Jump to content
SAU Community

Recommended Posts

Originally posted by 25GTT

Heya Wassabi,

If you already have a cat back exhaust then Brett at PSI can prob help!

I got my full exhaust system (Dump Down pipe and hi flow cat) done with him added 20HP at the wheels, I have the dyno sheets to show this! i was VERY happy with his work and didn't charge too much at all! then i had SAFC and boost wound up a bit  and it was another 20HP extra 40HP in 1 day made for quite an excitring drive home...need i say more:uh-huh:  

From my experience giv Brett at PSI a call..... some people have had probs but i don't want to start arguments but from the people that i have recommended to him such as IMACUL8 they are more than happy with him!

Hey man thanks for your help but i am kind of put off PSI after hearing horror stories from adam and from ND4SPD... i think i might go cypher

Originally posted by rev210

If the factory computer has anything to do with it, I'd say it retarded the timing on you.

Turbo's do not like backpressure at all! Get rid of back pressure on the turbo and power is there for the taking.

Retarding timing because of why exactly?

Please explain

If you're real picky about the quality, I thoroughly recommend Geoff at Exhaust Dynamics.

The following is a shot of my old S15 with a turbo back 3" s/s system.

http://www.exhaustdynamics.com.au/silvia.html

Whilst you pay for the quality - you won't be dissapointed.

Jeff Ash @ c-red is able to fit you up with a system thats almost identical to a Apexi N1 cat back system for around $1100. Its 3.25" from the cat back with no resonator to a large barrel style muffler to a 5" tip, sits at a nice angle its thin wall polished steel and looks the goods. I gained 15kw @ wheels on the dyno at SST from the exhaust and has a good throaty sound as well. All I need is a decent pipe off the turbo back and removal of the cat and It'd be even louder and blow flames. Jap exhausts and parts in general will also be a better alternative to australian made products, they will flow and work 100% better. The drawback, costs more.

Rob

Get a jap exhaust fit it, test it for noise output and power output, put an australian system on and it wont be as good. The in-cabin drone of the exhaust will always be lower on the japanese unit than a simular australian made one. Same thing goes for intercoolers, I compared a trust unit and a ARE core and just by visually looking at the core you can see how much better constructed japanese parts are. I cant wait to see a 9second GTR made souly from australian parts.

Rob

You may have more than 1 muffler in your system for example mine came across with no cat but with 2 small mufflers (resonators) and 1 large back muffler all straight thru Trust gear

Thats what is going to determine your loudness more than anything as they arent real mufflers if u can see thru them :-))

Jap or Australian the physics of exhaust design still remain. If you know the theory and can weld better than a monkey you can expect to produce a decent exhaust.

The japs go for larger pre-silencers on most of their exhausts thats why they don't drone as much, its quite simple and a good idea.

The less restrictive zorts are often louder as par for the course.

Here are a few ideas for high flow.

1) turbos don't like backpressure.

2) Make the exhaust length as short as possible (ie: fewer less angular bends decrease the total length).

3) Straight through mufflers flow the best , you just have to seek out the best brand for noise and flow.

4) muffler and cat placement effect the thermal dynamic aspect of flow but also noise. The exhaust is hottest up the front and gets colder as it goes back, it loses speed and energy as it does this.Pipe diameter as you go back should decrease slightly to accomodate, not increase as many people do. The exeption is the tail pipe if it is 'megaphoned' this produces an attractive pressure drop for exhaust to run to.

5)Trapping the heat energy in the pipe will increase the speed of the gas molecules making more power, do what you can to this effect. Coating the muffler bodies in HPC or more practical is wrapping the dump pipe in thermal wrap.

On the idea of the infallable jap exhaust - they are useless at doing NA rotory exhausts, possibly the hardest to design. If you know a place that does a good job of this type of exhaust then go running to them if you want the "best quality" in design they must know their stuff.

thats bullshit about jap exhausts being better, but if you want to spend twice as much on one, well im not going to stop you

they may be VERY SLIGHTLY better constructed, but as rev said, if you can weld better than a monkey and make it out of 3" mandrel bent pipe then youre going to produce an exhaust of reasonable quality. i dont think weve done enough laps around nurburgring to start counting 1-2kw gains from using an overpriced japanese unit as opposed to a locally made exhaust.

