rmcdaniels

Rebuilt my motor after hydro-locking it, it lasted a day. Here's the specs:


85.5mm 11:1 Wiseco gas-ported pistons
Dart tall-deck block
Eagle 5.967" rods
Eagle 95mm crank
Machine work by RLZ
All clearances checked with Mitutoyo micrometers

This motor ran great for 10K miles before I hydro-locked when I got caught in a sudden flood. I had it fully rebuilt -w- new rods and pistons. I started it up at my house, tuner was here for startup (AEM EMS -w- wideband), cranked up immediately, ran well. Ran it for about 20 miles, it ran fine, changed the oil/filter, put it on the dyno for break-in. Worked well on dyno, made 275 WHP at 6.5 PSI, although it did belch out a big smoke cloud at one point during the tuning. Drove it a hundred miles, changed oil/filter. Ran it at a local autocross with tuner there, kept an eye on wideband, was making 80 PSI of oil pressure, ran really well. It started smoking, so I drove it home. Leakdown was %20-%40 across all four. Pulled the pistons out today, pistons and cylinders all look like this on the exhaust side, and #1 is a little scuffed on the intake side. Ring lands are fine, all rings look fine and are loose in their grooves:






What would cause this?

STREETWERKZ

no!!!!!!!!!!!!!!!!!!!!!!

SlowReaction

To much heat causing the piston to expand and touch the cylinder walls.

Tad

dang, thats a shame man.

any signs of detonation??

if not, i'm thinking builder error..
bad clearances maybe?

Blue-Civic-Hybrid

iTrader: (1)

That sucks man, I hope you can get everything back together again...

Chiovnidca

Do you let it warm up fully before stomping on it?

rmcdaniels

Now that I think about it, the first set of plugs that we put in it on the dyno died after two pulls. The insulators cracked on all four of them. They were Brisk Racing turbo plugs, which I'd never used before, so I figured they were just junk. We didn't notice any detonation, and I would have noticed it, and any preignition should have shown up on the dyno graph, which it didn't. We put in a set of Iridiums and they worked well, the car picked up a lot of power and the plugs still look good. I've had plugs get hot enough to cause preignition before and it was very noticeable, the plugs were completely burned away and the pistons were melted:



That was from a boost controller problem running 30+ PSI on a 4th gear pull at the drag strip, vice 6.5 PSI on the dyno. We were running a wideband, so I know it didn't lean out, but we were not running an EGT sensor, although this damage doesn't look heat-related to me.

All clearances were double checked and were correct.

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca &raquo;</TD></TR><TR><TD CLASS="quote">Do you let it warm up fully before stomping on it?</TD></TR></TABLE>

Always, I've been driving motors with forged pistons for years now and never had a problem like this.

jadkar

First off....... I'm really sorry to hear and see all of this. I know you must have a lot of mixed emotions right now and this really sucks.


Now I'm just throwing this out there...... Many of us on the SC thread talked about excessive cylinder side loads when running a 95mm stroke crank. I realize you are running a DART tall block however I know the rod ratio is still less than ideal. Do you think this could have been a combination of excessive cylinder side loading + too much timing + possible piston to cylinder wall clearance too tight?

I mean instead of just one issue it may have been a few all tied together making this catastrophic failure.

rmcdaniels

I'm wondering about clearances myself. I've toasted pistoms from detonation and preignition before, and the damage is usually evenly distributed with more near the thin part by the valve reliefs. This damage is just on the sides, almost all on the exhaust side. As far as R/S, it's not as good as a GSR/ITR, but with the long rods it's better than an LS, and I set the redline at 8000 RPM. The other thing is that basically the same setup ran for 10,000 miles with no problems until I got caught in a flood. I pulled the motor tonight and it will be going back to the machinist tomorrow to see what he makes of the damage.

jadkar

Please keep us updated, I'm especially interested becasue as you know my engine is going back together very shortly.

rmcdaniels

JDogg picked it up this morning, he was headed for RLZ anyway today so he's giving my motor a ride in his trunk. Hopefully Howard at RLZ can look at it today and figure something out.

clemsonhatch

Looks like the cylinders got washed with fuel during start up and the
side load from the big crank deposited some piston on the sleeves...

