hellcat wot afr

[mbray01]

Just curious where everyone is seeing the afr at on these
Yesterday's dyno session kinda opened my eyes on these things, afr is very lean, very similar to direct injected engines
Car makes the most power and accepts timing best at 12.1-12.3
at 11.9-12.1 it looses 25-30hp
at 11.7-11.9 it looses an additional 30 hp and starts getting into kr, pulling timing to eliminate kr nets same hp.
I also noticed that loosening the knock sensor settings to get an additional degree or more timing netted no hp gains.
Basically dodge has done their homework on this.
Just curious if anybody else is seeing these same afr's

This was 15lb pulley
14.5* total timing after all adders
air raid cai
50hp cheater shot

[HemitunerAJ]

Just curious where everyone is seeing the afr at on these
Yesterday's dyno session kinda opened my eyes on these things, afr is very lean, very similar to direct injected engines
Car makes the most power and accepts timing best at 12.1-12.3
at 11.9-12.1 it looses 25-30hp
at 11.7-11.9 it looses an additional 30 hp and starts getting into kr, pulling timing to eliminate kr nets same hp.
I also noticed that loosening the knock sensor settings to get an additional degree or more timing netted no hp gains.
Basically dodge has done their homework on this.
Just curious if anybody else is seeing these same afr's

This was 15lb pulley
14.5* total timing after all adders
air raid cai
50hp cheater shot

Where are you reading the AFR? Where is your sensor located?
Thanks
AJ

[mbray01]

I had a wideband in tail which usually reads .3 leaner than when I install one at collector
factory sensor reads .85 lambda, or 1bout 12.1 on e10 and read 12.4 at tail, so everything seems in line. It just loved it there

[Mep_q8]

they run very lean from the factory. I'm tuning one now and actually find richening it up helps.

[InnovativeDiesel]

I'm also tuning on a hellcat. With a 3lb pulley, I'm making the most power around 11.6-8:1 A/F at ~16(still safe for pump) degree's timing. Once I go below 16 degree's timing, it'll lose a bunch of power if the fuel is too fat. With your cheater shot(not sure if it's wet or dry), you'll probably want to keep the timing down below 15.

[mbray01]

im at 15 total.
at the track the other night it got 18 and loved it. but track temp was about 58*
the 50 shot is wet.
i think im gonna play with fuelling again. try a few other things

[InnovativeDiesel]

Cool, let me know how it goes. Are you using the recommended fuel jet or running a hair richer?

Thanks

[mbray01]

well, I am jetted for 65psi, which would make it fat, with the ecm commanding up to 92 at wot. so we are letting the ecm pull the fuel on the spray, which it does quite well. on spray still hitting the 12.1-12.3.
i am going to bring to track next week, and see what she likes fuel wise in real world environment. I will try for 11.9, then 11.7 and see where it goes

[CactusG8]

So making it a little richer helps or hurts. The OP states it looses a ton of power when making it richer. Then another states it helps.

[Hemituna]

Leaner and less timing is the go.
Don't be scared, they only burn up if you have too much timing in them.

[ddtech]

Yea i'm doing a Hellcat and Scatpack right now, both bolt oncars, scat pack has a 125 shot on it, just.. amazing how lean they run from the factory, the scat pack was a complete opp, it ran rich as hell.

[CactusG8]

Yea i'm doing a Hellcat and Scatpack right now, both bolt oncars, scat pack has a 125 shot on it, just.. amazing how lean they run from the factory, the scat pack was a complete opp, it ran rich as hell.

I am hearing tunes from both angles on the hellcat. And I am not saying one is wrong or right. I appreciate all views. On the hellcat forum I am on the tuners state it was only lean to pass emissions. But adding around 5% fuel to it picked up 30 plus horsepower. It was also mentioned that the timing is pretty much maxed out. Maybe with the extra fuel 1 degree advance from factory.

[2therock]

Are you guys reading the spark plugs?

[ddtech]

I always read plugs..

Being on E85 makes that super hard, so when someone's on E85, i relay heavier on AFR / Trap speeds.. a Dyno yes.. but overall a trap speed will tell the better story.

[Abdulaziz_pe]

are you experience LTFT and STFT while WOT ?

[CactusG8]

I am using a diablo handheld tuner for the Hellcat. I still have hp tuners. I used that for my stroker G8. However I have no clue on tuning a Hellcat. But Diablo agrees with you. On their test cars without pulley additions they state from the factory it comes in the low 12s. 12.1-12.3. They stated adding fuel just slows it down. That this car likes to run lean to make the most power which is a little unusual. A few are saying that it is done for EPA reasons. But as far as I know EPA does not test at WOT. But I may be wrong on that. I think they loosened up the knock sensors a bit and maybe added a slight amount of timing on their 93 tunes. Not much. But you said that did not even do anything for the hellcat. So basically if you are near stock just stay with the stock tune. You can utilize the Diablo though to up the rev limiter 600, turn on the fans sooner, and play with the throttle booster. I hear if you up the rev limiter and put her in manual with the automatic she will shift at 6300 automatically without having to hit the paddle shifters. That is good since it is still building a little power up to 6300 rpm.

[Hemituna]

12 - 12.5 afr is not lean on these.
Most run their stuff too rich...cos it is 'safer', cos if it fails the client can't say it was tuned too lean.
That is old skool thinking...just trim fuel to where it makes power...that is where it likes it...as long as you don't have too much timing in it, it will go forever.
The smaller and/or better the injectors are the leaner it will like to be.
I've done some dual injector per cylinder stuff with newer super fine atomisation injectors and they like to run even leaner, use way less fuel and still make more power...go figure...
If you run big, lazy, fire hose style injectors, it will appear to like more fuel and a richer afr.

[CactusG8]

the afr on the heads up display how accurate is it on the hellcat on wot? the guys on the hellcat forum state that if it reads 11.8 the true reading is about 12.1. They believe it reads .3 too rich.

[tbrtuning]

Very possible people are comparing what their display reads vs a tailpipe sniffer on a dyno and assuming the dyno wideband is correct and the factory one is wrong.

[CactusG8]

I think you are right. The OP states at 12.1-12.3 the car made the most power. If the car still had cats it could of been around 11.8 which is where Dodge set these cars to be. I also saw some blogs stating these cars are run super lean. 12.7. Not! They were being read with a stoich of 14.7 when the car has a stoich set up by Dodge at 13.6 or 13.7. 14.7/13.7 is around 7 percent. 12.7/1.07 is 11.86. Amazingly that is what they are reading on the heads up display in the car.