AusS2000

There is a discussionin S2000 Talk at present about block guards.

A block guard fits between the cylinders and the walls of the block to turn an open deck block into a semi-closed one.



I've spoken to KMS about producing one for our engine but want some expert opinions first.

Are these things a good idea for boosted (or hi-po NA) F20Cs?

Are there downsides (like restricting coolant or conducting heat to the outer block)?

Slows2k

Block guards have to fit tightly against the outside of the bores to work properly. Most of the one's Ive seen have to be driven into the deck of the block, distorting the upper bores. If the bores are not rehoned and checked for taper, the rings can bind and sieze in the bore.

Since the FRM bores used in the S are very difficult to hone, and the only Factory oversize piston is .25mm, you really don't have much room for error.

If the bores are too out of spec, you'd have to sleeve to block to repair, which would negate the block guard.

Everyone I've talked to says you can't run Aftermarket pistons on the FRM bores, they tend to sieze.

I'd just sleeve the block instead of risk wasting the $ on a block gaurd + machine work. The AEBS or Golden Eagle T-sleeves will be stronger than a block guard. If you only take the engine out once to build it, the sleeves will save you time in the end.

AusS2000

Do you know how great this risk really is? I mean, if it happens often wouldn't we hear about it more?

I intend to one day build a block from scratch, but if I could get some extra strength from pulling the head and inserting a block guard this is something I would do straight away.

Slows2k

The only experience I have with them is second hand. The engines being "block gaurded" were Honda B18's, B17's. Another factor maybe the cheap block gaurds that didn't fit very well between the bores.

If I was to use one, I'd definitely check the bores very carefully for taper.

BTW Aus, I'm one step ahead of you on this one, Iv'e got a sleeved block waiting.

joes sled 2000

I used a block guard in a couple of my b18 engines without any issues.I really don't know about the f20/22 engines though.I cant see why they would not work unless the coolant holes were to small.The bottom end is VERY strong in the f series engines,so i don't really think its worth the trouble.If you're looking for huge horsepower then you should definitely sleeve the block.

Slows2k

From my understanding, block guards are designed to stabilize the top of the bore. The open deck bores are only supported at the bottom, and can crack /move around at high HP levels.


I agree, The main bearings of a B motor are much smaller than a F20C's 1 piece girdle/main bearing cap. The F series an K series engines. Even the Dart block B motors have smaller bearing caps than the integrated girdle/main cap.