Curious... MPG for an inline 6???? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72BlckButy · 02-24-2008, 12:08 AM

What kind of MPG do the original inline 6's get? I've seen a lot of threads about increasing MPG in a V8, but I don't recall hearing anything from the inline 6 crowd...

zeeklu · 02-24-2008, 12:29 AM

My 67 K10 short fleetside 292 with a 4 speed gets around 13 mpg.It has a Holley 390cfm , headers and 373 gears. Chris

zeeklu · 02-24-2008, 12:31 AM

http://67-72chevytrucks.com/vboard/s...d.php?t=172346 Here's a good post about mpg. Chris

**Palf70Step** · 02-24-2008, 03:26 AM

There is typically not a whole lot of difference(maybe 1 or 2 mpg) between the inline 250 and a small block V8with all other factors equal (driving style/tranny/gears)

68Stepbed · 02-24-2008, 03:30 AM

I remember mine used to get pretty decent mileage. It was better than my 350, but that was probably because I couldn't keep my foot out of the throttle with the new 350

I know my mileage got alot better with the headers though.

PanelDeland · 02-24-2008, 03:42 AM

I would think that a 6 with headers and a couple other power enhancements with a 3:73 and 700R4 would maybe get 17-18 under ideal conditions.If you are looking for real milage and want to pay top shelf prices,you might go to the 6 from a late model Trailblazer(w/EFI) and auto.Most I have looked at run a 3:42 gear ratio.I think they get around 22-24 MPG.

68gmsee · 02-24-2008, 04:04 AM

Quote:

Originally Posted by PanelDeland

If you are looking for real milage and want to pay top shelf prices,you might go to the 6 from a late model Trailblazer(w/EFI) and auto.Most I have looked at run a 3:42 gear ratio.I think they get around 22-24 MPG.

Mine (2006 LS) gets closer to 21-22 on the highway. Not sure if it would require major modifications, but it would be a great little engine for our trucks...

Willy Prost · 02-24-2008, 07:14 AM

15-17....up to 20 if you drive like you have a live grenade between your foot and the gas pedal and you don't have a death wish.

72BlckButy · 02-24-2008, 08:30 AM

I'm not looking to swap out the SB400, but I've always been curious if they got better gas mileage than a V8.

Now, if my truck had an inline 6 I would definitely keep it in there, because you don't see a lot of them out there anymore.

AuggieStyle · 02-24-2008, 08:34 AM

Quote:

Originally Posted by PanelDeland

I would think that a 6 with headers and a couple other power enhancements with a 3:73 and 700R4 would maybe get 17-18 under ideal conditions.If you are looking for real milage and want to pay top shelf prices,you might go to the 6 from a late model Trailblazer(w/EFI) and auto.Most I have looked at run a 3:42 gear ratio.I think they get around 22-24 MPG.

i have been thinking of this since i read your post, with the price of brackets for 6 cylinders A/C AND P/S it would almost make it worth it. i wonder how easily it could be done.

lukecp · 02-24-2008, 08:37 AM

I'm sure a Trailblazer 4.2 would get even better mileage in one of our trucks....a Trailblazer weighs around 5000 pounds if I remember right, and our trucks are closer to 4000 pounds or even less. I'm sure the 6 weighs less than a small block V8 too...plus with 270 net horsepower it would have some nice power, quite a bit more than a stock 350.

jm8872 · 02-24-2008, 08:50 AM

My '72 LWB has a 250 inline 6 with granny 4 speed and 4:11 gears and it gets 14 mpgs.

shifty · 02-25-2008, 08:46 AM

i was lucky to get 10mpg ith my 250 and a single bbl carb. 3.73 gears, 3spd on column, 15" wheels.

mvfd70 · 02-25-2008, 09:07 AM

I had a 68 with a 250 single barrel and 4 speed and I got 10-12. Don't know what rear it had though

Brad · 02-25-2008, 09:33 AM

Last summer I used a GPS for 50 miles on a straight and level freeway and calculated that I was getting 17 mpg at a constant 65 mph. That's with wide tires and a tired, high mileage, stock rebuild 250. See my signature below for more specs.

*ksjh1316* · 02-25-2008, 09:36 AM

My 71 LWB with a 292 granny with 3:73's is lucky to get double digits. She loves to drink gas.

02-24-2008, 12:08 AM	#1
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Curious... MPG for an inline 6???? What kind of MPG do the original inline 6's get? I've seen a lot of threads about increasing MPG in a V8, but I don't recall hearing anything from the inline 6 crowd... __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package) Last edited by 72BlckButy; 02-24-2008 at 12:09 AM.

