CAT ByPass Pipe

wcc · 10-31-2005, 10:25 AM

First off how can I tell if I already have this installed on my car or not? I've looked what I have now and I've looked at what they are new and from the outside they look very similar. Is there something distinct to look for?

Also, I've read past posts where some people say there isn't any difference and some even saying they are going to put the CAT back on? Also, some say they have lost power but increased top end. We don't have emission testing here in Michigan so the CAT isn't a big deal. If I don't have it, is it really worth adding it?

tonythetarga · 10-31-2005, 10:42 AM

You might want to show a picture of what you do have first. My personal opinion is that it allows the exhaust to get out quicker when unimpeded and if you have a K & N or similar air filter bringing air in quicker, then the car breathes and exhaust faster. It may have no real impact for normal city driving but on the track, I think it helps and it also drops a few a few pounds of weight you don't really need.
If you aren't tracking it, I'd say leave the cat on.

wcc · 10-31-2005, 11:09 AM

Ok, I'll take a couple of pics tonight and post 'em. I don't track the car but this spring I was going to pick up one of those performance chips. I just want to make the car a little quicker.

tonythetarga · 10-31-2005, 11:14 AM

I have an 86 and put in a chip, cat by-pass and K & N filter. I haven't dyno'd the car after (yet) but did dyno the before set up. I am hoping for a little pick up in HP as well.

wcc · 10-31-2005, 11:19 AM

When you dyno it let me know what you gained. That is pretty much the same set up I'm in the process of doing.
I did the fresh air intake, and put on a Borla exhaust. At least it sounds SWEEEEEEET!!!

tonythetarga · 10-31-2005, 11:30 AM

I am not sure if that will get done this fall or next spring. My car is a high miler that has had some refreshing. Dyno results at the tires was 188.5 HP and 157.2 ft/pds of torque. I was reasonably pleased to see that it differed only 15.5 HP from the factory rated 204 horsepower on the engine stand. I would think the chip and freeflow of air and exhaust will bring me back over 200 at the wheels.

cbeers · 10-31-2005, 11:32 AM

My '87 with Fabspeed bypass pipe, Borla exhaust and SW chip did 201hp at the wheels when tested last.

175k on the clock

-Chris

wcc · 10-31-2005, 11:40 AM

How much do these have from the factory? I thought it my owners manual said like 200hp. If that's FWHP then how much HP is at the wheels? So how much improvement was there for you?

BTW I have 204000 miles clocked now.

cbeers · 10-31-2005, 11:46 AM

I don't know the exact specs, but in '87 the factory bumped HP a nudge, possibly to offset the added G-50 weight. I THINK mine had about 210-215 factory, now roughly 235ish? (convert 201 at the wheels to flywheel numbers)

So, not wheel spinning material, but a nice upgrade

-Chris

wcc · 10-31-2005, 11:50 AM

That's nice! I can't wait to add that chip. I know that is going to "wake up" my car like eveyone says.

I just want to get these things in place first. I'm going to add the chip in the spring cause it is getting to be about that time in Mi where I have to put it away for the winter.

kepperly · kepperly's Garage

The cheap way to go is the bursch cat bypass, one in one out muffler , an aftermarket cone filter and go ahead and pay the extra bucks for the steve wong chip, thats what realy woke my 87 carrera up.

Keith Epperly
87 slant nose turbo look carrera cabriolet

TerryH · TerryH's Garage

Quote:

Originally posted by wcc
First off how can I tell if I already have this installed on my car or not? I've looked what I have now and I've looked at what they are new and from the outside they look very similar. Is there something distinct to look for?

You could say you either have a cat or a bypass, however I found my cat gutted so in effect I have a bypass that looks like a cat.

If you have a pipe no larger than your exhaust, you could assume it to be a bypass. If you have a smallish chamber that looks like a small muffler, that could be a working catalytic converter or as in my case a gutted cat.

Emission · Emission's Garage

When I had my CAT off, my engine ran cooler (by about 10-15 degrees F) and the turbo spooled much faster. You also save weight without a CAT.

wcc · 10-31-2005, 04:04 PM

Well, what do ya think? I'm guessing it's a CAT. It's definitely not a straight pipe.

Spede · 10-31-2005, 04:17 PM

Looks like a regular cat but only a part number will tell. Some euro pre-mufflers look exactly like stock cats.

fuelie600 · 10-31-2005, 04:38 PM

Its a cat. The OEM premuff has a smooth outer can.

Here's a pic of both:

The lower one is the cat. The upper is the OEM premuff.