Welcome to Modern Mopar Forum

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customize your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

Sign in to follow this  
Followers 0
toyak

Supercharger/AFR

Tonight I just picked up my 2012 392 A5 from an engine rebuild secondary to piston ring failure. The pistons are forged diamonds (compression is 10.1 to 1), rods are forged Manley, hellcat injectors, comtec gaskets and otherwise basically stock. It is a Magnuson 2300 at roughly 5.5 PSI and otherwise stock. The tune is currently a "break in tune" and for 90 octane gas. My concern is that my indicated AFR both banks is consistently running 14x-15x, usually between 14.5-15.5. I am thinking I should be be running between 11x-12x, opinions?

Share this post


Link to post
Share on other sites

Thanks,’the shop recommend no w/o throttle for the first 250 miles. I have to check my boost gauge which appears to be inop. I have only put 5 miles on the car.

I flew home from the lower 48, picked the car up after hours, drove home raised the hood,looked at it, shut it and went to bed.

Share this post


Link to post
Share on other sites

I am hoping it becomes a fun machine. The back ground: this is my 4th challenger. In 2009 October when Chrysler looked like it was going to die I bought a 6 speed R/T. On Dec. 31, 2010 I bought the last new 2010 SRT 6.1  6 speed in Alaska at a very good discount, pretty much a daily driver and raced as much as I could in the summer months. Put about 150 trouble free passes and several auto crosses on it. I sold it after 36,000 miles in the fall of 2013 and in late winter of 2014 I bought a 2012 6 speed SRT, ran it in 2013 and part of 2014 when a half shaft snapped and after fixing that I glazed the clutch. I sold yet again and promised myself never again. This lasted 4 months and I bought another 2012 auto this time. I had a great season with it racing, an extremely consistent car. I was down to a 12.04x with just drag radials and essentially the trinity 93 octane tune. Of course I could not leave well enough alone and decided to supercharge. Living in Alaska has many good aspects to it and some bad ones. Getting things shipped to Alaska is a bad one. The shipping costs to get a supercharger up here was going to be pretty outrageous. Luke, at Steve Whites was willing to work with me on problem solving shipping and was also offering a lot of advice {including tuning the car remotely the magnuson tune is not particularly good (understatement)}.

I ordered the supercharger and fortunately decided not to do the install myself. Written instructions from Magnuson had several mistakes, wrong and missing parts in the kit including the fuel injectors (a bad mistake and not realized until much later) and handheld tuner. The kit was installed by a local speed shop with a good reputation. I insisted on using the tune from Magnuson (supercharger warrenty and a daily driver) so the installer emailed magnuson and installed the tune. The car was immediately  dyno'd and I was making 30hp less then before the install. Two tunes later and no real improvement. The installer then looked at the tables with his own hp tuning software and realized the tunes were way off and very high AFR's 18-19's on dyno pulls. This led to heated email exchanges between the installer and the magnuson tuner. The magnuson tuner sent 7 more tunes and eventually the car got up to 465hp but that was the best it could do with the last three tunes. I and the installer then decided I would bring it back in spring for him to do the tune. The car drove fine other then the MDS system was still on and every once in a while it would stumble on acceleration if I did so from about 1500 RPM. I contacted Magnuson immediately about the MDS and stumble and after multiple emails and calls finely got a response but their technical service person could never get answers from the tuner. I never had the opportunity to really drive the car hard because it was winter and snow covered road. March came and I took the car in because I wanted a compression check done before the tuning session in April. The installer tried to talk me out of it because he was convinced I would have more symptoms other then an occasional stumble. The compression was low in both cylinder 1 and 2. About 1/3 of the piston ring was MIA in cylinder one (later found during install down by the catalytic converter). A lot of phone calls and emails were exchanged between myself and Magnuson. They did agree to pay for the cost of pulling the engine and installing it but for nothing else as a take it or leave it (no warrenty because the car is a 2012). I did investigate going to court but the advice was the cost/benefit was not worth it even though the case would be a win (I saved all the emails from Magnuson and the installer had saved his and copies of the tunes from the magnuson tuner).

So the car is back with an engine that has been built for 700 plus HP. I am expecting to make 500hp and I should be able to have the engine broken in and the final tune done by the final races of the season, Labor day Weekend. Go team go!

Quote

 

 

small challeger picture.jpg

Share this post


Link to post
Share on other sites

Yeah man what a mess! Doing this to any car is a risk, and especially with Mopars it would seem sometimes.... but the reward mostly removes all the stings of the past!! Good luck and keep us posted!!

Share this post


Link to post
Share on other sites

Brief update. I went to the track this Sunday after an unexpected invite to a closed event. The Chrysler dealer (Gene's) in Fairbanks Alaska rented the only drag strip in Alaska (Palmer Raceway) which is 20 miles from me but 325 miles from the Fairbanks. This was an event for employees, family and friends plus people who had SRT's and all for free which I thought was pretty cool and thoughtful since many us did not travel to Fairbanks to buy a car from them.

I had not reached the 500 miles the builder wanted but i was knocking on the door with 460 miles. Of course I did not bring my drag radials because I had no intention of racing and in fact was still on my snow tires because the car went into the shop with them on and I had no time to change to my all seasons this week. 

There was no track prep and I did a lot of spinning. 6 passes netted trap speeds between  116.0 to 117.5. My boost gage indicated only 4.5 PSI on what is advertised as 6psi super charger and after my adventure this winter Magnuson noted "well it is only about 5.5psi because the 392 pistons are weak. The belt does not seem to be slipping nor does anything look, sound or act loose. Hopefully it is just my gauge. My car goes back to the shop next Friday to refine the tune while dyno'd and that should provide answers. Best case it is a gauge off by one PSI and worst case, well I won't dwell on worst case, maybe just a smaller pulley. 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0