Best Pre-Cat Destroying Tool
Discussion
Just finished doing this and it sounds lovely with the sleeve conversion! As well as cutting down on ambient engine temperature.
Did most of the job with one of these on a corded drill and wouldn't have used anything else in hindsight.
Does anybody know of anything better they'd like to share?
Well worth doing in my opinion, wear a mask though and prepare to look like you've been wearing eyeliner from the dust.
Alex
Did most of the job with one of these on a corded drill and wouldn't have used anything else in hindsight.
Does anybody know of anything better they'd like to share?
Well worth doing in my opinion, wear a mask though and prepare to look like you've been wearing eyeliner from the dust.
Alex
Brilliant I have been contemplating removing my pre cats. And have had the y piece off and seen my pre cats still in place but not been game to start bashing them out with the limited access but this looks like a Winner to initially break up the honey comb and extract the pieces. You say you are happy with the sound, does it " drone" at all ? because this is another reason why I haven't removed them.
NZ fan said:
Brilliant I have been contemplating removing my pre cats. And have had the y piece off and seen my pre cats still in place but not been game to start bashing them out with the limited access but this looks like a Winner to initially break up the honey comb and extract the pieces. You say you are happy with the sound, does it " drone" at all ? because this is another reason why I haven't removed them.
Get them out We had my manifolds off the car, and in a vice. Started with the long drill, finished it off with an angled crowbar and hammer. You can bash pretty hard without risk. Its the bits around the corner that are difficult with a straight drill.
The fully decanted sound is lovely, a nice brutal noise, about 102 decibels. I would advise against changing the main exhaust section - the silencers keep it bearable and legal for track days.
The fully decanted sound is lovely, a nice brutal noise, about 102 decibels. I would advise against changing the main exhaust section - the silencers keep it bearable and legal for track days.
Dr Mike Oxgreen said:
Shirley it wouldn't wise to do this with the manifolds still bolted to the engine? Risk of pieces going into a cylinder?
This is a very good point, I wonder if you jack up the rear of the car as high as pos. might help? Or is there a position you can Turn the engine to that leaves all the valves shut on one side, (prob. Not thinking about it) I know why not run the engine while doing the job. Wearing eye and ear protection of course. No but seriously has anybody bashed out there pre cats in situ. And had a problem with debri entering the cylinders?
Best get them out. It is a PIA getting the manifolds off, but you can the slot the lower bolt holes to facilitate future removal and quicker refitting and there's no risk damaging anything else whist hammering them out. It's also a good opportunity to do the fuel lines, inner-wing heat shielding and replace the gaskets whilst you have them out.
I know people have done them in situ, but it must be a back breaking job and cant do the bolts or gaskets any favours.
I know people have done them in situ, but it must be a back breaking job and cant do the bolts or gaskets any favours.
It took me about an hour per side, with the manifold in the vice. It's like drilling toffee with a pencil. You drill and bash and seem to be getting nowhere, then suddenly you are through to the other side, which cheers you up.
But it took the angled crowbar to shift the big bit that's around the corner on the side nearest the engine, and advice from someone who knew how hard you could bash it without risking going right through!!
But it took the angled crowbar to shift the big bit that's around the corner on the side nearest the engine, and advice from someone who knew how hard you could bash it without risking going right through!!
rburnham11 said:
Alex did you do it with the manifold still bolted to the engine or did you remove it. This is a job I've been wanting to do for a while.
Yeah I did it in situ. Wasn't that bad looking back, had the car up on jacks but I'm only 5ft 8 so I can fit more snugly into the gap between the bonnet and the wing when it's up! As for it sounding drone-y I haven't noticed anything like that, it sounds lovely to me, quite AC Cobra. I found that getting a henry hoover with no attachments and sticking it in the big end of the manifold when done was very beneficial for sucking all the soot and rubbish up. The big bits eventually come out by hand but with the huge bit it takes about an hour a side! Then start it up and put sheets over the wings and watch a load of crap go everywhere and experience the sound of V8 tractor until it all clears.
Then bolt the Y piece back on!
QBee said:
We had my manifolds off the car, and in a vice. Started with the long drill, finished it off with an angled crowbar and hammer. You can bash pretty hard without risk. Its the bits around the corner that are difficult with a straight drill.
The fully decanted sound is lovely, a nice brutal noise, about 102 decibels. I would advise against changing the main exhaust section - the silencers keep it bearable and legal for track days.
The fully decanted sound is lovely, a nice brutal noise, about 102 decibels. I would advise against changing the main exhaust section - the silencers keep it bearable and legal for track days.
Spot on 
jojackson4 said:
Read a post on hear the gent in question ( not me) did it with the
Manifolds in place
Smacked them out with the weapons to hand then tied a pillow
Case round each one and fired it up
Crap in the bag nice and clean
Not sure if I whould have done it
did this, no problemsManifolds in place
Smacked them out with the weapons to hand then tied a pillow
Case round each one and fired it up
Crap in the bag nice and clean
Not sure if I whould have done it
does removing the precast actually gain any BHP? I'm soon going to be de-catting mine by just cutting and welding it back up. So ideally I will leave the de-cats in place I think purely for the noise. But if they are restrictive then I would rather get them whipped out to free up some ponies
brett84 said:
does removing the precast actually gain any BHP? I'm soon going to be de-catting mine by just cutting and welding it back up. So ideally I will leave the de-cats in place I think purely for the noise. But if they are restrictive then I would rather get them whipped out to free up some ponies
Do the precats firstAnd yes more bhp and less heat under the lid
As long as you don't whack or poison a lambda sensor then the car seems to settle down to a nice idle quicker and is a bit more responsive, it might just be my head though! If I had to quantify the improvement I'd say 5 horsepower. Just from what I feel!
If you are don't remove the lambdas and accidentally hit one quite hard then you'll probably find the ECU goes into get me home mode and the car runs very rich until you get new ones.
Main thing is the cooler under bonnet temperature. The fans come on a lot less!
If you are don't remove the lambdas and accidentally hit one quite hard then you'll probably find the ECU goes into get me home mode and the car runs very rich until you get new ones.
Main thing is the cooler under bonnet temperature. The fans come on a lot less!
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