Or get mandrel bent ones that are suited to your engine and what you want and it will go faster?

Or get mandrel bent ones that are suited to your engine and what you want and it will go faster?[/quote]


When they start making extractors for skateboards i may value your opinion until then hahaha

When they start making extractors for skateboards i may value your opinion until then hahaha[/quote]
Mandrel bends on a stock to lightly modded motor is rice talk.

Must have taken a lot of thought to put that into words.

It wasn't an opinon either. Do you even have any idea how an exhaust system works or how headers are designed apart from being able to tell the difference between a mandrel and press bend?

Mandrel bends on a stock to lightly modded motor is rice talk.[/quote]

HAHA. I think what you're trying to say is its not worth paying for a system with mandrel bends on a stock or lightly modded engine, which is probably true seeing as I would assume most off the shelf mandrel bent manifolds would be designed for gains in mid-upper rpm. A properly designed mandrel bent system for what you want (ie low to midrange torque) with longer thinner primaries will outperform a likewise designed press bent manifold though.

press bends have no benifit full stop. they are cheaper to manufacture ie. factory items. smaller inside diameter pipes means gas velocity is faster. mandrell bent extractors will have bigger inside diameters meaning lower gas velocity but will flow more and be benificial on modified motors rather than having resticteive systems.. also press bends vary the diametres of the pipes meaning the gas velocities fluctuate. my motor is fairly stock and i have mandrel bent extractors and they made a huge difference all over the rpm range. they are a 4 into 2 into 1 or "tri y" design and non tuned length and not overly big inside diametre and primary lengths are fairly long, it is a good design for low rpm to mid range torque for something not heavily worked but it helps in top end as it breaths much better than the stock header

Yep. The only time press bends will show better results is if your exhaust gas velocity is too low in the first place (ie oversized pipes) but mandrel bent, correctly sized pipes will give better results than this.

Got the quotes mixed up there pal, and yes mandrel bends on a stock motor is rice talk- that is my point exactly, thanks for backing me up

Mandrel bends on a stock to lightly modded motor is rice talk.[/quote]
You my friend are a dumbass- i didnt even say that quote about mandrel bent skidder did.
Its like dealing with retards around here- you are trying to pull the piss out of me with some one elses quote you idiot.
If your gonna try to prove me wrong dont make yourself look like a dumbass in the process.

You my friend are a dumbass- i didnt even say that quote about mandrel bent skidder did.
Its like dealing with retards around here- you are trying to pull the piss out of me with some one elses quote you idiot.
If your gonna try to prove me wrong dont make yourself look like a dumbass in the process.[/quote]
It wasn't me that set the quote like that it was the way site set it up. I didn't do a post preview. I was agreeing with you.
If you want to call me names take it to PM and stop clogging up the thread with s**t.
BTW What the f**k is wrong with you have you got multiple personalities.

I've actually had an I6 for over 10 years now but before that I did have a V8 Commondung which started out as 4.2 with 3spd Auto and ended up as a worked 5.0 with 4 spd Manual.

When i did the exhaust on that it was when it was 4.2 litre Auto and driven by the fact that it wouldn't go over about 140kph. I took it to a small workshop run by this old guy who had his own dyno machine out back. He put the car on this dyno and we found fuel spewing back out the carby - severe exhaust restiction was the diagnosis.

So... - I made a booking at an exhaust place for first thing on a Saturday morning - and on the Friday afternoon got under the car and hacksawed off the exhaust on each side under the driver and passenger floorpans - when I took it for a blat around the backroads (I was living at home - which was out in the country - 15 minute drive to town) the performance increase was absolutely breathtaking - the front wheels damned near came off the ground when I stood on it and it flew up to 150 or so (the fastest I was game to go with it - twas a Commondung after all...). The noise was not what I expected either - it sounded bloody lovely to be honest and was only "loud" as such when accelerating gently at lower rpms - once it kicked down and/or the revs were up the volume was actually lower than most performance systems on the street.

So I took it to the exhaust place - passed a cop speed trap on the way - in the mirror two cops walked onto the road and watched me after I passed them - had heart in throat until I reached the workshop. I asked for the biggest pipes they could fit - "will 3.5 inch fit - or twin 2.5?" I asked. They gave me the full "2.5 single is enough" brainwashing treatment so I drove away with a "straight thru" 2.5 single system and extractors. Power was maybe 3/4 what I had been experiencing with the cutoff pipes at best - I went back to them but they s**t me again and sent me away thinking there must be something wrong with my engine (what can I say, I was an impressionable 19 y.o.) - took a few days for me to realise that looking at the situation scientifically, the EVIDENCE indicated that my engine LIKED having F-ck all restriction... But I left it all as it was and so life went on.

Several years later I tried to get a twin 2.0 system put on my XF 4.1 and again allowed myself to be beaten down to a single 2.5 system. Then a couple of years later I was having a high flow cat fitted at some exhaust place (not either of the two I'd dealt with before) and while waiting, a conversation struck up at the counter between the guy in charge and a couple of blokes booking in a V8 Commondung about 3 inch systems. The exhaust guy was saying that for many years he had councelled probably 100's of guys about going with single 2.5 systems - then one day they had a guy come in who would NOT be swayed and they reluctantly fitted a 3 inch system - "and bugger me if it didn't work a ****ing treat!! - now we fit 3 inch to V8's as standard".

SO.... make of that what you will...

haha what a story

Yep I did, but what I have contributed so far has managed to be technically relevant and correct, instead of trying to pick at an accidental error or making statements implying a press bend is better than a mandrel bend because you found one example of press bent headers that happened to have better design for your engine than the mandrel bent ones you used. Go figure.


And Greenmachine, you will find a lot of exhaust fitters will recommend whatever they believe from their experience to be the best based on only a very generel knowledge of the physics behind it (after all generally their jobs aren't based on the intricate design of performance systems, and those that have that knowledge don't work at your average exhaust place). It's like the arguement of 3in v 2.5in with the i6's for which many just say straight up that 2.5 is all that is needed regardless of engine specifications or what it is used for.

Quite true,...

What is all comes down to is that excessive scavenging thru the exhaust system is exactly the same as restricting your intake.... - think about that.... - so within the framework that you don't want any significant backpressure but you also don't want negative I really think a too clean 2.5 system (this is including the extractors / headers) on a 4 to 5 litre engine - number of cylinders immaterial - can be seriously robbing performance and this will be proportional to intake setup in that the less optimised / more stock the intake / cam are, the more profound the negative effect. This also accounts for those situations where people say "my new press bent extractors perform better than the old mandrel bent ones did" etc. - I think in those case it could well be a matter of the reduced flow helping to correct excessive scavenging.

In short I think the bigger the system the safer as far as staying out of the situation of having too GOOD a flow - else you'd need to be considering - for example - in the case of a clean, straight thru 2.5 mandrel bent system - possibly leaving the stock manifolds on so as to limit the scavenging effect....