Author Topic: Let's Talk 408's  (Read 1313 times)

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Offline inzane

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Let's Talk 408's
« on: September 8, 2020, 01:27:34 pm »
Specifically longevity and bore wear, and ring flutter issues due to the less stable short skirt pistons.

Some of you guys are running small block strokers, any issues?

 If I were to build one it would spend the majority of it's time loafing along at 2500 pulling a 20ft camper. Rev limiter would be set at 5000. Eddy RPM heads, Pro Flow 4 efi, mild Hughes roller cam, headers.
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    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #1 on: September 8, 2020, 01:57:22 pm »
    Specifically longevity and bore wear, and ring flutter issues due to the less stable short skirt pistons.

    Some of you guys are running small block strokers, any issues?

     If I were to build one it would spend the majority of it's time loafing along at 2500 pulling a 20ft camper. Rev limiter would be set at 5000. Eddy RPM heads, Pro Flow 4 efi, mild Hughes roller cam, headers.
    I'd jump on it.
    Except for the mild cam. I'd go moderate to take advantage of the freer flowing heads. High lift/ semi short duration... a hydraulic roller. Why stifle the flow?
    You'll have so much more torque all over.
    Set the rev limiter to 6,000.
    « Last Edit: September 8, 2020, 01:59:13 pm by KurtfromLaQuinta »
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline ToxicDoc

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    Re: Let's Talk 408's
    « Reply #2 on: September 8, 2020, 02:02:38 pm »
    I use my truck very little, so I can't speak about long-term wear based on my use. It's definitely a theoretical issue, but I don't know how that translates to actual hours-on-engine effect. I have used mine for plowing as well as general use, and so far so good.
    '85 W150 SB, 408 stroker, Magnum manifolds, Performer RPM, 670 Truck Avenger, HEI ignition, Auburn LSD 9.25 and '82 D44 (non-CAD) with 3.55/3.54,  NV4500/NP241

    Offline inzane

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    Re: Let's Talk 408's
    « Reply #3 on: September 8, 2020, 02:54:52 pm »
    I use my truck very little, so I can't speak about long-term wear based on my use. It's definitely a theoretical issue, but I don't know how that translates to actual hours-on-engine effect. I have used mine for plowing as well as general use, and so far so good.
    Cam's 226/230, .521/.530 on a 110 lsa. I'm after torque not big hp numbers. The Pro Flow 4 uses the Vic Jr single plane. Port velocity is a little soft below 2500 on a 360, I figure  increasing piston fps will fix it some.
    CANCER SUCKS.

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    Offline inzane

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    Re: Let's Talk 408's
    « Reply #4 on: September 8, 2020, 03:03:08 pm »
    One thing I wonder about is hyperutectic vs forged clearance and piston rock in the bore. This motor won't see nitrous, boost or high rpm. Thinking the tighter .0015" clearance of the hyperutectic would be the wiser choice with a short skirt piston.
    CANCER SUCKS.

    '86 RC.  Fresh '90 MPFI LA360 with some shiny crap on it / 727/208 / 60's on 35's w/4.10's / rear Spartan/front E locker / 4" Softrides / ORD crossover
     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline ToxicDoc

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    Re: Let's Talk 408's
    « Reply #5 on: September 8, 2020, 03:40:45 pm »
    One thing I wonder about is hyperutectic vs forged clearance and piston rock in the bore. This motor won't see nitrous, boost or high rpm. Thinking the tighter .0015" clearance of the hyperutectic would be the wiser choice with a short skirt piston.

    I think if are getting pistons from a good manufacturer, you are likely correct if your compression ratio isn't too high.
    « Last Edit: September 9, 2020, 11:18:49 am by ToxicDoc »
    '85 W150 SB, 408 stroker, Magnum manifolds, Performer RPM, 670 Truck Avenger, HEI ignition, Auburn LSD 9.25 and '82 D44 (non-CAD) with 3.55/3.54,  NV4500/NP241

    Offline Chilly

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    Re: Let's Talk 408's
    « Reply #6 on: September 8, 2020, 04:53:52 pm »
    I wouldnt be afraid of a little more cam than "mild".  Your displacement and CR bump (what will you aim for?) will give you all the bottom endd you want.  But agree with avoiding high revs, and the parts that are made for such.  Piston velocity increases with a stroker kit so I like what you are saying about RPM.

