Hi guys,
I don't know if i am in the right section, if not please moderators let me know and will gladly move along.

Yeah gas right... tell me about it! Let me start by:

*I had a System Charging issue on my Vette before the Meth kit. Causing the car to stall and run rich.

-Had my SC belts changed (TVS2300)
-Had the belt changed
-GM ignition wire set (MSD's causing misfire under load)
-Swapped GM alternator causing DIAG ELECTRICAL ISSUES for a MECHMAN high amp alternator 170v
-Last step was the ALKY kit
-Dyno tune (by a very reputable shop)

-MY SET UP
-LS2
-M6
-STOCK CLUTCH
-STOCK BOTTOM END
-STOCK TRANNY
-Cam (mild)
-Headers
-Xpipe
-CAI
-TVS2300 SC
-MSD FUEL BOOSTER

Having electrical issues with the Charging System was a PIA causing the car to run rich and that annoying beeping sound come on every 5 minutes it was just nerve wrecking. Took my car over to (reputable shop) and had it diagnosed and came out with the solution of swapping the GM alternator which i had just replaced along with the battery 5 months ago for a MECHMAN 170v....IT WORKED! No more beeping crap at the very least. After the alternator they moved along to replacing the supercharger belt since the old one had a rip on it (never slipped). Finally before the ALKY KIT they changed spark plugs and recommend e to change to OEM GM cables since the MSD ones that i had cause issues with misfire under load. Dyno Tune came along and even though i requested a before baseline run on the Dyno to see where i am standing before pulling the METH numbers it was never done, not sure why they choose not to even though they requested $100 extra for a baseline and agreeing on it.
A month went by (alternator was in back order) car was ready Picked up the car and drove it home (14 miles) and notice high coolant temp 225 at 45MPH and occasionally it would stall and also notice that on a FULL TANK i was ranging 174 miles with an Average consumption of 8.8 MPH!!!

Call them and let them know of such issues and that in my humble opinion it was a calibration tune related problem. Took it back the next day and they told me it was because a bad wire connected on the SC that was causing that and that there was no need to Dyno the car again. TODAY 8/17/18 Picked up the car again and the car was running much smoother even though it was very hot out there (92 FL) i was getting Coolant Temps of 205 A/C on stuck on traffic and it will drop to 199/200 as soon as started moving...BUT,,, once i started switching to the MPG I notice that on a FULL TANK i was ranging 174 miles with an Average consumption of 8.8 MPH!!! AGAIN!

My question to you guys is this normal? Should i see that much gas consumption with such mods? I was getting 28MPG before the Meth kit.

Attached are the pics of my dashboard were you can see the MPG and a FULL TANK picture @174mpg, ignore the Check Engine light since that turned on as soon as i took my car from the mechanic shop the first time right now it has been corrected. Also if you guys would like to chime in about the Dyno numbers for such mods it would be greatly appreciated.

THANK YOU!

 

Anybody care to chime in on the Dyno numbers?

 

Don't really know where to start on this one. Shoot, the dyno numbers look good. What supercharger, rear, and crank pulley combo are you running? What spark plugs are you using?

 

depends if they had to scale the injector data in the tune. if so, it can skew the math when calculating gas mileage

 

How many threads did you start in this?

 

Hey Mr. Motorhead!
I have the TVS2300 SC, changed the pulleys just as you had advised me to do so a while back to make a bit more boost, spark plugs are OEM, crank pulley is a Summit Racing.

 

Yea, i am a bit inclined on to the tunning side having something to do with it...i was told today by my mechanic to drive it a bit more on the Highway and see from there how it works ,,, there goes another tank of gas in less than 160 miles

 

It looks like you're running richer AFR wise before you start the dyno run. Your AFR and/or timing has to be way out of whack to only get those few miles out of a full tank. You're also running lean above 5000rpm. That needs to be addressed before doing much more WOT work. If you're running the injectors that came with the Maggie kit (probably 52#), they need to be upgraded. Also, you need to run a colder plug than what came stock with your Vette. I recommend the plugs that came stock with C6 Z06's and ZR1's. Don't remember the part number, but any parts store should be able to look them up.

 

Man you have never steer me wrong OldMotorhead! I'll follow your advices and stuff gets DONE ALWAYS! I found these spark plugs related to the ZR1, which one would you recommend? and what size injectors should i get? You are right the injectors on the Maggy are 52#, i thought that they were 80#...

 

 

Can't comment towards the coolant temps, but that average mpg includes the fuel burned while tuning and on the dyno. Reset it, drive the car for the tank, and then reevaluate your average mpg.

 

Hand calculate it to double check, my old heads/fat cam ls2 was getting like 35 on the highway and like 16 city.