Author Topic: Beware of Oversized Gen 2 Cylinders (Read 25535 times) Tweet

TrickTom1 · « **Reply #25 on:** April 14, 2009, 06:24:12 PM »

Pistons and head still look new.

PetriK · « **Reply #26 on:** April 15, 2009, 01:31:12 PM »

This is from kawi engine - but lets tell the story here. After rebore and replating the engine was assembled using a non oem but hot brand name studs. The studs were tightened using the instructions from stud manufacturer - the particular tighness was also checked by asking from the stud manufacturer as it was higher than stock initially. Soon after the head assembly was completed, a crack sound was heard from the engine. At this point the engine was not run at all.

Here are piccies of the the middle cyclinder wall, the windage hole was not enlargened for this one at all - anyhow with the two outer ones the windage holes was made much bigger than stock.

Cookie · « **Reply #27 on:** April 15, 2009, 04:40:12 PM »

Those are before pictures, Petrik?

Got-Busa? · « **Reply #28 on:** April 15, 2009, 05:50:35 PM »

Quote from: speedninja on April 14, 2009, 03:50:57 PM

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.

Damn, those pics are crazy...

TrickTom1 · « **Reply #29 on:** April 15, 2009, 05:55:15 PM »

FYI-This had APE Pro Mod studs torqued to 65' #s

PetriK · « **Reply #30 on:** April 15, 2009, 08:53:03 PM »

Quote from: Cookie on April 15, 2009, 04:40:12 PM

Those are before pictures, Petrik?

Nope its after the engine was shortly run. YOu can see the crack starting from the windage hole. The crack is less visible there as no combustion residue in the crack here. Also were using hardened studs whicih we believe was the cause for this crack together with the nikasil heat up cycle maybe causing problems to aluminium.

show2ime2000 · « **Reply #31 on:** April 15, 2009, 09:49:42 PM »

We run all motor apps and cracked them back in December this same way. We went to the old model blocks..it is a common thing on the 08's and NOS is not a factor. The relief pockets have weakened the blocks. Get the old if you build one...We wwitched to the old and have not had any issues since..oh yeah, motor had aftermarket studs in them from the initial build so that will not help with the cracking...

Cookie · « **Reply #32 on:** April 15, 2009, 10:52:25 PM »

I see it now. Do you think it is a case of changed elements in the new Gen blocks that would cause this day and night difference?

Yngve · « **Reply #33 on:** April 16, 2009, 02:02:33 AM »

I wonder if this is an issue with both 83 and 84mm bores or is it only 84mm who has this problem ?

TrickTom1 · « **Reply #34 on:** April 16, 2009, 06:28:57 AM »

Quote from: show2ime2000 on April 15, 2009, 09:49:42 PM

We run all motor apps and cracked them back in December this same way. We went to the old model blocks..it is a common thing on the 08's and NOS is not a factor. The relief pockets have weakened the blocks. Get the old if you build one...We wwitched to the old and have not had any issues since..oh yeah, motor had aftermarket studs in them from the initial build so that will not help with the cracking...

Oz Booster · « **Reply #35 on:** April 16, 2009, 05:40:57 PM »

I think the material may be different , mostly as i have always relieved my gen 1 blocks for windage and never seen a prob even with 1/2 inch motorhead bolts at 80ft'lbs or on another motor when a rod exited damaging the bottom of the block and i would think putting a lot of stress in the area cracking ???
How many others relieve there gen 1 blocks and have you had any probs ??

HyperHayabusa · « **Reply #36 on:** April 18, 2009, 01:41:30 PM »

I have a 08 Turbo Busa RCC STG 1 3.5 psi and have had no problems............

dakinebusa · « **Reply #37 on:** April 18, 2009, 08:53:06 PM »

How about a bit of basic fracture mechanics?

There is a measurable parameter of any material called fracture toughness.
It is the measure of the stress needed to make a preexisting crack to run and cause the fracture to grow.
Fractures start from a flaw.
The stress needed to make a crack run is proportional to the fracture toughness of a material multiplied by the square root of the flaw size.
When a component starts failing by cracking either the fracture toughness of the material or the flaw size has changed.

Critical flaws are usually either machining marks or grains of the material's crystal structure that have become unusually largedue to growht in heat treatment.

In production the engineers are constantly tinkering with the material of a casting.
Usually they are trying to make it as machinable as possible so the tooling on the line doesn't wear out.
Alloy changes sometimes don't work out too well as any guy that really knows small block chevvys can tell you.
"Butterblocks"

Suzuki made a design change with the holes that puts machining marks in a high stress area.
If I was building one of these blocks I would polish those holes before re coat.

bulletb · « **Reply #38 on:** April 18, 2009, 09:06:32 PM »

Maybe early stage of detonation?

dakinebusa · « **Reply #39 on:** April 18, 2009, 09:22:03 PM »

All stress in a running engine is cyclic.
Detonation can certainly cause severe stress spikes that would cause a critical crack to run.
Detonation can be transient and subtle.
You can "rattle" and engine and doom it to failure in milliseconds then wonder why it failed.

But, if a jug nearly cracks when you are torqueing it up it is so close to the limit tjhat it will never live in the real world.

