Exhausts: Noise ='s power :)

[whatsisname]

On Friday arvo I took the car down to Boost Worx to do the usual oil & filter and diff fluid change. While I was there we also did a muffler change (I'd been keen to do it for a while).

I now have a straight-through N1 style muffler with the drift spec angled tip (looks very cool). The original Trust pipework went under the diff with a nasty angle that undoubtedly robbed power. It wasn't a lot of power, but still worth the change. Unfortunately during the dyno runs we discovered that from 6000rpm and up it was getting dangerously lean (13.0:1) Up till 6000 it sits at low 12's.

With a peak of 1.5bar it made 297rwkw at 5500rpm (well before it started to go lean). In fact back to back runs netted 292, 295 and 297rwkw. On Wednesday we're going to check the filter (fairly new - shouldn't be blocked?) the tank pick-up (might be blocked?) and then the pump itself. If need be a new 044 will go in. It is 100% before the fuel rail, as we took off the return line and watched the flow drop to buggery as the revs climbed towards 6000rpm.

I might just crack the 300rwkw mark yet? Shaun kept putting more fuel in up top and it continued to make power (292-295-297). So once the fuel pressure issue is sorted and we can get it back into the low 12's/high 11's at 6400rpm (were it usually makes peak power) it should be interesting.

[Freebaggin]

Shit mate that's alot of grunt anyway, bloody good stuff. 1.6 bar mate, that'll get you there.

Cams will give you another 20 easy.

Anyhow, how does it sound now?

[Steve]

Sorry Matt, but I gotta do this - told you so:p:D

Good to hear, how is off boost and spoolup? Mine came in a lot harder and earlier when I ditched the old exhaust, as well as crisper off boost. What fuel pump are you currently running? Have you consider the Tomei in tank pump? they can be had for pretty cheap these days, only a bit more than the bosch, and they are a straight fit without rooting around.

Come on Matt, give us the full story instead of just teasing:)

[Busky2k]

Hmmm I would have thought pushing 13:1 ratio down to 12 wouldnt get you any more power at all? I reckon 1 more degree of ignition timing at peak power RPM will get you 300rwkw since your so close Otherwise, drop the exhaust from the cat back and try again! Haha j/k

[whatsisname]

Thanks Lach'. Yeah I'd love to do cams mate! But no money for them atm I actually rang your Mobile while I was at BWX, but it went straight to msg bank.

How does it sound? Very very angry! 'Tuff' would be a good description The down side is it's much louder, and therefore attracts more attention. You can't have everything though (without one of those exhaust flap thingy’s).

Yeah yeah Steve But I don’t mind you giving me the ‘I told you so’, ‘cause it was you that convinced me to do the exhaust swap in the first place.

Off-boost and spool haven’t seemed to change that much? On the dyno sheet there’s only a few extra kw in it. Basically, up till ~4000rpm it’s not much different. But from 4,000 to 5,500 (and no doubt till 6,400 once all is ok) it out powers the old system, by upto 20rwkw in some places! The peak gain is only minimal (6rwkw).

I thought I had a 044 (200 lbs/hr), but it may well be a 984 (165lbs/hr) Even the 984 “should” easily handle 300+rwkw. The 910 (130lbs/hr) can cope with 300rwkw. I’m hoping it’s just a clogged strainer that has only just started to show up due to the extra demand.

I hear what your saying Busky, but I watched Shaun opening up the duty cycle and putting more fuel in and it was making MORE power rather than less. The good thing is, it makes high 290’s at just 5,500rpm and that’s with low 12’s A/FR. Peak torque is at ~4,400rpm.

Once we get the pump issue sorted I’ll scan the resulting dyno sheet for all to have a gander. Stay “tuned”

[grepin]

Good work Matt. I have been considering a new zorst for a while. Looks like I have some work to do after my 3 month stink overseas. Back in about 3 weeks. Freebie doing some work as well. Interested to see where mine is at in the cooler weather.

[whatsisname]

Thanks Greg. If you don't mind the extra noise it's well worth it mate.

With a less restrictive exhaust and nice cool air temps you'll probably hit the magic 300. Get some Nittos and then see if you can't bag yourself an 11sec 1/4. I'm hoping to prove my theory on June the 6th.

[EnricoPalazzo]

Well done matt. In regards to the new exhaust being alot louder, do u have an apexi exhaust valve. Would be a good investment and can be bought cheap form greenline.

[whatsisname]

Thanks Deano No I haven't got an exhaust valve mate. A silencer insert will probably do for now.

[TIMMMAYYY]

dean knows the apexi exhaust valves work so well cos he has on for his arse..

[whatsisname]

:bahaha:

[EnricoPalazzo]

hehe its also useful for that. It dropped my ass decible level by 10db!!!