    Nobody puts a class 3 hitch on a Corvette but a lot of people want a race car engine in a truck.
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    Offline inzane

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    Re: Let's Talk 408's
    « Reply #7 on: September 8, 2020, 06:12:30 pm »
    I figured I was going to shoot myself in the foot with the 110LSA cam and the PF4's single plane intake on a 360. I should have [and could have] gotten the same grind on a 114. That would have reduced turbulence in the plenum a little, but the 114 gives up torque vs the 110 too, so probably six one way half a dozen the other.

    It runs fine, the idle is bumpy but cleans up immediately when the the throttle is opened. There just isn't any port velocity to help fill the cylinders at low rpm with the large, short runners, open plenum and a cam that throws a little reversion into the mix. And just as I figured, not too impressed with the torque. But it's the only MPFI intake on the market with an LA bolt pattern.

    That only leaves a few choices. Shitcan the brand new PF4 in favor of a dual plane and modern TBI like the Holley Sniper etc. Those are not of the best quality, they seem to be somewhat trouble prone. I like the Eddy, the PCM is remote mounted which helps quell EMI/RFI issues, and it stays cooler. It's Bluetooth for tuning which is also pretty cool. Overall it's a higher quality system, just uses the wrong intake for a small motor in a heavy truck with a stiff converter.   

    I could add injector bungs to a Performer intake or similar and try to tune the PF4 to work with it. That might require a custom tune, and since the PF4 uses prewritten base maps as a starting point I'm not sure that is even possible. It doesn't have data logging ability. I already have an intake, Induction Solutions can weld in the bungs for a couple hundred bucks. But it could turn into a couple months of BS trying to make it run right and never pan out.... Or it might run fine with no tune issues at all. It would be a cool experiment if I had the time to piddle with it. But I don't.

     Which brings us to the 408 option. Increase piston speed across the same rpm range to increase port velocity, plus a longer arm on the crank during the power stroke. Given my choices a stroker seems the most feasible way to kick the thing in the ass torque wise, but I don't want to rebuild it every 40,000 miles either.
    CANCER SUCKS.

    '86 RC.  Fresh '90 MPFI LA360 with some shiny crap on it / 727/208 / 60's on 35's w/4.10's / rear Spartan/front E locker / 4" Softrides / ORD crossover
     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #8 on: September 8, 2020, 06:36:31 pm »
    Almost all single plane manifolds on small blocks are higher rpm units.
    Years ago Mopar (Direct Connection) said single planes on small block were a big no- no. Unless you were going drag racing.
    That would change if you were flowing just air... a la port injection.
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #9 on: September 8, 2020, 06:40:32 pm »
    By the way... higher HP figures to more torque.
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline inzane

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    Re: Let's Talk 408's
    « Reply #10 on: September 8, 2020, 07:09:45 pm »
    By the way... higher HP figures to more torque.

    Not necessarily, it can be the same torque figure, just higher in the rpm range. Torque x RPM = HP. 

    As for carbed vs TBI or MPFI on a given intake, port dynamics don't change according to how the fuel introduced. The booster in a carb requires air velocity to function, but beyond mixture issues it has little to do with torque production. Higher air velocity [inertial cylinder filling] is a function of several factors.
    CANCER SUCKS.

    '86 RC.  Fresh '90 MPFI LA360 with some shiny crap on it / 727/208 / 60's on 35's w/4.10's / rear Spartan/front E locker / 4" Softrides / ORD crossover
     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline Chilly

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    Re: Let's Talk 408's
    « Reply #11 on: September 8, 2020, 07:45:34 pm »
    Not necessarily, it can be the same torque figure, just higher in the rpm range. Torque x RPM = HP. 