PetriK · « **Reply #40 on:** April 19, 2009, 01:04:54 AM »

Quote from: dakinebusa on April 18, 2009, 08:53:06 PM

If I was building one of these blocks I would polish those holes before re coat.

That is a thought that may carry us forward ! Nikasil plating a very tough material that is very crackprone.

Speedninja, could we have pictures of the pistonts stock and 14441 next to each other. Particularly from the side so that we can directly see into the piston hole.

dakinebusa · « **Reply #41 on:** April 19, 2009, 08:12:26 AM »

Actually PetriK, the Nikasil type coatings are very hard but with a very low fracture toughness.
The coating itself is a type of nickel/aluminum/silicon/phosphorous ceramic formed from the aluminum base.
Because of its low fracture toughness avery small flaw and a moderate stress can start a crack.
Once the crack is started it can run into the aluminum base.

An existing crack acts like a lever that torques at the tip of the crack and causes it to run further.

PetriK · « **Reply #42 on:** April 19, 2009, 08:39:33 AM »

Sorry thats my english, thank you for correcting to the right termninolgy. Meant the same thing based on this: From experience Nikasil is very tough surface to hone (even with diamond honing equipment) or modify e.g. the windage holes if it has nikasil plating, but when starting to get to the block the tool is almost bound to generate some cracks to nikasil which comes off as chips. Just noticed that I dont know what is the english word for the hand tool / "drill" that is used e.g. when making a head porting? Also there may be a seåarate word for nikasil diamond tool that we use for honing nikasil block ?

Anyway - really would like to see pictures of the stock and 1441 pistons to verify the shape from pin side and see the wear of the piston skirts from the side.

dakinebusa · « **Reply #43 on:** April 19, 2009, 10:48:24 AM »

We call that tool a "die grinder"
From the tool and die industry.

The chipping happend because the ceramic coating has a much higher modulus of elasticity than the aluminum base.
The coating is formed at high temperature so when things cool the coating is put in compression because the aluminum shrinks more than the ceramic.
The interlayers between pure aluminum alloy and the ceramic coating are key to getting it to stick and withstand thermal cycling.

truekingbusa · « **Reply #44 on:** April 19, 2009, 07:59:35 PM »

That's why I keep my busa stock...to me it's fast enough

speedninja · « **Reply #45 on:** April 20, 2009, 06:26:37 PM »

Quote from: PetriK on April 19, 2009, 08:39:33 AM

Sorry thats my english, thank you for correcting to the right termninolgy. Meant the same thing based on this: From experience Nikasil is very tough surface to hone (even with diamond honing equipment) or modify e.g. the windage holes if it has nikasil plating, but when starting to get to the block the tool is almost bound to generate some cracks to nikasil which comes off as chips. Just noticed that I dont know what is the english word for the hand tool / "drill" that is used e.g. when making a head porting? Also there may be a seåarate word for nikasil diamond tool that we use for honing nikasil block ?

Anyway - really would like to see pictures of the stock and 1441 pistons to verify the shape from pin side and see the wear of the piston skirts from the side.

PetriK,

I will post piston pics tomorrow night. I have been very busy.

Jay · « **Reply #46 on:** April 20, 2009, 08:13:04 PM »

We have heard of this, but not had it happen to any blocks we have sold. But in all fairness, we have only done 25 or 30 08s. The failure rate seems to be about 5%.

I am wondering if these blocks that have cracked were blown up when stock. Over the years on our block exchange program, we have had gen 1 blocks come in that had bore damage from a valve or stuck a piston, etc. These blocks make perfect 84 mms with no problems. I don't believe we have ever received an 08 core with bore damage.

As for the photo of the Kawasaki with a crack, I believe that was one we did that went to Finland. I have a hard time believing the studs could have caused it as there is at least 100 big bore ZX14's running out there with those head studs.

That was shortly after the 14s came out, and it was a 3 mill over. When I heard it cracked, we quit doing +3s and only did + 2's. Then we got reports of +3s with the studs and spraying.

Sometimes, motor stuff brakes and no one will ever be able to figure out why.

Jay

EllisCountyBusa1 · « **Reply #47 on:** June 17, 2009, 10:40:30 PM »

This thread is kinda old ,but thought I would tell you what happened to my 1441.
08 engine with 100 miles on it bored to 1441. Put it in a TG chassis. Ran it for the first time a few weeks ago. Straight motor , no nitrous. 1st pass it was blowing oil.
It cracked all the cylinders just like the pictures.
Also damaged the pistons. Going to rebuild it with the early model cylinder this time.

glenn71 · « **Reply #48 on:** June 18, 2009, 12:08:28 AM »

that sort of answers a few questions.An old race belief is to never use a brand new engine and turn it into a race engine.giving the block time to settle and cure after dong a fair few thousand street miles allows it all to settle into its happy position,then machine it up and race it.

Pat Dietrich · « **Reply #49 on:** March 21, 2010, 11:30:01 AM »

Might as well bring this to the top so people can read this and try to decide on what block to use for 1441. I would like to use gen 1 at this point after reading myself. Now I'll have to see if Jay can swap me out a gen 1 for my gen 2. That would be the easy fix

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Author Topic: Beware of Oversized Gen 2 Cylinders (Read 25535 times) Tweet