[Heideisadog]

Hey hey!
Just wondering what exhaust set up you sierra drivers have.
I'm running the stock exhaust but I just took it off to have a look and clean it and I have noticed some holes. Not to sure if they affect performance at all... But I'll add a photo to see what you think.

Anyway, I think it's time for a replacement and I have a few question... Are extractors useful or what are they good for? Should I get a exhaust kit online somewhere and could you recommend me any? Or should I take the car to a exhaust shop and get one made? Maybe there are some other options?

Thanks,
Thomas


Bad photo but the holes look like spot welds that are coming off...I think it's just in the guard, not too sure. Don't know anything about this exhaust system.

[sideways]

This dyno graph shows a 2" exhaust and extractors is proven to give a roughly 20% gain in on a 1.3l. That's a VERY large gain but with a shitty old stock exhaust system that's probably got half collapsed mufflers and the errr, easy to manufacture design of a 1.3l manifold it's certainly plausible.



Graph from this thread. viewtopic.php?f=14&t=29378

Extractors are cheap off eBay and an exhaust shop should be able to fit them and make a basic press bent 2" exhaust for around $400, depending on what you want (eg, how quiet you want it to be/how you want it to sound).

Make it absolutely clear to them that you use the car off road and thus don't want any of the exhaust comprising your clearance or in venerable positions.

[alien]

i'd also make them aware that you're not chasing a "sports" exhaust - ie: keep it quiet.

There's nothing worse than someone trying to spot you and you can't hear what they're saying over your own engine =)

[MacDaddy]

alien wrote:

i'd also make them aware that you're not chasing a "sports" exhaust - ie: keep it quiet.

There's nothing worse than someone trying to spot you and you can't hear what they're saying over your own engine =)

But a noisy exhaust is cool !
I say get a sports system, with hiflo cat, it doesnt have to be real noisy, but if you are going to get a proper system done, then at least get some noise... if you are going to get a larger freer flowing system done, then quiet kinda defeats the purpose, to get it quiet, you have to have a baffled muffler, which adds restriction, just get a medium noise muffler, its better than a quiet one...

[alien]

as an example - my system is pretty quiet, wouldn't you agree mark?

Mines:
Extractors -> 2" pipe -> 2" Cat (Commodore) -> 2" pipe -> Muffler with 2" openings -> 2" pipe.

ie: the muffler is designed for a 2" system... its actually quite large, bigger than stock, and still tucks away with the chassis rail.

[Heideisadog]

Wow 20% that's actually stacks! I'll go talk to an exhaust shop this weekend!
I wouldn't mind something that sounds good. But it's all personal preference I guess!

Thanks for all the help! Will look into it!

Can anyone recommend me some extractors? There are lots online and I heard some need massaging to fit...
What extractors do you run?

[JrZook]

MacDaddy wrote:

to get it quiet, you have to have a baffled muffler, which adds restriction

Biggest generalization ever. Technology has progressed since the 1960's Mac

[droverdave]

Hah i knew my exhaust made a difference! there is at least some sort of proof.r

The issue i had on my home made exhuast is that under a sierra you are quite limited in space. Im not running a cat on mine (pre 86), and i was onyl able to fit 1 resonator and 1 muffler. and its still a bit loud for me on the highway (the drone! arrgh). but it is better than the standard exhaust (which i think only had one muffler?)

I just bought a set of gineric looking extractors off some guy on here for like $40. I would be looking for a second hand set for cheap, over buy a brand new set. for what its worth mine look like this

http://galleryplus.ebayimg.com/ws/web/1 ... 0x1000.jpg

[alien]

droverdave wrote:

(the drone! arrgh).

This guy knows =)

[MacDaddy]

JrZook wrote:

MacDaddy wrote:

to get it quiet, you have to have a baffled muffler, which adds restriction

Biggest generalization ever. Technology has progressed since the 1960's Mac

Yes i agree, but, compare a quiet baffled muffler, to a noisy straight thru muffler, there is more restriction... i cant see the point of putting extractors on with bigger exhaust, and then getting a quiet muffler/restriction, but thats just me, each to their own... i like less restriction, which equals noisy, which i like...


