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454 Efficiency by carefull design

Discussion in 'The Garage' started by bigblock454, Oct 2, 2003.

  1. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    I am starting this thread to discuss gas engine technology focusing on efficiency with a power secondary. After many fill ups on my 1988 V3500/th400/4.10s with a 454 I have determined that careful design and thought could provide several if not more MPG. Currently my truck averages 10.1 MPG empty at 65 MPH on level ground. I am hoping to discuss changes like: engine, transmission, gear ratios, fuel management and even theoretical improvements like head chamber design and quench areas. As I have very limited funds this will be a long project.

    I will start with listing my current focus in no particular order:

    1. True dual 2.5” exhaust with hi flow mufflers and no cats, stock manifolds
    2. Electric fans to replacement stock clutch fan
    3. MSD 6A ignition (only because I have a free one)

    Below is a list of ideas that I believe will help but will probably never be able to afford:

    1. Roller CAM
    2. Flat top pistons to optimize quench area and raise compression (lots of discussion here)
    3. Wide band O2 sensor and custom EFI computer (I have a MegaSquirt custom EFI controller to try out)
    4. 4L80E Overdrive

    Things that claim improvements but I have doubts:

    1. Throttle body spacers
    2. Injector spacers
    3. Just about anything TurboCity sells
    4. Intake gaskets with a fine mesh to atomize fuel


    How about it, what do you guys think? How about some good web sites that already focus on this?
     
  2. 3car

    3car 1/2 ton status

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    just a thought about throttle body spacers.i never believed in them,but i bought a 91 k5 that had one installed already.i decided i was selling the truck,and before i did,a noticed a post on another board that someone was looking for one,and i sold it to him.i was shocked by the seat-of-the-pants loss of power once it was removed.my truck was a 350 tbi,700r4,3.08's and 31's truck.i think removing it killed the torque curve.fuel economy also suffered,probably because the engine was working harder. /forums/images/graemlins/thinking.gif
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    While I think maximizing economy is a good idea, there is one simple rule that you can't overcome. More cubic inches means more fuel required.

    It doesn't matter what you do, just like building an engine for power, if you do the *exact same things* to both engines, the larger one will make more power, and the smaller one will require less fuel.

    Current GM thinking (apparently) is that at cruise, shutting down cylinders will increase economy. This has already been tried by Cadillac, but that was back in the day, and engine management wasn't nearly what it is now.

    True duals, electric fans, and a hotter ignition aren't gonig to help measurably at all. Electric fans draw juice, the alternator has to supply it, and the engine has to turn it. Clutch fan is also driven by the engine, but *should* freewheel, minimizing drag when not needed.

    Dual exhaust may give you better mileage. A lot of variables in exhaust though. Is the diameter and length what the engine needs to produce the most power at ranges you can use it? Did GM tune the exhaust manifold design for max economy, or where they thrown on there with little or no thought, except for warranty, cost, and space?

    Hotter ignition won't help economy unless you've got some ignition problems already. If it increased economy, the automakers would use them. I'm sure that a stock setup now (if you can even get a GM engine with distributor) costs just as much as an MSD at GM's cost. Even disregarding the factory angle, where is the *proof* by dyno, believable independent testing, etc., that the claims are real? They don't exist that I've seen. You've got a free one, great. Sell it. /forums/images/graemlins/smile.gif

    Roller cams are great, but more for the cam profiles that you can run instead of drag. Roller lifters are heavier than flat tappets in many cases, which causes drag itself. Probably overall less than flat tappet, but it's not likely to be much with the same cam profile.

    Piston/head design is a big area, but just look at what GM is doing now. Higher compression, 87 Octane, more power than ever. Technology applied to the cylinder head/piston design.

    Apparently the megasquirt controller is "dumb", but haven't looked into it or wideband O2. If the megasquirt is indeed "dumb" and slow, I'm guessing a wideband O2 won't do squat. If I'm not mistaken, wideband O2 is typically used for tuning, as it gives a much better pictuire of whats going on. But if the ECM is too slow to interpret that, or is just pulsing the injectors on/off longer or slower just like a "narrow band" O2, it would be pointless.

    4L80E might be a good idea for strength, but for economy, I'm sure it's an abomination. The TH400 sucks more power than the TH350 or 700, so I'm assuming the heavier 4L80E does even moreso. Manual tranny is your best bet for economy. Even in this day and age, a new manual tranny trumps a new auto for economy. Very few people run automatics for any reason other than laziness. Between parasitic loss in the tranny, or exhaust, I'm not sure which is a better area to focus on. Both ar probably the two that are the largest drains on engine output, hugely generalizing there.

    Some of the items you were leery of actually do help, but thats been covered in other posts. I think the mesh intake gaskets were basically a "no change noticed".

