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De-cat diesel yes or no ?

Y

Yanny

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Location
Nr Salisbury
Car
Accord i-tdci
Thinking of removing cat and pre cat from my 05 ex diesel accord , will it give me more performance and extra problems . Or is it quite straight forward , I will be doing this with a K&N air filter .
 
Yanny said:
Thinking of removing cat and pre cat from my 05 ex diesel accord , will it give me more performance and extra problems . Or is it quite straight forward , I will be doing this with a K&N air filter .
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are you planning on removing the cat from the exhaust system?and are you also intending to install a k&n air filter to the diesel engine?? ..regarding the cat on the exhaust,im not sure if anyone has done this to thier diesel :unsure: regarding the k&n air filter to the accord diesel engine have a look as its has been done and discussed,in the end it was found that the diesel engines with after market intake system lose out on low end torque,due to the diesel engines working more on compression rather than combustion, in which the air filter did not make any improvements,apart from a louder turbo swooosh. :)
 
check out this thread guys...

http://typeaccord.co.uk/forum/topic/8476-decat/
 
You've all been very helpful , thanks .

Definitely food for thought , and as for the video , well that has actually put me off as its loader than I thought it would be , perhaps this can be tuned to be quieter
 
It's worth considering if you was also to tie it in with other mods but the best bang for your money is a remap, which Premier tuning offer. I disagree about back pressure you want to reduce it in a turbo which will help spool and maybe a few extra psi of boost.
 
I've personally seen a modern diesel blow a turbo following a decat and I would advise against it.

Best bang for buck is a remap as already said. Plenty of feedback in the Premier Tuning subforum on the main page.
 
Is it not more likely the decat caused overboosting, or spikes and thats what possibly caused a failure. Thats why its good for the owner to take boost readings after mods such as this. Still don't understand the backpressure bit?
 
Back pressure is crucial in performance of 2-stroke engines as the pressure waves are tuned to both draw out exhaust gasses from an opening port and then block (or rather reduce) escaping inlet gasses from the closing port, bearing in mind there are no valves on the ports. No idea what it's got to do with a diesel though?
 
I was told by the engineers that the backpressure aids spooling efficiency and by destricting it, you lose that efficiency. I didn't really think much about it until I saw one go pop :lol:
 
I guess it depends whether we're talking about pressure waves (as in what's crucial for a 2 stroke) reflected from a restriction or simply increasing pressure in the exhaust as a consequence of constricting the flow, which will presumably reduce the velocity of the exhaust gas and therefore limit the speed of the turbine? So what's wanted is not back pressure as such but rather a restriction on the speed of the exhaust gasses. If it's the latter then presumably you would need an equivalent of a waste gate ahead of the turbo to reduce flow through the turbo or a different turbo capable of higher revs?
 
The Honda ICTDI runs a VNT turbo so the correct volume of boost is always being generated as calculated by the ECU - a wastegate would be pointless. And this is the issue, once you reduce the backpressure (whether we're talking pressure waves or increasing pressure in the exhaust), then the ECU is requesting higher pressures from the turbo to compensate. The net effect is a turbo being forced to work harder.

I'm happy to be corrected on this however, it's my theory (based on some personal experience).
 
F6HAD said:
The Honda ICTDI runs a VNT turbo so the correct volume of boost is always being generated as calculated by the ECU - a wastegate would be pointless. And this is the issue, once you reduce the backpressure (whether we're talking pressure waves or increasing pressure in the exhaust), then the ECU is requesting higher pressures from the turbo to compensate. The net effect is a turbo being forced to work harder.

I'm happy to be corrected on this however, it's my theory (based on some personal experience).
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OK I see - the ECU is aiming to maintain the spin of the turbo by adjusting the vanes, and it does this by judging the pressure in the exhaust against a set of parameters, so low pressure would equate to low flow therefore close up the vanes to deflect more gas around the turbine and maintain boost. So if you remove the obstruction in the exhaust you would need to re-map the parameters for the VNT controller to allow for the reduced pressure in the exhaust.

Why doesn't the ECU just monitor output boost on the inlet side and control it from there? Or is the exhaust a secondary system to protect the turbo? Or am I still misunderstanding something?
 
No you're right, but that's what the MAP sensor is there for. Yes you need to remap once decatted, but you are still requesting the turbo to work harder overall.
 
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