Re: 225

One of the ways in which the internet is a two-edged sword is that it gives everyone a combination megaphone and printing press. It's never been easier to broadcast one's words. Unfortunately, the signal/noise ratio is very poor, because anyone can write stuff that looks believable to those who don't know any better. So not only is it easier for information to spread, it's also easier for misinformation to spread. As a result, open-and-shut questions that have one right answer get debated forever because spurious "answers" get continually injected into the conversation.

Me, I try to make statements ending in a period or exclamation point only when I'm really sure I know what I'm talking about and can support it. When I'm not sure or I don't know, either I use question marks or I keep my mouth shut. This is not one of those times. Ray, I'm sorry to have to write this, but you've got it mostly wrong. You've busted no myths -- in fact, you've done the opposite.

I'm fortunate to have had years of good, close, in-person friendship and dialogue with Bill Weertman -- Chrysler's longtime Chief Engine Engineer -- who wrote "A History of Chrysler Corporation's Slant-Six Engine" (published by Chrysler Historical) as well as this book: http://www.amazon.com/dp/0768016428/?tag=2402507-20 which has extensive Slant-6 design concept and development coverage. And extensive original, primary film and paper documentation of the engineering development of the Slant-6 engine and the Valiant car, with numerous eminent Chrysler engineers (not just marketers) all providing the same answers to the question of why the Slant-6 is slanted.

The efficient manifolding was possible because of the slanted orientation of the engine. It was not the other way round (the engine was not slanted so as to permit efficient manifolding). The engine was slanted to make the packaging as compact as possible primarily in the longitudinal horizontal dimension (shorter engine bay due to lateral shift of water pump not feasible with vertical engine block, because doing so would have moved the fan laterally, which could not be afforded in the narrow engine bay of the original Valiant car) as well as in the vertical dimension (lower hoodline vs. vertical block) That is the consistent and well-supported assertion of the engineers who conceived the engine and the cars it was originally designed for, and as such must be considered authoritative.

The guess that the engine package height wouldn't change if the block were vertical is flatly incorrect. Even if the engineers responsible for the design of the engine were silent on the matter -- they're not -- simple basic geometry informs us that it necessarily would. But this guess can easily be made to look plausible, if one is playin' around on the computer with line drawings, just by selecting a convenient axis of rotation and disregarding real-world inconveniences like oil pans, K-frames, steering linkages, hoodlines, and suchlike. The claim about air cleaner height isn't dispositive or well informed, either; the air cleaner clearance to the underside of the hood was minimal with the zero-drop air cleaner body used on the '60-'62 170 engine; one of the changes that had to be made to fit the taller 225 in the '61-'62 Valiant and Lancer was a lower-profile air cleaner.

The statement "the importance of raw engine height is further degraded by the fact that the manifold runs uphill from the ports" holds no weight. There is a slight declination from the carburetor mounting pad to the centreline of the ports, yes, but this doesn't "degrade" (???) the fact that the slanted orientation of the engine significantly lowers the overall engine package height.

The assertion "Another point in favour of the manifold efficiency being a major factor is the need for the manifold to avoid clashing with power boosters and brake master cylinder" appears to be purely a guess, and it is a baseless one. It cannot support the statement "In Australia the power boosters and master cylinders are on the opposite side of the car so there was no need to cant the engine". This is a retroguess on top of an assumption based on what someone thinks he might have understood of what he thinks he's seen, and none of it holds up. Moreover, the power brake booster on a right-hand drive car is _not_ necessarily on the right-hand side of the engine bay. Many RHD A-bodies with power brakes have a remote booster on the left inner fender. Likewise, a variety of different remote oil filter arrangements were used in RHD Slant-6 cars. The Australian R-model had the remote filter on the right inner fender, the Australian S-model had the remote filter above the water pump, the Australian AP5 through VF models had the remote filter down at oil pan rail level, behind the water pump. South African cars had the remote filter on a bracket welded to the valve cover. All of these different solutions got around the problem that the RHD steering shaft needed to go right through where the LHD on-pump oil filter would be.

Now, here's one reliable primary source:

http://pages.citebite.com/o3p7t9u2n6ggb

And some pages from Volume I of "A History of Chrysler Corporation's Slant-Six Engine" are attached to this post.

-Daniel

On Tuesday, 7 October 2014 04:26:15 UTC-7, Ray Bell wrote:

That's an interesting article. It lends weight to the whole idea that a significant part of the slant's slant was to give room for an efficient manifold. This is mentioned, as I posted previously, on the Allpar page referenced by 64ragtop.

I get the impression that many are not so impressed by my reasonings and suggestions, so I've used the sectional drawing of the slant from the Allpar page to make a composite picture that shows the slant slanted at 30° alongside the engine brought back up to the vertical.

You can clearly see that the height of the engine effectively doesn't change. Critically, the ports are at the same height and so the carburettor, the highest point of the engine, is committed to the same altitude as it would have been with the engine vertical.

The importance of raw engine height is further degraded by the fact that the manifold runs uphill from the ports. And my second pic, also from the Allpar page, shows clearly how the air cleaner is several inches above the height of the valve cover and would have remained so if the engine had been upright.

So we have a PRESS RELEASE that says that engine height was a reason for the design. This myth, in my view, is busted.

As far as the slant being to allow the water pump to be beside the engine is concerned, that's another product of the fertile minds of the promotional people. It's not hard to find vertical engines with the water pump beside the block.

Lower centre of gravity - that is certainly the case. I would think the centre of gravity of the engine would have been lowered by anything up to an inch.

The fourth item on the press release related to accessibility of the accessories. As has been pointed out, distributor access isn't good, but pretty much everything else benefitted from the slant.

Another point in favour of the manifold efficiency being a major factor is the need for the manifold to avoid clashing with power boosters and brake master cylinders.

To further emphasise this, I will point to the upright design of the Hemi 6 engine with its similar manifolding. In Australia the power boosters and master cylinders are on the opposite side of the car so there was no need to cant the engine. That engine is larger than the slant, it sits under exactly the same bonnet (hood) as the slant did in the same car but it is longer because of its bigger bore. Even so the water pump is not offset, but the engine bay was lengthened to cope.