Beware of Oversized Gen 2 Cylinders

[TrickTom1]

I've seen a set split in between the holes, done some checking around and it seems to have happened atleast 10 other times. get some Gen1 cylinders instead.

[bigbill1441]

I've seen a set split in between the holes, done some checking around and it seems to have happened atleast 10 other times. get some Gen1 cylinders instead.

Thanks for the info

[gazza414]

Wherabouts between the holes?..ie across the thinnest section ? and all the way down/...top or bottom?...any pics?

[TrickTom1]

vertical splits between the 1 and 2, 2 and 3, 3 and 4 cylinders top to bottom 

[portagee]

what size were these split cylinders bored out to?

[Got-Busa?]

1441

[speedninja]

I have some pics to post but won't be able to for a week or so.

Mine split from top to bottom in between every hole at the thinnest part. They were 84mm bore. They split on after 3 motor passes at the mile. I spoke with a "well known" engine builder and he says he has seen a few dozen of them now and recommend the gen1 cylinders on all the Busas and even the earlier cylinders on the 1000s also, they have a problem as well. It seems the reliefs in the bottoms of the cylinders weakens the core when overbored.

[portagee]

so they are splitting with 83 and 84mm big bore, that sucks. guess ill get a set of old ones. thanks for the heads up.

[ACE23]

sorry to hear speedninja but at least you figured what it was get it going again quckly

[PetriK]

Have seen this happened to an engine where we made the windage holes a bit bigger, but also seen this happening when we used a set of "faulty" head bolts.

I can foresee this happening for at least these reasons:
a) Material gets weak around windage holes after reboring, the crack started from the bottom
b) Something went horribly wrong with rebore which nikasil plating covered during assembly
c) This particular setup messes up with the engine balancing causing vibrations that are harmful to the block
d) Once it was claimed that faulty head bolts caused us to crack an engine, then the crack started fromt he top.

So a couple of practical questions...

1) How and by whom the crank was balanced - or not ? How about the counterbalancer.

2) What bolts were used ?

3) Are all the blocks from a same rebore / replating company ?

4) Will gen1 block fit directly to gen2 engine ? Has anyone done it already ?

5) Is the only difference between gen1 and gen2 blocks the way bigger windage holes or is there more differences e.g. in coolant paths etc. ?

Would like to understand this for my own engine building project asap too...

[Yngve]

Have seen this happened to an engine where we made the windage holes a bit bigger, but also seen this happening when we used a set of "faulty" head bolts.

I can foresee this happening for at least these reasons:
a) Material gets weak around windage holes after reboring, the crack started from the bottom
b) Something went horribly wrong with rebore which nikasil plating covered during assembly
c) This particular setup messes up with the engine balancing causing vibrations that are harmful to the block
d) Once it was claimed that faulty head bolts caused us to crack an engine, then the crack started fromt he top.

So a couple of practical questions...

1) How and by whom the crank was balanced - or not ? How about the counterbalancer.

2) What bolts were used ?

3) Are all the blocks from a same rebore / replating company ?

4) Will gen1 block fit directly to gen2 engine ? Has anyone done it already ?

5) Is the only difference between gen1 and gen2 blocks the way bigger windage holes or is there more differences e.g. in coolant paths etc. ?

Would like to understand this for my own engine building project asap too...

I have made BIG ( bigger than Gen 2 ) windage holes in my gen1 1550 without any cracks and I used STD bolts for the first couple of thousand km.

The Gen 1 and Gen 2 bolts are directly interchangeable. Done both ( Gen 1 on 2 and the other way around ).

Havent seen any other differences than the windage holes and the "plugs".


I guess there are a different ( more crack prone ) alloy in the new casting.   Maybye I will stick to 83mm bore and not go to 84 as I planned....

[PetriK]

Havent seen any other differences than the windage holes and the "plugs".

I guess there are a different ( more crack prone ) alloy in the new casting.   Maybye I will stick to 83mm bore and not go to 84 as I planned....

Have not compared block to block - what about plugs ?

If the alloy is the cause, then I am wondering if there needs to be a different (re)boring process for gen2 than with gen 1 ? Assuming the cause is harder alloy which is prone to cracking, and if its not a reboring processing fault, are we then likely to see this to happen over the time for std bore engines too ?

Having seen the piccies for cylinders being cracked all the way from top to bottom between all the cylinder walls my primary suspect would be the (over)heat cycle during processing making the block weaker or even possibly precrack already during reboring - but this is just a personall guess. Will be interesting to hear a professional opinion on this from suzuki and reboring/replating facility - if there will ever be a published one.

