I'm trying to figure out which way to go, either with a straight pipe or a high-flow cat. Since we have no emissions here in MN, a simple pipe is obviously cheaper. Will a straight pipe gain more power over a high-flow cat? Will there be more resonance/interior heat with just a pipe? Which one is better than the other?

 

First off, you lucky Bastard!!!!
Since we're talking about an 86 (I think), the L98 ECM doesn't need as much exhaust backpressure as the LT1/4's PCM. So here are my answers:

1. Straight pipe is the way to go, less backpressure = more Hp/Tq!
2. Yes a straight pipe will gain more power over a high-flow cat, 5-10RWHP!
3. There might be more resonance, Cat's act like mufflers. Interior heat
with just a pipe will probably be less, Cat's don't even start to work until
600F. The lack of chemical reaction and surface area of the straight pipe
radiates much less heat!
4. The straight pipe is better for performance, the Cat(s) is better for lower
emissions (although they do contribute to the Acid Rain problem[oxides
of Sulfur]):eek:!

My suggestion to is jack the car up, measure the Cat(s) Flange to Flange distance, and what kind of Flanges you have. Go to a local hometown Muffler shop (not a chain/mall store type) and ask them to fabricated you "off road" test pipe(s). That way you have the straight pipe now, and if down the road you need Cat(s) again, it's any easy bolt on!

:crazy:NanoBrain:crazy:

 

The cheapest/quickest route might be to just have the shop cut the ends off your cat and weld them to a 3" dia SS pipe.

Later, if you need a cat, just get a Random Technology to bolt up.

Just clamp the AIR tube to the exhaust pipe for now.

 

Thanks for the advice guys. Is the AIR tube connected to the air pump? If so, there's another reason to get the Air Pump Eliminator kit! :)


[Modified by FlyboyZR1, 9:24 AM 8/23/2002]

 

:yesnod: :yesnod: This is exactly what I did because I have to test emissions every 2 years...works very well

 

I just gutted my cat..........that way it looks like there's one there but it's almost empty inside.......we have a visual inspection here so if anyone looks (they haven't yet) it looks like it has one :seeya

 

I have eliminated the pre cats and added a high flow main cat. Th only problem I have had is the dredded code 32 from time to time. It dosen't create enough back pressure for the egr system. Haven't fund a way to cure this yet.

 

I didn't waste my money on a air pump eliminator kit. Instead I just gutted all the pump stuff out of my air pump. Now it freewheels just like the air pump eliminator, looks like all the emissions stuff is in place and it cost me nothing but the time to take it apart and do the work. :chevy :chevy :smash: :smash:

 

I am running true duals with no cat or precat, just mufflers. It does get to be a little loud especially on the highway but I don't mind. Mine does tend to throw the code from time to time as well and yes the side of the trans tunnel is a bit warm but you can just get some insulation and put down underneath the carpet.

 

Steel Blue 91, to eliminate that code, wire a diode in from the EGR command line to the EGR Solenoid back to the EGR Temp Sw.

This way, when the ECM commands the EGR On by pulling the EGR Solenoid line low, it will see the EGR Temp Sw in the low state and know that the command was executed OK. Yet on startup the EGR Temp Sw will be in the high state and no code will be thrown.

This would also work if you want to eliminate your EGR system, though I'm sure that never happens.

 

Cheap way/easy way=gut your cat.