3.5" Metal Cat Fitted To Std System Today

[Full Monty]

3" is actually less flow capacity that twin 2.25"

3.5" is about the same.

[IH8TOADS]

Yeah but on a BF 3" down pipe it doesn't matter, a 3" is the only way providing the body is of decent size....BA would be different. as 3.5" is better suited as a Y section needs to be made for the rear of the aftermarket cat.

[Taminator]

3" is actually less flow capacity that twin 2.25"

3.5" is about the same.

It doesn't matter the section with the most restriction is the limiting factor , since its got to get down a 3" dump pipe and go back into a 3 inch section after the cat I would think it didnt matter, all the restriction was in the flow of the cat itself, I was quoted that the stock heap of rubbish flowed only about 380cfm where as the installed one is around 700. It was on the dyno today to a quick check to get a baseline and it does make a difference getting rid of that bit of it. remember I am after affordable increments in performance. To get rid of that cat with new one installed for 550 is good value leaving cash for the tuner and somebody to custom it to how I want which isnt max power.

I would rather have bulk torque down at the bottom end that an idiotic number a KW only avaiable at 6 grand b/c my car never sees it. And I would think you only really need a mega high flow exchaust if you pushing lots of hot gas down it which would entail high revs which I just dont do.

15 years ago I had a custom built 360CU Cleveland built for straight gas, thought I was being clever and it produced heaps of power, but at over 4500 revs, it never saw it , that's the beauty of the turbo in such a big motor, piles or torque down low and that's what counts. that's the stat that lets us eat the commodores so easy, the big torque down low.

Now if I can just learn to shift that 6 speed smoothly I will be really happy, either mine isnt any good or a lemon becaue I reckon the feel of it is crap. Also my feet are too big for the pedals (Size 16) you think bloody ford were designing it for a pack of women in high heels

Taminator

[MiKa]

16!!! Bloody hell, I thought I had big feet at 13-14.....

[ebxmple]

I had the car retuned yesterday, this setup made an extra 8rwkw over a standard BA "hi floed cat"

I had the setup changed so the 3.5" mandrel pipe floes right back to the first bolt flange, at this point there is a nice 3.5" to twin 2.5" collector, which tapers down smoothly to twin 2.25"

its amazing what a difference it makes to pay attention to the inner joins in the pipes and collectors, any sharp edges or protruding pipes really rob you of top end flow, the inside of the new collector is really nicely made, totally smooth curves with a sharp divider to split the 2 pipes.

picked up around 10rwkw through the entire range over a BA gutted cat setup.

My theory is that keeping the pipe in a single large diameter for further back from the turbo really helps relieve back pressure?

will try to take a pic to post.

Who changed the position of the collector the second time for you with the collector being further back? Do you have any pics yet.

[Full Monty]

Jay at Hillside exhaust made the change, it was struggling on the dyno in the topend. the restriction was identified as the collector, so Jay spent a couple of hours making up a nice new one which had all die grinded internals and no sharp transitions for max flow.

we then decided to continue the 3.5" as far as possible before mating to the standard rear mufflers.

sorry I totally forgot to take pics over the weekend.

[ebxmple]

Thanks,I am in the process of organising a 3.5" cat and am very interested in your results. Did they charge you any more to make your new collector and have you had the car on the dyno again since then.Hillside sound like a good bunch to deal with. Hope to see some pics soon if you get the chance. Thanks.

'

Edited 12/02/08 01:14 AM by Dagabond

[Full Monty]

Yes I was charged a little extra to make the new collector, but Jay looked after me.

made a further 10rwkw over a standard BA "hi - Flo'ed cat and pipe setup"