Modify your Pre-CAT

[Doc Fizzix]

Here is an easy way to add a little more fun to your Elan by remove the pre-CAT and hollow it out.

The Pre-CAT is the first section of the exhaust system right under the turbo and before the down pipe.  The Pre-CAT is a designed to heats up the exhaust gasses more rapidly in order to increase the emission process and especially on “cold-starts”.  The Pre-CAT canister is filled with a ceramic material that is an extreme constrictor on the escaping gases.







In most situations, before you attempt to remove the Pre-CAT you will have to soak attaching bolts with some type of liquid wrench or liquid bolt remover.

Once the Pre-CAT is remove, you will see that it is “clogged” with a ceramic catalyst that will flake away if pried on with a screwdriver.



To remove the “innereds” of the Pre-CAT, you will have to hammer on the “catalyst-guts” on the bottom end of the canister.  Make sure you remove the two bolts on the side of the Pre-CAT that hold the ceramic catalyst in place.





The canister was placed on top of two 2x4s.  I started with a hammer but then quickly changed over to a large sledgehammer (the enforcer) hammering on a lead pipe.  The lead pipe was placed inside the bottom of the Pre-CAT and held steady by hand. Use several solid hits like you are driving a stake through a vampire.



After a couple of good hit, the “guts” will come out and that is about all there is to it.



Can you imagine the exhaust trying to force its way through all this crap?  WOW - what a horse power robbing thief the Pre-CAT turns out to be.

WARNING: The hollowing out your Pre-Cat is not a legal modification to your exhaust system. By doing this you are risking fines and penalties from your licensing authorities. Any claims made here are based on personal experience and by modifying this part, you are taking full responsibility for any changes to your car regarding emissions, and any other performance issues. By performing this modification you are doing so at your own risk!

[Doug]

nice pre-cat there, Al.   <br><br>look at the picture below--those cells allow gas flow straight thru the cells in the cylindrical portion of the housing.  It is so tight and angles right at the end, so how can the flow not be obstructed somewhat!<br><br>and people wonder why we say the pre-cat is a restriction to exhaust flow   <br><br><br><br>hopefully you will inspire a generation of Federal and S2 owners to follow suit . . .

[Doc Fizzix]

I forgot to add <br><br>A special thanks to Doug for letting me use his Pre-CAT<br><br>Thanks Doug ;D

[techlectic]

Hey Doc,<br>Was there a noticeable change in the sound of your exhaust after you did your "upgrade".

[Mike]

I had mine removed soon after I purchased the car. The two things I noticed immediately were a huge improvement in throttle response with the revs winding up quicker. I had this done together with a 2.5" cat back exhaust and Magnaflow muffler instal, and the exhaust note no longer went "fizzzz". I'm sure the pre-cat change had more to do with the improvement than the exhaust and muffler change. Anyone in the US who has not removed the pre-cat material should do so, although some muffler shops will refuse to do the job due to EPA regulations. After watching the mechanic work on mine, you will do a lot of banging and swearing to undo the precat if you do it yourself, and it would help to have the car on a lift to gain leverage. I can't imagine trying to do this job with the car on stands, laying on your back, but to each his own.

[F1 LOTUS]

[quote author=Mike link=board=exhaust;num=1114116208;start=0#4 date=05/07/05 at 05:10:11]... I can't imagine trying to do this job with the car on stands, laying on your back, but to each his own.[/quote]<br><br>Unfortunately I can :'( as that's exactly what I did and today I'm going in again armed with new gaskets and studs to put it all back together...smoke me a kipper I'll be back for breakfast!...I hope :-/

[Doc Fizzix]

The big thing is to take your time, I soaked my bolt for two days with WD-40 before I even started.  I had only one broken bolt but eveything else went smooth.  I had a hard time getting the busted bolt out but when it was all done, I had a nice smile on my face and the perfomance increase is very noticable. ;D<br><br>It was well worth the time on my back

[Doug]

glad and a bit impressed that you guyz were able to get the pre-cat out on your own.  I watched the exhaust guy struggle with mine for about 30-40 minutes, using penetrating oils, then resorting to heating with the old blow torch and using the impact gun to get things loose!  :o

