Re: got my viper dyno\'d - pic inside
all the tuning done on my vipers engine was done by manipulating the stock computers parameters. no aftermarket controller such as the mopar race controller or vec 1 & 2, etc. was used to tune my car. to my knowledge WCV is the only tuner in the world that has the ability to alter the stock computers parameters without resorting to some other means. the owner of WCV was a viper tech at a dodge dealer for 10 years and has a ex-caldwell lemans series race team viper tech working for him.
WCV has access to an "ENGINE DYNO" that gives accurate A/F ratios as well as EGT's etc. taking a A/F ratio reading from a vipers tail pipe on a gen 2 GTS coupe will give you a false lean reading as the tail pipe sniffer is over 10 feet away from the cylinder head as was the case on the A/F ratio reading you see on the dyno sheet i have provided here in this post. also don't forget you are analyzing the A/F ratio from a 10 cylinder engine not a V-8. also if you are running catalytic converters in which case i am this affects your A/F ratio as opposed to a viper that is not. thats why there are 02 sensors not only before your cats but after as well. that is also why catless exhaust systems get 02 sims installed on their rear 02 sensors. the vipers computer has different fuel maps that can richen or lean out the engines A/F ratio depending upon the prevailing atmospheric conditions such as the air intake temperature sensor, barometer sensor, manifold absolute pressure sensor, etc. if you want maximum performance from your vipers engine you need to do more research on the subject and then come back and play.
my viper engines A/F ratio at the headers is a 1/2 a point richer than what you see posted on the dyno sheet above. as an example if you were to richen up the vipers A/F ratio on the chassis dyno you would see a loss of power as we did. this indicates that the A/F ratio is to rich. also if you lean the A/F ratio out more than it already is you would loose power as well. it would be foolish to simply rely on A/F ratio reading from a dynojet chassis dyno to determine whether or not your car is running lean or not. i suggest you have your engine dyno tested on a "ENGINE DYNO" as well as chassis dyno too. all of WCV R&D on A/F ratios have been verified on an "ENGINE DYNO". also don't forget to check your EGT's and take plug readings. the type of spark plugs you are runnin as well as the heat range and gap they are set at all should be factored into the equation. also the spark advance and timing have to be taken into consideration as well. last but not least you have to know what your engines compression ratio is, which in my case is 9.8:1. obvioulsy if you are running a supercharger, turbos or nitrous you have to run a richer A/F ratio than i am. my motor has none of these power adders.
WCV shop resides at an elevation of 1,000 feet above sea level. depending on the elevation at which i will be driving my viper at dictates which type of fuel i run. at high elevation race tracks like nevadas silver state classic which is 6,000 feet above sea level i will run 91 octane fuel only. in my hometown where i live which is 3,000 feet above sea level i run 91 octane + an MMT octane booster which will yield approximately 94 octane. at low elevation road race tracks like phoenix international raceway in phoenix, arizona which is at 1,200 feet above sea level i will run 100 octane unleaded race gas. elevation is the biggest factor your vipers computer faces in deciding which fuel map its gonna use more so than air temperature or humidity. its also important to note that your vipers computer is slow to react to these changes as well, unlike cars with engines that have mass air flow sensors which the viper does not have. so make sure you give your computer a little time to adjust when you trailer your car to a lower elevation race track than the one you ran at the week before that was several thousand feet higher in elevation. thanx everybody for all of your concerns but i am fully confident in WCV work and my ability to manage it. they have given me a 1 year warranty on their parts and labor.
you know it was funny to see all the cars stacked up in their parking lot shipped to them from across the country to correct other well known viper tuners work that was done incorrectly. i even got to see the bills that some of these fools had paid these other so called tuners to do a botched job on their car and i was blown away by how much they were overcharged for a job that wasn't even done correctly.
good luck on your choices fellas.