    As for carbed vs TBI or MPFI on a given intake, port dynamics don't change according to how the fuel introduced. The booster in a carb requires air velocity to function, but beyond mixture issues it has little to do with torque production. Higher air velocity [inertial cylinder filling] is a function of several factors.

    I dont think I agree with that, but I'm not saying that as an argument.  Fuel introduced at fromt of runners can come out of suspension with large slow runners.  TBI is slightly better than a carb in that atomization is better.  With TBI one can have YUGE runners without fuel de-atomization because fuel is injected just in front of the heads. 
    92 Ramcharger
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    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #12 on: September 8, 2020, 10:45:51 pm »
    Not necessarily, it can be the same torque figure, just higher in the rpm range. Torque x RPM = HP. 

    As for carbed vs TBI or MPFI on a given intake, port dynamics don't change according to how the fuel introduced. The booster in a carb requires air velocity to function, but beyond mixture issues it has little to do with torque production. Higher air velocity [inertial cylinder filling] is a function of several factors.
    As far as intakes are concerned, a dry air, single plane works great for SMPI/ MPI. Single planes suck for lower rpm torque figures with a mixture flow... as we talk about torque figures at rpm ranges.  Chrysler engineers figured that out in the early 50's.
    Yep. If your going down a drag strip/ road course/ whatever racing you can think of... single planes are great. When your rpm range is 3,000 to 12,000, and your not taking off from a stop sign. They are hard to beat.
    « Last Edit: September 8, 2020, 10:55:25 pm by KurtfromLaQuinta »
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #13 on: September 8, 2020, 10:51:05 pm »
    I dont think I agree with that, but I'm not saying that as an argument.  Fuel introduced at fromt of runners can come out of suspension with large slow runners.  TBI is slightly better than a carb in that atomization is better.  With TBI one can have YUGE runners without fuel de-atomization because fuel is injected just in front of the heads.
    TBI isn't the best route. They were advanced tech 25 years ago. They're pretty much glorified carburetors now. There isn't any car manufactures using that tech today. Computers have refined fuel systems so good... it's hard to beat the stuff that's out there now.
    « Last Edit: September 8, 2020, 10:56:22 pm by KurtfromLaQuinta »
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline inzane

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    Re: Let's Talk 408's
    « Reply #14 on: September 8, 2020, 11:38:24 pm »


    As I said, beyond mixture issues. Mpfi does take fuel suspension out of the runner design equation for the most part, but the runners themselves still have to efficiently use pulse wave resonance and velocity to make power through a given rpm range. A large volume, short runner single plane will still favor higher rpm, be it wet or dry runner.

    There is far more going on in the intake tract than just fuel suspension and/or booster signal. Note the dual runner length mpfi intakes of recent years, with the computer switching flow paths from smaller long runners to larger short runners at higher rpm to broaden the torque curve. Why go to the trouble and expense of manufacturing that if dry flow runner length/volume is irrelevant to peak torque rpm? Why bother to make a beer barrel Magnum intake for low end torque? Why did the OEM's not just slap a cheap to manufacture large port volume short runner single plane on and be done with it?

    Anyway, back to pistons, rings and bore wear.  :)

     
    CANCER SUCKS.

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     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline dodge82273

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    Re: Let's Talk 408's
    « Reply #15 on: September 9, 2020, 02:12:07 am »
    I don't like the hyper pistons used a set and didn't like the slap , stock stroke , cold hot changes them alot , too much ....    imo

    single plane ( big hole , no "runners") ng for low end grunt .   

    tbi mpfi 2 different animals  .... 
    modern hot rod mpfi don't use a LOG intake , they seem to use runners .... don't really know tho ...
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    Offline Mad Max

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    Re: Let's Talk 408's
    « Reply #16 on: September 9, 2020, 08:15:43 am »

     Which brings us to the 408 option. Increase piston speed across the same rpm range to increase port velocity, plus a longer arm on the crank during the power stroke. Given my choices a stroker seems the most feasible way to kick the thing in the ass torque wise, but I don't want to rebuild it every 40,000 miles either.