    Well, those are some thoughts of mine. By no means gospel, so I'm sure others will chime in to disagree if they see a reason to! Nothing wrong with that.
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    You've missed the most important modification of all. Headers will provide more of a difference for less of an amount of money than any other modification. You might as well not spend ANY money at all on anything else if you don't include headers in the mix.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I didn't miss that at all, or so I thought:

    [ QUOTE ]
    Dual exhaust may give you better mileage. A lot of variables in exhaust though. Is the diameter and length what the engine needs to produce the most power at ranges you can use it? Did GM tune the exhaust manifold design for max economy, or where they thrown on there with little or no thought, except for warranty, cost, and space?

    [/ QUOTE ]

    or

    [ QUOTE ]
    Between parasitic loss in the tranny, or exhaust, I'm not sure which is a better area to focus on. Both are probably the two that are the largest drains on engine output, hugely generalizing there.


    [/ QUOTE ]

    Obviously (at least when I wrote this) I intended those bits to mean that if the manifolds are not efficient for the intended use, headers would be something to consider. If it wasn't clear, it should be now.
     
  6. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    454 efficiency by careful design: Maybe should read
    454 efficiency by careful acceleration.
    454 inefficiency.

    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Sorry, I didn't mean for that reply to be directed at you at all. I meant it to be directed towards the first poster.

    Edit:

    I make a habit of replying to the most recent post.

    Flat top pistons will not optimize quench area. Only decking the block and using the proper head gaskets can do that.
     
  8. fortcollinsram

    fortcollinsram 1/2 ton status

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    Go over to www.454ss.com and ask them about Feuling Heads...IIRC, they are the single most effective upgrade if you are after economy from a BBC...

    Chris
     
  9. SUBFAN

    SUBFAN 1/2 ton status

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    Gas engines generally have trouble in this area, especially BB Chevys. An engine is most efficient at it's torque peak, and often in a gas motor that peak is above the normal operating range....(diesels come to mind)

    A larger stroke and smaller bore with a very conservative camshaft would help bring the torque peak down closer to the usual operating range....

    This can also be done with gearing to an extent....

    Aerodynamics is also a huge factor to consider, no matter what engine you are building....
     
  10. 3car

    3car 1/2 ton status

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    [ QUOTE ]
    While I think maximizing economy is a good idea, there is one simple rule that you can't overcome. More cubic inches means more fuel required.

    It doesn't matter what you do, just like building an engine for power, if you do the *exact same things* to both engines, the larger one will make more power, and the smaller one will require less fuel.


    [/ QUOTE ]

    maybe not.in terms of a fullsize truck, heavy, oversize tires and probably undergeared,the superior torque of the larger engine could make up for the additional inches of displacement.simply put,a 454 dosent work as hard to move a 6000 pound blazer as a 350 would,especially if the truck is running gears that are too high.
    another example...my dad has a 2003 dodge ram with the 4.7 v8.our neighbor has an identicle truck,gears tranny,ect,but,he has the 5.7 hemi,and he gets 1.5 mpg better with a much larger engine.i know the engines are totally diferent designs,but it still supports my point.
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Driving habits have far more effect on mileage than the size of the engine, within reason.
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    10.1? Now that I found the vacume leak on my 88 3/4 454 burb with TH400 I am getting almost 10.5 runing between 70 and 75 (3.73 gear) .

    Gear vendors OD will get you up to about 12. Put the engine closer to it's peak torque of 385lbft at 1600 RPM at 65 your turning 3k. Gear venders will get you back down to around 2200-2400 at 65.

    Couse they are about $2k so it will take a LONG time to make up for it.
     
  13. 84_Chevy_K10

    84_Chevy_K10 Banned

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    My 350 TBI / TH 400 / 4.10 geared 2wd 1 ton gets 13-14. You guys are doing great, quit your whining! I bet you do much better than I do when you're pulling too. I really have to lay into the throttle to pull my 32' camper.

    EDIT:

    If my camper was only 32" long I bet I could pull it about 120 mph!!
     
  14. Twiz

    Twiz 1/2 ton status

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    [ QUOTE ]
    theoretical improvements

    [/ QUOTE ]

    Limit wast:

    Piston ring friction equal about 50% of the total mechanical loss (Losses consumed by a "free-wheeling" an engine)
    Pumping losses. The piston, pushing the spent exhaust fumes out of the chamber, equal about 40%
    Valve train friction is somewhere around 5%
    Odds and ends is another 5%

    A carefull look into the current manufacturing trends will show a simular intrest.
    They have attempted to limit pumping losses with exhuust manifolds that are more favorable to exhaust flow. Still typlicaly cast - but cast with an "eye" for making them flow better than the old cast-iron logs. They have also, invested time and money in exhaust tube routing aswell as converter design.
    Extensive use of roller valve trains. Cam-lifters are all rollers now, and there has been a trend towerds useing roller fulcrum rockers for sometime, also. (NOT roller tip)
    Electronicaly controlled engine driven accsessories, such as the alternator, a.c. compressor, and even the engine driven cooling fan on some models (4.2L I 6, Trail-Blazer - for example)
    I would assume, allthough I do not know for-sure, that they have been trying to limit piton ring frition as-well. One way to limit piston ring friction is to limit the over-all diameter of the piston - which kinda explains the trend for "over-square" engines currently used.

