Hi-Flow Cat help - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

NiNJA · 02-01-2002, 04:22 PM

Hey all,

I just got the APEXi N1 Dual and was wonderin what size hi-flow cat would I use on it? A 2.5inch or 3inch cat? Sorry if this has been posted before, I'm busy installing my Intrax springs and KYB shocks...

            Thanks In Advance

S14KAT · 02-01-2002, 08:39 PM

To be honest with you I have the Random Tech cat and they don't offer(or at least I don't think they do)different diameters in there cats.  Other manufacturers may be different, but 2.5 inch is the only size that I'm aware of.

Nismos14 · 02-01-2002, 08:46 PM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from S14KAT on 10:39 pm on Feb. 1, 2002
To be honest with you I have the Random Tech cat and they don't offer(or at least I don't think they do)different diameters in there cats. Other manufacturers may be different, but 2.5 inch is the only size that I'm aware of.</td></tr></table><span id='postcolor'>

did it make a big difference in performance?

NiNJA · 02-02-2002, 09:27 AM

I think im gonna go with the Carsound cat, it comes in 2, 2.25, 2.5 and 3inch .

allmotorKA · 02-02-2002, 10:30 PM

You CAN get 3" diameter inlet/outlet cats from Random instead of the 2-1/2" diameter they list for the 240SX. For the 89-97 240SX, Random lists the 2-1/2" diameter cat as part number as 822530...but according to Random, part number 823030 is a 3" diameter cat which was made for the Maxima, but will work for the 240SX as well.

If the N1 dual has a 3" inlet, I would recommend the 3" Random Tech Cat since the Random Cats have slip type flanges. What I mean is that the mounting flange of the cat is free to slide and rotate on the inlet and outlet pipes of the cat. So if you get the 2-1/2" Random Cat, the outlet pipe may be swallowed by the N1 exhaust making it difficult to seal properly without a steel reinforced exhaust gasket.

NiNJA · 02-03-2002, 09:07 AM

Well to my further research, I think the APEXi N1 Dual is 2.5inch in diameter, and I heard the APEXi N1 Single is 3inch with a 2.5inch converter that you can take off when you go turbo ?? (Not sure on that, if someone can explain for me) ....I'm staying N/A for a while so I'm gonna stick with 2.5inch hi-flow cat...

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02-01-2002, 04:22 PM	#1
NiNJA Leaky Injector Join Date: May 2001 Location: Atlanta Age: 40 Posts: 111 Trader Rating: (0) Feedback Score: 0 reviews	Hey all, I just got the APEXi N1 Dual and was wonderin what size hi-flow cat would I use on it? A 2.5inch or 3inch cat? Sorry if this has been posted before, I'm busy installing my Intrax springs and KYB shocks...             Thanks In Advance

02-01-2002, 08:39 PM	#2
S14KAT Leaky Injector Join Date: Dec 2001 Posts: 123 Trader Rating: (0) Feedback Score: 0 reviews	To be honest with you I have the Random Tech cat and they don't offer(or at least I don't think they do)different diameters in there cats.  Other manufacturers may be different, but 2.5 inch is the only size that I'm aware of.

02-01-2002, 08:46 PM	#3
Nismos14 Zilvia FREAK! Join Date: Jun 2001 Location: New Jersey Age: 44 Posts: 1,213 Trader Rating: (0) Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from S14KAT on 10:39 pm on Feb. 1, 2002 To be honest with you I have the Random Tech cat and they don't offer(or at least I don't think they do)different diameters in there cats. Other manufacturers may be different, but 2.5 inch is the only size that I'm aware of.</td></tr></table><span id='postcolor'> did it make a big difference in performance?

02-02-2002, 09:27 AM	#4
NiNJA Leaky Injector Join Date: May 2001 Location: Atlanta Age: 40 Posts: 111 Trader Rating: (0) Feedback Score: 0 reviews	I think im gonna go with the Carsound cat, it comes in 2, 2.25, 2.5 and 3inch .

02-02-2002, 10:30 PM	#5
allmotorKA Zilvia Member Join Date: Nov 2001 Location: SoCal Posts: 204 Trader Rating: (1) Feedback Score: 1 reviews	You CAN get 3" diameter inlet/outlet cats from Random instead of the 2-1/2" diameter they list for the 240SX. For the 89-97 240SX, Random lists the 2-1/2" diameter cat as part number as 822530...but according to Random, part number 823030 is a 3" diameter cat which was made for the Maxima, but will work for the 240SX as well. If the N1 dual has a 3" inlet, I would recommend the 3" Random Tech Cat since the Random Cats have slip type flanges. What I mean is that the mounting flange of the cat is free to slide and rotate on the inlet and outlet pipes of the cat. So if you get the 2-1/2" Random Cat, the outlet pipe may be swallowed by the N1 exhaust making it difficult to seal properly without a steel reinforced exhaust gasket.

02-03-2002, 09:07 AM	#6
NiNJA Leaky Injector Join Date: May 2001 Location: Atlanta Age: 40 Posts: 111 Trader Rating: (0) Feedback Score: 0 reviews	Well to my further research, I think the APEXi N1 Dual is 2.5inch in diameter, and I heard the APEXi N1 Single is 3inch with a 2.5inch converter that you can take off when you go turbo ?? (Not sure on that, if someone can explain for me) ....I'm staying N/A for a while so I'm gonna stick with 2.5inch hi-flow cat...