I'm wondering if it's normal to only see exhaust coming out of one set of pipes out of the mufflers...I mean only one of the two on each side has any exhaust flowing out...the outboard ones...the inboard ones have no soot inside...or not much anyways...

Also I'm wondering if I should change my cat converter as it's old and has about 60000 miles on it...an 88 stock one...I'm reading that it might be a performance killer if it's plugged...I don't think it is, I think the 3800lbs of car plus me in it might have something to do with the non tire smoking burnouts??? :confused:

I've got an 88 convertable with no mods...thanks for the help
Dave

BTW where I'm from I don't get emmissions testing so if I wanted to what would be the best performance for the cheapest in terms of the cat converter???

 

i believe in that year only 1 set of yips was functional, thats why you only get a buildup on one from each side.

and if you don't got emissions testing...dump the cats. weld in some straight pipe in place of them. and it will sound a little better too :thumbs:

 

:iagree:

 

That's true, out stock mufflers only flowed from the outer pipes of the two in each muffler.

You will get a nice air flow increse from replacing the front Y with a 2 1/2" mandrel-bent unit, cut the ends off the cat and weld onto a piece of 3" pipe of the same length, install muffler elims out back.

Also install a K&N air filter with cut lid and add an AFPR to match fuel flow at WOT to the increased air flow.

Also install a 160 deg theremostat & fan switch.

Delete the spare & jack and try those burnouts with 1/3 tank of fuel.

If it's still a probelem put about 35-37psi in the rear tires.

Oh, and remove that "frisbee" (the 10lb disk) from the front of your water pump pulley. It's sucking up 10hp.


[Modified by 65Z01, 2:48 AM 6/10/2003]

 

The reason only one of the 2 muffler outlets on each muffler works is because you do not have the Z51 or Z52 option and because Chevy thought that the high performance 2 outlet mufflers were too loud for the convert. I believe they only came with the performance axle also. My 88 Z51 coupe has the 2 functional outlets and a louder exhuast note than the standard suspension cars. On my ex 85 Z51 both outlets were functional but the muffler was not any louder than the non Z51 1 outlet mufflers. In 88 the non Z51 cars were rated at 240 hp and the Z51/Z52 cars were rated at 245 because of the less restrictive mufflers. Of course the Z51 package in 88 included the larger 13" brake rotors and HD calipers (which is why they came with 17" wheels to fit the larger rotors), HD cooling ( with extra cooling fan),finned PS cooler, longer air dams, engine oil cooler, fast ratio steering, plus the HD suspension upgrades. Having owned or driven most Z51 and non Z51 cars I feel the 88 was the best handling C4( it had the heaviest spring rates and larger stab. bar than other years except the 84 but same front rates i believe). While the 84 might have been a little better, only on totally perfect roads, but the 88 was better if there were any road imperfections. On a mountain road my 88 will totally lose my 95 non Z51 car. If I ever see a Z07 95 in the same condition as my 95 I will buy it and trade/sell the non Z07 95 (they did not make a Z51 option in 95)

 

If your cat is plugged, youll really notice it bogging and there will be alot more heat in the footwell. You can replace it anyway if you want, Id use a Random Tech or Car-sound cat.

GM made a stupid call to put 4 tips on these cars and not make all 4 functional. I have Z51, and still only 2 tips are functional.
Apparently it varies from year to year and options as to whether all are functional.

 

Thanks for the ideas and tips guys...

Around town I think my vette is very quiet...as quiet as family cars, I can barely hear the exhaust...and on the highway I think there is more noise from the wind or tires than anything...I will look into the cat removal and since these stock mufflers are getting old maybe some new higher performance ones with 4 functioning outlets...

See I made the error of painting my exhaust when I put in the new Y pipe last month...it was all out on the bench and I thought what the hell lets shoot the whole Y and mufflers(pretty bad looking) with some nice metalic exhaust paint...and they looked awesome, untill now I see one pipe out the back shinny silver and one soot black :eek: guess I'll have to paint the inside black to match???

And the 10lb frisbee? I should take that off? I'm guessing it will idle worse??? Is this a very common thing to do? I was just looking at it yesterday as I inspected the front area for the rd camber brace I'm thinking of getting...My convert has the X brace underneath already and seems pretty stiff like you said...I didn't know the 88s had a suspension upgrade but I do see the heavy brake callipers with the heat sinks you talk about...

K&N filter and cut the top off of the lid? I'll have to look into that more too...

Thanks again for the help guys... Dave :)

 

What everone said about the tips is true.

Even if you don't have emissions testing now, you will. That's the way things are going. If you plan on keeping the car awhile I wouldn't get rid of the cats. You can get good power without doing something that drastic. It would only have a small improvement on top end anyway but your problem seems like it's on the bottom end.

And what the heck is a Frisbee. I don't have one whatever it is.

BIG JIM


[Modified by BIG JIM 54, 8:33 AM 6/10/2003]

 

The frisbee is a 10lb weight sitting on the front of the Water Pump, I forget exactly why it was put there, something about a different pulley on another component, but removing it adds about 5-10hp and it wont affect the idle at all. It might make the car a little louder from the extra power though. (it started in 88)

K&N open lid, all you do is remove the air lid, and cut a big square hole in it. Its proven to help the L98 by say 5hp. It wont hurt anything, Ive run mine that way for about 12K mi. It doesnt help the LT1 so much.

Please run searches on them, the K&N thing comes up once a week.

 

Yeah, the frisbee looks prety easy to remove, just 4 nuts holding it on...I'm wondering if I need to hold the bolt heads from behind the pulley...very tight back there...or are they studs that won't turn...and I read about spacer washers I need to maybe install instead of the frisbee...this sounds to me like the bolt heads would be too far aft without the disk there??? And hitting things? I'm going to have to pull it off and see for myself what I need to do...

Oh yeah and the air filter lid...you mean to cut on the part that has those few slanted gaps and holes for the air...just cut a big hole in that? Sounds like overkill but I'll take a look...I don't have the K&N filter yet anyways...

I'm thinking now I'll leave the cats alone as I don't want troubles if the emmissions testers get on my butt...

And the rd camber brace, well it looks pretty tight near the front passenger side for me to bolt anything to the a arm??? I'd love to see some nice drawing or diagrams to show me what the installation would require...

Oh well lots to think about this weekend in Montreal at the Canadian Grand Prix...lets all hope for a big Ferrari blow out and have Micheal Schumacher regain the F1 points lead!!! :cool:

Thanks guys Dave