JR Supra
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Im getting the Armytrix Catless Downpipe will I get CEL?
JSmoothBui
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I switched to armytrix catless that has the o2 simulator, no CEL for me
the downpipe will throw a check engine light, if you are using an O2 simulator it might trick the ECU. It's more about the simulator than it is about the downpipe brand as you can do the same with any brand.
Jackyl tm
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I have the aa catted downpipe now, if I went catless would it add any noticeable hp?
Mimosa
Well-Known Member
No. You will actually have power loss without any sort of tune.
I have the Armytrix DP w/ Sim. No CEL after 2700+ miles. It hasn't failed me yet. But the powerband on the car is a little funny now since there is no back pressure.
No power difference between a high flow catted downpipes and catless under these conditions
1- the cats are high quality and not restrictive
2- stock turbo
If you upgrade the turbo, the catless will make 20-30 more whp
WITCH3R
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No cel same dp.
zrk
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In theory, the loss of backpressure from a free-flowing cat could result in a loss of power on some cars, though I'm not exactly sure that's been proven on the B58. I'd expect the ECU to compensate the electronic WG to maintain targets.
underdonk
Well-Known Member
Yeah, basically what I was thinking. Like adding a higher-flowing exhaust on a NA car and losing bottom end power due to a loss of backpressure (i.e., increasing max power and shifting the power curve up in the rev range). Would be interesting to see a before/after dyno, which I know is unlikely we'll ever have for this specific type of setup.
Mimosa
Well-Known Member
I just know what's happening with my car. I'll try to have it dynoed before I slap on the new turbo and get it tuned. The powerband feels like its wavy. Maybe not a loss in power, but something is definitely going on. I don't know how to explain it properly because I'm not a car guy.
Last edited:
SupraTimo
Well-Known Member
Hi all, sorry to revive this thread.
So I’m about to buy a armytrix catless DP.
My question is, there’s two options,
One that says opf model and one that doesn’t, do anyone have an idea what’s the difference?
I’m looking but can’t find a straight answer!
Best regards
So I’m about to buy a armytrix catless DP.
My question is, there’s two options,
One that says opf model and one that doesn’t, do anyone have an idea what’s the difference?
I’m looking but can’t find a straight answer!
Best regards
suprawr
Member
EU spec vs US/JDM
just an extra filter for emissions
https://www.supramkv.com/threads/opf-non-opf-cars.9562/post-137808
Thraxbert
Well-Known Member
It's not "backpressure" that costs an N/A car performance. Backpressure isn't a real phenomenon. What happens is that the exhaust diameter becomes too wide and the exhaust velocity is no longer sufficient to scavenge pulses from the headers, which means the overall exhaust velocity decreases and the VE of the engine goes down. Power is lost. Exhaust scavenging is what must be monitored on an NA car.
This doesn't happen in turbo cars, because the VE >1.0.
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