    Joel - to me there always seems to be some underwhelming 'unawesomeness' with a 408 built for torque, and the ones built for horsepower rip real good but they tend to eat themselves, so, that's why I went with a 440 for my Dakota, which if it runs as good as it should it'll be a sweet and polite torque monster with no voodoo at all in the engine - just good ole big block Mopar hardware.  Is a big block an option for you?  If not...there is always the option of building a nice strong supercharged 360 - just a mildly boosted engine with the hair dryer under the hood...?
    « Last Edit: September 9, 2020, 08:20:19 am by Mad Max »
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    Offline inzane

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    Re: Let's Talk 408's
    « Reply #17 on: September 9, 2020, 08:55:17 am »
    Joel - to me there always seems to be some underwhelming 'unawesomeness' with a 408 built for torque, and the ones built for horsepower rip real good but they tend to eat themselves, so, that's why I went with a 440 for my Dakota, which if it runs as good as it should it'll be a sweet and polite torque monster with no voodoo at all in the engine - just good ole big block Mopar hardware.  Is a big block an option for you?  If not...there is always the option of building a nice strong supercharged 360 - just a mildly boosted engine with the hair dryer under the hood...?

    I have a fair amount already invested in the 360, plus everything is set up for a small block. If I were starting from scratch a 440 would definitely be a consideration.

    How many miles does Homer have on his 408? It's been several years since it was screwed together. He had any issues with the rotating assy? Burning oil or anything? That motor is fairly mild and makes 450ish hp and nearly 500lbft correct? I realize those numbers are at the mid to upper end of the rpm scale, but it pulls pretty good off idle doesn't it?
    CANCER SUCKS.

    '86 RC.  Fresh '90 MPFI LA360 with some shiny crap on it / 727/208 / 60's on 35's w/4.10's / rear Spartan/front E locker / 4" Softrides / ORD crossover
     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline Mad Max

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    Re: Let's Talk 408's
    « Reply #18 on: September 9, 2020, 09:04:29 am »
    I have a fair amount already invested in the 360, plus everything is set up for a small block. If I were starting from scratch a 440 would definitely be a consideration.

    How many miles does Homer have on his 408? It's been several years since it was screwed together. He had any issues with the rotating assy? Burning oil or anything? That motor is fairly mild and makes 450ish hp and nearly 500lbft correct? I realize those numbers are at the mid to upper end of the rpm scale, but it pulls pretty good off idle doesn't it?

    well...he also has 5.86 gears in the axles which helps a lot.  His engine seems to be doing well enough - it makes power, but like you said it has to be cranked up to really get moving - those big numbers are at the top of his rpm band which is north of 5k rpm.  It also seems to be a big 'noisy'...but that could be normal - IDK. 

    Bottom line is if we were beginning Homer's build now I'd suggest starting with a big block.  Of course he's heavy - his truck weighs more than 7k lbs, but I'm just not convinced a 408 (built for torque) is worth the effort.  Other options include both the 6BT Cummins and the new R2.8 Cummins...
    « Last Edit: September 9, 2020, 09:08:12 am by Mad Max »
    2002 Dakota Quad Cab 4x4 - 440/46rh/Atlas4/D60/14b/40s
    2007 Cummins Ram 3500 Megadually 4x4 "Big Mack" - 5.9/G56 6-speed
    2016 Durango Citadel AWD - 5.7 Hemi/8-spd auto
    1952 Willys M-38 "Poncho"

                    .there's always a way...

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    Offline Chilly

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    Re: Let's Talk 408's
    « Reply #19 on: September 9, 2020, 09:31:40 am »
    TBI isn't the best route. They were advanced tech 25 years ago. They're pretty much glorified carburetors now. There isn't any car manufactures using that tech today. Computers have refined fuel systems so good... it's hard to beat the stuff that's out there now.

