idk wut but since i changed my flowmaster 40 to flowmaster 10 and changed my sct tuner files that hemifever modded a hair so it wont have spark knock on low rpm under load. feels like i lost alittle get up and go! ive emailed hemifever to get back the original files and see if thats wut the problem was but if not.. u think it has something to do with not enough back preasure?

 

Backpressure is bad. You don't want it. You want smooth, even FLOW.

What does the rest of your exhaust consist of? (starting at the motor)

 

goes from pacesetter headers to aftermarket y-pipe to flowmaster super 10 to downflows. its as free flow as possible besides going with open headers or straight pipes this moslty started after hemifever switched the tunes im hoping when i get the original files it goes back to normal

 

Well, shucks... backing off on the timing will cost you a bit of pep, but if you run it hot enough to get pinging it can cost you a bit of engine destruction.

Exhaust systems are tricky things. Running a system that doesn't flow quite enough will rob you of top end power when back pressure builds up at higher RPM, but running one that flows too much will cost you on the bottom end by diminishing scavenging efficiency at low RPM. Then you've got other considerations that aren't about raw flow rate numbers... heat retention characteristics, acoustic reflection, and so on that aren't testable if all you do is shove a constant stream of cold air through them.

It's best to only change one thing at a time because when you change two things you can't know which is responsible for any gain or loss. I've known guys who've changed lots of things all at once and were thrilled with the gains they got, but who didn't know that one of those changes was actually costing them gains they could have had.

It seems a good idea to reload the old tune and see if it brings things back -- but if it pings, you'll want to unload it straight away. As much fun as a little extra punch can be, a blown engine sucks.

 

What's your pipe diameter dodgeman?

 

Similar story here. Had Sean (hemifever) fix my pinging issue as well, but had to cut it back slightly. Once a change my timing chain and get the gears installed (SOMEDAY), I will be having him reload the original or better.

 

what plugs ya running i changed to autolight 923 because i had the same problems but it went away. after install the airgap it runs awesome ill prob will never have to worry about it even on a lower grade and a higher tune it dont ping

 

the stock 2.25-2.5

 

Ive never had a ping or knock so the old tunes were fine even running 93 tune with 87 gas still none. But i only ran that for a few days

 

good news.. changed the tunes back and now i have no problem...