Exhaust discussion.

[Snikty]

Car has been in the workshop for ages and I wont get it back til January...there is still some debate going on about my exhaust. My mechanic thinks he can get the best flow doing it in 1.75 piping...and he point blankly refused to go over 2 inch as he is sure it will lose power and most likely give me no end of idle problems. I just had a friend get their CA18 done in 2.5 piping and it ended up being too much and she destroyed a brand new gt28. So 1 3/4 isnt sounding too bad for my little 930cc.

 

[smidge]

mines 2 or 2.25 inch and have no problems at all

its nothing but good for a turbo car to have a massive exhaust as they don't need backpressure after the turbo, it just needs to get out ASAP

thats cause the turbo is a pretty big exhaust restriction as it is, its totally different story for NA cars

whack a 2inch mandel bent system on there and be merry

i don't have idle issues because of my exhaust, its 100% to do with my intake

 

[Snikty]

Yeah I'd say it'll be done in 2. And although the theory of bigger is better on turbod cars is true you cant go too big otherwise your air starts to expand outwardly too much which will create back pressure. You want to try and get the right amount of pressure so that the air moves directly out and travels faster. That's the best i can relay what has been told to me and it sounds like pretty solid advice...I even got diagrams of air flows... And the fact that lots of high performance 2.0 engines are done in 2-2.5 piping would suggest it should be scaled down on a 1.0

 

[Ed]

he point blankly refused to go over 2 inch as he is sure it will lose power and most likely give me no end of idle problems

Quite simply nonsense! I have a GT28 turbo and 2.5 inch exhaust, and had the same exhaust for quite some time on the old turbo. Turbo's don't want back pressure. In fact a tapered cone much like the intake to TBS but on a larger scale would be the ideal exhaust for any turbo.

Hi performance 2.0s I setup rarely have anything less than 3 inch systems and some are more.

Anyway, you'll be fine and for your own reference, the Japanese Fugitsuturbo March ST exhaust system is 2.0 inch

Ed

 

[smidge]

and my HKS one is the same

 

[Snikty]

Thanks for that, Ed.

When I started discussing my exhaust with em I had a very firm idea what I wanted...and I knew it would sound a bit over the top to start with so was expecting him to tell me it wouldn't give the best performance.

Having said that. If I walked into your workshop and said I wanted a 2' down pipe into middle box with two 2' exits going into two small back boxes with twin dump pipes out the back. Would that sound viable to you?? Ultimately I want the best performance I can get but it would be a nice bonus to get the look I want also. Cheers

 

[Ed]

I you want best performance go for one middle and one back box with a single tailpipe. I'd say good call otherwise. The OEM downpipe is however terrible. If you can re-do that and get an inline performance cat perhaps instead of the middle box. It would add a fair bit to the cost but you may as well do it right and only do it once!

 

[smidge]

i gotta lose the stock dump thats on mine, i know its not gonna be cheap tho!

 

[SammoHung]

If you want the looks of a twin....but the performance system as recommended...then may be you could have a dummy twin exit fabricated...for the looks that you want...but only one exit would be functional for the performance?

 

[smidge]

until you start it on a cold morning and only get steam out one side

 

[Snikty]

Ok thanks guys. I'd say I'll just go a single system then. Doing a dummy exits sounds good in theory but probably too expensive if its just for looks.

And yeah you're right Ed. Doing it right the first time is what I'm all about, hence why its taking me so long to get done lol And cost doesn't bother me too much, if I cant afford it I'd rather just wait til I can afford exactly what I want.

 

[smidge]

the little HKS cannons or similar hanging out the back look pretty good too i reckon, a centre muffler made a BIG difference on my car as well, didn't change performance much at all and gave it a nice low bother-free note

 

[Ed]

True I used to love the sound of the Fugitsuturbo twin system that came on my ST. Sounded nicer than the current one, but was too subtle for drag events etc. It eventually rusted away unfortunately.

 

[Baz]

True I used to love the sound of the Fugitsuturbo twin system that came on my ST. Sounded nicer than the current one, but was too subtle for drag events etc. It eventually rusted away unfortunately.

Was there not a s/steel version of the fujitsubo?They will still mate a system for an st if you pay them upfront:wasntme:

 

[Ed]

I don't to be honest.

 

[SammoHung]

a centre muffler made a BIG difference on my car as well, didn't change performance much at all and gave it a nice low bother-free note

Mine is a 988 NA...but I can vouch for the center muffler resulting in nice music. The inside of my car is minimal and the exhaust noise inside the car was agnoying on the stock galvanised steel exhaust.

After fitting the exhaust, it was almost completely silent on idle and performance was noticably improved up the higher RPM

For me, my required spec included:

...VERY quiet please
...Car ground clearance has been reduced by 46mm (-35mm suspension & -8mm wheel & tyre combo) so please tuck it up nice and high


the guy used an epitical center silencer to maximise the ground clearance at the point between the back and front wheels...

heres a cople of pics incase they might be any use

 

[Snikty]

That a very neat job, Sammo. And thx for putting up some pics. The epitical silencer is a good idea too, that sits really nicely. So do you have as split system from turbo to cat?? That's how my friend's XR6 turbo is set up too, 2 x 2.25 from turbo going into 3 (I think).

I agree about keeping it quiet, I am pretty sure I can use any cat I want over here so long as it is quiet. So I'm thinking if I get a good racing cat and do a Y split into two nice silenced backboxes I can probably get something like I want as far as looks go and still get a respectable power increase.

I have another week or two before I commit to anything so will no doubt be back on here with new theories and noob questions until then lol

 

[SammoHung]

no probs mate!

So do you have as split system from turbo to cat??

No, mine is a natrualy aspirated 988cc . The two pipes that come into one before the flexi-joint are the "2" part of a sequential 4-2-1 manifold...(so: no turbo or super charging at all on mine)..I do use +25bhp of nitrous with this exhaust system though and it responds well at all RPMs due to free flowing manifold...and the sound on nitrous is quite pleasent IMO..

I have a low quallity audio recording somwhere that I did while comissioning the nitrous...but to be honest most of the sound / noise is from the engine bay...(the exhaust is so quiet...lol)...and its a little distorted too...lol (pc mic)

 

[Snikty]

Ahh ok gotcha. I should have known the dato wouldn't be turbo'd but just assumed it was. I really like the work you've done on that car and now that I know its n/a I like it even more

Do people have any tips on brands of cats and exhausts to avoid or ones they know are especially good quality/well priced?