    I mis-typed.  Meant to say that with PORT injection you can have huge runners.  With carb or TBI one should want to keep velovity high to prevent droplets.
    92 Ramcharger
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    44F, 9.25R posi, 3.54 gears (yeah, I know)
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    Offline inzane

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    Re: Let's Talk 408's
    « Reply #20 on: September 9, 2020, 09:46:39 am »
    well...he also has 5.86 gears in the axles which helps a lot.  His engine seems to be doing well enough - it makes power, but like you said it has to be cranked up to really get moving - those big numbers are at the top of his rpm band which is north of 5k rpm.  It also seems to be a big 'noisy'...but that could be normal - IDK. 

    Bottom line is if we were beginning Homer's build now I'd suggest starting with a big block.  Of course he's heavy - his truck weighs more than 7k lbs, but I'm just not convinced a 408 (built for torque) is worth the effort.  Other options include both the 6BT Cummins and the new R2.8 Cummins...

    He also has pretty big tires, so the 5.86's might not be as steep as they would appear. My 4.10's/35's give a true ratio of 3.36.

    Does his motor have forged pistons? Those run a bit looser in the bore than a hyperutectic.
    That's what I'm trying to decide, if the tighter clearance of hyperutectic pistons add much of anything to longevity by reducing rocking in the bore. One would think it would.
    CANCER SUCKS.

    '86 RC.  Fresh '90 MPFI LA360 with some shiny crap on it / 727/208 / 60's on 35's w/4.10's / rear Spartan/front E locker / 4" Softrides / ORD crossover
     '94 Dakota Sport Club Cab
     '75 Dodge Travco 270

    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #21 on: September 9, 2020, 11:09:54 am »
    He also has pretty big tires, so the 5.86's might not be as steep as they would appear. My 4.10's/35's give a true ratio of 3.36.

    Does his motor have forged pistons? Those run a bit looser in the bore than a hyperutectic.
    That's what I'm trying to decide, if the tighter clearance of hyperutectic pistons add much of anything to longevity by reducing rocking in the bore. One would think it would.
    I'm running forged pistons.
    They really aren't that loose. They are way stronger than hyperutectic.
    I get a little noise from them at start up. After that they are quiet.
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline GusChiggins86

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    Re: Let's Talk 408's
    « Reply #22 on: September 9, 2020, 02:51:07 pm »
    I have a torquey 408 Magnum being shipped from Hughes Engines for my '89 RC any day now. I'll let you know how that one turns our in the Projects forum.
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    Offline Killerbee

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    Re: Let's Talk 408's
    « Reply #23 on: September 10, 2020, 01:21:34 pm »
    Havent seen it discussed yet... so I'll throw in another stick in the fight.

    How about a supercharged 360?

    Simple 'maths' is that a regualar motor is running at about 14 PSI, so adding a supercharger with just 4 pounds of boost would 'kinda' equate to 18PSI....  Which kinda translates to 460 cid.

    The supercharger is able to be set up for low end torque.  It'll always help and the centrifigal type is not super expensive.

    And you can instal different pulleys to adjust your boost after the build.

    With modern fuel injection you can  properly fuel it and properly set the ignition timing.

    -Ben

    Offline ToxicDoc

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    Re: Let's Talk 408's
    « Reply #24 on: September 10, 2020, 01:32:20 pm »
    Havent seen it discussed yet... so I'll throw in another stick in the fight.

    How about a supercharged 360?

    Simple 'maths' is that a regualar motor is running at about 14 PSI, so adding a supercharger with just 4 pounds of boost would 'kinda' equate to 18PSI....  Which kinda translates to 460 cid.

    The supercharger is able to be set up for low end torque.  It'll always help and the centrifigal type is not super expensive.

    And you can instal different pulleys to adjust your boost after the build.

    With modern fuel injection you can  properly fuel it and properly set the ignition timing.

