extractors and cats help!

[ryanssv]

Hi guys, first time posting on here.

I have a manual 2010 ssv redline ute with 2 1/2 inch cat back exhaust.
was wondering if anyone could help me decide on what size extractors to get and what cats.
would 1 3/4 or 1 7/8 be best? i wouldn't want it to drone at all. and would tri-ys be best or 4-1. and not 100% on what cats i would get either haha
i will be doing an vcm otr along with the extractors and then a tune.

any suggestions would be very appreciated! THANKS!

 

[monstar]

Hi guys, first time posting on here.

I have a manual 2010 ssv redline ute with 2 1/2 inch cat back exhaust.
was wondering if anyone could help me decide on what size extractors to get and what cats.
would 1 3/4 or 1 7/8 be best? i wouldn't want it to drone at all. and would tri-ys be best or 4-1. and not 100% on what cats i would get either haha
i will be doing an vcm otr along with the extractors and then a tune.

any suggestions would be very appreciated! THANKS!

What sort of driving do you do?

 

[ryanssv]

What sort of driving do you do?

Mostly daily but still want down low power more than high end

 

[monstar]

Well that's simple, 1 3/4" primaries and decent length like 28"-32". Given you are not seriously looking to beat a 1/4 mile time and could use more mid range I'd go for tri-y.
I can recommend HSV extractors, 2.25" mandrel connector to 3" steel bullet HFCs. Else get more by paying a bit more for new off-the-shelf long tri-ys like Pacemaker PH5387 and 4" steel bullet HFCs.

 

[ryanssv]

Well that's simple, 1 3/4" primaries and decent length like 28"-32". Given you are not seriously looking to beat a 1/4 mile time and could use more mid range I'd go for tri-y.
I can recommend HSV extractors, 2.25" mandrel connector to 3" steel bullet HFCs. Else get more by paying a bit more for new off-the-shelf long tri-ys like Pacemaker PH5387 and 4" steel bullet HFCs.

ok cool! thanks for the help! will have to try get them soon!

 

[Not_An_Abba_Fan]

I don't fit anything but 1 7/8" primary 4-1's. Low to mid difference between any extractor on a computer controlled EFI engine is negligible. Big primary 4-1's have the advantage of top end over anything else. You will see a difference in EVERY extractor on a dynp but not enough to feel it on the street. 100 cell cats are the way to go as well, cats are restrictive, they have to be for them to work. The highest flowing cat you can get will give you the best performance increase.

Anything is an improvement over factory manifolds and cats. The bigger you go at the engine the better everything will flow as that is where the gases are hottest and take up the most space. Get as much exhaust out as fast as you can and you will have much better performance, both power and economy.

 

[ryanssv]

I don't fit anything but 1 7/8" primary 4-1's. Low to mid difference between any extractor on a computer controlled EFI engine is negligible. Big primary 4-1's have the advantage of top end over anything else. You will see a difference in EVERY extractor on a dynp but not enough to feel it on the street. 100 cell cats are the way to go as well, cats are restrictive, they have to be for them to work. The highest flowing cat you can get will give you the best performance increase.

Anything is an improvement over factory manifolds and cats. The bigger you go at the engine the better everything will flow as that is where the gases are hottest and take up the most space. Get as much exhaust out as fast as you can and you will have much better performance, both power and economy.

oh okay. i was wondering if there was much or if any noticeable difference at that against the two. ill be getting it dyno tuned straight away so I'm sure i will like it regardless. thanks for the help!

 

[Xplaya]

I don't fit anything but 1 7/8" primary 4-1's. Low to mid difference between any extractor on a computer controlled EFI engine is negligible. Big primary 4-1's have the advantage of top end over anything else. You will see a difference in EVERY extractor on a dynp but not enough to feel it on the street. 100 cell cats are the way to go as well, cats are restrictive, they have to be for them to work. The highest flowing cat you can get will give you the best performance increase.

Anything is an improvement over factory manifolds and cats. The bigger you go at the engine the better everything will flow as that is where the gases are hottest and take up the most space. Get as much exhaust out as fast as you can and you will have much better performance, both power and economy.

Abba do you get much customers with lowered vehicles complaining about scraping on the cats etc I have a full xforce setup (4-1 Headers to Muffler). But I dont want to raise the vehicle
Do you know of any 100 cell cats that may be smaller physically? I have been thinking delete the cats altogether and go straight pipe, since my car has been tuned to ignore the bottom 02 sensors anyway (Seems to be Legal in NZ), but haven't looked further into what issues this may cause.

 

[Not_An_Abba_Fan]

The system that I do on the VE's sit up fairly high. the lowest part of the system is actually where it goes under the rear axles but the Manta sits up as high as the factory system, it's the only one that I have seen that sits that high. I have never had extractors or cats scrape on a VE when using Hurricane headers and the Manta system.

Cats are ONLY there for legal reasons, they are a restriction and have nothing to do with performance. The rear sensors only measure the change in O2 from the front sensors just to check if the cats are working. High flow cats always trigger a fault as the change in O2 from the front sensors isn't enough for the rear ones to pick up.

What ever cats you fit have to be fitted right at the outlet of the headers. Not only is that the highest point, it's also the best for performance as that is where the engine "sees" the end of the collector. That is the critical thing for performance, the length of the collector. If you delete the cats then the "collector" (the pipe from where the 4 goes into 1) will continue until the first change in diameter. Usually it's the cats, but deleting them will see the first change in diameter either the front muffler or hotdogs. This will push the torque curve way down and lose top end.

Some people see exhaust design as some sort of black art, but the principles of exhaust have not changed since the invention of the internal combustion engine. Some people also try and reinvent the wheel with whiz bang software, but a V8 is a V8 is a V8. All off the shelf big primary 4-1's work well. The magic is in the tune in the ECU. You can't "tune" an exhaust on a street car because there are too many variables on the street, it's not like a race track where the engine is kept in a small rev window or a drag strip where the revs are flat out. Old school tuning was done with carby jets and dizzy springs to change the timing curve, now it's done on a computer. Get the exhaust out fast and keep it moving fast, that's all you really need to do for performance.

Sorry for the long winded post.

 

[rucxy]

^

Sorry for the long winded post.

I see what you did there....

That is a really good writeup on how an exhaust works in layman terms.