[Andygoodbloke]

Hi All
Those with the G13A motors - does anyone run exhaust headers and a larger exhaust?

Do you notice any improvements in power / performance / fuel economy?

I was always taught the better a motor can breath in (snorkel, K&N filter, inlet manifold port) and breath out (exhaust) the more efficient the motor is and the myth of a little back pressure is rubbish, there is usually a point however where under the pressure of your right foot where the increased pressure has to force its way through the exhaust as efficiently as the system will allow, the better it does this the more efficient the system is.

So is it worth going up to 2 inch or what size are people going with to make it work well - after all it is only a 1325cc motor
Are the cheap stainless headers any good?
Are the headers the same ones as a G16A motor?

Thanks Andy
(I am after opinions not arguments)

[sideways]

I fitted extractors and a 2" exhaust to mine and it picked up quite a bit of mid range power, I could go a gear higher up the hill from my house. Top end power was about the same. Before that I had the whole original exhaust and manifold, the muffler was rusted out and the cat was not blocked. From memory, economy was unchanged. I didn't change the jetting or anything.

If you're fitting extractors they need a flex joint otherwise they will crack.

I went 2" because of the availability/cheapness of muffler/cat/pipe/bends compared to 1.75 or 1.5.

No idea about the stainless ones, never seen them.

G16a vitara headers are different to Sierra, probably wont fit... My Sierra now has a G16a and the 1.3l extractors fit fine but needed a bit of port matching because of the larger exhaust ports in the G16a.

[Andygoodbloke]

Thanks Sideways
I asked about the G16A headers as there is a cheap set available
Appreciate your feedback and advice on the flexi join, 2 inch looks like a good size, did you also go for a resonator exhaust? If so how noisy?
Thanks Andy

[sideways]

I fitted an 18" dog leg muffler and a 12" hotdog. Later I deleted the hotdog to make room for a long range tank.

In both cases it was fine for in cab noise, not obtrusive at all. But louder outside the car than I'd like it to be. One day I'll cut the dog leg muffler out and put a triple pass one in. I think at the time I built it I couldn't get a triple pass with the right dimensions.

[Jezzer]

I have steel extractors and a two inch exhaust with an oval muffler. It was in it when I brought the vehicle so can’t say if it has more power than the factory system. I have replaced the muffler and can’t remember the spec but it’s not a full muffler so it has a bit of noise (but not loud)

There is two versions of the G16a the 8 valve and the 16 valve.

The 8 valve ones will fit the g13a (I have gone to a 8 valve G16a and used the same exhaust)

The 16 valve will not as the ports are a different shape

But I think they are shaped a bit differently for the location of the rest of the exhaust pipe. And might have a hole for the 02 sensor.


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[Andygoodbloke]

Thanks Jezzer
If you still have the headers for a G13A / G16A let me know a price for them or the whole system.
Thanks Andy

[Jezzer]

Sorry I wasn’t saying I was selling it. Just saying what is fitted to mine


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[laager]

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[fordem]

I'd say no, they're certainly not what we got - we got cast iron manifold with a flange to the down pipe up above where that wye is - what you have is a very nice long tube tri-y header.

[SPEEDY]

I always put a Webber carby and extractors with a 2" exhaust on all my Sierra's, they made a huge difference.
An exhaust and air intake on a gen 3 ir gen 4 does not give nearly the same performance as it does on an older carby engine.
Engine swaps used to be cheap and easy too, combining all the above and they were real little weapons.
I wish you could simplify a gen 4 like that.

[sideways]

fordem wrote:

I'd say no, they're certainly not what we got - we got cast iron manifold with a flange to the down pipe up above where that wye is - what you have is a very nice long tube tri-y header.

+1 standard is a 4 into 1 cast iron manifold. That said a lot of Sierras have been fitted with extractors like yours pictured due to cracked manifolds being a common problem.

[laager]

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[Sutho]

I have had 2” exhaust and extractors on a G13A, it was great, mid range power was nice and the noise was great for a 17yo, however now 32 and G16b running the same exhaust, even with 2 mufflers it is very loud.
I am looking at adding another hotdog to try and bring it down further.

[Andygoodbloke]

Thank you all for the input
Headers ordered, and a flexi section, once here will get some pipe 2 inch and add a couple of resonator mufflers.
I went for mild steel as I have access to a MIG and not a TIG and could not see any benefit in a stainless steel exhaust system
Thanks Andy

[Sutho]

Yeah, that will be fine mate, I have had the same system since 2011, no issues

[Andygoodbloke]

Headers installed, flexi join behind it, through to a single muffler at the rear but this will get replaced once the funds and wife allow

Sounds a lot better and mid range power has improved.

The snorkel is next.