About this new 6.6 gasser...

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Thread: About this new 6.6 gasser...

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    About this new 6.6 gasser...

    Any chance it will be a tall deck (9.720 deck height vs the standard 9.240) LSX style block?

    https://www.gmperformancemotor.com/parts/19260100.html

    A long stroke LS would certainly be great for torque.

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    Re: About this new 6.6 gasser...

    I am more interested in a high revving Chevrolet motor, about 800 bhp horses natural

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    Re: About this new 6.6 gasser...

    Quote Originally Posted by mbukukanyau View Post
    I am more interested in a high revving Chevrolet motor, about 800 bhp horses natural
    for HD /MD trucks??

    I want TORQUE DOWN LOW and a tall deck LONG stroke engine is better then a short deck wide bore "screamer" that will never be OE fitted to a VETTE

    the PSI big block based stuff VS the FORD V10 witch is based on the 5.4 MOD motor the PSI motors pull LOADS better and return better fuel economy

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    Re: About this new 6.6 gasser...

    Quote Originally Posted by serpico View Post
    Any chance it will be a tall deck (9.720 deck height vs the standard 9.240) LSX style block?

    https://www.gmperformancemotor.com/parts/19260100.html

    A long stroke LS would certainly be great for torque.
    I don't know for sure, but I think that is a good possibility. I have been told that the 6.6L will be similar in some ways to a Gen. V LS. If it is an LS derivative a long stroke tall deck version is a lot more likely than an engine with increased bore centers. Changing bore centers pretty much results in an all-new engine, while raising the deck height of an existing engine family allows a lot of parts sharing and possibly even using the same plant machine line (a major cost savings). It's been done a lot before, the Ford Windsor, Olds and Pontiac V-8's, Chevy straight 6's, Chrysler B/RB V-8, and even the old Slant Six. There were tall deck 'truck' Chevy Big Blocks, but the increase in deck height was done to accommodate a taller 4 ring piston, not to increase displacement. Of course the aftermarket did use those tall deck blocks to get more cubes......

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    Re: About this new 6.6 gasser...

    Yeah I don't see the bore size going up from 4.065. At 4.125 for the LS7 GM had to basically reengineer the whole block and go with siamesed sleeves.

    I don't know that they really have to change the deck height either to achieve ~400cid of a 6.6L, an LS3/LT1 with a 4" stroke gives you 416 cubes, a popular LS displacement and deemed safe for longevity's sake with the stock length sleeves.
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    Re: About this new 6.6 gasser...

    I have been told the piston is unstable at the bottom of the bore if the stroke is much greater than the 6.0L's 3.62" with current production LS iron blocks. Of course that doesn't mean GM couldn't revise the iron block casting to accommodate a longer stroke while retaining the same deck height, but I think a tall deck block would have other advantages for HD pickup/MD truck service. One would be more coolant capacity. Another might be a better rod ratio.

    I am assuming the new 6.6L will have an iron block with a 4.0" bore.

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    Re: About this new 6.6 gasser...

    Quote Originally Posted by Sierra12 View Post
    I have been told the piston is unstable at the bottom of the bore if the stroke is much greater than the 6.0L's 3.62" with current production LS iron blocks. Of course that doesn't mean GM couldn't revise the iron block casting to accommodate a longer stroke while retaining the same deck height, but I think a tall deck block would have other advantages for HD pickup/MD truck service. One would be more coolant capacity. Another might be a better rod ratio.

    I am assuming the new 6.6L will have an iron block with a 4.0" bore.
    A GenIV 6.0 is fine with up to a 4" stroke, a 408 is a pretty popular motor for the racers. 4.1" starts to get to the point where piston rock can become an issue although people will still push it for the extra cid but run a custom piston to help longevity. Anyway that's assuming this 6.6 is going to stay as an iron block. GM could simply chose to go with the 6.2 aluminum block and add stroke for a displacement increase.

    Keep in mind tall deck adds some mfg issues - you lose some parts commonality among the LT V8s, now need a separate intake manifold, probably some other top end and accessory changes. Also potential clearance issues in the engine bay though that should be less of an issue in the trucks.
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    Re: About this new 6.6 gasser...

    I hear it's an iron block. Remember that duty cycle for a medium duty truck engine is different than a light truck/passenger car, or even a race car for that matter.

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    Re: About this new 6.6 gasser...

    Quote Originally Posted by NHRATA01 View Post
    A GenIV 6.0 is fine with up to a 4" stroke, a 408 is a pretty popular motor for the racers. 4.1" starts to get to the point where piston rock can become an issue although people will still push it for the extra cid but run a custom piston to help longevity. Anyway that's assuming this 6.6 is going to stay as an iron block. GM could simply chose to go with the 6.2 aluminum block and add stroke for a displacement increase.

