tib

i had planned on going with 2.5...wasnt thinking of anything smaller...but if what you say is true then maybe ill go with 2.75

hamhead

EDIT: I've never heard of a shop do a 2.75inch bend. Chances are they can't do it, especially in mandrel.

3inch mandrel is way too big and HIGHLY expensive... unless your planning on running 350whp or more... bigger is not always better, even with turbos. And you will lose backpressure when running 2.5inch mandrel exhaust, even with stock headers...


Either go with 3inch SS crushed, or 2.5inch mandrel. Both offer good flow for turboing up to around 350whp. Pricing depends on your location as well. Big city = lower prices. Small town = higher prices. Get the mandrel if you can, 3inch crushed would probably be too much for running before a turbo if you do any city driving at all.

In essence, get 2.5inch mandrel if you can or 3inch crushed if you can stand being a slug around town until you get a turbo. Both offer good flow for most street turbo applications.
-----
As for your other question, what to buy beforehand. 1.8L cam is out of question, you want lower lift and duration with a turbo if you want the most reliability. You could get the underdrive (not overdrive... smile.gif) pulleys if you wanted... but I would much rather save the money for a piggyback like an S-AFC, SMT-6, EManage, etc. or to get the turbo sooner.

Alex01tib

<div class='quotetop'>QUOTE (hamhead)</div><div class='quotemain'>EDIT: I've never heard of a shop do a 2.75inch bend. Chances are they can't do it, especially in mandrel.

3inch mandrel is way too big and HIGHLY expensive... unless your planning on running 350whp or more... bigger is not always better, even with turbos. And you will lose backpressure when running 2.5inch mandrel exhaust, even with stock headers...


Either go with 3inch SS crushed, or 2.5inch mandrel. Both offer good flow for turboing up to around 350whp. Pricing depends on your location as well. Big city = lower prices. Small town = higher prices. Get the mandrel if you can, 3inch crushed would probably be too much for running before a turbo if you do any city driving at all.

In essence, get 2.5inch mandrel if you can or 3inch crushed if you can stand being a slug around town until you get a turbo. Both offer good flow for most street turbo applications.
-----
As for your other question, what to buy beforehand. 1.8L cam is out of question, you want lower lift and duration with a turbo if you want the most reliability. You could get the underdrive (not overdrive... smile.gif) pulleys if you wanted... but I would much rather save the money for a piggyback like an S-AFC, SMT-6, EManage, etc. or to get the turbo sooner.</div>

yah thats what i thought about the 3inch...2.5 wouldnt make me slow right?...did i say overdrive? LOL i kept telling this guy on Ebay not to post it as an overdrive pulley and now here i am saying it...jesus... i said it correct in the first post..LOL

hamhead

2.5inch should be fine. Since you'll be running stock headers, you shouldn't lose low-end TQ (maybe a hair). It will by no means make your car a slug like a 3inch exhaust would.

Mad-Machine

I still can't quite figure out the whole huge exhaust makes you slow thing.. Sport Compact car took one of their project hondas and ripped out the exhaust, mounted a HUGE header to a dump pipe... and gained HP and Torque across the board.

Zman

<div class='quotetop'>QUOTE (hamhead)</div><div class='quotemain'>EDIT: I've never heard of a shop do a 2.75inch bend. Chances are they can't do it, especially in mandrel.</div>
Yeah, well, at least thorically it can be made.

<div class='quotetop'>QUOTE (hamhead)</div><div class='quotemain'>...And you will lose backpressure when running 2.5inch mandrel exhaust, even with stock headers...</div>
Hamhead (or anybody else) please correct me if I'm wrong:
you would loose backpressure ONLY if you go 2,5" all the way from the header collector to the end. Think of it this way, in a water hose (the common garden hose) if you have a 1" diameter hose, 6" long, the amount of water going through the hose is "X". Now, if you could weld three sections of hose, one 1" diameter, and two 2" at both ends of the 1" section, and you apply the given water pressure, how much water is going to flow? "X", because flow will be limited to the smallest section of the hose/pipe/exhaust, etc. The thing in cars is that pressure is variable with rpm's, so you "feel" the difference at certain rpm's, but with a restriction at some point, difference in flow should be minimal with larger sections only and not the whole thing.
:Thinkingo
Wow, that was long... I'm exhausted laugh.gif:

hamhead

Mad, you might gain some top-end, we're talking more low-end here. With a overly large exhaust pipe your going to lose low-end, but you still might show gains at the top. Also, if the engine was pushing a lot of power a dump pipe is a more effective means of getting it out. Depends on what the car's power is pushing.

ZMan, your talking more "flow" than "backpressure." Backpressure is a limit in flow that keeps unburnt gas in the combustion chamber. Backpressure can be caused by anything restricting flow. Even the muffler at the end of small pipe can create more backpressure, even though the muffler is more free-flowing than that small pipe.

Also, your talking water. We're dealing with exhaust gas, and exhaust gas likes to move around fast and expand, especially when hot. Once it hits a larger section of piping, its going to expand as fast as it can to fill that part.

Zman

Yeah, that's exactly my point... if you have a huge exhaust line, and you put some restriction at the end, it will create backpressure. In the case of keeping your exhaust stock till the cat (let's call it pre-cat exhaust) THAT will creat all the back pressure you need, hence, it does not matter what you put AFTER that, you won't "loose" backpressure...
or I'm not getting your example?

hamhead

Every part of the exhaust system creates backpressure. When you measure restriction distribution, you can see what contribution to the total backpressure is from the pipe, the cat, and the muffler. I've measured backpressure from after the header, then after the converter, then at the muffler, and it changes every time.

If you go to large on exhaust, then the number from the pipe is going to decrease backpressure enough that your going to lose too much backpressure. On turbocharged cars, especially ones with internal wastegates, that can cause the wastegate to malfunction and cause problems like overboost.

Mad-Machine

This was SCC's response to a question about backpressure.. it is in this month's "letters" section.

"There are no absolutes, but replacing our "high flow" headers secondaries and exhaust with a 3 inch diameter, 3 foot long dump pipe made 14hp, 13 lb-ft of torque everywhre on our near stock B16 powered project civic. We say "backpressure backsmeshure"