Hypothetical - 426 stroker w/kegger

[Yeret]

Been another long time since I've posted here. I really should check in more often!

Anyway, I've got a hypothetical scenario that I could do with some insight before the day comes when I actually have the funds to even consider this.

Here's what I'm thinking: A Hughes Engines "360 to 426" stroker kit (here it is) with an appropriate camshaft, upsized fuel injectors, and a slightly modified kegger. By "slightly modified," I'm talking a simple gasket-match port job on the intake side and boring out the throttle body inlets if necessary.

My goal for such a build is to pass 300 horsepower and have at least 450 lb/ft of peak torque, both of which coming in at as low an RPM as possible. Yeah, not what you'd call ambitious numbers, especially considering the displacement and expense, but I'd be quite happy to have 8.0 power without the hassle of doing such a swap in my 1500.

Do you think the kegger would flow enough to feed such displacement to achieve my goals? Maybe I could achieve the same numbers with a much cheaper 408 stroker? Should I bribe someone at Hughes for a FI AirGap since they've been on backorder all year and use that instead? Or maybe my 360 could simply be built up to attain the same numbers (I would prefer to keep things naturally aspirated, but I've nonetheless given thought to slapping on a blower)?

I'm just curious to hear opinions/facts from people who've made similar builds or have appreciable insight.

 

[Bear_Gibson]

Oh I have wanted to do that very badly. Make that diesel torque. There's only one way to find out. Although, If I was going that far I might feel greedy and want the 440 setup, lol.

 

[Yeret]

Nice to see some interest in this. I wish I could say I was working on such a build right now, but with my budget, I'm gonna consider myself lucky if I can get the axles rebuilt within the next year or two and then after that, the tranny's probably gonna need another redo. But hey, gives us plenty of time to contemplate, right?

So, after some quick reading, I realize that the 8.0 V10's actually have a 3.88" stroke, which means that they're certainly, simply more than a 360 (3.58" stroke) with two more cylinders attached. This particular build would yield 7.0 liters. We're giving up an entire liter of displacement, so to match the torque (450 lb/ft at 2,400 RPMs!), there is certainly going to have to be some sort of emphasis on efficiency. Those 8 liters are true monsters in the gasser world! Makes ya wonder how much power they could really make with some tweaking...

At any rate, in factory form, the 8.0 is only rated at 8.4:1 static compression ratio. Now, at the moment, I know absolutely nothing of the cam specs, nor do I know if the engines are prone to the relatively extreme cylinder quenches that the V8s seem to have, so I'm not sure of the dynamic compression ratio that these engines would typically have and therefore how much they may or may not be giving up for the sake of "emissions" or whatever the hell.

Now, whether you say he's a con man or not and assuming you believe his dyno charts, the dude over at Utawesome Performance manged to chart 400 lb/ft torque with a punched 5.9 with a custom cam, flat-top pistons, a few modifications to the kegger (the mods in question I'm somewhat tepid) and factory heads. With an extra 66 cubes and setting up to maximize the relatively high piston velocity of a 1.46:1 rod/stroke ratio, can we tack on those extra 50 lb/ft torque?

Also, 1.46:1 rod/stroke ratio seems pretty lousy for general longevity due to the ****** angle the pistons would have against the cylinder walls, but unless someone can find a way to reliably fit a 440's 6.768" rods to the Magnum's crankshaft and then find pancake pistons to fill the itty, bitty deck clearance that's left over, we're kinda stuck with it. Then again, for an engine that's only going to, ahem, occasionally see the other side of 3 or OMG, heaven forbid 4-thousand RPMs, we might be able to get away with it. Hey, hauling *** is hauling *** even if that tach needle is just barely passing that "3" mark!

EDIT: [clarification] Apparently, t-h-r-u-s-t, as was used above in reference to the potential side-loading, and therefore potential wear and tear, effects that the pistons would exert upon the cylinder walls upon switching directions with hundreds of feet per second's-worth of momentum is a censored word now. Just wanted to clear that up!

 

[G-Ride990]

The HP/TQ numbers you want seem do-able from a 408. But not at that low RPM range. I don't think the kegger intake could support the extra flow of the larger engines either. At least I have never seen someone build a 408+ and use the kegger. But everyone that builds 408s revs them at least as high as the stock fuel cut was which was like 5500 or higher.

You are going to have to have some weird custom torque converter made for whatever engine you are going to end up with to make the power down low too right?

Have you considered doing a cummins swap? That really seems like the obvious choice here.

 

[Joe w.]

I've wanted more power and torque for awhile now. I have access to 383s and 440 motors but not sure how to go about doing it. How do you bypass the computer etc. My truck is 4wd so I'm thinking that would make things more difficult. My dad ran into a guy who had a 98 model 2wd that had put a 383 in his truck

 

[Bear_Gibson]

Joe. You could go stand alone computer. you could retrofit a modded (larger bore) throttle body to a 383/440 intake and make custom fuel rails to keep efi. I'd bet someone makes an intake that can be setup for efi. You could go old school with a carb, and DUI distributor. I'm not sure if the bellhousing is the same, but if I understand correctly, the 46re is a 727 with an overdrive added to the tail housing. Here's a link to a stand alone 46re controller. http://www.e-transcontrol.com/dodge-transmission/

 

[Joe w.]

I found on another forum that you can get a bell housing adapter for the 46re for big block motors. I've been researching this for awhile now. Thanks for the info.

 

[Yeret]

Just to stir things up a little more, I've also given consideration to simply leaving the engine as is but then bolting on a Procharger. Going by their claims, it would seem that I could easily achieve, if not outright blow past, my goals by running a blower.

They sure ain't cheap though, ~$6,000 to be precise. Doesn't factor in cost of uprated fuel components and tuning, but both of those would have to be done anyway with a stroker.

I'm a naturally-aspirated person at heart, but there is just no getting around the massive gains to be had by boosting. Of course, I'm not sure how long the cast pistons would hold up to even 8 psi and upgraded con-rod fasteners certainly wouldn't hurt. To go this route would have the same expenses at the machine shop, but then the added costs of the blower kit. Seems to me that I could make more power going the blown route, but it's gonna cost more.

Anyone here running forced induction on their Magnum engines?

 

[EvilSpirit]

The short block needs to be able to withstand amount of power you make, regardless of how you make it. Exceed the limits and you tend to add windows where there were walls.
Making power at lower RPM'S - like with boost - easier on the swingie parts and valvetrain.
With that said - if you stick to the kegger, forced induction would overcome a lot of the poor/low airflow problems associated with it. With the Procharger - keeping the tune mild you could probably hit your 450 ft/lbs goal with a stock shortblock, a modded kegger, better injectors, etc. One good spark knock could install those windows I mentioned.