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i know the pros and cons of a block guard and i got one but what i want to check is it better to have it flush with the top of the block or go down a little bit i was thinking of going down about a 1/4in
 

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my suggestion (take it for what it's worth): the coolant passages have to line up with the engine's coolant passages or you'll mess up the flow and shoot yourself in the foot. If it were me, I'd put it where the manufacturer designed it and intended it to be. That's where they want you to put it because that's how they tested it for the coolant flow.
 

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that's not where GE puts their tangs on their sleeves though....



Originally posted on Dec/06/00 said:
There's a common misconception among Honda enthusiasts regarding cylinder breakage, what causes it and where it begins.

Truth be known, a properly tuned engine, running detonation limiting equipment will break the cylinders mid-way down the bore, where rod side thrust is the highest. Forces on the central portion of the cylinders on the primary and secondary thrust axis's cause the casting to break. The intake side is the major thrust axis, so the piston is really trying to shove itself through that wall when you're really cookin'. This is a primary reason we advocate longer rods.

Cylinder cracking will spread to the top of the cylinder, rather than starting at the top and traveling downward.

Blockguards seal the top of the cylinders from direct water contact and the additional aluminum mass acts to hold a lot of heat in that upper cylinder area, which in-turn, contributes to detonation.

We've only run sealed decks on engines that are drag racing only pieces...and most of those were combinations where we were extending the deck height to permit the installation of longer rods.

I do not recommend the use of Blockguard "type" devices in street applications, due to the issues I've pointed out.


I keep telling you folks that those things are one of the worst possible mods you can make...

You'll likely have to bore and hone the cylinders to make them round again (and pray that they don't "remember" the egg-shape).


If you want an engine to last and run properly with a more "correct" air fuel mixture, make sure you've taken necessary measures to limit detonation and don't do anything to compromise cooling.

We do "post" cylinders in engines we build. We'll have a feature up shortly showing just how it's done...and it'll also be in some magazine articles coming up.

"Posting" the cylinders gives them tremendous strength and it actually aids cylinder cooling, which is a pretty good deal in our book.
 

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So what are you saying MD??

I emailed GE to ask where they suggest putting the blockguard for optimum coolant flow and minimal possiblities of overheating.

They emailed me back and said that the suggest installing the blockguard 1/8" down into the coolant passage for optimum cooling.
 

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Do you know what posting is MD? Where do I find the info?
Why no block gaurds in street applications?
 

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I'm saying that blockguards have to be placed where GE had suggested (it's the correct place for their blckguard) but that place is not where they support the cylinder when they put in their sleeves. The "tangs" on their sleeves for support are at the primary thrust axes to brace against maximum sideloads where the sleeve can likely give way.

Blockguards give people this false sense of security because they believe that the weakest point is at the top. Manufacturers like GE oblige that notion by selling you the blockguard to be placed near the top of the sleeve. People wanted to close the deck cheaply and this is what was built for that consumer demand: the blockguard.

However, GE is also smart enough to know that for their aftermarket sleeves (for people who need resleeving), the place to beef up the support while maintaining an open deck and good coolant flow is elsewhere...not at the top.
 

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nicklk on Feb/03/04 said:
Posting seems like it is a "mideval" way of putting support into our motors, just something about it makes me quiver??


here's GE's sleeves. Notice that from midway up to the top, the liner is thicker and about 1/3 of the way down from the bottom, they place the support bracing or "tangs".

I didn't want this thread to be about posting cylinders. It should be about where block guards support the cylinder sleeves in an open deck vs. where the greatest sideloads occur and where one should place that support.
When Endyn "posts" those cylinders they place 2 supports on the major thrust axis (intake side) further down than 1/8 inch and 1 support on the minor thrust axis (exhaust side) about 2 in. down. The supports are definitely not at the top.


Clearly if detonation occurs, any support is better than no support but it won't save you from having to resleeve and replace the internals. It will save you from buying a whole new block.

Last point, posting cylinders, although "midieval" as you say, is still probably the only way to support those flimsy B20VTEC block's stock sleeves going to 84.5mm bore without affecting the bore shape or coolant flow. I definitely wouldn't leave it for someone who has never posted aluminum blocks or knows how to locate the major loading points. The domestics have used posting before .

The downside of the block guard is that they may change the shape of the cylinder away from being round and turn it into an oval or worse egg shape and therefore affect ring sealing.

If I were to use a blockguard and was upgrading pistons, I'd place the blockguard in first and then hone or bore-hone (depending on the condition of the wall surface) to ensure a round centered bore.
 

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I am using the Endyn posts on the b16a I am building.
If you think it is "medieval" then follow my analogy for a moment:
If a strong person (piston) was pushing on a door (cylinder wall), trying to get in, would you want to push back on only the top of your side of the door, as the block guard does? Or would it make more sense to support the middle part of the door, like the Endyn block posts do to the cylinder walls?
If posting is medieval then a block guard is mesozoic.

But actually I have considered posting the block AND using a block guard. Of course I would have the block guard professionally installed and welded in. And as, MD says, the coolant passages should match the block's passages. Does anyone know of a blockguard that matches the Honda block's coolant passages?
 
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