If knowing the alloy material strenght, would also be interesting to see what this forumula reveals:
http://emat.eng.hmc.edu/fracture/fcp/fcp.htm

All this adds one more question to the list:
6) How close the serial numbers of the engines were to each other ?

[TrickTom1]

Have seen this happened to an engine where we made the windage holes a bit bigger, but also seen this happening when we used a set of "faulty" head bolts.

I can foresee this happening for at least these reasons:
a) Material gets weak around windage holes after reboring, the crack started from the bottom
b) Something went horribly wrong with rebore which nikasil plating covered during assembly
c) This particular setup messes up with the engine balancing causing vibrations that are harmful to the block
d) Once it was claimed that faulty head bolts caused us to crack an engine, then the crack started fromt he top.

So a couple of practical questions...

1) How and by whom the crank was balanced - or not ? How about the counterbalancer.

2) What bolts were used ?

3) Are all the blocks from a same rebore / replating company ?

4) Will gen1 block fit directly to gen2 engine ? Has anyone done it already ?

5) Is the only difference between gen1 and gen2 blocks the way bigger windage holes or is there more differences e.g. in coolant paths etc. ?

Would like to understand this for my own engine building project asap too...

Factory balanced and counterbalancer, head studs torqued to 65foot pounds, don't know on the plating vendor, yes on the cylinders interchanging.

[speedninja]

Ok, I got some pics. Here are the differences between the gen1 and gen2 cylinders. Freeze plug diameter is different and the windage reliefs are the only obvious differences. Casting materials, I am unaware.

The cracked gen2 had less than 100 miles, break in, dyno, two full 1 mile passes. Crosshatch is still visible.

PetriK, as for the vendor doing the bore and replate, that info is unavailable to me. Brock has that info.

[__NATE__]

HOLY SHIT 

[Cookie]

  Is that black line drawn on the cylinder walls,,, or are those actually the cracks?!?  Holy shit is right!

[SKILLZ]

Have the failures only been on boosted applications? How much boost are you guys running? Any failures heard of in a N/A application?

[__NATE__]

Have the failures only been on boosted applications? How much boost are you guys running? Any failures heard of in a N/A application?

He has NOS on the bike but This happen on all motor no nos used ...........really sucked cause like he stated had less than 100 miles ... 

[__NATE__]

Is that black line drawn on the cylinder walls,,, or are those actually the cracks?!?  Holy shit is right!

That's more crack than a crack head has 

[Yngve]

Pretty obvious that the crack started from the top so the windage might not to be blamed.
I say that NOS probably had something to do with this but mostly there seems to be a crack prone alloy used....

[SKILLZ]

How about finishing splitting the cylinders with a saw and lets have a look at the material between the cylinders and see if its a casting problem??

[PetriK]

Ynve - sure about the starting point ? If so then its far easier to start looking for the cause...

A saw may reveal something - and then a metallurgy testing centre will tell if the metal properties are the same as those should be.

(Someone who knows properties of aluminium well could perhaps write what happens to the block properties after a heat treatment ?  Then the question of the used nikasil process arises - last time we had a block in nikasil treatment (rebore-replate-honing) it needed to be cooled down for a day.)

[Cookie]

Is that black line drawn on the cylinder walls,,, or are those actually the cracks?!?  Holy shit is right!

That's more crack than a crack head has 

 

I'm just wondering if the reduced walls could be a contributing factor in all of this. Bad design causing weakness?

[Yngve]

Ynve - sure about the starting point ? If so then its far easier to start looking for the cause...

A saw may reveal something - and then a metallurgy testing centre will tell if the metal properties are the same as those should be.

(Someone who knows properties of aluminium well could perhaps write what happens to the block properties after a heat treatment ?  Then the question of the used nikasil process arises - last time we had a block in nikasil treatment (rebore-replate-honing) it needed to be cooled down for a day.)

The crack is all the way at the top between all cylinders but only all the way down between 3 and 4 as I can see from the picture(s).

Damn... I was going to use a new B-King cylinder on my 1585 this year ( the B-King cylinder is Black, no other differences ). Guess I have to dig down in my garage and use a Gen 1 cylinder... Luckily I have several

[speedninja]

The pics are still not showing everything. The cylinders are cracked all the way through between all holes, top to bottom. NO NITROUS was used. Naturally aspirated with less than 100 miles. The cracks are worse at the top for sure, but I don't really know if that designates the origin of the crack.

If someone knows a metalurgist willing to sample this block I am possibly willing to sacrifice it. I am also sending these pics to the vendor I purchased it from for his opinion as well.