now i was led to believe that the exhaust piping for the 3.5ltr magna/veradas hav piping that is 2.5" is this correct?
or is it different?
also any1 know the piping size for the 3ltr?

nope the 3.5 is just shy of 2.5 inches. it is quite good but kinda cheap and corrugated.

Yep, the 3.5L system is about 2.4" in the wide in the straight sections, but gets down to about 2.25" in the tight bends.

As far as factory exhausts go, it's actually quite impressive (apart from the horrible power-sapping rear muffler of the execs/veradas).

the factory size of the magna piping on the 3.5L is 2-3/8", so 1/8" smaller than 2.5"

sorry to drum up an topic but what is the best size piping for a 3ltr??? i have 2 sizes in my garage 2.5 and 2 1/4, 304 stainless steel, but which one to use?

2.5". All Magna exhausts are the same size, so by using 2 1/4" when you've already got 2 3/8" will restrict things.

I will be making a 2 1/2 inch on mine. 2 inch is what i found on my car but it had been replaced. No bigger though.

unless forced induction, not much point in going over 2 & 3/8 inch standard pipe size. Not much point in getting carried away with fancy headers either - you will derive minimal benefit on any exhaust manifold that occupies a greater volume than the swept volume of the engine.

Well i will se a diff going to 2 1/2in. cause i have 2in ATM for some reason on my 3ltr:nuts:

Oh and i felt a difference just changing the headers to 2in and a better collector. with a 2in exhaust with the restricted tri flow muffler? What gives?

Not much point in getting carried away with fancy headers either - you will derive minimal benefit on any exhaust manifold that occupies a greater volume than the swept volume of the engine.

Uh mate, how did you arrive at that conclusion? What does the volume of an exhaust manifold have to do with the volume of a motor? How does such an absurd blanket statement help anyone?

Have you seen the the type of extactors used on race cars with small n/a motors? There is PLENTY to be gained in having well-designed extractors.

Varying the length and diamater of the runners in conjunction with a properly deisgned exhaust can alter a motor's properties enormously, why do you think so much effort goes into RnD of headers on racecars, and even street cars? Companies like Pacemaker do a huge amount of RnD on their designs.

Extractor design is main component of a car's exhaust, the job of the rest of the system after the collector is to vent with minimum backpressure, to avoid interfering with scavenging (e.g too slow gas velocity = backpressure = scavenging degrades)

I agree with the first thing you said, really unless you are planning on FI or further n/a mods like plenum cams and piggyback, it's probably better just to leave the stock system in place, and just get a quality rear muffler for a nice note.

The difference with a 2.5" exhaust by itself is tangible, but not huge. Basically a little boost in the midrange, and neglible gain in peak power (although it does extend the powerband somewhat, it drops off a little less sharply). You gain very little in peak power because a) the stock system is relatively good and b) the factory camshaft is the main limiting factor for top-end breathing.

Uh mate, how did you arrive at that conclusion? What does the volume of an exhaust manifold have to do with the volume of a motor? How does such an absurd blanket statement help anyone?

Have you seen the the type of extactors used on race cars with small n/a motors? There is PLENTY to be gained in having well-designed extractors.

Varying the length and diamater of the runners in conjunction with a properly deisgned exhaust can alter a motor's properties enormously, why do you think so much effort goes into RnD of headers on racecars, and even street cars? Companies like Pacemaker do a huge amount of RnD on their designs.
Leave him alone man - he's busy spending $25k to make a 13 sec AWD Magna. :badgrin:

Hm.. i thought it was 2.25" all the way. (except of bends) I saw the difference between 2.5" and stock and i would have bet my money on 2.25"

But oh well

basically dont really care about power increase (as i can see difference being SFA) just wanted to know as the 2.5 inch stainless i have is polished and the 2 1/4 isn't and same goes for the mandrel bends i have, didnt want to put an oversized pipe on as i had a camry which i put 2.5 on and it took power away from it.

So you're saying that I could very well just take off the crappy exec muffler on my TF, replace it with a VRX muffler (or the lukey equivalent) and essentially have the same piping all the way through of the VRX/Sports magnas (minus any difference in the extractors).

Uh mate, how did you arrive at that conclusion? What does the volume of an exhaust manifold have to do with the volume of a motor? How does such an absurd blanket statement help anyone?

Have you seen the the type of extactors used on race cars with small n/a motors? There is PLENTY to be gained in having well-designed extractors.

