This as was paid for by Hall-Scott, to bring attention to the fact that the new Mack LT “Western” truck series, targeted for those grueling jobs on the far side of the continent was available with the legendary H-S 400 engine, a 1091 cubic inch six cylinder monster with an aluminum OHC hemi head and able to crank out power that no diesel could hope to match back then (typically between 115 and 165 hp).
This was quite a change for Mack, as it was a fully integrated East Coast truck maker that built all the major components that went in them, including engines, transmissions and rear axles/bogies. That had to change to meet the demands of West Coast operations, which involved much larger loads, off-road logging, and of course mountains. The Hall Scott delivered the massive low-rpm torque and maximum power needed for those conditions, at a price: massive fuel consumption. One operator got 1.7 mpg hauling heavy over-the road loads.
Here’s a shot of a restored first year 1947 LT:
This one is H-S powered, and wows the crowds with its exhaust sound at truck shows.
And here’s a gathering of several different vintages. Cummins diesels as well as Mack’s own were also available.
An over-the road LT semi hauling a trailer with descriptive company name.
Update: butane is petroleum gas, a byproduct of natural gas and oil refining. It’s used in a number of ways, as a feed stock for further refining, and as a fuel for stoves, lighters, etc. It has an octane rating of 92, and has long been used to increase the octane of regular gasoline to create premium gasoline. It makes an excellent motor fuel, superior to propane due to its higher octane, which is why the H-S engine produced more power on butane than gasoline, with a concomitant increase in compression ratio, from 5.7:1 to 7.1:1.
Here’s an SAE article on butane as a motor fuel
More detailed info on the Hall Scott 400 Invader engine here
I love these old macks and Hall Scott engines (I have had a chance to work on Hall Scotts and old macks when I was a teen at a fire engine museum). The heft and quality in these is fantastic.
The engine ad here and the linked article mention more power “on butane”. How’d that work? A pressurised gaseous fuel system, as with propane…?
Yes, very similar to propane. It’s often mixed with propane to create LPG. It was cheap back then, as it was a byproduct of oil refining. It increased power of a gasoline engine somewhat, undoubtedly due to an effective higher octane.
it’s still used as a fuel, in camp stoves, and as a refrigerant.
It has an octane rating of 92, and has long been blended with regular gasoline to increase its octane.
It still makes a good alternative motor fuel, with some intrinsic advantages over propane.
Here’s a quick article: https://www.sae.org/publications/technical-papers/content/952496/
I don’t mean to argue against Hall-Scott’s published data or anything like that, I’m just having some difficulty with the numbers involved here. Both 5.7:1 and 7.1:1 strike me as very low compression ratios well below the ratios where the difference between (say) an 87-AKI gasoline and 92-AKI butane removes a barrier. The only thing I can imagine that would make all the pieces fit for me is if this engine’s long stroke and hemi head made it require fuel with strong antiknock performance (i.e., high octane) relative to other engine configurations.
I can’t answer this except to say that the 5.7:1 CR was not at all atypical for gasoline engines back then. For instance Packard’s straight eights had ratios of 6.5:1 to 7.0:1 until 1952, which was when high octane gas became readily available. That’s pretty much the case with other manufacturers.
Hall Scott’s last new engine, the 590, had a 6.0:1 CR ratio for gasoline and 8.7:1 for butane. It also had a different combustion chamber (semi-wedge, not hemi).
Clearly the higher higher octane of butane was the deciding factor in both of these engines to have a higher CR for the butane version. There’s no other logical explanation.
FWIW, a current giant (7040 CID) Waukesha industrial natural gas (CNG) engine has a relatively modest 8.0:1 CR. Given that car engines have to have their compression ratios increased significantly to operate efficiently on CNG (like around 12:1) it appears that very large IC engine do need to have lower compression ratios for some intrinsic reason, as these industrial engines are all about maximizing their operating efficiency. I don’t have time to look into that right now, but it would be interesting to know if scaling up an engine in dimensions creates a fundamental requirement for a lower compression ratio.
I think you must be right about that. I would be interesting, wouldn’t it, to learn just what the determinant is: TDC dwell time, combustion chamber diameter, something else? I have an idea whom I might ping about it, if he’s still around.
I’d be interested to learn more about butane as a fuel for IC engines. There’s a bit of a line in the linked article about how butane was available at/near oil refineries as a byproduct of refining, but I’d love a deeper dive into the topic.
Also, although it’s hard to tell from the photos, I can’t make out any sort of tank/cylinder for the storage of compressed gasses. Or perhaps none of the trucks pictured were so equipped.
Does anyone know of a deeper article about butane as a motor fuel?