Edit : And here is a cheap set of ebay extractors, i got my 89 Vit extractors from him, and they are good and well made, and with free postage, they come in two outlet sizes -
2in
http://www.ebay.com.au/itm/Suzuki-Sierr ... 1273009041

2 1/4in
http://www.ebay.com.au/itm/SUZUKI-SIERR ... 417d2d8391

[alien]

reallllly quick google search, and its motorbike related, but given we have small engines i'd be willing to accept these ideas:
http://www.vmaxoutlaw.com/tech/exhaust.htm

Its not focused as much on noise as performance, but the theory is sound (lol bad pun sorry).

I'm no engineer, but I don't believe that a loud exhaust will necessarily be more free flowing than a quiet one still... i mean, look at a didgeridoo -bit of pipe that you can just blow through, but if you hit the right resonance it makes a hell of a racket - either way its pushing the same air through though.

[Marko_SJ]

alien wrote:

reallllly quick google search, and its motorbike related, but given we have small engines i'd be willing to accept these ideas:
http://www.vmaxoutlaw.com/tech/exhaust.htm

Its not focused as much on noise as performance, but the theory is sound (lol bad pun sorry).

I'm no engineer, but I don't believe that a loud exhaust will necessarily be more free flowing than a quiet one still... i mean, look at a didgeridoo -bit of pipe that you can just blow through, but if you hit the right resonance it makes a hell of a racket - either way its pushing the same air through though.

Lots of things to think about here. The first is that the vmax looks to have almost 4 times the hp of a sierra and looks to be two v twins joined.

A baffled muffler is a very rare sight on a off road motorcycle, which are usually tuned for maximum power and light weight, they also often need to be quiet these days too.

I also know that a well maintained and designed glass pack muffler can be effective and still not rob power.

For all out power, a straight through design or even no muffler is best.

Whether its legal / socially acceptable / practical on your road going machine depends on you and the law however.

I agree with the last point of your article, which makes the opposite point to what you are making

Quote:

In a nutshell, the biggest decision for power is the diameter of the pipe and then the length. Choose these based on where you want your power band. Tuning the exhaust pulses with a 4-1 or 4-2-1 then should be done with the idea to compliment your first choice....and of course always have a high-flow muffler.

Mac is right, less restriction is better. Whether or not you want to be noisy is up to you. I don't really want a noisy zook either.

[SierraDan]

I have a 2" exhaust, straight pipe through the cat, and a triple flow muffler. Not obnoxiously loud but has a cool sound.
Cost $250 at an exhaust place.

[Pooke]

Why do people bother with a cat in the first place? Most engines seem to go alot better without them there

[Gwagensteve]

Because they are a legal requirement. The fines are steep for not having one.

Steve.

[alien]

there was also evidence somewhere to suggest that cars infact run better WITH them providing they're in working order - i can't recall exactly but i believe it was to do with the temperature / density of the air / flow etc... i can't be bothered trying to find it so get your google on =)

[droverdave]

I cant see how it can make an engine any better (apart from the smell), but the correct size for the application isn't going to make anything noticeably worse.

[Heideisadog]

Well anyway, I'm going to hopefully take it to a exhaust shop on Wednesday and see what they recommend and get a rough quote!
I'll post up here of what they say!

Thanks fellas!

[zedboy]

What are peoples thoughts on 2" or 2.25" I measured mine at the tailpipe on the weekend appears to be only 35mm which is 1"3/8'

Also looking at replacing mine from extractors to the rear and would like to continue the same diameter from the extractors right through.

Heideisadog wrote:

Well anyway, I'm going to hopefully take it to a exhaust shop on Wednesday and see what they recommend and get a rough quote!
I'll post up here of what they say!

Thanks fellas!

[alien]

2" is a super common size (commodore & falcon) so cat converters and mufflers are plentiful in 2". Not sure if 2.25" is the same? Don't forget .25" = about 6mm... not a massive difference really, go with whichever is cheaper at the time =)

[droverdave]

It's only 1.3L. 2" is heaps.

my wrx makes 200hp or whatever and its only got a 2" exhaust (factory exhaust)

Your and my 1.3L woudl be lucky to make 60hp, 2" will be heaps. And going too big can be more detromental than going too small....

