Outer Limits 4x4 Board

Can they sell me the versions for an auto 1300 sierra? apparently these ones are only for a manual

They do look quite nice though.

Steve.

has anyone used these?
i will be up for a new zaust system soon - got quoted $750 inc fitting. $500 if i provided the extractors myself.
does this sound like a good price?

I just got a system put on my Zook. $200 for extractors, $140 for the rest of the system, Cat was ok so no need for replacement. Otherwise that would have been another $300. So if that quote includes a new high flow cat and high flow muffler, it's probably ok. Otherwise you're getting stooged.

whats the best size for a stock 1.3 , 2 inch ?

Best size I would think is 1 3/4" unless you plan to do more to the engine. I went for 2" because I intend on supercharging in the very near future.

WasabiPimpNinja wrote:Best size I would think is 1 3/4" unless you plan to do more to the engine. I went for 2" because I intend on supercharging in the very near future.

oh ok thanks.

did u notice any loss in power goin to the 2 inch ? with the stock 1.3 ? how does it sound ?

No powerloss. Infact noticed quite a gain, but that's because I went from a cracked stock exhaust manifold and stock system to extractors etc. The power loss between 1 3/4" and 2" would be negligable I'm thinking, but all of it would be down low where you need it. You wouldn't be creating the back pressure needed and the engine suffers because of it.

The noise, well it sounds like a fart really. I guess it's better than the asthmatic fart that it sounded like before. I've only ever heard 3 exhausts that sounded good. One was on a $500k race Porsche, one was an Audi A8 Pace car at the 2002 Barbagello V8 Super Car Round, and the other was on my mates AUII XR8 ute, sounded great but was inefficient as all hell. If you want noise, just put a tip on it. I dont care what mine sounds like so I didnt bother

WasabiPimpNinja wrote: You wouldn't be creating the back pressure needed and the engine suffers because of it.

Please explain why you think backpressure is needed?

Sounds like a set up for a smack down
Peter.

As far as I'm aware, a certain amount of back pressure is used to help the cylinders back down once they reach TDC. Back pressure is not really needed, as proved by starting an engine without any exhaust manifold at all. But with the correct amount of pressure it should run better.

I know you are going to say "But when it's at TDC, atleast one of the other cylinders will be on the power stroke and that's easily enough to keep the rotation". This is true, but a properly tuned exhaust, with correct amount of back pressure, should run an engine with more efficiency and power than an engine with no back pressure.

This is what I've been told by quite a few people and makes sense to me.

If you can prove otherwise I'll happily listen

*Attempts to dodge said set up *

cjdeane10 wrote:has anyone used these?
i will be up for a new zaust system soon - got quoted $750 inc fitting. $500 if i provided the extractors myself.
does this sound like a good price?

Sounds expensive to me. mine cost 200 from extractors back in perth.

Extractors look ok. u may want to try get a set of wildcat ones from mettlams exhaust in midland. My vit ones cost me 180 from there

Nic

Yeah the quote was from Suzi-store in Midland... they arent the cheapest, so yeah, i am probably getting stooged.

But the crappy, original system should get me over the pits - i just bought a $5 chrome tip to cover up the old rusted out one!

(p.s. i am dreaming at the moment as Rego is the main thing i need - zaust will come later).

how much would be custom extractors .... soon going to putting a exhaust system in but i want it tucked up as possible

ofr57 wrote:how much would be custom extractors .... soon going to putting a exhaust system in but i want it tucked up as possible

Shouldnt need custom extractors but yeh when u get the zaust done, get them to tuck it up much as possible. mine is and is great, not had any dramas with it. all above the chassis rail.

This is not really a smack down but I see so often someone saying how you need some backpressure or it will lose power. Normally it comes from them spouting what someone else has said who is just repeating it from someone else etc. etc.

Weighty books are written on this subject by far more knowledgeable people than me but basically an engine is just a pump. How many pumps do you know of that need back pressure to run at their best? What happens is that when people use too large a dia. pipe for the application they do lose power but it is not from removing back pressure. Back pressure is limiting your potential power. What happens is that the exhaust gases cool down and lose their velocity and cylinder scavenging is reduced. What you are aiming for is to find the point where back pressure has been relieved but the gas velocity hasn't dropped and the scavenging waves are timed correctly. Headers or extractors are another area where there is a common misconception that 4 into 1 equal length headers are no good for low down performance. This is not correct, although the Tri-Y design is meant to be better as an all around design for spread of power and bottom to mid-range it is not always the case. Poorly designed Tri-Y's can be outperformed by well matched 4 to 1's. Just because somebody has designed and is selling it as ideal for your car doesn't mean it is the best option for your car. Most people will just buy whatever is the cheapest available. Things to consider are the header pipe lengths and dia., the collector length and dia., the collector cone etc. Low rpm power though is not really subject to scavenging as you can get multiple waves during the same stroke but more based around compression and the cam/s control of the valve timing. There are a lot more factors at play here than just those that I have mentioned but it gives you a little more insight into what is going on.

