Duramax Diesels Forum Truck of the Week
Old 09-24-2018, 05:29 AM
Lt. DMAX Lt. DMAX is offline
Join Date: Nov 2016
Location: Southern Tier of NY
Posts: 23
Default Mileage drop after Banks Intercooler tube

Sequence of events, LMM as it approaches 100k. Always ranged 12-13 around town and 15-17 highway.

Cleaned injectors with GM cleaner via fuel lines - noted a bit more responsive throttle and power. Didn't assess MPG.
Torqued all intercooler V bands, very noticeable increase in power and MPG increased. On a long trip into ADK park, mileage jumped significantly reaching 20-21! Around town up to 14-15.
With the noted increase in power just by torquing V bands, decided to pull the trigger and Installed Banks Intercooler Tube on the hot side with all bands torqued. Definitely more powder! But mileage has tanked. Back to 12-13 around town and on another trip to the ADK 17-18 on the trip.

Other than going back and double checking torque on the V bands, any thoughts on the MPG drop? All readings are via the DIC.


2008 GMC 2500HD, SLE, Crew Cab, Red (of course...)
Banks Intake/Filter, Diamond Eye downpipe, Banks DPF back exhaust, Banks Boost Tube.

New OEM Headlight assemblies at 100k, all exterior and interior lights upgrade to LEDs from Superbrightleds.com.

Pioneer AVIC-W8400NEX Stereo, (4) Pioneer TS-A1686R speakers and "Frost King" sound deadening to all (4) doors , Camera Source 5CS-GMTRO Backup Camera w/ Tailgate Bezel and harness.
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Old 09-24-2018, 05:35 AM
clrussell's Avatar
clrussell clrussell is offline
Join Date: Sep 2013
Posts: 5,189

Hand check your mileage. If installed correctly the banks will have zero negative effect in my experience
03 reg cab. Low and slow

07 crew long classic- stolen
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Old 09-24-2018, 09:28 AM
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gmduramax gmduramax is offline
Shits broke
Join Date: Jun 2008
Location: Nor cal
Posts: 3,143


Shitty diesel
2008 GMC duramax crew cab short bed 2500.

Thanks to Mike L, SoCal Diesel, and Abel Chevorlet.

Tailgate Crew Member #1
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Old 09-24-2018, 09:56 AM
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2004LB7 2004LB7 is offline
Join Date: Dec 2010
Location: Norcal
Posts: 1,572


Tail wind, head wind, up hill, down hill, colder weather, hot weather, fuel station #1 vs #2, 65 mph or 75 mph, etc.

Way to many variables to make an informed decision on the results. You would need to log the same trip multiple times through the same weather and speed, hand calculate the mpg and do it again with the banks.

Two or three tanks is hardly enough to get what you need to see real data. Try five or ten before switching over

When I do MPG testing it takes months because I can never get the exact same run at the exact same speed consistently enough through a whole tank to be reliable so I have the needed information. So I do it many times and average it out then make the changes and do it all over again

Oh, and dont forgot to take the placebo effect in to account when judging power and responsiveness
2008 Chevrolet 3500HD DRW LTZ
285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

2006 BRM Jetta TDI. Injectors, turbo, Malone custom tuning on ecm and tcm
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Old 09-27-2018, 10:28 AM
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monster50iii monster50iii is offline
Join Date: Dec 2014
Posts: 195

I bet you got a tank of good fuel.
Love your country, never trust your gov't
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