WOW, Boost in Performance on my '84

Well guys, just for shits and grins I hollowed out my catylitic converter the other day. I wasn't expecting much at all to tell you the truth. Well after clearing it out completely, and bolting everything back up I started the car, and the flowmaster just sounded AMAZING. If I wasn't looking at the car at the moment I would not have believed it was MY Caprice. It sounded like it was so powerful that it could pick up the front end upon takeoff (exaggerating). Well, I was happy with the sound, but then I took the car out for a drive. It had great accelleration, and felt as if the car was more peppy. But the thing that really showed me an improvement in performance was while I was passing some traffic from a stoplight where two lanes merged into one (as I always do :wink: ). Anyway I'm pressing my luck but my car was really moving, and by the time the 2 lanes merged together roughly 900 feet from the light I looked at my speedometer was doing 75 MPH. My car has never gotten up to that kind of speed in that short of distance before. I mean its not exacty a huge gain in performance, and I don't have any bragging rights, but hollowing out my cat was definately worth it. I'd reccommend it to anyone who isn't trying to save our environment, and who doesn't have exhaust checks as part of thier emmissions tests.

The cat could have been partially clogged all along if you got that much performance out of it. You probably could have put a low restriction cat on it and still get more power out of it. You will probably notice better gas mileage with the restriction gone... that is if you can keep your foot out of it

Crasen nailed it. You should not have really noticed any difference - if you did then it's because the old converter was plugged at least partially.

I could see the mid-80s cats being restrictive though the possiblility it was partially clogged is good as well. These guys are right at least for newer stuff hollowing the cat/s is uaually a waste of effort, they have come a long ways in the 30 years they have been original equipment, the early stuff was very restrictive and in some cases the new stuff can actually help torque a LITTLE by providing an expansion chamber for the exhaust right near the motor.

A few years back I had a 84 Caprice ith a 305 and a 84 Stepside 4X4 with 305, I got an Edelbrock Performer intake for christmas one year and put it on the truck, made a nice difference and always wondered how it would have been on the Caprice, that little 305/4bbl was a decent combo for the car good milage and adequate power, the rest of the car rotted out from around it though.

I had replaced the converter in my '84 last year. It did make a big difference in low end torque and passing as well. I'm in the NYC region where emissions standards are tight on the older cars. It barely passed with the plugged up converter, now it passes well within limits.

NY State had tightened up the standards twice in 2003, as a result you hardly see any of the cars from the same era on the road. I took it as a personal challenge to keep the car emissions compliant and give NY state a big "up yours" at the same time.

Bob

I live in upstate New York (Spencerport/Rochester) and I've removed / disabled nearly all my emmissions in the car (PCV valve, EGR Valve, crankcase breather, extra vaccume hoses, hollowed cat) aside from the smog pump and the "spider" lines that go to the exhaust manifolds. The car suprisingly passed inspection 2 years in a row with no questions or complaints. Slackers maybe? Hey I'm not complaining, each time I disable/remove an emmissions component, the car runs better :wink:

I would re-enable the PCV system, Pete. If for nothing else - it will help prevent or retard the formation of engine-harming sludge.

when you say you "hollowed" your cat what does that mean exactly? what kind of process is it?

I live in upstate New York (Spencerport/Rochester) and I've removed / disabled nearly all my emmissions in the car (PCV valve, EGR Valve, crankcase breather, extra vaccume hoses, hollowed cat) aside from the smog pump and the "spider" lines that go to the exhaust manifolds. The car suprisingly passed inspection 2 years in a row with no questions or complaints. Slackers maybe? Hey I'm not complaining, each time I disable/remove an emmissions component, the car runs better :wink:
haha, my dad passed emmisions for 25 years without a cat in a '77 olds 442 w/403 :) I think you really only need a cat if the engine isn't running well (efficently).

Definitely hook up the PCV again as others have suggested. I used to be a believer in taking off all the emissions equipment myself, but I feel that the car does run more efficiently for me with it all operational. The car rides incredibly smooth and anyone that drives it likes the car.

Since I'm in the down state NY area, we have stricter pollution standards to meet that the rest of the state. I think it changes north of Rockland County. NY State is trying to get the older cars off the road (except anything over 25 is emissions exempt) and I wasn't buying into that crap. It was me against the NYS Emissions Nazis and I won.

Bob

Quote: "when you say you "hollowed" your cat what does that mean exactly? what kind of process is it?"

When I say hollow it out I mean smashing the ceramic type innards of the cat with a blunt object and a very long corkscrew type drill bit, and blowing it all out by running the engine before hooking the rest of the exhaust system back up. Its not very hard to do, just disconnect the catylitic converter from the pipe that leads to the muffler, and work at smashing the stuff out through the exit hole.

As for my PCV system, I may reinstall it. The only reason for keeping it off for so long is I saw a very big improvement in how smoothly the car ran without it. My buddy even commented on how well it idled afterwards while the car was sitting in his driveway.

Pete, that tells me then that you have a vacuum leak somewhere else in the system. The PCV system is factored into the A/F ratio and will not affect idle on a properly tuned and maintained engine and emission system.

Hmm, interesting. Its possible that when eliminating the PCV valve and associating hoses, I also eliminated the vaccume leak. If/when I reinstall the PCV system, I'll put all new hoses in with it. I might as well get a new PCV valve while I'm at it.

Apparently Texas doesn't have quite as strict emmission laws, we drove our old 85' Caprice Classic wagon for over 10 years without a cat. Whoever owned the car before us had it removed. Not having it gave the exhaust a nice rumble, though :biggrin:

hey pete you should make another recording of the exaust i would love to hear it now :devil:

Oh, you're right! I'll get on that tomorrow, and post it ASAP.

haha sweet. im looking forward to it

haha sweet. im looking forward to it
same here

on a related note: I purchased some fuel system cleaner tonight and put in my vurtually empty tank. I noticed the difference literally after 5 mins! My car runs MUCH better now... it responds faster and runs soooo much smoother. It used to have a hesitation/missing feel to it before... not anymore!

Yeah, that fuel treatment can really make a difference if an older engine like that. I know I still haven't gotten that recording of my exhaust yet, but I might hold off on that. I was looking though a local junk yard earlier this week and I was checking out an engine in an 85 monte carlo. It was a 305, with all the emissions just like the Caprice. But I noticed the exhaust manifolds looked different, and after taking a second look I realized they were headers!! They were emission legal edelbrock headers (even had the smog pump attachments) and a complete dual exhaust system in amazingly great shape (possibly a low grade stainless). Its not true dual because the two pipes connect together in a 3" pipe to go to the cat, then splits off again into to mufflers. So far I've gotten the headers, but tomorrow I'm going back to get the rest of the exhaust system. I'll have one of the workers turn the car on its side with the bulldozer so I can get it off easier. I'll use the flowmaster I've got now and get a second one just because I love the sound of a 40 series flowmaster. Talk about luck!!!! I never thought I'd find something like that in a junk yard.

haha now you really have me excited