New 2-1 Exhaust System Fitted

[Celsiorous]

Hi,

I ummed and ahhed about what to do with my exhaust for along time and found it hard to get information on the internet so I thought id post up what I did and the results I got. It may help someone out there....
When i purchased my 1990 Celsior the previous owned had allready gutted the cats (in NZ cats are not manditory) so my system bolts straight to the manifolds.
The setup:
2.5 inch Chase resonators mounted directly onto the manifolds.
Then twin 2.5 inch piping converging into a Y just after the gearbox.
Then a single 2.5 inch pipe to a Lukey muffler mounted in the same position as the passenger side first muffler.
Then single 2.5 inch piping to the rear.

NB. I argued with the exhaust guy that it would be better with 2.25 from the manifolds and then converge to a single 2.5. He was adament and basically talked me out of it. In the end I think he must have been right because of the performace gains I got.

I was very suprised and happy when I heard it for the first time, it has a deep note and most importantly for me - no cackle at all. Every 1UZ Soarer/LS400 ive heard that has an after market exhaust has had a comparitively tinny sound and has cackled when reving high. This is what i really wanted to avoid and thankfully the single system came through for me.
It is quite loud, probably louder than i would have liked, it also drones in the cabin when accelerating hard at low revs, as the revs climb the in car noise decreases.
I am considering adding another smaller muffler to reduce the sound however I really do not want to adjust the tone so I might be trapped here.
I have noticed a few changes since changing the exhaust, firstly when motorway cruising at 110kmh it now runs 150 rpm lower.
It also used to have a big increase in power when it got to 4000 rpm, i could feel it really start pulling from 4000. After changing the exhaust it feels smoother all through the rev range.
I was worried about losing low end torque but I have gained it. I say this purely because it lights up the rears much more easily now and also holds burnouts longer than it used to. I dont know if I have gained much hp but it definately feels more responsive and feels like the power comes on more quickly and evenly.
There is a particular set of lights and corner that i have always tried to lose the backend on and have only been able to get the rears spinning in the wet. I went around it this morning in the dry and had the inside tyre roasting to the point that there was sticky rubber stuck to the guard. So overall im happy with the gains ive got from doing the exhaust, im really suprised that it has changed soo much.

 

[Peewee]

That super drone you now have will have been caused by using 2.5" up the front instead of 2.25".
I highly doubt you would have had any performance losses by using 2.25", I'd actually say you would have had more gains by using 2.25" instead of 2.5".

The raspy/tinny noise of the 1UZ is caused by the twin-cam head, and either hidden or exagerated by the muffler.
Some mufflers make it worse, some mufflers hide it.
Sounds like you bought a muffler that has hidden it. Thats a big plus in my book.

And now you only have one outlet? Where the car still has provision for two ?

 

[Kiwi.in.aus]

I have a Celsior that had no rear mufflers when I ADR'ed it , as it was still so quiet with out the two rear mufflers so I went up to 3" pipe from the last join and straight out the back and it was still deathly quiet in the cabin so it just shows that the rear mufflers do very little .
If I wind the windows down you can just hear the rumble .
The prob I have is that on the over-run [ when I back off the throttle ] I now have a drone , I also have an internal rattle in the centre muffler , I want to replace the system [ it is 16 years old !! ] BUT I don't want any noise in the cabin , I like it being quiet !!
I have a V8 supercar exhaust builder who is going [ sometime ] to build some headers for it , they won't be quite equal length but very close , so because of this they will extend past where the cats are now , I don't want any extra noise with the headers either , so what do I put /use down the line , taking in mind that it will have cats .
Are jointed twins better with an "X" or go down to a single then back up to twins and how many mufflers should I use ?
I expect with the headers to gain some HP and that it will be crisper , but the main consideration is lack of noise , NO DRONING !!
Help please .
As to the Kiwi guy in this post [ by the way sorry for the long post , but it is a technical thingy !! ] he has helped by showing what I don't want !! LOL .

 

[Peewee]

Droning is caused by pipes being too large.
Resonators can help, but sizing the pipe correctly in the first place is the key.

 

[1ndecent]

I have noticed a few changes since changing the exhaust, firstly when motorway cruising at 110kmh it now runs 150 rpm lower.

Interesting. Torque convertor not locking up before?