I have a supercharged 91z28 with a rebuild motor and tranny. I rev it in the garage and the headers glow red just at the point where the headers mate with the heads? I thought it was a clogged cat. I just had the cats inspected, cut off to look inside and they are fine. My problem is that the car runs great but lacks power??? I put AFR heads, A ZZ3 cam edlebrock headers with a 3in cat back system, slp runners, ford svo injectors 24lb, crane hi6s with boost retard and I ran the same time with the new engine and supercharger as the stock engine last year??? 12.95 @ 108mph. I increased my mph by ONE MPH>>>>big whoop? Can ANYONE Help me figure out why my Z is running so sluggish? NO codes either?? an occasional code 32..egr.

 

You need to have it programmed. Glowing headers on idle mean your really rich.

 

well, i have my own chip burning kit and wide band o2. My o2 is at 12.5 and red headers indicate a lean condition since it will cause a very hot exhaust. They are only red just a little bit?? my plugs look good too. I've retarted the timming and advanced it from 0deg to 16deg advanced and no real change in performance??? Ive added fuel and taken fuel out via the chip and wide band, no change??? I thought my cats were plugged, had them checked and they are perfect???? changed the ingnition module and no change?

I'm stumped! HELP!

 

Actually this is a rich condition.

 

just a shot in the dark here, is there any chance the header itself could be clogged?

 

How do you figure that it is a rich condition? When more fuel is in the combustion chamber, there is more cooling, the a/f ratio is in favor more to the fuel, thus there will be less oxygen burnt = less heat, its the oppisite with a lean condition. A lean engine creates insane amounts of heat, why do you think it is a big no-no to run an engine lean besides the lubrication properties?

 

Open's mouth... inserts own foot.

NM man, I was off in a never never land.

Check your O2 sensors.

 

12.5:1 isn't all that bad off, if your O2s are still accurate (remember wideband lifespan is short, do you run the constantly or only for tuning?).

Maybe your timing needs work?

 

Could it be overtightened rockers? Seen that once Just an idea though.
Steven

------------------
383 Inches of stroked turbocharged fun.
If one is good shouldnt 2 be great?????
TURBO=TORQUE
TORQUE=FUN

My Car

 

No, my timming is at 6 deg advanced and i put my valve lash at 1/3 turn. Another symptom i am having is that when we have weather with 80deg pluss temps, my Z gets really hot in stop and go traffic??? When the Z gets to around 220, it rockets to 240 to 260??? As soon as i'm out on the open road, it cools down quick?? the only difference with teh new engine vs the old is that i removed the headder wrap from the headders. Could the removal of the headder wrap cause this? It does claim to keep underhood temps down up to 70% ???

 

ever fix the problem?

 

have you checked to see if your injectors are running at full duty cycle. If so you will need to go to a bigger set of injectors

 

Advance the timing. Retarded timing will make the headers glow red and over heat as well.

 

I would concur with the post above - retarded timing will result in a still burning charge in the header - which when it burns in there will make them glow.

Also the 6 degrees of advance indication above would worry me - if you are only seeing 6 degrees of total advance anywhere but probably cranking (and it may want more than that also) you are probably too low.


Chris

 

I am not fully informed about the relationship of AF ratio and EGT's. But I do believe that some of what has been said here is not accurate, or at least is oversimplified. Here's what I know.

If you start at stoich (~14.7:1) and go leaner, EGT's will initially rise. As you go very lean, they will start to decrease. If you go richer than stoich, EGT's will go down due to the evaporative cooling effects of unburned fuel. However, if you go very rich, especially if you induce misfiring, enough unburned HC can escape the combustion chamber to allow combustion to occur in the exhaust system. This will produce very high temperatures in the exhaust. An excessively retarded igntion also allow unburned HC to ecsape into the exhaust system and potentially combust there, causing high temperatures. Small amounts of retard may lower the EGT.

You also need to keep in mind the nature of the measuring instruments. Some O2 sensors are temperature compensated, others are not. And the com-ensation may be inaccurate. I have seen excessively rich readings when it is too cool. So if you richen up the mixture, which cools the EGT's, you may start to see an inaccurate (even richer than the real AF ratio) O2 sensor reading. The EGT's will be going down and the apparent effect will be exaggerated. As you richen it up further still, combustion starts to occur in the exhaust system, the EGT's will rise, the O2 sensor heats up, and the measured AF ratio is now closer to the "real" AF ratio. What I am trying to say is that excessively rich AF ratios tend to make O2 sensor readings inaccurate and interfere with establishing the true relationship between AF ratio and EGT.

How does this translate into a glowing exhaust system? Causes include very rich or very lean AF ratios. It can also be normal under high load conditions. I suspect, if the original poster is seeing glowing headers under no load, and 12.5:1 on his meter, that his meter isn't accurate and he is actualy very rich. Try leaning it out to 14:1 and see if the glowing headers go away. Obviously, don't run it at 14:1 under boost/load.

Rich Krause