What was old is new again

[tom120]

There is a propane version of the V10 for the Bluebird Bus. Thomas bus is using the recently brought back and redesigned 8.0L big block Chevy engine fueled on propane as well. big shift happening in the medium duty truck market away from diesel to LPG power. Next engine for our 47 Clipper will hopefully be that 8.0 l engine(hopefully on propane). the current GMC 401 v6 is 49 years old. the 8.0 is now available as an over the counter long block from GM.  Tom

[HB of CJ]

Back in 1970 we drove "Flexxies" for the Yosemite Park And Curry Company.  They all had that big V6 gas engine.  Straight 5 speed transmissions.  Four road gears, one granny.  I got to ferry one from Fresno CA to the Park.  Very slow if memory serves.   Greatly needed a gear between third and fourth.

They were cheap painted white, yellow and orange.  Wonder where they are now.

That Hall Scott Powered Crown Supercoach fire pumper created big problems on grass fires.  Seems it was better starting back fires than helping the small weed burner one ton trucks put out the grass fires.  Policy back then was NOT to drive the thing off road with dry vegetation.  Yikes!  Long ago.

[CrabbyMilton]

IC bus(formerly known as NAVISTAR, IH, ELMER FUDD. etc) nowis offering a propane engine. It's a 8.8L V8 built by PSI based on  GM block. Who knows if they to offer a gasoline version of this one too.

[tom120]

HB. The GMC 6 is slow in the hills and in direct drive with the 6.17 axle top speed is 55 mph. RPM was about 3k. Did an Allison 1000 automatic conversion this year.  the 6 loped along very nicely at 60mph and about 2200 rpm. Still slow in the hills though but quick downshifts and the ability to make speed before the hill helps. Tom

[Scott & Heather]

I am young and stupid so I don't have a nice story from long ago like the rest of ya's but I'm enjoying reading them   but I'll throw in my two cents. I know everyone is convinced that diesel motors go further and longer than their gas counterparts, but in my own personal experience I have seen gas motors go a long time without any kind of major overhaul. Many times I've seen Toyota Camry's hit half a million miles on their original motors and even then the tranny has finally worn out or the car body is rusted or something. I currently own a land cruiser and several of these 100 series land cruisers have already made it well past the 400,000 mile mark in our land cruiser club. All from merely changing the oil, and occasionally running injector cleaner through the system. They never overheat, I've started mine in -22F temps, cheap to buy spark plugs for, and easy to work on and cheap to fix. I love diesels and they are perfectly suited for their applications, but reading my truck trend magazines, I'm seeing more gas motors with little turbos that are getting amazing MPG and power at the same time. Ford eco-boost is just one example. Is anyone reporting what the MPG of the skoolie is with this gas motor?


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[TomC]

The main reason the big gasoline engines got only 1-3 mpg was they were using carburetors and old style point distributors. Now with gasoline engines being direct injected, electronic ignition, variable cam timing, etc, we're seeing gasoline powered cars getting incredible mileage. In fact, when both Diesel and gasoline are offered in cars, the mileage difference is the 20% difference in BTU's between gasoline and Diesel. Considering big rig trucks at 80,000lb are getting 8mpg, 20% less fuel mileage would put a modern gasoline engine (with the same power) at about 6.5mpg-which is better than my bus gets.

Freightliner has come out with a propane powered truck. It is NOT a conversion. Freightliner Custom Chassis Corporation (FCCC) took an 8 liter GMC block, went with hardened valves, higher compression, liquid propane injection (big difference in performance). While it is about a $10,000 price over Diesel, propane is easy to handle (compared to natural gas). And since many of us use propane anyway, it is a natural. The engine is rated to 33,000lbs. Good Luck, TomC

[greg158]

