[clg82]

Well finally reached break-in mileage and took the car to ventura and did some spirited driving on the highway as well as some side roads, buddy that I was driving with in a GT350 (i know i know ) said he noticed some puffs of black smoke coming from my tailpipes when going full throttle.....the car is basically stock aside from a throttle body and catback borla exhaust, is this normal to have black smoke coming out when going full throttle? Something I should keep my eye on?

[Crusher Camaro]

Yes, more obvious under WOT.

I notice it even more when traction control kicks in.
Pretty sure they keep these engines on the rich side when under boost.

[Stephen12ZL1]

normal for a little puff as these things run pretty rich...nothing to worry about. If you did it more than once, the smoke would likely be less.

[clg82]

Probably a stupid question, but why would GM tune the car to run so rich?

[Stephen12ZL1]

Originally Posted by clg82

Probably a stupid question, but why would GM tune the car to run so rich?

fuel has a cooling effect in the cylinder so richer is cooler with less tendency towards damaging detonation. This is especially true in supercharged applications because of the heat generated by greater cylinder pressure.

[LT4Greg]

The engines are tuned pig rich to keep from blowing up. If it runs too lean then you get engine damage and or failure.

[Camaro1973]

Originally Posted by clg82

Well finally reached break-in mileage and took the car to ventura and did some spirited driving on the highway as well as some side roads, buddy that I was driving with in a GT350 (i know i know ) said he noticed some puffs of black smoke coming from my tailpipes when going full throttle.....the car is basically stock aside from a throttle body and catback borla exhaust, is this normal to have black smoke coming out when going full throttle? Something I should keep my eye on?

Be very careful with this, as puffs of smoke may not be simply from running rich. This is a very common sign of detonation. Puffs would be bursts of black/greyish smoke. Common black smoke from running rich doesnt usually happen in puffs, unless its happening immediately going full throttle. If the puffs are under load and at WOT its very possible its detonation.

[hawk02]

Originally Posted by Stephen12ZL1

fuel has a cooling effect in the cylinder so richer is cooler with less tendency towards damaging detonation. This is especially true in supercharged applications because of the heat generated by greater cylinder pressure.

This and the computer is also programmed to dump more fuel to cool the catalytic converters. It referred to as cat over-temp protection or COT.

[Gunkk]

Originally Posted by clg82

... is this normal to have black smoke coming out when going full throttle?

Yes it's normal. Don't worry about it.

[JSH]

Black smoke normal, blue smoke death

[Joshinator99]

Originally Posted by Camaro1973

Be very careful with this, as puffs of smoke may not be simply from running rich. This is a very common sign of detonation. Puffs would be bursts of black/greyish smoke. Common black smoke from running rich doesnt usually happen in puffs, unless its happening immediately going full throttle. If the puffs are under load and at WOT its very possible its detonation.

This. The OP is in California, where if I’m not mistaken only 91 octane is available. So some knock retard is not off the table.

[JSH]

And no or high flow cats equal lots of black smoke

[SJFGTO]

Originally Posted by hawk02

This and the computer is also programmed to dump more fuel to cool the catalytic converters. It referred to as cat over-temp protection or COT.

Yes^^^

[Z OH 6]

Originally Posted by Stephen12ZL1

fuel has a cooling effect in the cylinder so richer is cooler with less tendency towards damaging detonation. This is especially true in supercharged applications because of the heat generated by greater cylinder pressure.

That may be the generic answer, but I can tell you that we had two Hellcat's for over 2 years and one never puffed smoke, the other always did on hard acceleration and I doubt the tuning was any different between the two. Most of the Hellcat videos I've seen rarely ever puff any smoke. I've seen a lot of ZL1s online that seem to puff black smoke so I know its apples and oranges comparing a Hellcat to ZL1 but both are similar engine configurations, the only major difference being that the ZL1 is direct injection. Quite frankly, performance car or not, I think its embarrassing to have a car puffing smoke on hard acceleration. I haven't noticed mine doing it, I've seen a little smoke once or twice in the rear view, maybe its doing it more often than I think but I haven't been following my car while someone else was driving it.