Vulture Posted July 25, 2011 Share Posted July 25, 2011 A straight forward question for owners of GMC 352 and 353. What is the average mpg you get ? I keep reading different articles and the figure seems to vary between 7 and 15 mpg. Kind regards to all Cheers Vulture Quote Link to comment Share on other sites More sharing options...
Willyslancs Posted July 25, 2011 Share Posted July 25, 2011 does it matter what mpg you get as long as it makes you smile when you drive it? Quote Link to comment Share on other sites More sharing options...
Lewis Garner Posted July 25, 2011 Share Posted July 25, 2011 We used to get 10-12mpg from ours Quote Link to comment Share on other sites More sharing options...
Tony B Posted July 25, 2011 Share Posted July 25, 2011 It really is, if you worry about such things you shouldn't be in the hobby. The US manuals for all WW2 vehicles quotes 8 miles per gallon, bear in mind a US gallon is smaller. Quote Link to comment Share on other sites More sharing options...
alant Posted July 27, 2011 Share Posted July 27, 2011 I get 8 to 11 mpg with my 353 H1 but worth every penny. Quote Link to comment Share on other sites More sharing options...
Big ray Posted July 27, 2011 Share Posted July 27, 2011 A straight forward question for owners of GMC 352 and 353. What is the average mpg you get ? I keep reading different articles and the figure seems to vary between 7 and 15 mpg. Kind regards to all Cheers Vulture Anyone getting 15mpg they have either converted to diesel or they are being towed..... mine will do about 10mpg, at the end of the day its how you drive it. Dont thrash it up through the gears and just feather it along on the flat..... but for how often I am out fuel consumption is a low priority........... you should try my Halftrack.!!!!!!! ( 3mpg) Quote Link to comment Share on other sites More sharing options...
deadline Posted July 27, 2011 Share Posted July 27, 2011 I think you could get up to 15mpg if you used milled front hubs and pulled an axle or two from the rears. Its a common mod for M35a2 owners to improve MPG. I would plan on 8mpg. I live in the Appalachian mountains and hills kill my MPG... so depending on where I am going I could dip down to 5 or 6. The engines are such a low compression that they really don't extract as much from the gasoline as they could. I would think that if you bumped compression up to 8 or so you would see solid mid upper teens. The 270 has lots of hi-perf parts and the block sure can take it. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted July 28, 2011 Share Posted July 28, 2011 One big factor often overlooked is the grade of engine oil used. A lighter weight oil will give significant imoprovements in mpg - less resistance to rotation, and higher oil flow gives greater heat flow and therefore better cooling. A friend proved this over many years with cars/trucks/plant. That said I would consider it better to select the right grade of oil for engine protection and durability over mpg :cool2: Quote Link to comment Share on other sites More sharing options...
Stormin Posted July 28, 2011 Share Posted July 28, 2011 One big factor often overlooked is the grade of engine oil used. A lighter weight oil will give significant imoprovements in mpg - less resistance to rotation, and higher oil flow gives greater heat flow and therefore better cooling. A friend proved this over many years with cars/trucks/plant. That said I would consider it better to select the right grade of oil for engine protection and durability over mpg :cool2: What about fitting a higher temp thermostat? Most older vehicles especially military run at extremely low temperatures, presumably to allow for harsh conditions, blocked rads, off roading, towing etc. In normal use I think some benefit and improved thermal efficiency hence higher mpg can be had by fitting a higher temp rated thermostat. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 29, 2011 Share Posted July 29, 2011 I think you could get up to 15mpg if you used milled front hubs and pulled an axle or two from the rears. Its a common mod for M35a2 owners to improve MPG. I would plan on 8mpg. I live in the Appalachian mountains and hills kill my MPG... so depending on where I am going I could dip down to 5 or 6. The engines are such a low compression that they really don't extract as much from the gasoline as they could. I would think that if you bumped compression up to 8 or so you would see solid mid upper teens. The 270 has lots of hi-perf parts and the block sure can take it. I dread to say this, it has just popped in to my crazy mind, but with the very low compresion has anyone fitted a turbo to a GMC engine :red: Don't suppose the pistons would last long !! Sorry I wont suggest this again... Quote Link to comment Share on other sites More sharing options...