Varying the length and diamater of the runners in conjunction with a properly deisgned exhaust can alter a motor's properties enormously, why do you think so much effort goes into RnD of headers on racecars, and even street cars? Companies like Pacemaker do a huge amount of RnD on their designs.

Extractor design is main component of a car's exhaust, the job of the rest of the system after the collector is to vent with minimum backpressure, to avoid interfering with scavenging (e.g too slow gas velocity = backpressure = scavenging degrades)

I agree with the first thing you said, really unless you are planning on FI or further n/a mods like plenum cams and piggyback, it's probably better just to leave the stock system in place, and just get a quality rear muffler for a nice note.

The difference with a 2.5" exhaust by itself is tangible, but not huge. Basically a little boost in the midrange, and neglible gain in peak power (although it does extend the powerband somewhat, it drops off a little less sharply). You gain very little in peak power because a) the stock system is relatively good and b) the factory camshaft is the main limiting factor for top-end breathing.


so you are saying that on an unmodified engine the exhaust volume should exceed the swept volume of the engine - and this will give a signficant improvement in the engine performance?

its not a blanket statement, nor is it its a basic tenet of mass flows in an I/C engine. I won't go any further since my primary discipline is not mechanical engineering, and I was probably at the pub during most of those lectures anyway.

And i disagree that research necessarily produces a good product.

an ideal system will provide a surface and path that is conducive to laminar flow - not turbulent flow. every bend and every perturbation in the surface provides an opportunity to set up eddies that stuff up your fluid (gas) velocity.

I don't see a lot of sophistication in this exhaust header design, and I'd guess this engine makes a bit of power.

Dragsters are the exception. The best exhaust system is none - that's been said a million times. But when you're talking about production cars that have to pass stringent testing for noise and pollution it's a different story.

I already think you're a complete tosser tbb - but this just stiffens my opinon.


And i disagree that research necessarily produces a good product.

I guess we should just stop trying to cure cancer cause we'll never get there. Stop trying to bore into the earths core for renewable energy - waste of time! :roll:

I don't see a lot of sophistication in this exhaust header design, and I'd guess this engine makes a bit of power.
that's because you aren't looking close enough. you see that small amount of exhaust that they do have? well they would've put a lot of time and money into getting the length of them just right. as on a road car the length of the primaries can alter performance greatly.

so you are saying that on an unmodified engine the exhaust volume should exceed the swept volume of the engine - and this will give a signficant improvement in the engine performance?



No, that would be pointless blanket statement.

I fail to see the relevence of exhaust volume to swept volume of engine, it's not like you just apply some magical fudge formula, and the headers design them themselves.

As I've said, header design is all about the diamater, length and arrangement of the runners. You decide on the specifics of these variables depending on the goal intended and the motor in question. There are NUMEROUS factors to consider in RnD for headers, specific to what the goal is (e.g where you want the most efficiency, the peak volume of gas you must flow, volume/density/velocity of each exhaust pulse etc).


I don't see a lot of sophistication in this exhaust header design, and I'd guess this engine makes a bit of power.

And you'll likely ind plenty of RnD went into those, to determine the optimum runner diameter, length etc. Just because they look simple doesn't mean they are. Although perhaps the design is simpler compared to a street car, as you don't need to contend with trying to make a compromise over a broad reve range etc. Top fuelers use a lock-up clutch and the revs are basically constant the whole way down the strip, so pretty much it's just all about making maximum power in an extremely narrow powerband.

Basically after the headers, the the rest of a well-desgined exhaust is just there to vent gas while creating the least amount of backpressure as possible. You don't gain anything after the headers, it's just about minimising the losses. Which is why race cars like top fulers do away with it, as they aren't required to have an exhaust.

However the headers are there because they play a vital role in how efficiently you can evacuate the cylinders, and therefore how much power you make (along with many other factors of course).



And i disagree that research necessarily produces a good product.


That's true, sometimes research doesn't deliver what's expected. But in the case of exhaust design, it's pretty obvious we have it working fairly well (even if alot of it may have just been trial and error over the years).

Like it or not, mega-budget racing teams and large reputable aftermarket companies go to considerable effor/cost to get it right, they don't just tack a random bunch of pipes onto the exhaust sid of the head(s) and assume it doesn't matter.

well the research into the headers that went on my old 6G72 triton materialised a 1kW gain.

well the research into the headers that went on my old 6G72 triton materialised a 1kW gain.

