Hi All!

I do not know if somebody already has problem of cracked block, we had 2 equal cases, had cracked in 4º cylinder. One of the engines was with 515hp@7500rpm, and the other with 558hp@7700rpm. To resolve this problem we decide make a species of block guard, placed bars of the same material of the block in the water galleries, and use steel shirts forged with 2,5mm of thickness. The problem was resolved, the modification was approved. I am showing to share the owners of the Coupes, therefore engine is the same Fivetech 2.0 20V Turbo.

Cracked Block
http://i2.photobucket.com/albums/y39/TETEUS/Variados/blcrch.jpg
http://i2.photobucket.com/albums/y39/TETEUS/Variados/blcrch1.jpg
http://i2.photobucket.com/albums/y39/TETEUS/Variados/blcrch2.jpg

Block Guard
http://i2.photobucket.com/albums/y39/TETEUS/MWT%20STAGE%20II/07-06-07_1705.jpg
http://i2.photobucket.com/albums/y39/TETEUS/MWT%20STAGE%20II/07-06-07_1621.jpg
http://i2.photobucket.com/albums/y39/TETEUS/MWT%20STAGE%20II/07-06-07_1619.jpg
http://i2.photobucket.com/albums/y39/TETEUS/MWT%20STAGE%20II/05-06-07_2127.jpg

Bye, Mateus.

interesting,

I was told and then saw a similar bhp cracked 20VT block.
The mechanic did a similar thing (I recall he only welded short plates to the water galleries of the mid cylinders)

V.

Interesting, I've never seen any blocks that have gone like that. I suppose all blocks have their limits tho.

Was it a high boost application? What sort of torque?

Vas, good for knowing that more equal cases had existed, Thanks!

Johns, it is really interesting, never we saw this to also happen, but when it happened they had been in the 2 engines.

Boost used is 32psi, also finds that it can have happened for using a higher pressure. The good one is that with this modification we are using more boost and the cylinders are perfect.

I made this topic to show this possible problem and a good solution, I wait that it is of good advantage!

Thanks, Mateus.

32psi

bit of a hint why your liners are literally blowing apart !

excellent machine work though

32 psi is about 2.2 bar isn't it? And you're running more boost now? That's pretty impressive.

Looks, great and good research.

could also overcome the problem with decent liners, although that is a lot more expensive

Thank's to all!

Sorry my bad English, but what he is "liners"?!

Mateus.

Liners are the surface that contacts with the piston ring, i.e. the 'sleeve' of each cylinder.

Hi

Here's a top end liner supplier.
http://www.darton-international.com/

Definitely a first for me to.
Seen every other failure of this engine

Only 3 years and 5 months later with a reply Si

looking at the motors that have cracked can anyone else see that there is a reason other than cylinder pressure/boost..more to do with combustion or so it looks

I'n my opinion it's more to do with the water jacket overheating. Too high water temps, det would hole the piston first would it not.

its not det i am thinking but what do i know

good solution though

no offense gents, look at the crack propagation, right where the block waterways end & the liner begins = stress raiser = crack point.

Basically the liner is expanding at the ends ( weakest part ) = split

when you are at 36 psi ( CR of 8:8 or higher ), you are talking massive pressure cycles = FAIL.

consider it, I did when I thought about my build.

JohnS to be fair was at a similar power but not like the Brazil lads....never that sort of boost.

only my tuppence

Cylinder pressure. Just use a 16v block, stiff as can be ;-)

I don't know the 20v block well, what is it they are doing that they call a block guard?

putting in those bars in the waterways to stop the expansion/movement thats the block guard they are talking about

He He - there's my utterly reliable use of the forum once more...better late than never I guess.

I have it done on my block ....
it is the first in Portugal...

So they drill bars down the water gallery? Do they go all the way to the bottom? What holds them in place?

What ambient temps typically are in Brazil??

HI did a block guard as well, but with heavy duty dowel pins. I wanted to have little continuous pressure to the inliner, but no warping. Nevertheless the cylinder inliner moved up to 2/10 mm measured from pin to pin. I see it critical. It is not the boost pressure, which kills the block. It is the cylinder point pressure, resulting from cams, comp. Ratio, boost, ignition etc. It is a must
for 600
+hp in my opinion. It is enough to support max. 2cm. Only in this upper region pressure is critical.

No no, you're all doing it wrong, you need to pour cement and sand down there

Still not convinced that cylinder pressures alone can cause that, it must go hand in hand with another cause.

I've heard of honda's needing a block gaurd, but thier deck is completly open.

I can't see how that helps. The little pieces of metal won't do anything more to stop a block cracking at extreme pressure as it will just crack where there is no re-enforcement. You need to properly regard the bores. It looks like a good DIY mod but I personally can't see it helping anything. Like what they do on an open deck bloack but with a closed deck you need to put lots of little holes for the water jacket.

This is for open deck:
http://www.wonderbart.com/2009/04/d16z6-block-and-parts-are-back-from-machine-shop/

It does help - normally there's a big big hole each side of the cylinders. Putting supports in there is the best you can do, although you have slightly less cooling. Look at it like a bridge: if it's too long and it would collapse, you just put extra supports in the middle.

I'm also thinking MWT was running on alcohol.

does anyone else think these are rare occasions?

the amount of coupes that are running around these days and there has only been less than a handful of bore cracks..

now I understand these guys are running 500+ bhp..
but there has to be an underlining issue with them blocks, have they been bored out?
did they weekend the bores at that point?