save your money there is minimal power gains to by fitting extractors, just go the 1 3/4" system and spend your $200 on something else for your car you will actually notice like skimming the head or getting a set of extended shackles

Not sure on the "performance" side but in my swb rag top I had extractors into 2" with "sports" muffler. At highway speeds I would wear ear plugs and still pull up with ringing ears. Now in my lwb rag top I have extractors into 1 3/4 with a quiet free flowin muffler. The weber intake easily roars loader then the exhuast.
Just my experience and something to think about.
Nik

hey guys just wondering what your input is on what the biggest/best size exhaust would be for a mighty 1.0L 970cc of pure grunt. Was thinking og going 2" but not so sure now.
cheers.

so extractors dont really giv u that much power increase? i just had a 2 1/4" exhaust put on my vitara and the change is amazing. well it sounds cool and definatley feels like a slightly more respnsive vehicle. i thought i could add to that by fitting sum extractors is this not the case?

The faster you get the air in and the faster you get it out = power at the wheels .
un unrestricted intake plus a good flowing exhaust can achieve more power , but backpressure is important in a normally aspirated situation as explained in cj's post , heres a better way to explain it it laymans terms rather than technical jargon....

at some stage of the cycle you will have what is called valve overlap , this is when the exhaust valve is still partially open and the intake valve is starting to open to suck in a fresh charge of air and fuel , without any backpressure you will lose some of the air/fuel charge out through the exhaust valve decreasing the amount/volume of fuel/air that can be turned into usable power.

with forced induction , eg turbo or supercharging , this isnt an issue so you can go as big as you want.

I actually lost .5 of a second on the 1/4 mile from going too large of an exhaust system.

in a sierra 1 3/4 is the maximum size you would want to go.

Didn't know there was low end torque and back pressure in a 1.3 suzi.

i think that by fitting a 1 3/4" for a standard car or 2" exhaust for worked motor you get alot more of a gain than by fitting extractors, mind you if the exhaust if press bent then go 2" for a standard car and spend your $200 on somethig else. on my 1600 i would say extractors gave me
1-2 bhp tops

OK, can't help my self.
If the pipe at the end of the extractors is 1 3/4. Why would you go to a 2" pipe after that ?
Going bigger after the Extractors will slow the gases in the pipe as they expand to fill the larger pipe. Keeping it the same size all the way through maintains the velocity (speed) of the gasses, thus expelling it fast/better.
That all said, unless you use mandrel bends. 2"with crush bends, would probably work better over a crushed bent 1 3/4 system. But you get the idear.

Once you get past the extractors and the cat assuming that they are matched to your engine setup it doesn't really matter although there is a theory that you could step down the size as the gas cools to try and keep the velocity up.

The 1.3 and 1.6 need attending to on both the intake and exhaust for maximum benefits and getting the right cam in the middle for your needs is even better. Doing half a job will not give the full benefit.

It is my understanding too that past the collector on a set of extractors or down stream of the exhaust turbine of a turbo engine, you can't be too big.

the scavenging effect is a result of extractor design. Once past the collector it's all over, although collector design and diameter is important.

Bear in mind though that as pipe diameter increases, so does noise, fitment issues and weight, as an example, 2.25 and 2.5" exhaust tube is heavier wall than 2" and much heavier for the same length.

Steve.

put this in the bible I recon

Definitely good discussion going on here So has anyone bought a set of the MPH (Maximum Performance Headers) off Ebay yet? Price is good, just looking for feedback, if any?

cj wrote:basically an engine is just a pump. How many pumps do you know of that need back pressure to run at their best?

All of them, you know shit about pumps. All pumps have what is called a pump curve, too much flow not enough pressure = bad, too much pressure not enough flow = bad.

Yes engines like a small amount of back pressure to prevent valve issues.

Gwagensteve wrote:It is my understanding too that past the collector on a set of extractors or down stream of the exhaust turbine of a turbo engine, you can't be too big.

the scavenging effect is a result of extractor design. Once past the collector it's all over, although collector design and diameter is important.

Bear in mind though that as pipe diameter increases, so does noise, fitment issues and weight, as an example, 2.25 and 2.5" exhaust tube is heavier wall than 2" and much heavier for the same length.

Steve.

To an extent yes but the sudden drop in airflow when going from the collector to a too large pipe could directly effect the airflow of the air inside the secondaries/primaries.

But in the end nothing sounds worse than an exhaust that is too big.