That's my guess

Crx Jimmy

Well welcome to the world of seizeco, wiseco pistons are known that way in the 2 stroke world. from my experience (only with wiseco 2 stoke pistons) Is that the clearance might be the opposite, it might be too loose. They like it to be real tight and will end up looking like yours if too loose, usually if the pistons came with specs from wiseco they are wrong. I have had problems running their clearances. It doesn't help when you have 2 of the same part # piston manufactured at different times and they spec sheet they come with recommends different clearances in each box.

here is a pic of a wiseco with their clearances, now I run a stock honda spec clearance without problems




Modified by Crx Jimmy at 10:18 PM 4/3/2007


Modified by Crx Jimmy at 10:21 PM 4/3/2007

rmcdaniels

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clemsonhatch &raquo;</TD></TR><TR><TD CLASS="quote">Looks like the cylinders got washed with fuel during start up and the
side load from the big crank deposited some piston on the sleeves...

That's my guess </TD></TR></TABLE>

Cheater.

JDogg took the motor to Brad at RLZ, who made what is probably the correct diagnosis (RLZ's built a lot more 95mm strokers than I have). It looks like it got too much gas when it was first started and the pistons scraped the cylinders a bit. We did have actually have a problem starting it because the ignition controller wasn't plugged in, but it only got turned over a few times with no spark. JDogg did find after the first 20 miles that the new pistons like a lot less fuel than the old ones did, so it probably got too much gas and washed the cylinders down, causing the pistons to scuff from the side load. Apparently the marks on the cylinder walls are just some aluminum deposits from the piston, so it just needs a quick hone to clean up the cylinder walls and a new set of pistons. I should have it running again soon.

The pistons are custom units, built to JDogg's specs with a shallow hemispherical dish design by Brad. Nobody really makes standard pistons for my application, although Eagle does sell some crappy custom JE's that don't fit right.

jadkar

I'm not debating you, I'm actually just trying to learn a bit. I have heard of something like this happening before but can you please explain why the pistons being "washed" with some excess fuel would cause them to scrap the sides of the cylinder wall. I mean the pistons have a set piston to wall clearance whether they have fuel soaked on them or not.

Please explain the science behind this.

rmcdaniels

Pistons rock, they are continually coming in contact with the cylinder wall, regardless of the clearance. Proper clearances keep the angle of contact oblique so that there is less stress when they do come in contact, but they do not prevent contact. Usually there is an oil film on the cylinder wall that keeps them from scoring or scraping. Scoring isn't so bad, some marking of the cylinder wall occurs, but no material transfer occurs. Scoring is actually pretty common if for some reason the oil film is temporarily washed or brushed away. If for any reason (like if the walls of the cylinder are getting washed down with gas) the oil film does not immediately return, then scoring will turn into scraping, where material is transferred. Excessive side loading of the piston (like from using a big 95mm crank) exascerbates the situation, so scoring turns into scraping much more quickly with a stroker crank.


Modified by rmcdaniels at 12:10 AM 4/4/2007

SlowReaction

Actually thats kind of odd to see contacts on the side of the pistons. I would like to hear what howard has to say about that.

rmcdaniels

From what JDogg told me that Brad told him, the location of the damage is because of the 95mm crank. If the cylinders are washed down with gas in a 95mm stroker, then the damage is high on the piston and low on the cylinder wall. Apparently Brad's seen this type of damage before.

jadkar

I'm glad I decided to stay with 89mm. It seems even with a tall block the risk is there. At least the block is OK and you just need some new slugs. Is a hone all it really needs??

rmcdaniels

That's what RLZ says, and they are pretty serious about making sure everything is correct.

hondamanwill

looks like a oil feed problem.

Tad

so basically it in simple terms,

super rich, plus the long stroke is what killed it?

rmcdaniels

yep