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Senior Member
Fuel Economy
Quick question...gotta drive the G8 to Michigan this week, any tips on fuel economy? How well does the AFM work? I dont wanna bring it, but our other car is a lease and already is too close to the mileage than I want it, so the G8 gets a road trip.
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If you want to get any advantage out of the AFM you cannot exceed the speed limit, have a headwind, or go uphill.
Rotohack 102 intake - 102 MAF - TPIS 102 TB - TVS1900 ported & plated w 8 rib 2.5" front + OD rear
PnP Interchiller - RCR ported heads - RCR Lunati 219/231 113+1 - Forged Bottom End
ARH 2" LT headers - Solo 3" CB - MT DRs + M&H FRs on Weld RT-S
CTS-V fuel w Vaporworx - FAST 85s - Alkycontrol meth M15 + M10 - RCR tune
9.75@139.2 ? rwhp ? rwtq
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My AFM works up to around 75-78 if the road is flat; the lower the speed, the more it will stay on.
2009 Hot White G8 GT, CTS-V v1 fronts, Camaro 20's, BMR Sways, Eibach Springs, Rear Cradle bushings. GXP FE3's, BMR rear susp. Kooks 1 7/8 LT headers, RCR custom 3” exhaust, ported LSA blower, 2.38 pulley; Ported heads and TB; LS7 MAF, Racetec pistons, Scat rods, CTS-V crank; FAST 85 injectors; RCR Lunati cam: 223/238 .615/.601, 116 +2 LSA. CTS-V pump/VaporWorx cntlr. Built trans, Methanol injection. Rick Crawford built and tuned. Best 1/4 9.68 @142, 1.42 60'.
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Yeah, my AFM worked well at 73 MPH which is usually where I lock the cruise at. Sure, inclines would switch it off, but it took one HELL of a headwind to do it. I live in the plains and while not the flatest part of the plains, there aren't any mountain grades.
OP, make sure tire pressure is up to par and your air filter is clean and that's about all you can do short of tuning it for better MPG.
Chris
2009.5 MSM GXP 500ish N/A RWHP. Mods include but aren't limited to: Texas Speed 418 (6.8L) fully forged held together with ARP from top to bottom, PRC 255cc heads, Rick Crawford intake plenum, TB port, polish and tune, Roto-Fab 102mm CAI w/LS7 MAF, Kooks 1-7/8" headers wrapped with DEI, Corsa catless system, Circle D 3200 Stall, 3.45 final drive, BMR's complete street bushing kit and sway bars, Eibach Pro Kit, G-Force Axles, running on staggered VMR 710's with Bridgestone RE11 rubber. HSV triple gauge pack with Calais smokers kit mod, V6 tails, debadge/rebadge, V6 door handles, AU black door trim, Maverick Man under hood strut covers, & washer and bolt kit, fully corrected paint thanks to Adams Polishes and my hard work. Built with reliability in mind with some power for those times when you need to pass or go over a big hill. Just a poser, not a racer!
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Moderator, Retired
LOL
Don't ask cammed and supercharged guys questions about fuel economy. They have no clue. LOL
Start the car in engineering mode. Hold down left scroll wheel and start. Use the scroll wheel to find all active. When engine is in AFM it will change to half active. This is very helpful if you have stock exhaust. After market you can hear the tone change when it goes into AFM.
After 10 minutes in AFM it will kick out for 1 minute. You can defeat this. Kick it out before the 10 minutes and the timer will start again. It takes effort, but you need to feel the throttle to keep it in AFM. Cruise control hurts for the most part. Slight incline cruise will kick you out, but if you can feel the throttle you can stay in AFM.
Down hill you can keep AFM active to almost 80. Use that to have some speed going up any hills. Slowly back off the gas as you go uphill.
Rest in Peace Charlie!
Sold
Just a GT
Originally Posted by
RichsGreyGT
this site is hardcore modding central.
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Beyond Help
Fuel economy??
I thought that was how much the bastards jack it up from one week to the next.
things are not what they appear to be.....
2009.5 Liquid Red,Onyx Red, Premium Package, e85 Surprise Package
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Senior Member
Hahaha guys Im right there with you...this car was not bought with the intention of saving gas. I just dont have a choice, family emergency and my gas mileage car is a lease. Eventually ill be modding it! Thanks for the input though, it is greatly appreciated
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Senior Member
My H/C/I LS3 can get between 25-30 highway. The secret is to find the car's power band and put it in cruise control. Usually it's around 70 mph. Cruise control is the key though. Our only problem is the small gas tank.
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Moderator
Originally Posted by
-Ray-
Don't ask cammed and supercharged guys questions about fuel economy. They have no clue. LOL
I got 24.4 MPG on the trip to and from the dyno in CT. That included the dyno pull.
Len
White Hot 2009.5 Pontiac G8 GT
TVS1900 | Custom Texas Speed & Performance cam spec'd and remote tuned by Patrick Guerra | LS9 Injectors | Rotofab CAI | Corsa catback | Kooks 1-7/8" LTs with catted connectors
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VIP Member
I was getting about 26 running 85 according to the DIC. You can air up the tires to 50 psi and get less rolling resistance.
2008 MGM G8 GT Mods: Cam, Heads, Maggie 1900, Kooks, Corsa,BAP, Homelink, Auto Dim Mirror, Camaro brakes, BC Coilovers, and some fancy wheels w/ 265/40/18 ET Street II. Tuned by Howard at Redline Motorsports. 524hp 454tq on 7.5 lb boost
recorded at XP Racing, OKC OK 3/30/14, 11.82 @ 120 at TRP 5/3/14
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