Jump to content
SAU Community

Recommended Posts

Has enyone used a straight through replacement pipe for their cat converter?

I am looking at getting one made up for track days and drags, but not sure whether to keep the Lambda sensor just behind the cat.

My thoughts are that, removing it will cause the car to run rich as it is missing a sensor and may try to run in a " safe " mode. Or if I leave it, it will cause the sensor to read worse pollution levels than if the cat was present and it may run lean.

I am currently runing a full 3" systems, PFC, FMIC, 550cc injectorsand T3/T4 turbo.

If anyone has used one let me know if you have had any ill effects, and any noticable performance gains/losses.

Link to comment
https://www.sau.com.au/forums/topic/74897-cat-replacement-pipe/
Share on other sites

the sensor in the cat is a cat temp sensor. the O2 sensor is in your dump pipe, well before the cat. no need to hook up the temp sensor, it just activates the warning light on the dash which is there to prevent you parking on long grass when your cat/front pipes are glowing red thus igniting the grass and burning your car to bits.

Thanks for your help guys,

I need to get a custom one because the car has the cat welded to the exhaust system, and I will need to get flange plates installed to bolt it on and off.

Any idea on the performance gains of doing this?

I know it depends on how effiecient your current cat is, but what has been your experiences?

i always thought it was to tell you when your cat was overheating, so you can back off to avoid damage?

steve

no, it's to warn you of all that heat in your exhaust so you wont park in long grass and blow your car up or start a bush fire.

Thanks for your help guys,

I need to get a custom one because the car has the cat welded to the exhaust system, and I will need to get flange plates installed to bolt it on and off.

Any idea on the performance gains of doing this?  

I know it depends on how effiecient your current cat is, but what has been your experiences?

Best I have seen was a 40rwkw gain. Least I have seen was a zero rwkw gain, that was with a Magic 4" cat. Pick a number:cheers:

The magic cat manufacturers can supply 3 inch reducers if you want or you can get your local exhaust shop/yourself to do it.

They retail for $500.00 or $350 trade.

Search "magic cat" and look for sydneykids comparison with a magic cat, "highflow" cat and straight pipe. Interesting stuff.

I was quoted $100 to get flanges put either side of my cat so I can swap it to a straight through one for track days as someone above mentioned. He said the flanges would be about $60 and whatever labour, they are a cheap workshop though but that should give you an idea on price.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...