I am pretty sure that all of the straight-six blocks aren't the same and don't all use the same molds. I now for a fact there was at least one update pertaining to overall flow in the block that happened sometime in the late 90's. Do not know exactly what those changes were, but it was something along the lines of what people do with they port and polish. Not trying to argue with you. I'm definitely open to being wrong. Can you provide a little back up as to why you are so sure of this?

The information I got about the WJ block had nothing to do with Scotty Kilmer. You're talking about the YouTube guy right? I'm not too much of a fan. Some videos are good, but his whole approach is to tell you "whats right" and "whats wrong". I just want information.

Where I heard that the WJ block was thicker is from the Newcomer Racing video. The narrator might be wrong about it being a WJ, but it's a Grand Cherokee. I do not know much about the letter designations. The wall being thicker between the chambers was the entire reason why he chose it. If I had to put my money on who was right about this I'd say it's the stroker guy breaking world-records, but for all I know you are doing the same kind of thing. Anyway, I'd like to hear why you think that. Going to go reread the replies to make sure I didn't miss anything vital.

 

We were talking blocks here, not heads. Heads are another story altogether. As far as the walls being thicker between the cylinders are concerned, there are no water passages between the bores because of the spacing and it's all solid metal, so how came they be thicker unless the bores are smaller?

I'm no professional engine builder, but I have built a few in my day and have a very good working knowledge of this one, although I've only once had one apart down to all it's parts. Also, I've been wrong before and am willing to hear your facts, but make sure you have them correct.

Most of the changes were made to the cylinder heads and intake/exhaust manifolds/ports. The major problems with this engine is the large pistons and short stroke causing the pistons to rock at the bottom of the stroke and crack piston skirts. Building a stroker should include forged pistons and a rebalanced crank in my opinion.

 

seems like the block is one of the least important items for building a good engine

probably the cheapest too...

I missed a complete '96 engine for $50, which I wanted certain parts to start building a stroker, the guy was having a cleanout and I couldnt get there quick enough, so it went to the metal scrapper

 

Sorry to let this thread die and not answer your question. The block is only important when it comes to everything be in order, no stripped bolt holes, no cracks, and no u repairable damage in the cylinder. Buy a block with he understanding you're either going to run it till it does or rebuild it. Change the oil religiously no more than every 5000 miles haha that'll make the motor last a heck of a lot longer than anything else will.

https://540ratblog.wordpress.com/

 

From your link:

"Only dynamic wear testing under load, at a normal operating temperature, can reveal how the various motor oils truly compare regarding wear protection. So, that is precisely what I do to discover the facts. And that is why merely looking at an oil’s spec sheet is worthless. A spec sheet cannot show you an oil’s wear protection capability, because Engineering tests and real world experience have proven over and over again, that the zinc level does NOT matter. That is only a MYTH that has been repeated a million times until people just assume is true, which it is not. Only the psi value from my test data will actually show us how motor oils truly perform regarding wear protection."

This fellow's engineering results show that an oil film's resistance to total displacement (break-down), causing metal-to-metal contact, is all that's important to consider when choosing the right oil for our needs. After reading many times on the internet how Zinc plays a beneficial role in wear protection, and then reading this guy's blog, I have to say that Googling for the truth, even from sources implicitly trusted, may not always provide it.

Great blog, once you get past his defenses.

And then we have this:

https://www.hemmings.com/stories/201...-older-engines

"What was discovered through oil testing by several engine component manufacturers is that many older engines experience a short period of time during engine start-up where critical lubrication is insufficient between metal-to-metal lubrication points when using modern oils with reduced amounts of ZDDP/ZDTP."

The coin still seems to have 2 sides.

 

I know right, I think he's an older guy and he's been testing for so long that he's kind of stuck on proving to everyone that his tests are accurate xD. He never shows how he tests everything which is actually how he could show everyone that his tests are qualified .

Anyways though he gives more examples that proves his tests to be real and goes the extra mile to test things much more than any bobsoilguy

 

The one thing I read in his blog that he repeatedly emphasizes is that the best performing motor oils are the ones that have the highest PSI ratings that resist compression and shear wear-through to (obviously) prevent metal-to-metal contact. He attributes these high performance oil characteristics not to the base oil but the additives formulated in them, and discusses them as proprietary formulations the various producers add to the base oils they use. So, bending my brain a little bit more, I inquire about those additives and the one ingredient that keeps popping up is Zinc. In his blog he dismisses Zinc as irrelevant (a myth) as a component of anti-wear properties in his tests, but it would seem that it is the key ingredient in the "proprietary additives" he promotes as key to the high performance specifications of oils. In other words, he's promoting Zinc and dismissing it at the same time, albeit obliviously. Very confusing.

I give you a paper produced by AAA on motor oils in the following link. Scrolling down you will find the section on additives that produce the high anti-wear properties of high performance motor oils -

https://www.ilma.org/PDF/ILMANews/2017/AAAreport.pdf

"3.4.2 Anti-Wear/Extreme Pressure Components (AW/EP Additives) Zinc dialkyldithiophosphates (ZDDPs) have been used as a multi-functional additive in engine oil for over 50 years [9]. ZDDPs mainly function as an anti-wear additive; however, they also impart oxidative and corrosion resistance to the base oil. ZDDPs also exhibit mild EP characteristics. As an anti-wear agent, ZDDPs react with surface asperities (surface roughness) to reduce metal-on-metal contact. When applied loads are high enough to collapse the thin-film on the surface, ZDDPs react with the entire metal surface to reduce wear. In a general sense, the anti-wear film can be said to be composed of ZDDP degradation products; the thickness and composition of the products are directly influenced by temperature [9]. The nature of the ZDDP film has been extensively studied; however, no analysis provides a concise description of the film within automotive lubrication regimes. There is a multitude of AW/EP additives besides the described ZDDPs. Discussion of these additives is outside the scope of this work."

 

The thing about ZDDP is it adds a cushion to the bearings under high loads when the combustion pressure forces all the oil out of the bearings at wide open throttle and low crankshaft speeds, like pulling a heavy load up to speed or extreme acceleration as in racing. The bad part about it is the phosphorus portion of it contaminates catalytic converters. It has a very good ability to provide a film of lubricant on high load surfaces without pressure, as in flat tappet lifters.

The only debate about removing it from engine oil is the possibility of harming converters.

Why does every discussion become one of engine oil?

 

Same reason that for decades real computer discussions always degenerate into which is better 'vi' or 'emacs'. Of course the answer is clearly vi.

 

DON'T START!

The only differences in blocks generally is the thickness of the cylinder walls on later engines made to accommodate larger bores, as in Chevy small blocks, but since the 4.0 was never made with a larger bore and always had 7 mains, there shouldn't be any need to change it, excepting of course the mounting bosses for the WJ and all the changes were external. Even the bearings are the same size.

 

My hope was not to start an oil debate. Everyone can have their opinion on oil. I was simply just trying to provide him with something of fact. That guys blog post is one of science.

Dave is cut throat y'all watch yourself you might get bit trying to talk about oil with him so just follow my lead and end this subject before you get your feelings hurt.

 

Naa, I'll blow gently in your ear before I'll bite your neck. Let's just stay on topic and we'll all be safer.