cylinder wall thickness

[metalman]

Okay, I've heard disagreements from all over the place on this one

Through kind of random luck, I have a pretty good variety of blocks to choose from.

I have two renix blocks, one is a 90 for sure
I also have two 98' blocks
and a complete 258 I'm pulling the crank and possibly main caps from.

I'm going to be running a tupy head, but the junk yard I'm pulling from I get the whole block for 50 more, so I might just pull the whole engine, and I probably will to check

I'm curious, has anyone put this whole question to rest, one guy claims all blocks are the same, the next guy claims that all the renix blocks are thicker in the cylinders, and a third guys comes up and says the 2000+ blocks are the thickest (although few claim the nvh blocks to 98 are better, most agree they are thinner)

If I can of course I'll grab a newer block to see, but I'm just wondering how hard I should try looking for one.

Thanks

[IH 392]

What is your concern for max cylinder wall thickness?, are you trying to go for the absolute max over bore?
I'd probably chose the block that fits the application best, also I've heard that there is a rumor that the "RENIX" blocks have more nickle in them???? , as far as I've seen they are the softest blocks, every one I've torn down had a HUGE! ring ridge, my '97 block with 147K on it had virtually no ring ridge and the '00 block I'm using for my build with unknown mileage would have went back @ STD bore if I could have gotten the IC944's in STD.

[metalman]

I don't have some crazy plan to overbore it. I'm not going to be pushing the bore, however I'm getting custom pistons made, and I'd rather not leave free displacement on the table since a turbo isn't an option (emissions tech inspection plus its the wifes project and she isn't a fan), so if one era casting is going to give me an extra tenth in the cylinder wall, I'd certainly take it. I'm well aware that core shift keeps the field somewhat level, and I've pretty consistently heard people recommend the renix blocks over the NVH blocks, but I'm curious about the 2000+ blocks, I've caught a mention or two that they actually had the thickest bores, I'll check whatever block before I'm building it, but really I want to know if the 2000+ block is even going to be worth my time finding or if someone was confused when they stated that.

[metalman]

http://www.jeepstrokers.com/forum/viewt ... r&start=15

This is just about the only reference I've found of the 2000+ being cast thicker, it seems like he was pretty thorough, in another thread he listed sonic checks at various positions and depths, but its still the one and only place I've seen recommending the newer blocks

[metalman]

http://www.jeepstrokers.com/forum/viewt ... =328#p6646

This is the other post from plechtan, it seems like he was pretty thorough, in this thread he listed sonic checks at various positions and depths, but he is still the one and only source I've seen recommending the newer post NVH blocks.

[gonridnu]

This is a discussion which points to the cylinder walls being pretty much the same thickness in the thin areas regardless of year and style block. http://www.jeepstrokers.com/forum/viewt ... lit=blocks

[5-90]

Okay, I've heard disagreements from all over the place on this one

Through kind of random luck, I have a pretty good variety of blocks to choose from.

I have two renix blocks, one is a 90 for sure
I also have two 98' blocks
and a complete 258 I'm pulling the crank and possibly main caps from.

I'm going to be running a tupy head, but the junk yard I'm pulling from I get the whole block for 50 more, so I might just pull the whole engine, and I probably will to check

I'm curious, has anyone put this whole question to rest, one guy claims all blocks are the same, the next guy claims that all the renix blocks are thicker in the cylinders, and a third guys comes up and says the 2000+ blocks are the thickest (although few claim the nvh blocks to 98 are better, most agree they are thinner)

If I can of course I'll grab a newer block to see, but I'm just wondering how hard I should try looking for one.

Thanks

It may be apocryphal, but...

- I have heard that the alloy that AMC used for the RENIX block is comparable in nickel content to the high-nickel alloy used by ChryCo for the Gen-II Hemi engines. I have yet to verify this, but it would be in keeping with AMC's design philosophy (note that pretty much all Gen-II/Gen-III AMC V8 blocks have forged internals.)

- Reports from the field seem to indicate that RENIX blocks are cast with heavier walls - and this is in keeping with the fact that the wall thickness has been reduced TWICE by ChryCo - to lighten the engine casting, and supposedly to reduce NVH (Noise, Vibration, Harshness.) Considering that Mike Parrish (Accurate Power) had a RENIX block that was bored out to 4.000" (+0.125") and running just fine for somewhere around 80-100Kmiles when I first heard of it - six or seven years ago - I'm inclined to believe it.

Considering an ultrasonic casting thickness tester runs about $600 at last check, I obviously haven't been able to get one and pillage around checking engine thickness. I'd like to get a chance to go through the ChryCo archives in Dearborn and/or Auburn Hills, but I haven't yet had anything approaching an opportunity to do so.

[metalman]

makes sense, I'll be going back to the yard and if its got the tupy head I'll be pulling the 2002 motor complete anyways, I'll check the gap between the cylinders, but it kind of seems like a shame they didn't siamese them for the added strength.

[metalman]

I guess thats where I'm not totally convinced either way, I've pretty consistently heard from the reliable sources that the renix blocks are best because of the metalurgy which makes sense and I can believe that, kind of indirect, but you can beat the knuckle of an early XJ with a hammer and deform the daylights out of it, and newer castings will actually crack and break before deforming if hit the same, but on the other hand the most accurate data I've seen posted points to the 2000+ blocks particularly on the thrust side of the cylinder being thicker, although as mentioned the area between cylinders has been equally as thin on all of them and thats pretty consistent as well. I've got two renix blocks, (one still in the jeep), so I'm going to move ahead with that, and if I can pull a complete engine with a tupy head for a good price I'll check that and find out, but if not I don't think I'm going to lose sleep just trusting the renix and not looking back, I'm not going with a turbo or crazy compression anyway, and I don't plan on pushing things with the bore, so I could probably use an NVH and be fine anyway.

Hopefully I find one of the new motors, the new yard I'm going to is pretty good, but they don't seem to go much newer than 2002 with the jeeps, so we'll see.

[racing89]

having had over 12 blocks sonic tested, only the 91-98 were acceptable for a 4" bore( Actually, only 2 x 91 and 2 x 92 blocks made it). No 87-90 blocks were good enough( tried 4 ) Coinincidence? After racing the same block for 10 years and then installing in my daily driver with no problems, I wouldnt consider investing in renix block testing. Just my experience, maybe newer blocks are better again.