[Doc Fizzix]

I was not too bad, just had to take my time.  <br><br>loosened one bolt at a time, took several long beer breaks, and tried to stay calm.  The biggest thing is to soak the bolt real good before you start.<br><br>The hardest part was getting the shield off.<br><br><br>I have some more pics of me removing and installing the pre-CAT, maybe I should also post those pics

[Doug]

[quote author=Doc_Fizzix link=board=exhaust;num=1114116208;start=0#8 date=05/07/05 at 22:45:22]I have some more pics of me removing and installing the pre-CAT, maybe I should also post those pics[/quote]<br>video would be best to capture all the 4-letter-words and see the blood dripping off the hands . . .

[techlectic]

Tips on getting the cat away from the car once it's unbolted?  Mine has a sensor in it with a wired tied up against it (not connected to anything).  Anyone know what's up with that?

[Doc Fizzix]

You will have to remove the down-pipe before you can remove tha pre-CAT, once the down-pipe is removed the pre-CAT will drop right out without any problems.<br><br>Yes, mine also had a sensor but is was not plugged into anything,  from what I understand, some of the federal cars had this sensor connected but none of the US version Elans used this sensor, in fact, some of the US versions did not even come with the sensor installed.

[lotos]

Any problems passing emissions with this mod?  I was thinking you could just keep the engine running for a while before they test...

[Doug]

[quote author=lotos link=board=exhaust;num=1114116208;start=0#12 date=05/09/05 at 09:49:24]Any problems passing emissions with this mod?[/quote]<br>nope  ;D<br><br>[quote author=lotos link=board=exhaust;num=1114116208;start=0#12 date=05/09/05 at 09:49:24]I was thinking you could just keep the engine running for a while before they test...[/quote]<br>not absolutely necessary in practice, but in theory it is best to run at higher RPMS to 'light up' the main cat well

[lotos]

Well s**t, if it still passes the tough Cali emissions, and improves performance, and is FREE, why the heck NOT do it?  Not like any of the feds have any idea what the stock Elan emissions system consisted of.  GREAT MOD!

[Gregor]

I will also kill the pre-CAT of my Elan  ;D <br><br>We have to pass emissions in Germany too... But my main CAT  is also "out of the Elan" one year ago without problems during the emission test <br><br>But for this I have a spare pre-CAT in my garage.....   ;D  ;D

[Doc Fizzix]

Anyone in Texas know if the new emissions standards are the same as Cali? Austin is starting emissions testing this fall. I am sure this is nothing new to Houston or Dallas area.

[Elanlover]

Hi folks, I know I'm late to the party on this thread but I've got a question I'm hoping someone can answer for me. As some of you know, I've juist picked up a California Elan. One of the things I'd like to do is remove the precat but I'd like to do it in a way whereby the original precat is not changed in any way so it can be refitted if required. My original thinking was that this "stiffy" upgrade might do the trick but I'm not that knowledgable in this area so a couple of quesiotns come up.

First, is this "stiffy" a direct replacement for the precat (and some other piping)? In other words, would getting a "stiffy" (no pun intended) accomplish my goal of replacing the precat? Second, I'm led to believe that the Cali Elan has an additional emission sensor on it. How does replacing the precat affect this sensor? Does the sensor mount after the "stiffy" or where the precat is today? Would making this change cause the engine light to come on?

Thanks for your help!

[Doug]

there's no additional sensor in the CA car--at least in the actual exhaust--there IS one in the EGR vavle but that is up by the intake plenum

there could be an EGT probe in the precat in a CA car, but it is not for sure, and if it is there it is not connected to anything (I didn't check for this )


check the "stiffy thread" but I don't believe the stiffy would connect to a stock exhaust, it is a good pipe, but would have to be built onto a replacement exhaust. The stiffy connects to the TURBO and replaces the pipe from the turbo to the Pre-cat and the pre-cat.

you could knock the pre-cat cells out and then remount the pre-cat like Al did in this thread.

if you've got the cash the best idea is get a stiffy and get it Jet-Hot coated, then build a 2 1/2" exhaust behind it all the way out !