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Old 04-25-2005, 06:42 PM   #1
jzvette
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Default 89 Pre-cats, Do I need them???

I have an 89 coupe and the floor gets very hot in the summer. On the advice of a friend I put down additional insulation, it helped but floor is still hot. Could my pre-cats be bad or getting bad??? I know that Eklers offers a replacement Y-pipe with no pre-cats, would that be a solution or will the floor still remain hot??? Any suggestions on how can I tell if my pre-cats are bad?? Any solutions to may hot foot problem. It's not to bad when the weather is cool. JZ
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Old 04-25-2005, 07:05 PM   #2
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The pre-cats help with the emissions when the car is warming up, but after that the main cat takes on the work. If your state uses a visual inspection to check for them, then you need them. Another thing to think about is a high flow cat, I got one last year, and the handwarmer in my cupholder doesn't work any more.
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Old 04-25-2005, 07:13 PM   #3
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A clogged cat will usually show up as excess heat, yes. They probably are plugged up.

Precats are unnecessary to pass sniffer tests, a new main cat would do the job better than the stock precats and main cat.
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Old 04-25-2005, 08:41 PM   #4
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The pre-cats went in due to old technology in the main cat. Replace them with a 2 1/2" SS front Y and a hi-flow 3-stage main cat to easily pass the sniffer, so long as there is no visual check. In case of a visual, gut the pre-cats.
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Old 04-25-2005, 09:54 PM   #5
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65Z01,
Are there sensors in the pre-cat and if so where will I put them if I install Y-pipe??? Will this make my cup holder and floor cooler?? Thanks JZ
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Old 04-25-2005, 11:04 PM   #6
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No there are no sensors in the precats. The Oxygen sensor plugs in on the drivers' side Ypipe just below where it bolts to the exhaust manifolds.

Most aftermarket Y's will have the O2 bung already, a custom job would require you to have a bung put in the new pipe.

If the precats or main cat are indeed clogged, you'll notice a gain in power and response, and a sharp reduction in temperature.
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Old 04-26-2005, 02:51 AM   #7
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Can anyone recomend an aftermarket Y-pipe with no cats and a better flowing main cat.
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Old 04-26-2005, 09:04 AM   #8
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I bought a 2 3/4" y-pipe from Allen's Stainless Steel exhaust. They are a little cheaper than Ecklers I think $180 for stainless and $150 for aluminized. They have a pretty good website. I bought a Magnaflow stainless steel cat off of Ebay for $55 but it was a little short so I had to make a little pipe in between. This really made the car sound much better and I could feel the difference because I think one precat was plugged.
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Old 04-26-2005, 10:21 AM   #9
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I tried the $199 SS mandrel bent front Y from MAM, but it was a little mangled when it arrived so I returned it and had a local custom exhaust shop build a front Y.

I installed a 3-stage hi-flow Random Technology cat, about $225 from TPIS. If you are on a budget, try Summit Racing for a low cost main cat.
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Old 04-26-2005, 09:37 PM   #10
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How can I tell if my pre-cats ot cat is clogged???
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Old 04-26-2005, 10:02 PM   #11
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Quote:
Originally Posted by jzvette
How can I tell if my pre-cats ot cat is clogged???
I went to a C4 class at Bloomington Gold where Ron Kane stated that you could diagnose a plugged cat with an infared heat detector. Some mechanics have these in their shop. You point it in front of the cat and behind the cat after the car is warmed up. If the temp behind the cat is significantly lower then it is plugged or partially plugged.
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Old 04-26-2005, 10:08 PM   #12
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will taking off the cats and running a 3 inch system in a L98 lose hp?
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Old 04-26-2005, 10:25 PM   #13
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No, it'll gain HP. It would lose a little low-end torque if it was 3in all the way. That torque didnt disappear, you just moved the peak to a higher rpm.
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Old 04-27-2005, 12:26 AM   #14
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How hard is it to hollow out the pre-cats??? Or is it not worth the trouble, and I should just buy a new Y-pipe without cats???
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Old 04-27-2005, 02:05 AM   #15
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Get the 2 1/2" SS front Y. I would only hollow the pre-cats if visual inspection were a problem.

The stock front Y is quite restrictive due to the waffle bends that narrow the true internal diameter. The same is true of the stock rear Y.
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Old 04-27-2005, 06:37 AM   #16
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Does anyone out there have the Dynomax Y-pipe without cats and rear cat set??? If yes, was it a good install and does it work well. I've seen the Dynomax set in Eklers.
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Old 04-27-2005, 11:32 AM   #17
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I didn't know dynomax made a front Y-pipe. I have their rear Y-pipe with Ultra-FLow SS mufflers, fit well.
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Old 04-27-2005, 12:07 PM   #18
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Quote:
Originally Posted by jzvette
I have an 89 coupe and the floor gets very hot in the summer. On the advice of a friend I put down additional insulation, it helped but floor is still hot. Could my pre-cats be bad or getting bad??? I know that Eklers offers a replacement Y-pipe with no pre-cats, would that be a solution or will the floor still remain hot??? Any suggestions on how can I tell if my pre-cats are bad?? Any solutions to may hot foot problem. It's not to bad when the weather is cool. JZ
You can diagnose this youself with an infared thermometer. The temperatures in front of and behind each cat should be within 100 deg. or so of each other. If there's more of a difference than that, the converter is probably plugged.

I use a GM Canadian export front y-pipe (no pre cats) and a Random Technology high-flow cat on my 89. It EASILY passes Ohio emissions, but we don't have a visual inspection. YMMV.
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Old 04-27-2005, 12:22 PM   #19
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Where do you buy the Front 2 1/2" SS front Y?
My two front cats were gutted out when one of them broke loose on the inside and started making a very lowed vibrating sound.

The car does sound better, deeper and a bit louder. My front Y was also cut and re-welded in the past... for god knows why?? and has been re-welded crooked and was rubbing on my X brace (I have a convertible) and have added washers on my X brace to fix the vibrating but this is really a plaster on a cut that needs stiches.

Is this Front 2 2/1 Y pipe a straight forward swap with the stock front Y pipe and will it fit on a convert without any clearance issues with the X brace and will it fit on the stock CAT and will it need any welding

I'm seriously considering it and plan on doing it myself... unless it requires welding.

Thanks!

Last edited by TheStef; 04-27-2005 at 12:41 PM.
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Old 04-27-2005, 09:37 PM   #20
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Has anyone out there now have the Dynomax replacement front Y-pipe without cats??? Along with it comes a main cat, I saw it in Eklers for about$250. Does anyone out there have this set-up and how good does it fit and perform. Thanks JZ
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Old 04-27-2005, 09:37 PM
 
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