As I said in the comment above: it’s similar to propane, and when combined with propane, is referred to as LPG (liquefied petroleum gas). It’s still widely used in camp stoves, lighters, as a refrigerant and in other refining uses as a feed stock and such.
It was a natural byproduct of oil refining, and cheap back then, as there were few other uses for it then. It has an octane rating of 92, so that was much higher than gasoline back then, resulting in higher power output.
It’s been blended with regular gasoline for decades to create higher octane gas (premium).
here’s an article:
https://www.sae.org/publications/technical-papers/content/952496/
It’s still around.
For those looking to learn more “Autogas” would be a more precise search term.
An interesting somewhat recent application was a fleet of EFI Big Block GM engines fueled on Autogas.
Yes, the OEM gasoline EFI system reconfigured to inject Autogas.
No it’s not. “Autogas” is LPG (liquified petroleum gas), a mix of propane and butane, with propane being by far the primary constituent.
Butane has not been readily available as an automotive fuel for many decades despite some that have advocated for its greater uses as a superior automotive fuel than propane/autogas.
Absolutely, autogas = LPG.
My brother happens to have 2 vehicles that run on LPG. His 1977 Jeep CJ7 304 (aftermarket system, installed in 2003) and his 2021 Dacia Sandero Stepway (factory bi-fuel).
“No it’s not. “Autogas” is LPG (liquified petroleum gas), a mix of propane and butane…”
Ehhh, Paul… Butane along with propane and other “sister” gases and their blends are ALSO Liquified Petroleum Gases.
Excuse me, I wasn’t trying to write a thesis on gaseous engine fuel blends.
Folks who seemed completely unfamiliar with liquified gas engine fuel seemed to be asking for a concise summary. I was simply trying to help direct those people to information by suggesting that “Autogas” would be a good search term for information on what for all practical purposes is the same method of fueling an engine as butane. IE, a hydrocarbon fuel is stored under pressure to allow dense storage as a liquid. The fuel then “feeds” an engine as a vapor, to be ignited by spark.
My own hands-on experience is limited to just buying, storing and then transferring fuel to vehicles. That required some familiarity with the unique characteristics of blends, such as critical vapor pressure to prevent blow-off or freeze-up. Naturally along the way one learns a thing or two about gas-fueled engine maintenance peculiarities.
That’s it for me, just a strong working knowledge. I can’t help much with hair-splitting semantics.
To me, to say that Butane fueling is completely different than Autogas fueling, would be akin to telling someone who’s completely unfamiliar with gasoline, that using Economy Regular grade pump gasoline is a COMPLETELY different process than burning High-Test Premium. Semantics. He says diesel engine, she says oil engine.
For anyone still interested, I’ll attach a vapor pressure chart that gets to the punchline. Namely, that at 32F “straight” butane stops vaporizing. Your truck had better be parked when temps drop, because you’re effectively out of fuel.
Or… the butane could be blended with another gas to raise the vapor pressure of the truck’s fuel blend. Propane, as used in the (not) “completely different” process of Autogas fueling is a favorite mixer.
In closing, straight butane fueling applications are severely limited by its low vapor pressure, part of its unpopularity as an engine fuel.
Jim, a mighty long but failed effort to try to exonerate yourself because you can’t bear to admit you just might have been wrong.
The question from Evan was: I’d be interested to learn more about butane as a fuel for IC engines.
Your response was: For those looking to learn more “Autogas” would be a more precise search term.
That was a wrong answer and not helpful, period. If you search for the term “Autogas” it takes you to a Wikipedia page on Autogas, which is of course just another term for LPG, commonly called “propane” in the US, something everyone is familiar with. That would hardly be helpful, and provide no insight into the use of butane as a motor fuel, as it once was used as referenced in this ad. That was the reason for his question.
The only “precise” search term is “Butane used as a motor fuel’. Which I used in order to find the article that I linked to in my comment.
But go ahead and keep trying to split hairs or whatever you’re trying to do. Next time someone asks a question like that, either direct them with the proper search term, or don’t comment at all. Guess what: sometimes it’s better not to comment than to comment. In case you haven’t noticed, I’ve been doing a lot of that lately. But then you force me to correct you and now respond to your attempt to correct me. It’s all so very tedious.
My primary target was Mr Stern’s comment:
“The engine ad here and the linked article mention more power “on butane”. How’d that work? A pressurised gaseous fuel system, as with propane…?”
The short answer is: “yes!” for all practical purposes just like propane.
Aha, more prevarication.
In that case you screwed up and left it at the wrong comment thread.
Paul, I’m going to forget this, but please don’t do it again. lol
Thanks, Paul!
LPG was a common low cost fuel when I lived in Aussie Holdens and Falcons could be bought as dedicated LPG fueled cars direct from the factory all taxis ran LPG a lot of people ran dual fuel setups it was popular on gas hogs like F100/150s.
