Restriction In The Exhaust

[rondofj]

Behind my rear muffler- I measured 3 inches

[wolverine]

Na Wolverine, I had a HKS cannon before, got rid of it, I much like my quiet oval, just hope its not a restriction, Blackkers do you mind taking a pic up inside your muffler tip like I did above, I want to see how big your hole is cos mine looks small lol..

Do you guys not think my mid-muffler could be the culprit with that tapered 2.71inch exit at the back?

The noise is the reason I took mine off too. I love the sound but less attention is desirable these days.

[Dale FZ1]

If it is going back onto the rollers on Monday for a quick run, I see good merit in Scott's suggestion.

Firstly, drop the exhaust and see what result that gives. You'd want to at least eliminate both mufflers and the restriction they offer. Unigroup may want the cat dropped too, so rely on their opinion.

Secondly, have a spare good CAS handy and be prepared to slip that on.

Neither step is going to take much time and you will soon know what sort of changes are needed to get the best from your setup.

The overheating issue is concerning - before Monday can you install a new thermostat and/or check the fan belt for tension so the fan is getting good drive? One is fairly cheap to do, the other only takes 5-10 mins.

[rondofj]

Nope mate- overheating the turbine and intake charge because of backpressure- turbo has to work harder, engine more prone to detonate, thats somewhat what I understood from Mark

[boostn0199]

That pic you posted of the inside of your muffler there is a restrictor in it also ontop of that it looks like its a lourverd muffler that isnt the best aswell.

Edited March 22, 2014 by boostn0199

[Dale FZ1]

If you have a post-turbine restriction then with reduced pressure drop across the turbine you will end up with less efficient scavenging of the combustion chambers and retained heat.

From there, agreed that the thing shouldn't/won't take as much ignition advance as you have it running closer to the knock threshold.

Your compressor discharge temps shouldn't be any higher, it simply pulls in mass flow of x, squeezes that mass to a pressure ratio y (boost pressure + atmospheric pressure), at an efficiency rate z as shown on maps (if they are published) and then that is ducted to the inlet. Compressor efficiency simply describes how much heat is added to the air mass while it is being squeezed. Backpressure across the combustion chamber can mean that the turbo is working against itself to a certain degree.

It's good to know that your ECT is not going through the roof.

[rondofj]

Looks like I might have to get another mid-muffler and main muffler, will keep it both oval, I dont understand how my mid-muffler has entry 3'' and exit 2.71''? That's confusing.

Plus I got ripped when I asked for 3'' in/out xforce main muffler fitted, looks like it has a smaller guts now . When I got it couple years ago I saw that rear entry pipe joint was 3'' after fitting and thought thats correct.

Where do I get a used highflow 3'' mid muffler and main muffler? Hard to find on ebay and forums, everyone selling cannons

[KiwiRS4T]

I have spent so much money over the last few years trying to get my exhaust right I could have easily paid for a quality custom made 3.5in system. What I have now is a full 3.0in system with a Venom 5in 100 cell cat a mid resonator and a cannon all of which are legal (in that I have an LVV cert for all my modifications although I am not sure the cat would pass a more stringent test). I know you don't want a cannon but here is a mid resonator (quality ain't cheap):

http://www.trademe.co.nz/motors/car-parts-accessories/performance/exhaust/auction-708667850.htm

they also do a big range of mufflers including oval ones:

http://www.adrenalinr.com/productdetail.php?productID=574

[PN-Mad]

Maybe I missed it, but has anyone just said to unbolt the plumb back section of the ext gate?

Would take about 5 mins at the workshop, run the car up and see what happens. You're bypassing the exhaust then. I bet your car will be happier.

Now, obviously you don't want that for the road if your daily driving it, but it's going to give you an indication.

From my experience, I have a true 3 inch exhaust, a "high flowed" cat, when my gate is plumbed back power drops from 289kw to 272kw with nil change in boost.

[scotty nm35]

Where do I get a used highflow 3'' mid muffler and main muffler? Hard to find on ebay and forums, everyone selling cannons

Magnaflow is unfortunately the best option imo.

Speak to Chris at Best Mufflers, tell him Scotty sent you. Keep in mind he's a V8 guy, doesn't like turbo cars much. Perhaps ask him if he can drop the whole system and clean it up internally with the die grinder. It's what should have been done when it was made, but no-one cares what the inside looks like, do they...

[rondofj]

Wow thats a large power drop and nah, I will ask for my cat back to be dropped not plumb-back. Yeh no screamer for me.

