Honing with torque plate or without

Time for a good old engine tech thread, we haven't had one in a while...

I'm getting conflicting opinions on whether to use a torque plate (i.e. block of metal that's bolted on the block to simulate the head and any distortion it puts on the block) when boring/honing the cylinders.

Some people say (like a couple of machine shops I've spoken to) there wouldn't be much point on a 2JZ because it's a very solid lump of cast iron, and the aluminium head is going to distort rather than the block if anything. Of course that could be because they haven't got a torque plate! Others that it's essential to avoid wonky bores. A lot of what you read on the internet about it relates to either modern aluminium blocks or flimsy American blocks.

So what do the engine techy types think?

All depends how close the head bolt holes are to the bores I suppose, but at the end of the day it is a big block of cast iron and not ally as you say

skylines have cast iron blocks and they move like belly dancers!! that is why a torque plate is needed, and for other things also!!!

Would not harm it to hone it with a torque plate. I would check the bores for ovality before undoing the plate after honing.. then again after releasing the torque plate just to ensure the stresses have not come into play.

Like this ....I Doubt that many have seen one for the 2J .

http://img130.imageshack.us/img130/7001/463369125fullil7.jpg

If a 430 ci ls2 block can move around I bet the 2J will .......and does.......2c

They're not used in OEM world, when the blocks are machined for the first time.

There may be some milage in using one for re-boring. It depends on how much residual stress you relieve by taking 0.5mm or whatever off the bore. I think it will also depend a lot on the deck design. A fully open deck is going to need more support than a partially closed deck. On a fully open deck I think you would want to have a gasket in there as well in order to put the proper clamp load on the top of the cylinder bore.

I don't think simply re-honing would remove enough material to warrant using one.

totally depends on how much material you want to remove, i personally would always use a plate but thats just old habit

They're not used in OEM world, when the blocks are machined for the first time.

 

 

There may be some milage in using one for re-boring. It depends on how much residual stress you relieve by taking 0.5mm or whatever off the bore. I think it will also depend a lot on the deck design. A fully open deck is going to need more support than a partially closed deck. On a fully open deck I think you would want to have a gasket in there as well in order to put the proper clamp load on the top of the cylinder bore.

 

 

I don't think simply re-honing would remove enough material to warrant using one.

I agree, particularly with the OEM statement.

Also, re Spidermonkey's comment, if you remove enough material to warrant needing a plate as support during machining, I'd suggest you've potentially weakened the block enough to create durability issues (cracking etc) later on.

Just my 2p.

Well, we'd be talking about a 1mm larger bore (86mm to 87mm).

IMO the finished bores move more under temp changes than through lack of a boring plate. Perfect Circle will hone with the block at operating temp, with a plate, if you have deep pockets. Unless you are looking for the last 3 BHP I think your money would be better spent elsewhere myself.

i work with a constant temp of 20 degres everyday.. and if if is 21 our 19 i have bores sizes changing!! but im only a cnc prog!! i realy dont know how the honing dep works with tolorances!!