Customizing'it!

[VTECMACHINE]

I never knew non-mandrel bent exhausts existed. I want to open an exhaust shop now, and just find random pipes and bend them with my foot, and bolt them up to cars - Rip people off, haha.

[rbk_212]

^ its called a press bent system, most exhausts you see on street cars are like this

[VTECMACHINE]

^ its called a press bent system, most exhausts you see on street cars are like this

No they aren't...

Edit: I have looked at our 5 family cars, and some cars on the street... all the stock systems are all mandrel bent. Only crappy exhaust systems are press bent. If stock exhausts aren't press bent... why decrease performance and get one made?

[Tegzieboi_BAR]

stock dc2r exhaust isnt mandrell, im no exhaust speciallist but u wont find too many non-modern cars that hav mandrell exhausts

[VTECMACHINE]

There are some places that litrally bend it, so that the corners of the crease in the metal are pointy, and the bent is really flat. I have seen some really bad examples of that. But googling it now, if you want to get technical, Normal (I'm assuming Press) bent is like this:



Here is a pic of a mate exhaust we pulled off (Was worse in other places, but this is the only pic I have):



Mandrel:



So that means my Buddyclub exhaust wasn't even mandrel bent properly?

[rbk_212]

"all stock systems are mandrel bent" is a very big generalisation, most cars have a press bent system and i was specifically referring to aftermarket exhausts that people fit, as most catbacks are installed for the noise not for performance (performance gains from a catback are the subject of some debate any way)

when most people get a catback they get larger diameter piping so even though the bends arent as good as mandrel's they are still better flowing than the stock system which is usually press bent anyway

i know mandrel is better but some people cant justify it for the price they have to pay

[VTECMACHINE]

How much more is Mendrel bent than press bent?

It's worse to go from a mandrel to press bent system, regardless of piping diameter. I have asked the question to a few japanese companies when I first got my car, as I didn't have a clue what an exhaust system even was, and didn't even know forums existed, lol.
Reason being as exhaust gases go to a larger diameter to a smaller one... being at the bend makes it worse as there is backflow of gas. It technically restricts the gases flow more than a smaller mandrel bent system. Also, catbacks do add power. So many systems have been dyno proven to gain 7-11ish kW's ATW. Felix's DC2R on CITR is one example, and Justin fox on his S2K.
A muffler alone however will not do much with out opening up the b-pipe.

Why change an exhaust for noise? I wish I had a quiet car...

[GSi_PSi]

One thing about catback systems is from i learnt. If its got a brand then expect gains, otherwise dont expect much. I went from a drift (autobarn crap) catback to a jun.b.l exhaust leading to toda power 4-2-1 extractors and there is big difference in accelleration and topend.

[VTECMACHINE]

One thing about catback systems is from i learnt. If its got a brand then expect gains, otherwise dont expect much. I went from a drift (autobarn crap) catback to a jun.b.l exhaust leading to toda power 4-2-1 extractors and there is big difference in accelleration and topend.

Not always true in relation to a catback... well b-pipe anyways. Headers, yes. It's important that you have a well designed header, and will notice gains. You might notice sliigghhttt differennces in response with different axel backs (muffler).
The only difference you'll see with different branded catbacks is the resignator (a pipe if a pipe after all, as long as it follows the straightest line possible on the underbody). I had a long chat to the head of J's Racing when he was here in Oz, about the J's exhaust as I had just bought one at the time, and told him I had noticed quite a large gain compared to the Spoon exhaust. He explained that there was a great deal of engineering in resignator technology, ie: where a resignator is placed on a B-pipe, different mid resignator and muffler resignator size combinations and what materials are in a resignator. Hence the price tag of the J's exhaust (It's also Ti)

But he said... end of the day, an exhaust with no resignator is the best for gains. But Japanese companies have to satify consumers, and make the sound of the exhaust bareable for occasional weekend racers that drive their cars on the street.

But yes, if you're not after that extra bit of power and response, a custom 60mm (i'm talking about a DC2R here) mandrel bent b-pipe with a resignator (if you wanted one) slapped anywhere along it will yield sufficient gains, with a good headers.

[squish85]

Mugen Twin Loop for the win !!!

How much more is Mendrel bent than press bent?

It's worse to go from a mandrel to press bent system, regardless of piping diameter. I have asked the question to a few japanese companies when I first got my car, as I didn't have a clue what an exhaust system even was, and didn't even know forums existed, lol.
Reason being as exhaust gases go to a larger diameter to a smaller one... being at the bend makes it worse as there is backflow of gas. It technically restricts the gases flow more than a smaller mandrel bent system. Also, catbacks do add power. So many systems have been dyno proven to gain 7-11ish kW's ATW. Felix's DC2R on CITR is one example, and Justin fox on his S2K.
A muffler alone however will not do much with out opening up the b-pipe.

Why change an exhaust for noise? I wish I had a quiet car...

[rbk_212]

How much more is Mendrel bent than press bent?

It's worse to go from a mandrel to press bent system, regardless of piping diameter. I have asked the question to a few japanese companies when I first got my car, as I didn't have a clue what an exhaust system even was, and didn't even know forums existed, lol.
Reason being as exhaust gases go to a larger diameter to a smaller one... being at the bend makes it worse as there is backflow of gas. It technically restricts the gases flow more than a smaller mandrel bent system. Also, catbacks do add power. So many systems have been dyno proven to gain 7-11ish kW's ATW. Felix's DC2R on CITR is one example, and Justin fox on his S2K.
A muffler alone however will not do much with out opening up the b-pipe.

Why change an exhaust for noise? I wish I had a quiet car...

well a press bent catback can be like 450 and a mandrel can be 900 and upwards depending.

hah yes i too wish my car was quiet i only meant to point out that alot of people with "zorsts" only get them for noise, they arent really performances enthusiasts obviously..

also 10ish kw ATW is brilliant they must have been some really good systems, a generic systems probably wont be getting that sort of gain

dammit i wish i had a mandrel bent system now, i got my catback done when i was 17 and didnt have a clue... lol tell me, can i just get the B-pipe changed in future to a mandrel?
coz i already have a good muffler, stainless x-force extractors and a hi-flo cat

[VTECMACHINE]

Go out and buy a Vision B-pipe. They make the Spoon ones, but are half the price. Or yes, you can go get a new b-pipe made up which in mandrel bent.

A custom exhaust can yield the same gains as an expensive JDM exhaust. Like I have said, only difference is resignator technology.

Anyways, don't worry yourself about peak power, cos it doesn't mean much unless you drag race alot. Also don't take dyno results seriously. A dyno is a tuning tool, and different dynos read very differently. An exhaust gives slight power/torque and more response throughout the rev range - well, a mandrel bent pipe anyways. Press bent, i don't think you'll notice a difference from stock, or maybe even a decrease in performance even, as there is a heaps of restriction which screws with response.

Also I wouldn't say Xforce headers are "good". They normally leak where they press against the block. Design... Meh. But for a DC4 (that's what you have right?) xforce headers are OK. Also if you have a DC4, don't be expecting 10kw gains.