This has been a very interesting thread to read indeed! I didn't know some of these different manufacturers were building big block gas engines and pumping propane through them. From my experience, in the climate i live in (Winterpeg MB), Winnipeg for those not familiar with the great white North, the minute someone says DPF, DEF and EGR in the same sentence as diesel engine, check your pockets to see how deep they are! In my opinion, nothing beats an old school diesel in any climate or operating condition. They are built for serious duty work. We run diesels here in -40c, yes we start them at that temperature too. The ones with DPF's requiring DEF, not so much.   DEF freezes... end of that discussion. Now on to EGR's. Remove your intake tube after a hundred thousand miles and take a peek.  You'll be shocked and disgusted at what the EPA wants you to put back into your motor. And you'll ask yourself, "what was that air filter for?" Oh, and did someone say fuel mileage? no, not here. The new diesels with all the environmental crap are a total sham plain and simple. The amount of money it costs the operator to run a new diesel is completely over the top. You're paying huge sums of money to burn dirt (soot) and the costs don't end there. I have a feeling this is one of the reasons this thread was started to begin with. I'm not going to get into the costs associated with every brand of pre-emission diesel out there, but I will say they are now worth a fortune in this neck of the woods and very sought after, especially in heavy trucking. In my bus I have a 6v71, full rebuild on this engine is under $2000 for parts. Down the road it gets roughly ten miles per gallon. There's just no comparison in terms of cost compared to the new diesels. Hopefully these new gas/propane engines can do better pushing 30,000 #'s down the highway, but I don't think so. This thread is just gaining momentum
Greg

[CrabbyMilton]

Well I the reason BLUEBIRD is returning to offering gasoline engines in skoolies is to market them to smaller schools and churches who may only use the bus once in awhile and plain just want to hassle and extra expense of diesel where the annual mileage won't offset the cost in short order. Like I said, IC and THOMAS offer propane engines as well but it's unknown to me at least if they will offer gasoline versions of those engines or not.

[lostagain]

Pretty hard to beat a diesel for the torque when towing. Or in a heavy truck or bus. A big gas engine may have lots of horse power, but has to be revved up high to pull anything heavy.

The Cat 3406B (mechanical, pre EGR) in my Pete dump truck is one the sweetest engines I've had. I can see why some truckers rebuild their trucks rather than buying new.

But today's electronic, low rpm, diesels pretty well have all the bugs worked out of them. They are very efficient and reliable. All the big fleets use them. At 3000 miles a week, they can recoup the up front cost fairly quickly.

I remember a few years ago Tom C (salesman at LA Freightliner) was saying they put road side assistance on every new truck because of reliability problems. Tom, how is it now with new trucks?

JC

[luvrbus]

Yep the 425 hp 3406 Cat was the best engine ever built

[tom120]

The 8.0l GMC propane engine has an impressive 500 ft lbs of torque. For the med duty truck market its respectable. That engine will hopefully be the next engine for our Clipper. The 5 speed OD Allison 1000 w the GMC 401 V6 gas engine gave us 9.5 mpg on flat highway runs this summer. Hilly highway stretches were about 8 mpg. in city 6.5 to 7.5 mpg. We did 4,000 miles in 23 days. Bus ran awesome. Tom

[digesterman]

What does your bus weigh Tom ?

[belfert]

I have at different times had both an F-350 with the V10 gas engine and an F-350 with the 7.3 diesel.  The diesel F-350 was a joy to tow with.  Towing was a white knuckle affair with the V10.  Same trailer with both F-350s.  Give me the torque of a diesel any day for towing.

[lostagain]

Tom120, 500ft/lbs of torque is less than the diesel pickups. It is half as much as the 6V92TA in my bus, which goes down the road nicely, but will not pin me back into the seat with my foot to the floor. Most big rig engines now have torque approaching 2000ft/lbs. I think your Clipper will be pretty slow with the 500 ft/lbs 8 L GMC.

JC

[tom120]

You are correct lostagain. the 8.0l def not for the heavy duty big rig market. I noted the 8.0 is a med duty engine in prev post. Freightliner is installing the propane version of the 8.0 in vehicles up to 33,000 GVWR and for the most part vehicles that are used locally like school buses and fuel delivery type vehicles. Duramax has 5-600 ft lbs(I believe)and even more in turbo versions. The propane engine is approaching those lower#s but will never reach what the turbo Duramax engine has. With 6.17 gearing and overdrive trans the 8.0 will move the 47 Clipper quite well. Current 401 engine has only 235 ft lbs and is very adequate but slow on long  hills. Automatic Allison 1000 trans now helps there though. Not sure what your bus weighs but it is probably heavier than a Clipper. Tom