desiel or gas

Discussion in 'Trucks and Trailers' started by dudley, Dec 20, 2008.

  1. TXNSLighting

    TXNSLighting LawnSite Fanatic
    from DFW, TX
    Messages: 6,464

    That had to be sarcastic...But just incase your welcome. I want everyone to be well educated here! :laugh: It makes the world go round!
  2. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    The Allison on the 8.1 does a good job of braking on the downgrades. You just have to get use to the engine reving up to 4000 RPM with the throttle closed.
  3. Gravel Rat

    Gravel Rat LawnSite Fanatic
    Messages: 9,544

    A gas engine will always have more compression braking than a diesel.

    The best auxilary brake is a transmission brake like a retarder or a telma. A exhaust brake is like a potato stuffed up the exhaust pipe some trucks it works okay but most it just hisses and does nothing.

    When your decending a twisty 10 percent grade you just start of slow at the top and go down at a speed where you don't ride your brakes. Go down any of the hills in my area too fast your going to push up daisys for sure or you will be so crippled you will be in a wheelchair.

    You never really want to exceed the manufactures specs even then they are a little over rated for the conditions on the West Coast. Going down a 10% grade with a gross combined weight of 20,000lbs in a 3/4 ton P/U your just writing your last will and testiment. If your trailer brakes ever failed your done no questions asked your going down out of control smash into a rock bank. The air bags are not going to save you, the paramedics would have to remove you piece by piece.

    When Ford rates the F-550 at a 19,000lb gvw I don't know how they pulled that rating out of their azz. The F-550 has the exact same brakes as my F-450 and with my F-450 grossing 15,000lbs you know your heavy the brakes are close to max. The F-550 with 17,000lb gvw is maxed the braking capacity of the truck.

    You can have all the power you want you climb the steep grade but on the otherside there is a steeper down grade.

    Love to see you guys try pull the weight you do on your flat land and come try it on some hills. Better wear some depends underwear because you sissys are going to need it when you soil yourself :laugh:

    I'am a wanna be 18 wheeler I drive a Dodge Cummins P/U I can pull anything I'am invincible the super hero of the road. It is what I call moron with no clue ready to kill somebody.

    No offence but it must go to Dodge guys heads that they have a Cummins they figure they are driving a big rig. What does it do get the gerbil excited and run faster on the wheel. 99% of the time a Dodge truck is grossly overloaded its running illegal and the truck can't handle the road they are going to kill somebody.

    Had a Dodge guy last year thought he was a big rig semi he had a older body style Dodge 4x4 3/4 ton. He was grossly overloaded the truck couldn't handle the road. I was so freaking pissed off he wouldn't pull over. He was swearving all over the road the trailer was too heavy. You know his engine was turned up because he was belching black smoke he thought he had all the power in the world. When I finally got to a stop sign I said to him your reported to the cops and the DOT and I left.

    I'am glad the DOT/CVSE is clamping down on overloaded P/U trucks pulling trailers. There should be no warning just pull their drivers license. If they know they are pulling a trailer too heavy too bad the truck should be impounded for a month.
  4. Jerry Lee

    Jerry Lee LawnSite Senior Member
    Messages: 354

    yea i think id rather stick to the six speed automatic/manual selector to shift down and like u said peg out and hit 3500-4000 rpm, that will slow u down.
  5. nosparkplugs

    nosparkplugs LawnSite Gold Member
    Messages: 3,444

    The diesel cycle will always have a thermal advantage over the Otto cycle engine this with the (adiabatic thermal process) applies specific to compression braking. When it comes to compression braking the diesel cycle has the CLEAR advantage their are nosparkplugs that cause internal damage during compression breaking.

    Downshifting the transmission with any engine is a form of compression braking it does work; however it's far less efficient than a internal cam or external diesel exhaust Jake Brake.

    The 8.1L GM Vortec was the best option, but with the introduction of the Duramax diesel. The 8.1L is just simply outclassed when compared to the Duramax diesel, and if the diesel engine was going to become a dying breed? GM would have kept the 8.1L V8 in production, invested the billions of research dollars needed to improve the engine.
  6. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    GM dumped the 8.1 because too many people were buying the Diesel hype. Now that Diesel fuel costs more than gasoline, those of us with 8.1L Vortecs can sit back and laugh at the DM owners. And if I really wanted to out pull a DM, just change out to a 572 CI crate engine and still not have spent as much money. Both the 8.1 and a DM were rated for the same max GCWR of 21,500 when I got mine.
  7. nosparkplugs

    nosparkplugs LawnSite Gold Member
    Messages: 3,444

    The fact remains GM scrapped the 8.1L gas engine, diehards will use the "diesel hype" but the reality is different. Because; from the engineering standpoint it would have required a huge investment to increase the MPG equal to a modern diesel that is a simple "green" issue, yes the hp/torque are comparable to the diesel, but not equal. It is much easier to turn the wick up on the Duramax, without internal modifications, and does not require a crate engine swap to do it, like with a comparable gasoline engine.

    GM did not have a reliable modern diesel until the Isuzu Duramax came into production. Some folks just will never embrace or accept the diesel option thats fine, but know this. With a Big block your spending less money on fuel, but consuming more fuel to accomplish the same work. That is a direct contradiction to any argument to keep the 8.1L in production, the modern diesel has blown the old addage " their is no replacement for displacement out of the water" the diesel will always have the advantage in commercial towing/hauling applications, than any stock or crate V8 gasoline engine. The diesels higher thermal energy (heat) advantage diesel is 147,000BTU's gasoline is 135,000BTU. Diesel fuel is currently $1.00 more per gallon, but it's higher thermal enegry more than makes up for the cost. For some it's just more soothing to pump more gasoline at a lower price.

    The gasoline vs diesel debate will never be apple's to apple's, thermal efficiency of an engine determines it's true efficiency ie: brake specific fuel consumption law applies.
    Last edited: Dec 24, 2008
  8. CrystalCreek

    CrystalCreek LawnSite Bronze Member
    Messages: 1,778

    Man there is a lot of angry people in this thread. Can someone tell GravelRat that no one cares about his stupid % grades. Stop acting like your the only on with hills. Maybe the guys in Kansas dont have big hills, but the rest of America has some REALLY big hills. The rookies come to mind. The Catskills and Adirondack area also come to mind. You really need to stop pulling #'s out of your a$$. From your earlier post, it sounds like your the one who cant drive grades, running people off the road. Your a real prize winner with that move. If I ever saw a truck trying to drive me off the road you can bet that I would unload a few rounds of lead before I went off the edge.
  9. ryry278

    ryry278 LawnSite Senior Member
    Messages: 588

    Well said Crystal Creek. Hard time believing he has driven every truck at every different place in America to test them out lol
  10. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    Don't forget though, you also get more gasoline out of a barrel of oil than you do Diesel. So it evens out in barrels of crude used. So as I pointed out in the 12 for gasoline vs 16 MPG Diesel post, you save money, and use less crude. There are only so many BTUs in a barrel of crude.

    As for your last statement, I agree. The closer you can run to the peak effciency of your engine, the better.

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