    -Ben

    Supercharger setup is likely much more expensive. Think about the intake setup, pulleys, etc. Stroker kit (at the time I did mine) was about $1700 including crank, rods pistons.
    '85 W150 SB, 408 stroker, Magnum manifolds, Performer RPM, 670 Truck Avenger, HEI ignition, Auburn LSD 9.25 and '82 D44 (non-CAD) with 3.55/3.54,  NV4500/NP241

    Offline subwoofer88

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    Re: Let's Talk 408's
    « Reply #25 on: October 23, 2020, 10:32:27 pm »
    One thing you can do is find your Piston Speed. Stoke X Max RPM / 6 = Piston Speed. If you are under/around 4,000 it's a safe motor to rip on. 5,000 you're pushing it hard. Also thinner piston rings helps too. That technology is coming along as well.

    Looked through the 408 crate engines on Summit, and they all run Forged Pistons.
    "Fury" 1973 W200 Camper-7500, 360LA, NP435+NP203 (with part time conversion), 44HD front - 60 rear
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    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #26 on: October 24, 2020, 02:35:14 pm »
    Specifically longevity and bore wear, and ring flutter issues due to the less stable short skirt pistons.


    To quote Rick Ehrenburg in the latest Mopar Action... "Have you looked at the late model Hemi engines lately?" They all have very short skirts.
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline RXT

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    Re: Let's Talk 408's
    « Reply #27 on: October 31, 2020, 09:27:46 pm »
    ....but I'm just not convinced a 408 (built for torque) is worth the effort.

    Care to elaborate?

    Ed
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    Offline KurtfromLaQuinta

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    Re: Let's Talk 408's
    « Reply #28 on: October 31, 2020, 10:53:41 pm »
    Care to elaborate?

    Ed
    It's hard to beat a RB Block for torque.
    Especially in the 440/ stroked configuration.
    500 c.i.- Scat Crank, Scat Rods, Indy Aluminum heads, Comp XR280HR Cam, Six-Pack, Milodon 8 qt. Pan, 727  (reverse-manual, low band apply, 5 clutch disc, 3 qt. xtra. pan), N.P. 205, Ford 9" rear axle (4:11, 31 spline axles, Detroit Locker, converted/ disc brakes). Dana 44 front (converted/ disc, 4:10, Tru-Trac limited slip). Hydra Boost Brake Booster, Gear Vendors OD. 600+ ft. lbs. of torque

    Offline RXT

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    Re: Let's Talk 408's
    « Reply #29 on: November 1, 2020, 07:49:22 am »
    It's hard to beat a RB Block for torque.
    Especially in the 440/ stroked configuration.

    The biggest contributor to torque is displacement. (Or forced induction, if so equipped) A 440 will naturally produce more torque than a 408 stroker because the 440 has a 32 cubic inch advantage. However, if you want torque at low rpm, longer stroke is an advantage. This is because at any given piston speed, it still takes a bit longer for the piston to travel from TDC to BDC, thus making the crank to complete every rotation at a slower rate.

    With a 4.32" bore and 3.75" stroke, the 440 would produce it's greater torque at higher rpm and the higher rpm potential would make it great for horsepower. The 408 being slightly smaller, would mean that it makes slightly less torque, but it has a longer 4" stroke than the 440, and that means it should produce it's torque at lower rpm. From a torque perspective both engines should be pretty equal.

    Ed


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    Offline Mad Max

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    Re: Let's Talk 408's
    « Reply #30 on: November 1, 2020, 07:50:15 am »
    Care to elaborate?

    Ed

    well, after driving Homer's truck, and hearing about others who have built a 'torque' 408, they just...like Kurt said...don't have the same way low 'grunt' - ya still kinda haveta wind 'em up a bit.  They definitely run, but the silky smooth gooey torque just isn't the same.  Would it be enough - probably, sure. 

    It's going to be interesting to see how Homer's RC drives/wheels compared to both my 440 Dakota and Ben's 440 '77 RC.
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    Offline ram-it

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    Re: Let's Talk 408's
    « Reply #31 on: November 16, 2020, 08:45:04 am »
    Stroke a 400. Best of both worlds.