    Increaseing thermal eficiancy is another post all-togather.
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I honestly think emissions has more to do with the "oversquare" engines used today than anything else, although I'm sure that plays into it.
     
  16. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    My 350 TBI / TH 400 / 4.10 geared 2wd 1 ton gets 13-14. You guys are doing great, quit your whining! I bet you do much better than I do when you're pulling too. I really have to lay into the throttle to pull my 32' camper.

    EDIT:

    If my camper was only 32" long I bet I could pull it about 120 mph!!

    [/ QUOTE ]

    9.5mpg with 7,500lb of truck and trailer behind it.. It also wasn't running right when I did that.
     
  17. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    [ QUOTE ]

    Flat top pistons will not optimize quench area. Only decking the block and using the proper head gaskets can do that.

    [/ QUOTE ]

    With the current dished piston there is basically no quench at all. A flat top piston would have much more area against the flat surface of the head for quench area. Wouldn't it?
     
  18. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    [ QUOTE ]
    Current GM thinking (apparently) is that at cruise, shutting down cylinders will increase economy. This has already been tried by Cadillac, but that was back in the day, and engine management wasn't nearly what it is now.


    [/ QUOTE ]

    I think this could be achieved if you can "turn off" the pumping action of the cylinders.

    [ QUOTE ]
    minimizing drag when not needed.

    [/ QUOTE ]

    I wonder how well drag is minimized on clutch fans!

    [ QUOTE ]
    Dual exhaust may give you better mileage. A lot of variables in exhaust though. Is the diameter and length what the engine needs to produce the most power at ranges you can use it? Did GM tune the exhaust manifold design for max economy, or where they thrown on there with little or no thought, except for warranty, cost, and space?

    [/ QUOTE ]

    In my opinion, vehicle production in the 80s was 100% cost. Unless it was grossly inefficient they didn't care about it. I used to have a 90 C1500 with a TBI 350 (I broke the crank!). I installed cheapo headers and 2.25" strait pipes and gained a true 2 MPG, I keep a mileage log book on all my vehicles and can back up my claims, I am a believer in exhaust!

    [ QUOTE ]
    Hotter ignition won't help economy unless you've got some ignition problems already. If it increased economy, the automakers would use them. I'm sure that a stock setup now (if you can even get a GM engine with distributor) costs just as much as an MSD at GM's cost. Even disregarding the factory angle, where is the *proof* by dyno, believable independent testing, etc., that the claims are real? They don't exist that I've seen. You've got a free one, great. Sell it. /forums/images/graemlins/smile.gif

    [/ QUOTE ]

    I tend to agree, except! Increasing the spark voltage allows for a larger spark gap, although difficult to measure it should also increase efficiency.

    [ QUOTE ]
    Piston/head design is a big area, but just look at what GM is doing now. Higher compression, 87 Octane, more power than ever. Technology applied to the cylinder head/piston design.

    [/ QUOTE ]

    Yea, this area is big. For every point of compression you can count on about 3.5% power increase for the same amount of fuel given.

    [ QUOTE ]
    Apparently the megasquirt controller is "dumb", but haven't looked into it or wideband O2. If the megasquirt is indeed "dumb" and slow, I'm guessing a wideband O2 won't do squat. If I'm not mistaken, wideband O2 is typically used for tuning, as it gives a much better pictuire of whats going on. But if the ECM is too slow to interpret that, or is just pulsing the injectors on/off longer or slower just like a "narrow band" O2, it would be pointless.

    [/ QUOTE ]

    The MegaSquirt is a complete closed loop controller. With a wideband O2 is has the ability to cruise at any specified air/fuel ratio. You could set it to run at 17:1 or whatever your engine is capable of.

    [ QUOTE ]
    4L80E might be a good idea for strength, but for economy, I'm sure it's an abomination. The TH400 sucks more power than the TH350 or 700, so I'm assuming the heavier 4L80E does even moreso. Manual tranny is your best bet for economy. Even in this day and age, a new manual tranny trumps a new auto for economy. Very few people run automatics for any reason other than laziness. Between parasitic loss in the tranny, or exhaust, I'm not sure which is a better area to focus on. Both ar probably the two that are the largest drains on engine output, hugely generalizing there.

    [/ QUOTE ]

    This is true, I was thinking a 4L80E for the overdrive. Is there a manual overdrive suitable for my application?
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    With the current dished piston there is basically no quench at all. A flat top piston would have much more area against the flat surface of the head for quench area. Wouldn't it?

    [/ QUOTE ]

    I suppose that's true, but if you've got .060" of deck clearance already, it doesn't really matter what pistons you use. Your quench is already going to be WAY too high. /forums/images/graemlins/smile.gif
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    I honestly think emissions has more to do with the "oversquare" engines used today than anything else, although I'm sure that plays into it.

    [/ QUOTE ]

    Emissions has a part to play in every motor built nowadays, but to think that power benefits aren't in the engineers mind would be a mistake. They can't sell vehicles that don't get up and go (to some people) so an efficient engine that produces more power with less emissions is a win win for everyone involved.
     

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