    Keep in mind tall deck adds some mfg issues - you lose some parts commonality among the LT V8s, now need a separate intake manifold, probably some other top end and accessory changes. Also potential clearance issues in the engine bay though that should be less of an issue in the trucks.
    Agree, think it will be 4.00" Stroke with an Iron Block for durability using the same deck height.

    Interesting numbers are with a 4.125" Bore and 4.00" Stroke you get a 427 (7.0L) with a 4.250" Bore and 4.00" Stroke you get a 454 (7.4L) which would make great crate engines and potential options for Medium Duty Gas Trucks - of course those will need some changes to the block and might be where you would see a "Raised Block".

    Other displacements are 3.78" Bore (5.3L) and 4.00" Stroke you get a 365 (5.9L) and 4.065" Bore (6.2L) and 4.00" Stroke you get a 415 (6.8L)

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    Re: About this new 6.6 gasser...

    I think they will hold the bore at 4.00" for good emissions and to maintain good cylinder wall thickness and head gasket sealing. Remember, it's primarily a commercial engine.

    BTW- I may have mentioned it before, but the 6.6L is also slated for use in the Isuzu FTR and Chevy 6500 LCF.

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    Re: About this new 6.6 gasser...

    Quote Originally Posted by SierraGS View Post
    Agree, think it will be 4.00" Stroke with an Iron Block for durability using the same deck height.

    Interesting numbers are with a 4.125" Bore and 4.00" Stroke you get a 427 (7.0L) with a 4.250" Bore and 4.00" Stroke you get a 454 (7.4L) which would make great crate engines and potential options for Medium Duty Gas Trucks - of course those will need some changes to the block and might be where you would see a "Raised Block".

    Other displacements are 3.78" Bore (5.3L) and 4.00" Stroke you get a 365 (5.9L) and 4.065" Bore (6.2L) and 4.00" Stroke you get a 415 (6.8L)
    I actually have an LS-based 454 in my T/A, but it is a Darton resleeved aluminum block. Probably not sufficient for long term OEM level durability. But it is a 4.185 bore by 4.125 stroke. Keep in mind the LS bore spacing is only 4.4", so 4.185 is about as big as you want in an LS with enough meat left in the cylinder wall/sleeve for head gasket sealing.

    But enough of my speculation, I am interested to see what GM does with a 6.6 LS
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    Re: About this new 6.6 gasser...

    Quote Originally Posted by NHRATA01 View Post
    I actually have an LS-based 454 in my T/A, but it is a Darton resleeved aluminum block. Probably not sufficient for long term OEM level durability. But it is a 4.185 bore by 4.125 stroke. Keep in mind the LS bore spacing is only 4.4", so 4.185 is about as big as you want in an LS with enough meat left in the cylinder wall/sleeve for head gasket sealing.

    But enough of my speculation, I am interested to see what GM does with a 6.6 LS
    Good Point about the Bore Size for larger than 7.0L Engine, won't be an issue with the 6.6L since it will probably be "Square" 4.00 x 4.00.

    Wonder if GM will ever add a S/C or really surprise with a 6.6L Turbo?

    Could add a Voltec Powertrain to it for Diesel-Like Torque for far less cost than a HD Diesel and the "Chemical Factory" that comes with it - might even be lighter and have better weight distribution....

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    Re: About this new 6.6 gasser...

    You know what's bad about all this? I really like my '12 GMC 3500HD with it's L96 6.0L. Going to be hard to resist a new one with the 6.6L!

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    Quote Originally Posted by Sierra12 View Post
    I have been told the piston is unstable at the bottom of the bore if the stroke is much greater than the 6.0L's 3.62" with current production LS iron blocks. Of course that doesn't mean GM couldn't revise the iron block casting to accommodate a longer stroke while retaining the same deck height, but I think a tall deck block would have other advantages for HD pickup/MD truck service. One would be more coolant capacity. Another might be a better rod ratio.

    I am assuming the new 6.6L will have an iron block with a 4.0" bore.

    Interesting you bring up GM accommodating a larger stroke with a modified Iron block design That is exactly what Dart did with their aftermarket "LS NEXT" Iron block it is a great way to reliably run a 4.1" stroker crank. In addition to the standard 9.240 deck height Dart also makes a 9.450 deck height version for even greater reliability, durability and clearance.

    http://dartheads.com/dart-product/ls-next-iron/

    • Siamesed cylinder bores with extra thick walls.

    • Cylinder barrels extended .375” at the bottom.

    Hopefully GM will at the least make similar adjustments to the skirt length if they continue to use a 9.240 deck height block, as I understand it the skirt length on the 6.0 vortec block is actually shorter then the aluminum (LS3) version.

    Ideally they will employ a tall deck, and run a 4.1 -4.125 stroke. Though this is doubtful.
    Last edited by serpico; 01-08-2019 at 12:19 PM.

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    Re: About this new 6.6 gasser...

    the longer skirt length should mitigate the "rock" issue of the long stroke

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