SRT Hellcat Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 13 of 13 Posts

·
Registered
In The Market
Joined
·
43 Posts
Discussion Starter · #1 ·
Hi Everyone,

Im currently in the process of getting tuned, my logs are showing a good amount of knock.
My current mods are JBA cat deletes, 2.85 hellraiser, blower spacers, BT Catch Can, LMI, FIC 1200s and a dual pump system. I only run 93 from one of my trusted gas stations in town. Tomorrow I will be double checking my catless mid pipe for any rattle or vibration. Ruling out bad gas and exhaust vibration, what else could possibly cause this? Does anyone have any insight towards tracking down the KR?

Thanks in advance!
 

·
HOTM Winner
2017 Challenger SRT Hellcat
Joined
·
3,506 Posts
You are on the edge of strait 93, should be adding some octane boost if running it hard. Cat delete will cause higher knock, just like headers will too. Knock setting in the tune should be turned down 30 > 40%.
 

·
Registered
In The Market
Joined
·
43 Posts
Discussion Starter · #3 ·
I believe where I live is almost sea level DA. I know a few other cats around me running more boost on 93 than I am. I’m doing logs of pulls between 1500-4000rpm and KR spikes up around 3k rpm...I’m seeing about 4-8 degrees. Thanks for the info though! My tuner is trying to figure out if it’s false knock (like what you mentioned with cat deletes) or if I have crappy gas in the car at the moment.
 

·
HOTM Winner
2017 Challenger SRT Hellcat
Joined
·
3,506 Posts
It's probably some of both, false knock & needing more octane or gas issue. I'm at sea level also so your making more power than higher altitude which is why some octane booster or splash of race gas would be cheap insurance.
Good luck getting it dialed in.
 
  • Like
Reactions: 2fast4u

·
Registered
In The Market
Joined
·
43 Posts
Discussion Starter · #5 ·
Thanks I appreciate! I’m going to splash in some octane booster tomorrow after I tinker with the exhaust to see if it cleans it up.
 

·
Registered
Charger SRT Hellcat
Joined
·
234 Posts
2.85 with 1100 injectors is a mild set up, how much boost are you pushing and what kind of timing curve did your tuner use? Sounds like your tuner went a little too aggressive on the timing. Back off the timing , you’ll lose some hp but you won’t grenade your engine on a crisp cool morning or when you get a bad tank of gas.
 

·
Registered
Charger SRT Hellcat
Joined
·
234 Posts
You are on the edge of strait 93, should be adding some octane boost if running it hard. Cat delete will cause higher knock, just like headers will too. Knock setting in the tune should be turned down 30 > 40%.
Turning down your knock sensors is a dangerous proposition. Agreed it is a technique but I never let my tuners due this for any of my cars. Knock sensors save your engine, I wouldn’t touch them.
 

·
HOTM Winner
2017 Challenger SRT Hellcat
Joined
·
3,506 Posts
Turning down your knock sensors is a dangerous proposition. Agreed it is a technique but I never let my tuners due this for any of my cars. Knock sensors save your engine, I wouldn’t touch them.
Yes it's normal when adding more boost or changing exhaust which is louder, if you don't desensitize it some then it pulls too much timing & will not be optimized within reason.
 

·
Registered
In The Market
Joined
·
43 Posts
Discussion Starter · #10 ·
I’m only seeing 14lbs with the cat delete (assuming 15 with cats). Anyway I checked over the exhaust everything is tight. I also added in half a bottle of VP Octanium to treat a little bit over a quarter of a tank and drove a good 10 miles to make sure the octane booster is mixed in. I’m still seeing the spike of KR around 3k rpm all the way up to 4k rpm.
 

·
HOTM Winner
2017 Challenger SRT Hellcat
Joined
·
3,506 Posts
I’m only seeing 14lbs with the cat delete (assuming 15 with cats). Anyway I checked over the exhaust everything is tight. I also added in half a bottle of VP Octanium to treat a little bit over a quarter of a tank and drove a good 10 miles to make sure the octane booster is mixed in. I’m still seeing the spike of KR around 3k rpm all the way up to 4k rpm.
Contact Peitz Performance here in Houston & talk to Alex Peitz the owner & tuner & he can figure it out for ya.
 
  • Like
Reactions: 2fast4u

·
Registered
Joined
·
107 Posts
I see 5 degrees KR just after 4k rpm and it releases shortly after 4500 rpm. My tuner isn't alarmed by it. He says it’s false because we are on E85 and that fuel cause more false KR in these cars and it varies from car to car. Couple forum members told be they had exhaust touching the subframe cross brace just in front of the rear diff and they adjusted that and it cleared most of their 4K rpm KR if you are running 93 octane.
 

·
Registered
Joined
·
107 Posts
I don’t see any thing more than 1 degree sprinkle KR here and there when I’m Running 93.


Sent from my iPhone using Tapatalk
 
1 - 13 of 13 Posts
Top