Catalytic converter removal
Discussion
quote:
Any serious petrol heads know any pitfalls?
Other than the legality and impact on insurance, you mean? Yes I believe you would have to have it re-mapped as the back pressure characteristics will be changed significantly. Consider leaving the main cat but taking the pre cats out, this is a simple (and legal!) mod that gained me 10 BHP with no disadvantages that I've noticed.
Cheers,
Peter Humphries (and a green V8S)
So Peter, just for clarification, I can remove the pre cat, not have to modify the ECU and still pass an MOT emmissions test?
If so, where is said pre-cat, is it the big collector at the front of the engine bay where the 2 manifolds meet, or is it somewhere else?
Is it an easy mod, who does it and how much would it cost? Would it make the exhaust any louder? any flames spitting from the rear on the overrun?
If so, where is said pre-cat, is it the big collector at the front of the engine bay where the 2 manifolds meet, or is it somewhere else?
Is it an easy mod, who does it and how much would it cost? Would it make the exhaust any louder? any flames spitting from the rear on the overrun?
So Peter, just for clarification, I can remove the pre cat, not have to modify the ECU and still pass an MOT emmissions test?
NO you still need a remap as the exhaust manifold characteristics have changed if you want to get the best out of it. You could run as is though but you may not gain anything.
If so, where is said pre-cat, is it the big collector at the front of the engine bay where the 2 manifolds meet, or is it somewhere else?
That's it. Some are riveted in and need a replacement unit, some can have the cat lifted out. Depends on the car and what was fitted.
Is it an easy mod, who does it and how much would it cost? Would it make the exhaust any louder? any flames spitting from the rear on the overrun?
Relatively but depends on how easy it is to remove the cat and whether you need a new manifold bit. Might make the exhaust louder but you still run under lambda control so no flames.
Steve
www.tvrbooks.co.uk
Mark Adams/Power Engineering in Uxbridge.
He can also set the car up to run U/L which can help.
He set up my Griff 500for both the previous owner and for myself. Costs around 125 pnd an hour for the road and his time plus what ever goodies he fits like a new chip etc etc.
All I would say is if the rest of the car is standard, then don't expect anything radical. It isn't until you go esoteric and start playing with the engine do you get the real benefit. But that costs a lot more pennies!
Steve
He can also set the car up to run U/L which can help.
He set up my Griff 500for both the previous owner and for myself. Costs around 125 pnd an hour for the road and his time plus what ever goodies he fits like a new chip etc etc.
All I would say is if the rest of the car is standard, then don't expect anything radical. It isn't until you go esoteric and start playing with the engine do you get the real benefit. But that costs a lot more pennies!
Steve
quote:
I already put unleaded in mine, should I not be? Its a 4.0 97 chimp. Should I be putting LRP in it instead?
It should run on Super U/L with higher octane. My Griff runs on premium U/L which is cheaper and helps keep the costs down.
As for exhaust note being fruitier... It may change but again you can achieve the same effect for less dosh by changing the exhaust.
Steve
quote:
So Peter, just for clarification, I can remove the pre cat, not have to modify the ECU and still pass an MOT emmissions test?
Yes you can remove the pre-cats, see a moderate performance gain without re-chipping, and still pass the MOT emmissions test. I would advise you to inform your insurers but that up to you.
quote:
If so, where is said pre-cat, is it the big collector at the front of the engine bay where the 2 manifolds meet, or is it somewhere else?
There are two pre-cats, one in each manifold, where the four pipes join into a single collector. The pre-cats are necessary to control the emmissions when the engine is cold but are not necessary to pass the MOT. I understand the pre-cats are often loose within the maifold and just fall out, but Sod's law says yours will be stuck in.
quote:
Is it an easy mod, who does it and how much would it cost? Would it make the exhaust any louder? any flames spitting from the rear on the overrun?
Don't know what effect it would have on yours, but on mine there was no significant increase in noise levels or exhaust note, it does spit flames but it always used to do that anyway!
Main reason mine came out is they were clogged and breaking up, and starting to cause a problem. The extra few BHP didn't hurt but frankly 10 BHP in 200 is not enough to notice and I wouldn't bother taking things apart specially to take the pre-cats out. But if you have it in bits for some reason, chuck 'em.
Cheers,
Peter Humphries (and a green V8S)
quote:
Peter,
As it happens I will have the exhaust off in a couple of weeks and was planning to replace the existing manifolds with a pair of de-catted items.
Is it reasonably straightforward to remove the pre-cats in the originals ????
If you remove all the cats then you need to change the ECU chip as well. If you remove the pre-cats, then you don't.
Steve
If you replace the manifolds with cat-less ones, you will have to run it without the lambda sensors (there's physically nowhere to fit them) so you *have* to get the chip reprogrammed to run open-loop. If you simply take all the cats out and keep the original ironmongery you have the option of leaving the ECU completely unchanged. Taking just the pre-cats out shouldn't affect the tune much and you could reasonably leave the chip alone IMO, although if you're planning to have it remapped at all I'd take the cats out *first*.
I would expect taking the main cat out to have a bigger impact and I'd recommend you get the chip remapped if you do this. If you do get it remapped, Mark will install a catless map if you ask him to. I don't see any particular reason why you should, it will work perfectly well in closed-loop mode without the cats present.
Hopefully this gives you some idea what your options are. But if you want final, authoritative confirmation that what you're planning will all work then I strongly recommend you talk it through with Mark Adams before you commit to it.
I would expect taking the main cat out to have a bigger impact and I'd recommend you get the chip remapped if you do this. If you do get it remapped, Mark will install a catless map if you ask him to. I don't see any particular reason why you should, it will work perfectly well in closed-loop mode without the cats present.
Hopefully this gives you some idea what your options are. But if you want final, authoritative confirmation that what you're planning will all work then I strongly recommend you talk it through with Mark Adams before you commit to it.
Gassing Station | General TVR Stuff & Gossip | Top of Page | What's New | My Stuff