:cool: Yeah, what they said :P

Originally posted by rob77

Same thing goes for intercoolers, I compared a trust unit and a ARE core and just by visually looking at the core you can see how much better constructed japanese parts are.

Sure you weren't comapring apples with oranges? If the ARE was tube & fin while the Trust was bar & plate, of course the trust is going to look like it flows a lot more air, its a by product of the core's design. AFAIK, ARE use top quality cores.

Most of you probably know this, but heres an insight on why the Japanese sell everything (from exhausts to underwear) in kit form: Laour. Its just too bloody expensive to pay someone the labour to build custom parts, works out cheaper for them to mass produce.

Asking us to build a 9sec GTR without Japanese parts is a bit silly. Why not ask the Japs to build a 9sec LS1 without Aus or US parts? I'd like to see a PowerFC for that one! :P Note: the GTR probably could be built, but why reinvent the wheel for things like tubular exhaust manifolds.)

I'll stick with my jap stuff, I know it works, its tried and tested. The trust unit is a tube and fin and yes I was comparing a tube and fine ARE unit to the trust unit. And you're right, why re-invent the wheel? Jap's have done the research and created what works best and it bolts practically straight on and in. My exhaust took less than 10 minutes to fit and the intercooler wont take much longer than a day after cutting and trimming the front bar to suit.

Rob

so i got my exhaust fitted today, decided to go for 3" after hearing a line with 3.5 (too loud, dont like police attention) and anyway dosent sound heaps different to my previous 3" cat back BUT now it seems its making more boost higher up in the rev range and knocking!!@&@!* does this sound right?

i think i might just turn down the boost till i take it to cypher next week :cool:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yeah, hard to find and a pain in the ass to change with the transverse engine. I’ve worked on a GTiR before and it’s not a job I’d ever want to do again. theres a company in South Africa that makes RS3 gearbox adaptors for the AWD SR20 including gearbox mounts, so I could modernise it and go a dual clutch with paddles. For now tho, it ticks all the boxes. Super cheap, can throw the kids and their junk in the back, and SR20 that I can turbo cheaply, a CVT that’s not a dog’s breakfast like the V35, and has 80% interchangeable parts with stuff I can source from the wreckers cheaply…. But it’s still unique. I love the wagon back of the Autech version. It’s cheap enough that I can buy another stock manual FWD Primera with SR20VE, swap the gearbox to the N15 pulsar short gear ratio box, swap out the brakes to the R32 ones I pulled off my 32, register it on club plates and take it racing. $1300 shipping from NZ. Heaps of parts and aftermarket builders for transverse SR20’s in NZ.
    • Hard to say, just pop the rocker covers off and have a look if you think it's cammed. You probably need to replace the valve cover gasket/half moons anyways.
    • From my youth: GTi-R clutch change is a massive pain. The gearboxes are fragile? But the car is super cool and I want one 😢 
    • Remember this is 1988 tech.
    • Driveline vibration is resolved. I ended up loosening all my engine mount and trans mount bolts, giving it a good shake then retightening everything and it's gone... Let's just say I was surprised that fixed it.  I've been happily driving it around again but unfortunately put zero time into my direct port/constant pressure WMI setup. I'm on vacation next week, so I'll try and finalize it then.  On a different note, I spent all week fuel/ignition mapping 2x 216L V16 engines. Turbo's were burning glycol and we swapped them out for larger units. We also had planned emissions testing on site, so I figured I'd be there the same week to use their instrumentation and massage any emissions issues out if needed. This was a first for me. Fuel management is similar in certain ways to automotive (i.e air density as load variable) but very different in others. It's all PLC based and AFR's are controlled by air and not fuel. They use a control valve between the turbo and air manifold to control pressure which in turn controls AFR's. Due to this, target AFR tables supplied by the OEM are in pressures and not mass which really through me off. They use air pressure vs fuel pressure tables. I also relied on an O2 concentration sensor the emissions team had in the exhaust. Ignition timing was also all over the place and we were losing a fair bit of power. They're now happily sitting at 16-40BTDC depending on load. We were making about 1600kw at 900rpm at 90% load. Engines were running a lot smoother as well.    
×
×
  • Create New...