Melted Piston.

fiatfactory said:
I've got no more 87.0mm 0872 pistons to sell I'm afraid Hussein ...you'll have to hunt around. KS/Mahle did sell pistons individually, so you might get lucky and find a single sitting around...the other option is adapting /machining a set of taller CH pistons to suit the longer stroke 1600, or getting some forged pistons custom made.

What is the crushed thickness of the replacement head gasket you used? When did you change from the Felpro?

You static CR might be higher than what you think if the crushed thickness is under 1.5mm.... as all my calcs are based on using a Felpro headgasket on this style of build.

Broken lands are definitely a detonation issue... and judging by the shiny area next to the crack and the residue under the broken section, probably hasn't just happened, it's been like that for a while.

SteveC
Click to expand...

Dang. No luck searching over here so far. Summit Racing lists a custom order for single Mahle pistons. I'll contact them tomorrow & see if they can manufacture one to 0872 modified spec.

My HG fire rings are .060" compressed - this is a thicker than stock gasket - .078" new vs. .070" for stock thickness HG fire ring.

Both the thicker & stock (Italian) HG have a fire ring ID of 87.2mm (or slighter larger). All your computations should be valid. My combustion chamber volume ended up at 34cc, which I think put my CR * between 10.6 - 10.7:1.

I'm looking at cupping the intake valves & recessing the exhaust valves to reduce CR as you mentioned in earlier posts.
 
87mm pistons

You can get 87mm pistons here:

https://www.axel-augustin.de/shop2/Fiat-Oldtimer-Youngtimer/Fiat-X1-9/Engine-mounts-Engine-Parts/Piston-Sets/Kolben-Satz-0-60-Bohrung-O-87-00-mm::546.html

... albeit for an entire set. Not sure of which make.

Dom.


lookforjoe said:
Dang. No luck searching over here so far. Summit Racing lists a custom order for single Mahle pistons. I'll contact them tomorrow & see if they can manufacture one to 0872 modified spec.

My HG fire rings are .060" compressed - this is a thicker than stock gasket - .078" new vs. .070" for stock thickness HG fire ring.

Both the thicker & stock (Italian) HG have a fire ring ID of 87.2mm (or slighter larger). All your computations should be valid. My combustion chamber volume ended up at 34cc, which I think put my CR * between 10.6 - 10.7:1.

I'm looking at cupping the intake valves & recessing the exhaust valves to reduce CR as you mentioned in earlier posts.
Click to expand...
 
fiatfactory said:
Dom,

Hussein used 34.15 CH pistons (0872's) for this build, those are 34.7 or 34.9 CH...too tall.

SteveC
Click to expand...

Steve - any chance you have the full part number / spec on the Mahle 0872? I'm in contact with Mahle USA, but they need more info - I wish I had saved one of the boxes, or at least taken a pic of the label :(
 
Pics of #1 & #2 bores - hard to photograph - no evidence of untoward marking from the ring lands. Wear (shiny dark area in rear lateral face) in the high load area of the bore should not be an issue. I only have under 3K miles since the build. Hoping I can get away with a hone if needed to fresh up the bores. I can check for out of round.

I also reached out to Matt regarding their Wiseco pistons to see if they can be ordered with 34.15 CH to work with my crank / rod setup. Those already come with 39mm flycuts, so that would make life easier in that regard. They are listed for 87mm bore, but the piston gap is double that of the Mahle - .08mm vs .04mm - so I don't know if that means the piston is correctly sized to achieve that gap with an exact 87mm bore, or if I will in fact need more than a simple hone to achieve the clearance.

I don't have good experience with Wiseco pistons after the skirts all broke on my Volvo build, so I am also hesitant to use them.

I really don't want to remove & tear down the motor again. Of course I will if it cannot be avoided, I just wanted to dedicate my time on the body :(

X19_0073b.jpg


X19_0073a.jpg
 
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Wiseco pistons ordered yesterday. MWB flattop design (87mm X 35.2) with change to CH (34.15) to match my stroker setup. Has 39mm fly cuts for int/exh valves, so that will drop compression slightly compared to my tailored to bore fly cutting - and I'm still looking at some valve work to get compression back down closer to 10.3:1 max.
 
Pistons arrived Friday

X19_0250.jpg


X19_0202.jpg

Have to check the bores next to confirm sizing. Also ordered new Clevite rod bearings from Bayless. Recovering from knee surgery last Wednesday , so not sure when I will be working on this in ernest.

Hopefully back together before the end of June, though.

I do have three good Mahle 87mm 34.15 CH if anyone else ends up in my situation ;)
 
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Doing the math to figure out chamber volume changes & what revisions will be needed to drop compression from 10.7:1 down to 10.3:1.

I had 34cc chambers. plugging numbers into the formulas SteveC provided some time back, it looks like 36cc will be the magic number.

The Wiseco's have 39mm flycuts for int & exh - I had 39/34 for the Mahles with a volume of 1.5cc. I'll have to measure, but that should give me approx 2cc with the Wiseco's.

They also have greater depth off the crown to the ring land, and smaller OD of the crown above the ring land (8mm vs. 6.5, and 86.15 vs.86.5) which should net me almost .5cc volume gain over the Mahles, again plugging the revised numbers into the formulas Steve provided :) .

This means that I need to find another cc per chamber. Again, based on Steve's expertise, if I can recess the exhaust valves 1mm, I should net a .88cc increase. If I then have a small scoop taken out of each intake valve, I should readily fall into the 10.3:1 range.

I'm going to work on this plan, and then remeasure the chamber volumes once the valve work is complete, to verify the results.
 
