Hey guys.. just curious.. i can't seem to find any hard facts on the block guards.

lets say your running forged internals with a quality block guard on a B-Series.

Aproximate compression ratio being 9.5:1

what would be the limitation there, how much boost b4 u need to draw the line & sleeve the blocks ?

 

The problem is youre not going to find anyone with any hard evidence for or against them. Most people just jump on the "they're stupid" bandwagon without any knowledge.
Its not a matter of how much boost, necessarily, its a matter of how much power the stock sleeves will take.
If you have good tuning Ive seen/heard/read of people making 400-500hp on stock sleeves - its all in the tuning.
Im for them on mild power (I wouldnt go above 350, but thats because mine's a daily driver) and will be purchasing a GE guard for my ls-t

 

Stock sleeves are generally good to 500whp, provided proper tuning.

Make sure that you get the block guard installed properly (i.e., welded in and then a bore/hone). Don't just tap it in

 

The only real bad thing that i know of is less water flow was never a good thing.

 

The stock sleeves should survive most of what you can throw at them and still be functional as a street car (IE sub 350-400 or double the stock output). How long they will survive a bad tune or a hotspot that cause detonation is the problem. I think the factory rods will probably fail first in that situation and travel through the sleeves destroying both but still.

I've personally never been big on "slide in" block guards. For one thing, the location is horrible. Where is the one place in your engine where the most heat is generated and you want coolant as close to as possible, the top of the sleeves and bottom of the head. A block guard will occupy that space keeping coolant away. I've seen sleeving companies that actually "close the deck" or pin the new sleeves to the block an inch or so down from the top deck of the block and I liked those. Another issue is expansion. Most guards are made of the same material as the actual block itself (aluminum) and will expand at a simliar rate but being as close to the combustion chamber as it, it will most likely get heat first and expand faster if not more than the rest of block. This could put compresion forces on the top of the sleeves themselves and cause problems. I've never built and engine with one and I'm sure there are people who have used them and had success but I've personally never been a big fan.

 

i agree andy. Ive had rods bend into a most curious shape and the cylinder walls were ok. I would worry about upgrading the rods way before the walls.

 

I read in SCC magazine that the guards are not for detonation purposes but to prevent the tops of the cylinders from deforming at high rpm's & temps.

 

has absolutly nothing to do with detonation.. has to do with strenth of the cylinder walls.. hondas are notious for having weak cylinder walls due to the huge water jacket that is all the way aroudn them.. thats why in high HP applications.. sleeves are recommended!

 

What do you think causes the damage at the tops of the cylinder walls?? Its detonation

 

more than detonation can cause the cylinder walls to get jacked up