deadline Posted July 30, 2011 Share Posted July 30, 2011 You can turbocharge anything... but for the several thousand dollars to make a new header/exhaust, cost of the turbo and an oil line reroute you could simply put hiperf parts in it to bump the compression. Plus you just lost your brakes becuase turbo's don't allow the engine to pull much vacuum. A higher temp t-stat wouldn't do much. The basic issue is the low compression due to the 70 octane fuel source. Now a days 80-85 is standard and can handle 8 8.5 : 1 compression. Extracting more energy out of the fuel is the key. The ultimate MPG boot would be an aftermarket TBI injector. No more carb and its inefficiency. If you wanted to do something cheap in your own garage: Do a mild port job on the head increase the compression to 8:1 3 angle valve job If that doesn't get you over 120hp (up from the stock 90) nothing will. With a more efficient engine you should see about a 20-30% increase in MPG (8 x .3 = 10.4) but you will also have a much more responsive motor and better hill climbing. Quote Link to comment Share on other sites More sharing options...
deadline Posted July 30, 2011 Share Posted July 30, 2011 Thinner oil kinda works... you get a miniscule improvement.. 1-3% in MPG. So 3% of 8 = .24 mpg improvement 8.24 MPG vs 8.. blow one shift and you just lost that .24 mpg. General rule is nothing you pour into a motor fixes anything. Now if your car was getting 35mpg 3% * 35 = 1.05 or 36.05 MPG now you are talking. Quote Link to comment Share on other sites More sharing options...
Vulture Posted August 9, 2011 Author Share Posted August 9, 2011 (edited) Guys thanks for your thoughts. As far as I can tell, I achieved around 9 to the gallon on the 180 mile journey to get it home. Kind regards to all Vulture Edited August 9, 2011 by Vulture To adjust formating Quote Link to comment Share on other sites More sharing options...
Willyslancs Posted August 9, 2011 Share Posted August 9, 2011 Guys thanks for your thoughts. As far as I can tell, I achieved around 9 to the gallon on the 180 mile journey to get it home. Kind regards to allVulture more importantly mate , were you smiling when you got out of the truck ?:drive:.......... Quote Link to comment Share on other sites More sharing options...
Vulture Posted August 9, 2011 Author Share Posted August 9, 2011 more importantly mate , were you smiling when you got out of the truck ?:drive:.......... Totally ! As I pulled up outside the house I just could not stop smiling In fact I'm still smiling now I've posted a short narrative of the day and a few photos on my blog. Link Kind regards Vulture Quote Link to comment Share on other sites More sharing options...
Willyslancs Posted August 9, 2011 Share Posted August 9, 2011 looks good mate , like usn gray :thumbsup: ........ Quote Link to comment Share on other sites More sharing options...
willysmb Posted August 9, 2011 Share Posted August 9, 2011 Quote, "30mph on the Humber bridge ..... we are a moving road block" oh yeh :nut: know that feeling :cool2:.. And to answer the question ...8-10mpg.. Quote Link to comment Share on other sites More sharing options...
psychoman Posted August 9, 2011 Share Posted August 9, 2011 Nice Blog write up. Reminds me of bringing my Pinz home for the first time and negotiating the tiny lanes around the lake district in the dark, driving a LHD forward control. A steep learning curve, but great fun. Wait 'til you drive it down to W&P next year!?! :-D Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 9, 2011 Share Posted August 9, 2011 Well done - a great initiation! Don't worry too much about that long list of jobs - even after 20 years with the GMC you'll probably have a few left to do (having done several of them at least twice :-D). Enjoy. Quote Link to comment Share on other sites More sharing options...
Vulture Posted August 9, 2011 Author Share Posted August 9, 2011 looks good mate , like usn gray :thumbsup: ........ Not sure I'm going it keep it grey in the long term, but for the moment I'll keep it as it is. More important things like changing the brake hoses (one of which has a bulge in it), and some of the pipework which is a bit corroded need my attention. It's quite possibly the only grey 352 in the UK unless anyone knows different ? (I've heard of a 353 in Grey) It's quite a good colour for me to get to know the vehicle, ie, the slightest bit of rust, and its v obvious, there is just no disguising it. Vulture Quote Link to comment Share on other sites More sharing options...
Vulture Posted August 9, 2011 Author Share Posted August 9, 2011 Nice Blog write up. Reminds me of bringing my Pinz home for the first time and negotiating the tiny lanes around the lake district in the dark, driving a LHD forward control. A steep learning curve, but great fun. Wait 'til you drive it down to W&P next year!?! :-D Ohhhhhhh yes, I'm definately planning to be there Vulture Quote Link to comment Share on other sites More sharing options...
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