[JrZook]

alien wrote:

Don't forget .25" = about 6mm... not a massive difference really, go with whichever is cheaper at the time =)

Basic math says that 0.25" larger then 2" is a 12.5% increase in diameter. Since flow is related to the cross sectional area it has increased by 26%. I would call that only 6mm increase a significant difference in flow

Like everyone else has suggested, just go a common size like 2". Its only a low output, low capacity engine.

[alien]

Yeah i thought of that in my head about 30mins after i posted it, that down the length of the pipe its actually quite an increase in volume.

When i had a 1.3L engine still, i ran extractors and 1.5" pipe / cat / muffler and it was brilliant.

[BigRay]

My Jimny is getting a 1"3/4' exhaust system with two straight through resonators and a high flow cat installed tomorrow. Am hoping it will improve my really loud and tired exhaust system.

[MacDaddy]

I think 2in is to big for a 1.3L, its only a short length of pipe, exhaust gas velocity and scavenging will be reduced, with no gains until high RPM's... the biggest i would go is 1 7/8in... as Bigray said that he is getting on his Jimny, 1 3/4in would be perfect for a 1.3L, it will increase and maintain power gains over a wider RPM range... in my opinion...

[alien]

lol 1 7/8 vs 2" =)

[BigRay]

Got my new system on today. Very happy! Engine doesn't scream anymore, no more headaches and more torque with a nice sporty note!

[MacDaddy]

alien wrote:

lol 1 7/8 vs 2" =)

If my figuring is correct, and we go by JrZooks's facts and figures, dropping 1/8in under 2in to 1 7/8in, is a decrease of 6.25%, and a decrease in cross sectional area by 13%, so it does make a difference...

BigRay wrote:

Got my new system on today. Very happy! Engine doesn't scream anymore, no more headaches and more torque with a nice sporty note!

Awesome... when you say engine doesnt scream anymore, do you mean you dont have to rev it as much now to get the same power output ?
More torque is always better... Yeah, gotta love a more " Sporty " exhaust note...

[jdk81]

Touching on the simple maths
Flow in pipes is approximately related to the diameter to the power of 4, so changes in diam we consider slight can become significant.
Yes I know its from the laminar eqn, and the turbulent one is more appropriate diam^4.75 if we can get really picky, but a lot more complicated when including everything else etc

Stock sierra is 1.5"

1 3/4" is 85% increase
1 7/8" is 144% increase
2" is 216%
2 1/4" 406% increase

alien wrote:

lol 1 7/8 vs 2" =)

Don't scoff at the size difference, for all we know it could in fact be the ideal size for the 1.3.

It probably hasnt been tested/trialled etc because most just go with 2".
Very few exhaust mods are dyno tested, and of those that are, the accuracy can easily be affected based on air temp and many other factors.


As to what size exhaust, and the headers and how the seat of the pants dyno and sound output relates proportionately with the lightening of the wallet, this debate is somewhat reoccurring. And Im surprised no one mentioned backpressure

Some previous readings

viewtopic.php?f=5&t=9071
viewtopic.php?f=37&t=35548

BigRay wrote:

Got my new system on today. Very happy! Engine doesn't scream anymore, no more headaches and more torque with a nice sporty note!

Being happy with the outcome obtained is the what matters most

[JrZook]

MacDaddy wrote:

alien wrote:

lol 1 7/8 vs 2" =)

If my figuring is correct, and we go by JrZooks's facts and figures, dropping 1/8in under 2in to 1 7/8in, is a decrease of 6.25%, and a decrease in cross sectional area by 13%, so it does make a difference...

Maths works but in the end its $/performance that wins out. So common sizes FTW.

FYI performance characteristic from exhaust systems are usually dominated by the header/manifold design rather than the diameter of the tuba hanging off it.

Oh and no need for another "back-pressure" argument