Analysis. The new Hurricane twin-turbo six-cylinder is stunning in its power and efficiency, but many are skeptical, saying it’s too small for serious work trucks.
GM has its turbo four for the Silverado, and Ford has a 2.7 twin turbo pulling the F-150, and they do well—though the Ford seems quite thirsty when towing. But GM and Ford still have V8 choices, while indications so far are that Ram will end with the sixes. (Some do believe the 6.4 V8 will remain on the Ram 2500 and 3500.)
Would a different inline six family with a different vintage name be better? It could be dubbed the Hemi Six for those who recall the Australian inline sixes, which went up to 4.5 liters (265 cid) compared with the Hurricane Six’s 3.0 liters (183 cubic inches). Unlike their Aussie predecessors, they would be coupled to a (single) turbocharger and perhaps a hybrid transmission to build enough torque.
The added displacement, yielding sixes up to 4.0, 4.2, or 4.5 liters—would give Ram a relatively unstressed powertrain. The 4.0 and 4.2 sizes would bring up associations with the strong, powerful AMC/Jeep inline sixes.
A larger displacement engine with more low-end torque, achieved through a longer stroke, would give the Ram more of a truck-engine feel, and might also be used in the heavy duty Rams. Especially with a cast iron block, these would be a better work-truck option than the Hurricane family.
It would add to Ram’s “Pro Master” image to have special heavier duty engines for those who want to tow a boat or trailer to the lake without splashing out on a diesel. It would be a truck that could be used for mudding and such, too. Most buyers of vehicles that size expect old-school inline-6 stump pulling torque. It’s not about having a nose-heavy V8 under the hood, it’s about having torque and balance—for many, at least.
Is any of this practical?
Let’s look at bore and stroke for some key historical engines, keeping in mind that even the famed AMC straight six started out as a 3.2-liter!
| Engine | Bore | Stroke |
|---|---|---|
| 4.0 (232) | 3.88 | 3.4 |
| 4.2 (258) | 3.75 | 3.9 |
| 265 Hemi | 3.91 | 3.68 |
| Hurricane | 3.31 | 3.54 |
Unfortunately, a 3.31 inch bore would require an absurd stroke to reach even 4.0 liters; a 3.9 inch stroke, the longest in this group of engines, would only bring us up to 200 cubic inches (3.3 liters)—a good, sturdy V6 displacement in Chrysler history, probably not the association Ram would want.
For best results, the bore would also have to be increased, and that might prove to be quite expensive since the current Hurricane was designed to be compact and lightweight. It‘s likely the stroke is as big as it’s going to get without a hefty block redesign and an engine that’s (externally) just too large. For that matter, changing either the bore or stroke would throw off the optimization that was a hefty part of the GME in the first place.
Still, it does leave hope of at least a small increase in stroke. The 3.54 inch stroke is quite small for a torque-biased engine; it was likely chosen to keep the engine under 3.0 liters for countries where displacement is taxed, to allow for high revving, and because it left the combustion chamber the same as the well-optimized 2.0.
If the stroke could be lengthened, perhaps the resulting engine would be seen as better for trucks… because there does seem to be a perception gap among those who are looking not at torque numbers, but at displacement; and who are concerned about the long range lifespan of a twin-turbo engine in truck duty. One may even wonder if some sort of eight-cylinder is feasible using the combustion chamber design of the GME or GSE series—small stroke and all.
Remember, the Ford and Chevy/GMC trucks still have V8 options available. I doubt for competitive reasons that Ram will completely drop all V8 options. For one thing, those powertrains are already developed and proven. For another, pickup buyers are among the most traditional customers the automakers have, and catering to their needs is important. Redesigning the Hurricane six and likely giving it a new block to increase stroke and displacement would be a very expensive proposition. My money’s on their retaining the 6.4L V8, and quite possibly the 5.7L V8. These might not be the volume engines they are today, but I think they’re going to keep them available for now.
A new family of V8 engines based on the Hurricane would be very intriguing. Will it happen? It’s a very cost-intensive thing for them to do, but it might give them a huge competitive advantage. It would all depend on how the business case was formulated.
Another possibility is that the Hurricane gets coupled to battery electric power to form a high performance hybrid powertrain similar to the current eTorque system. This could easily exceed the current performance of even the Cummins diesel option. It eliminates the cost of developing, tooling, certifying and testing a new engine, and uses technology they already have on the shelf. If they drop the V8s, they’re going to need a compelling story to tell to customers, and this could be it. It’s pure speculation on my part, but I would be surprised if they haven’t at least thought of it, and possibly experimented with it.
Honestly, I’m seriously hoping they do a set of hybrid powertrain options for both Hurricane engines (S.O & H.O). I would love to see the same setup they have on the 4Xe put on the I-6 engines. It’d be awesome!
“…Hurricane gets coupled to battery electric power to form a high performance hybrid powertrain similar to the current eTorque system. This could easily exceed the current performance of even the Cummins diesel option. It eliminates the cost of developing, tooling, certifying and testing a new engine, and uses technology they already have on the shelf. If they drop the V8s, they’re going to need a compelling story to tell to customers, and this could be it.”
That’s basically my thoughts, for the same reasons. Do a hybrid with enough battery to make for good acceleration and to allow for running the engine optimized for electric generation to the electric motor instead of direct drive like a diesel locomotive. Way more efficient, one would think.