I'd be very surprised if those headers where researched and designed by a multi million dollar race team. lol

There are plenty poorly designed off the shelf "extractors" that will overall perform worse then the standard cast items.

well the research into the headers that went on my old 6G72 triton materialised a 1kW gain.

What headers? were they properly designed equal length ones, or just the wanky type for show? Is that a 1kw gain in peakpower, or wherever the most gains were?

Even the same dyno varies a little from day to day, so you coulda just got a lower reading for some other reason.

In our magnas I don't think there's much gain in peak power, it's all in the midrange. This is because the limiting factor for top-end breathing in our motors is mostly the factory cam profile. Do a cam swap and it's a different story, you'll see gains in the top end from breathing mods.

anyway the original poster was after advice, and there is a risk of this deteriorating into a discussion on heat engine behaviour *yawn*

I think we probably all agree that the best value exhaust bolt-on for a standard 6G74 that has to comply with noise and pollution is a Lukey muffler equivalent in specification to the type fitted on the VRX, anything beyond this provides diminishing returns for the capital involved.

btw standard bump sticks are quite suitable for the duty on the s/c set-up (of course the engine still lacks the upper range "breathing" required to make it a great engine)

So you're saying that I could very well just take off the crappy exec muffler on my TF, replace it with a VRX muffler (or the lukey equivalent) and essentially have the same piping all the way through of the VRX/Sports magnas (minus any difference in the extractors).

that would be the best value mod you could do.

and as has been said many times on this forum, there is nothing wrong with the standard exhaust manifold.

2.5". All Magna exhausts are the same size...
No it is not.


well the research into the headers that went on my old 6G72 triton materialised a 1kW gain.
I'd rather headers with a 1kW gain at peak power and 20kW gain at point of peak torque than something that gains 10kW at peak power and stuff all at peak torque.

Why is tbb banned?

Maybe he upset someone.

One thing that is definantly crap is the collectors that join the two banks into the one pipe before the flex-pipe. That is on 2nd gens, apparently the 3L sports has merged collectors rather than a T section which would grately improve flow - it doesn't take an idiot to see that.


And like others have said, extractors don't MAKE a lot of power but shift your power range into more useable areas for "sporty" drivers.

Why is tbb banned?

Because he's a donk (attacked ash3 in that huge thread).

Going to miss the progress of his 7 second magna.

Because he's a donk (attacked ash3 in that huge thread).

Going to miss the progress of his 7 second magna.
Oh I didn't read that thread - too long. :doubt: No doubt once his AWD is the fastest dragster on the planet running easily into the 3 second bracket on pump fuel we can unban him.

Thanks for answering my question. :)

Oh I didn't read that thread - too long. :doubt: No doubt once his AWD is the fastest dragster on the planet running easily into the 3 second bracket on pump fuel we can unban him.

Thanks for answering my question. :)

It's not the same when he can't defend himself with crappy reasoning :cry:

these pics will show what i did to improve the notorius T interection.....on the 2nd gen.

Hey all, i have been reading a couple of searched threads on exhausts. Though i would hijack this one for a little.

I have been looking at upgrading my TL stock exhaust with either a Lukey or a Redback, i am in WA. So far i have settled for RPW Lukey exhaust. However, i hear talk of a high flowing cat? i am a n00blar with this stuff, can someone tell me what this means? i have seen the inside of an exhaust is has several pipes going back and forth, does this just mean it has a single pipe like a hotdog?

How much better is it? because i have seen Mohits rada redback exhaust and it has the round design (hotdog). Could the redback be a little better than the lukey or is it just a case of '6 in one hand, half a dozen in the other'?

I assume when it mentions bolt on, it just uses the stock cat, i.e. a high flowing cat is something else that i have to buy on top of the exhaust system.

I am planning to also get a pod filter and race extractors put on at the same time.

Bah, i grew up and followed technology and computing, only started getting into cars when i hit this forum! Thanks AMC :P

EDIT: just had a little read of this thread - http://www.aussiemagna.com/forums/showthread.php?t=52439&highlight=lukey+exhaust
-it highlights the lukey
-where is the cat located? i assume it comes off the extractors

BirchY

the cat is a sort of oval shaped box located at the end of the headers (after the flex pipes). it will have flanges at both ends of it. if you look under the car it will be about in line with the pasengers feet.

a highflow cat is just a cat that has a higher flow rate.