How times have changed 300hp is considered shockingly underpowered in a tractor unit now and @ $10.00 per imp gallon nobody is using petrol in heavy trucks here I’d love to hear the big Hall Scott barking with 58 tonnes behind it on a climb.
Almost 20 years later Mack opened a plant in Hayward, California that was officially called “Mack Western”, building trucks until 1980, I think. However although these much earlier West Coast style trucks were colloquially known as western Mack’s, I’m not sure that exact term was used by Mack then (unlike the Emeryville IH’s). The ad that Paul shows mentions the “West” and “Far West”, not “Western”. As a kid growing up in California, I remember hearing the term “Built like a Mack Truck” and thinking that Mack’s must be exotic premium trucks, as they seemed less common on the roads than Peterbilts and Kenworths and Freightliners, or IH and GMC. And the Mack’s I did see seemed to be dump trucks, looking hugely overloaded in local use.
The engraver for that ad deserves credit. He clearly knew logs and knew trucks. Every single detail is there, down to the rivets in the spring shackles and the ears of the bulldog. It’s all done with lines, no halftones.
Wonderful, classic long-nose conventionals, always looking smashing!
I caught one 5 years ago, Cummins diesel powered.
So was this the first of the chrome dogs?
Or rather, since they had previously all been chrome was this the point where the gold Bulldog for trucks with all Mack-built components was introduced?
Do I see an opening illustrated in the bumper intended for a hand crank?
Butane is the bastard gas. I sell propane and propane accessories.
Hank Hill
I remember the biggest sand, gravel, and concrete company in town had a fleet that seemed to be all very big Macks, but I couldn’t tell what engines they had. One of the city bus lines had a bunch of Mack (diesel I believe) buses. They may have not been common out west but perhaps Portland had a hot shot Mack dealer.
“Built like a Mack truck” reminds me of a girl I knew when I was in the service 🙂
To say these are beautiful is a massive understatement.
Exotic. Delicious. Enchanting !
The 2 mpg. would be well worth the price of admission for that view down the hood and out across the horizon and beyond ……..
I own a couple of Ford F200 pickups (the F150-7700 heavy half with 7 lug wheels). They are powered by a 5.4 litre engine, run on CNG and unleaded fuels; a tank for each. According to website Ford Blue Oval, these are forged internally engines and nearly indestructible.
Does the compressed natural gas possess those same attributes as the butane or autogas engines, producing a more noticeable power increase ?
And how does CNG differ from propane or LPG ? I know availability is certainly one of the drawbacks in its use
LNG has a lower energy density than LPG. Which means they are not interchangeable without modifications.
CNG is dispensed at extremely high pressure (3000psi+), requiring very expensive tanks and compression equipment. LPG is low pressure with simple steel tanks and much simpler dispensing equipment. Natural gas is primarily methane (CH4), which is very low density due to the higher proportion of hydrogen atoms to carbon compared to other paraffin/alkane molecules such as butane (C4H10) and propane (C3H8). The carbon number and therefore density of gasoline (4-12) and diesel (10-22) blends of hydrocarbons is higher.
There’s some workaround to the high pressure storage problem by using cryogenic cylinders for storage. Well, temporary storage anyway,
because the fuel begins to “boil off” as soon as it’s transfered to the cylinder so it’s a use-it-or-lose-it proposition.
Cryogenic Liquefied Natural Gas (LNG) was tried on transit bus fleets late in the last century and apparently didnt work out. CNG fleets dominate today.
I have a lot of experience with LPG cars, having run a fleet of taxis using said fuel.
I don’t want to get into a big argument, but my direct experience with LPG is that is has an octane rating of 104-112. This is corroborated by the US Department of Energy website:
” propane has a higher octane rating than gasoline (104–112 compared to 87–92 for gasoline”
https://afdc.energy.gov/vehicles/propane.html
This site says the same:
https://www.need.org/Files/curriculum/infobook/PropaneS.pdf
In the rare cases I had to rebuild an engine (or more accurately order a crate engine) I used 11:1 pistons and a mild cam. On my personal 9C1 I sold the 350 and built a nice 305 4bbl. The top end was basically removed but below 3000 RPM it was a great motor. This made up for a good 15% of the fuel consumption of propane, which as about 30% less energy than an equivalent amount of gasoline.
The big logging truck reminds me of a couple of weeks every summer spent at my uncle’s in Camino, California. He worked for a lumber mill and lived right on US 50. All day and night the trucks roared into town with those big loads of logs. They were diesel by the early 1960’s and the exhaust brakes made sure I couldnt sleep, as my room was at the front of the house. West Coast trucking indeed.