Thanks Kiwi, those parts are in NZ but I got the idea, will keep it oval though, are the cannon resonators/mid mufflers louder?

[KiwiRS4T]

Wow thats a large power drop and nah, I will ask for my cat back to be dropped not plumb-back. Yeh no screamer for me.

Thanks Kiwi, those parts are in NZ but I got the idea, will keep it oval though, are the cannon resonators/mid mufflers louder?

These parts are in NZ but they are closer than Perth or Japan!

Having said that I would have thought there would be an equivalent manufacturer in Aus.

If you use a good mid resonator and a quality oval muffler you will definitely have a legal exhaust - not sure how quiet you want below that. My cat + mid resonator + cannon is legal so replacing the cannon with an oval muffler will make it a bit quieter still.

[rondofj]

Well update, back from Unigroup yesterday afternoon, they didn't drop the exhaust to confirm its a restriction, but Yavuz explained to me again that in his 15 years there he has had so many cars where 8 out of 10 have an exhaust restriction, and usually always its the cat as well as other elements, so even though its a 3" in/out 100 cell metal cat, it is a restriction that will make a good difference when removed /gutted. I have no doubts on what both him and Mark said, plus he also said the mid-muffler is a restriction -(the 2.71" necked joint in the pics), but not as big a restriction as the cat but still advised me to change it. Lastly the main rear muffler itself is a restriction, but last down in terms of importance, so according to him the main one is the cat, then mid-muffler then rear muffler.

Most Japanese (and some other) exhausts according to him n Mark have tapered down insides to control noise, so even though they may advertise as high flow 3" in/out, Mark said he wouldn't trust a muffler till he actually cut down and measured the insides of one himself. The safest (and also most expensive) way is a custom made exhaust but I ain't spending all that coin on a custom job for a few measly killawasps..

It does seem that they have among the lowest reading dynos in the country? And very safe/restricted and mild but not wild tunes..

[scotty nm35]

They didn't drop it? Fair enough. It's easier to simply blame something than find a restriction... Blame the dyno too, why not...

[rondofj]

Aah I'm not as experienced on cars as you, but I still think my mid-muffler and rear muffler is a restriction from pics, don't you? Also that damn cat from what I been told.. confused ;-

I mean from all the hundreds of cars and years they've done, its probably ok to take their word for it?

Edited March 25, 2014 by rondofj

[Manuel Kasko]

5min job and 2 bolts...8/10 times it's the cat.

I know which I would prefer to do

[XKLABA]

What do you call expensive for an exhaust, I had a custom one made for my 34, starts from dump pipes and consists of

Twin 3" to twin 3" 100cell 5" bodied cats

Then twin 3" to single 4" mid muffler

Then 4" to the rear muffler I supplied

And that was $1260 fitted, obviously, by Windsor Exhaust

I would and did just get a custom one made up for the car, 3.5" for your car is what I would suggest

I really don't understand why they wouldn't take the 5 mins it takes to drop the cat and remove all doubt, your paying for it so why not

[Dale FZ1]

Mick how does your system go for noise suppression?

It would have plenty of flow capacity, be good to see pics for how it looks and fits.

[Aggroman]

5min job and 2 bolts...8/10 times it's the cat.

I know which I would prefer to do

when you're busy with problem cars eating into others time on a busy dyno id say.. you go drop your own exhaust book it in for another runup if the problems gone then there is your answer..

2 bolts and a 5 min job, on a hot exhaust? yeah nah you would have to let that cool which is time, unstrap and take it off the dyno more time, put it back on the dyno yet more time, get it back to running temps YEP you guessed it more time

if I was getting something done and they said "this is a problem holding you back from your best possible results" well then id fkn change it regarless especially with something as important as an exhaust

[rondofj]

Well..had the same car with exact same set up but with Nistune (now Power FC) tuned by JEM and they didnt mention a word about my exhaust! But they said intake charge is heating up and cannot take more boost, kinda tuned on edge..Tried to convince me to go FFP to get cooler temps but nah. Made more power on less boost too. Much snappier, torqueyer n more exciting overall but crappy economy and cruise/cold start/low load wasn't tuned well.

Now this one with PFC and now I have an exhaust problem. Less power n less torque (at higher boost) deliberately to keep it 'safe'.. But perfect cold start and beautiful factory like low rpm street driving/cruise bar a couple minor probs.

Both very reputable very well recommended tuners.. Who to believe? Obviously something fishy goin on..two different tuning styles and of course dyno variances..