02-24-2008, 12:29 AM	#2
zeeklu Registered User Join Date: Dec 1999 Location: Northwest NJ Posts: 746	Re: Curious.... MPG for a V6??? My 67 K10 short fleetside 292 with a 4 speed gets around 13 mpg.It has a Holley 390cfm , headers and 373 gears. Chris Last edited by zeeklu; 02-24-2008 at 12:30 AM.

02-24-2008, 12:31 AM	#3
zeeklu Registered User Join Date: Dec 1999 Location: Northwest NJ Posts: 746	Re: Curious.... MPG for a V6??? http://67-72chevytrucks.com/vboard/s...d.php?t=172346 Here's a good post about mpg. Chris

02-24-2008, 03:26 AM	#4
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 46,702	Re: Curious... MPG for an inline 6???? There is typically not a whole lot of difference(maybe 1 or 2 mpg) between the inline 250 and a small block V8with all other factors equal (driving style/tranny/gears) __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! Last edited by Palf70Step; 02-24-2008 at 03:26 AM.

02-24-2008, 03:30 AM	#5
68Stepbed Registered User Join Date: Mar 2005 Location: 10-Uh-See Posts: 5,609	Re: Curious... MPG for an inline 6???? I remember mine used to get pretty decent mileage. It was better than my 350, but that was probably because I couldn't keep my foot out of the throttle with the new 350 I know my mileage got alot better with the headers though. __________________ Matt 68 C10 stepside, LS1/700R4, TCI Engineering suspension system

02-24-2008, 03:42 AM	#6
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Curious... MPG for an inline 6???? I would think that a 6 with headers and a couple other power enhancements with a 3:73 and 700R4 would maybe get 17-18 under ideal conditions.If you are looking for real milage and want to pay top shelf prices,you might go to the 6 from a late model Trailblazer(w/EFI) and auto.Most I have looked at run a 3:42 gear ratio.I think they get around 22-24 MPG. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

02-24-2008, 07:14 AM	#8
Willy Prost Senior Member Join Date: Jan 2000 Location: Arlington, VA Posts: 398	Re: Curious... MPG for an inline 6???? 15-17....up to 20 if you drive like you have a live grenade between your foot and the gas pedal and you don't have a death wish.

02-24-2008, 08:30 AM	#9
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: Curious... MPG for an inline 6???? I'm not looking to swap out the SB400, but I've always been curious if they got better gas mileage than a V8. Now, if my truck had an inline 6 I would definitely keep it in there, because you don't see a lot of them out there anymore. __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

02-24-2008, 08:37 AM	#11
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Re: Curious... MPG for an inline 6???? I'm sure a Trailblazer 4.2 would get even better mileage in one of our trucks....a Trailblazer weighs around 5000 pounds if I remember right, and our trucks are closer to 4000 pounds or even less. I'm sure the 6 weighs less than a small block V8 too...plus with 270 net horsepower it would have some nice power, quite a bit more than a stock 350. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

02-24-2008, 08:50 AM	#12
jm8872 Registered User Join Date: Nov 2007 Location: Cushing Texas Posts: 1	Re: Curious... MPG for an inline 6???? My '72 LWB has a 250 inline 6 with granny 4 speed and 4:11 gears and it gets 14 mpgs.

02-25-2008, 08:46 AM	#13
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	Re: Curious... MPG for an inline 6???? i was lucky to get 10mpg ith my 250 and a single bbl carb. 3.73 gears, 3spd on column, 15" wheels. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM. Last edited by shifty; 02-25-2008 at 08:47 AM.

02-25-2008, 09:07 AM	#14
mvfd70 Registered User Join Date: Jan 2007 Location: Opdyke, IL Posts: 775	Re: Curious... MPG for an inline 6???? I had a 68 with a 250 single barrel and 4 speed and I got 10-12. Don't know what rear it had though __________________ 1978 Chevrolet Silverado 3/4 ton 400 small block. 2000 F-250 Powerstroke 2002 GMC Yukon Denali XL

02-25-2008, 09:33 AM	#15
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,673	Re: Curious... MPG for an inline 6???? Last summer I used a GPS for 50 miles on a straight and level freeway and calculated that I was getting 17 mpg at a constant 65 mph. That's with wide tires and a tired, high mileage, stock rebuild 250. See my signature below for more specs. __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...

02-25-2008, 09:36 AM	#16
ksjh1316 Account Suspended Join Date: Jul 2007 Location: Wichita KS Posts: 1,599	Re: Curious... MPG for an inline 6???? My 71 LWB with a 292 granny with 3:73's is lucky to get double digits. She loves to drink gas.



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