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Not sure if this applies to the Tipo head you are using, but you could pick up some chamber volume and improve valve flow at the same time if it would be beneficial to shape the combustion chamber to further unshroud the valves.

Here's an example of John Edwards doing the work on a stock North American X1/9 head that has had material added to the chamber to compensate for the material to be removed by the unshrouding process.
https://www.youtube.com/watch?v=Jl4EFX0c9-Q
 
Thanks Dan - what he is doing is bringing it closer to the existing Euro BVH chamber layout :)

At this point, I should be good go with the revisions to the valve seating depth. Be a least a couple weeks before I can get the head to the machine shop to figure this out - can't do any auto work until my knee has healed some.

EDIT 6/03 - Got the head over to the machine shop today, so he'll check that its' still true, and work on recessing & cupping the valves.
 
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Got the pistons, rods and new Clevite rod bearings (three hole, got them from MWB, other vendors only had the cheap variety) assembled & back in the motor yesterday. Checked all the ARP rod bolts, and torqued to 50ft/lb to get the recommended stretch of .006"

X19_0127d.jpg


X19_0127f.jpg


X19_0239.jpg


Head work should be done early this coming week. #2 & #3 exhaust guides were also buggered. All valves will be recessed further to gain additional chamber volume. Shooting for 36cc, for a static compression of approx 10.3:1
 
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Thank you. Knee is doing well - been doing PT for strengthing - range of motion is good :)

Stopped at the machine shop - the valves have been cut back - .010" for the intake, .040" for the exhaust. He also reground the exhaust valve stems back to get them in line with the intake valve length, to compensate for the additional recessing into the valve seat. The head had to be decked - .006", so not much to worry about. He's just getting ready to resize the valve shims & set it up for .014" int/exh cold clearance.

Should be ready for me to pickup tomorrow afternoon.
 
Root cause

Hi Hussein,

any more ideas about the root cause of all the damage?

I know that you were suspecting a lean condition causing pinging, but over such a short distance I'd be really surprised. I've experienced pinging due to an overly aggressive distributor advance curve and separately due to a lean condition (incorrect float setting). In both cases, even though the pinging was clearly audible, and despite driving hundreds of kilometres in one case, there was no noticeable damage to the engine.

The engines are typically very strong. I know that a lean mixture will cause a very quick demise in a turbo application, but I'd be surprised that it could cause the amount of damage that you have described, especially in a short time frame and over a short distance.

The only reason I ask is because it would be a pity to invest all this time rebuilding the engine only to discover that the new engine suffers the same fate due to the original root cause not being identified.

Cheers,
Dom.


lookforjoe said:
Thank you. Knee is doing well - been doing PT for strengthing - range of motion is good :)

Stopped at the machine shop - the valves have been cut back - .010" for the intake, .040" for the exhaust. He also reground the exhaust valve stems back to get them in line with the intake valve length, to compensate for the additional recessing into the valve seat. The head had to be decked - .006", so not much to worry about. He's just getting ready to resize the valve shims & set it up for .014" int/exh cold clearance.

Should be ready for me to pickup tomorrow afternoon.
Click to expand...
 
dcioccarelli said:
Hi Hussein,

any more ideas about the root cause of all the damage?
Click to expand...

Thanks for the interest, Dom.

I can only attribute it to the lean condition, lack of adjustment for the timing curve / base timing, combined with the high compression ratio. I believe the overall combination was simply unworkable.

The HG fire rings were definitely toasted from detonation. The piston damage definitely happened in conjunction with the very lean condition at the end, as I clearly noted the change in idle quality / engine note / miss when it happened. Sounded kinda like one of those 70's V8 lumps chugging along. The broken lands would have come out & disintegrated had it been driven much longer like that - they were both still intact (albeit separate from the piston).

I'm confident it will run well with the LH2.4 / EZK 116 setup, and both of those have tuneable files available for use with TunerPro. I'm not familiar with the specific XDF/ADX files used to interpret the 2.4 bins, but that part shouldn't be hard to figure out - there are several self tuning Volvos using that software.
 
Machine shop head work completed. All valve clearances set to .014" - #1 exhaust bucket had to be machined a few thou also - the shim for that one was only .122", and that didn't seem to leave any shim rise above the bucket.

3DF55165-94E1-47AB-938B-DC1FF652C744_zpsny1gcsdk.jpg


Valves recessed, intake valve 'cupped'

X19_0127.jpg


measured chamber volume -

X19_0127b.jpg


they are all at 35cc, which is not enough to drop the compression down to 10.3:1

X19_0127c.jpg


took a little out around the back wall and the exhaust

3C6C7BAD-C73B-43C7-A474-6EAC7848344C_zpswilo4agz.jpg


now it's 36cc

X19_0127c.jpg


(took a smidge more out after this measurment to get exact 36cc)

82701B28-6B61-4295-BAFB-0D895C941262_zps6fddoknv.jpg


Just have to do the same for the other 3 cylinders....:(
 
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Finished up the chamber resizing - all four at 36cc on the nose



Now I just need time & knee in agreement to put it all back together :)
 
Measured the Wiseco piston pop-up & flycut volume.

.89mm / .035" pop -up (I'm hoping this is wrong, I must have mis-measured(!)

EDIT: pop up is .026" This is how I set TDC - bar bolted to block, crush washers thicker than popup, set screw turned to touch crown. Should have just measured the difference the first time, instead of setting a caliper at the piston edge.

F66D7A55-B9B8-432A-A26F-C5C10340BFBC_zpsytddxbs1.jpg



2.1cc flycut.
Deeper offset of ring land from piston crown, and smaller OD of the crown above the ring land (8mm vs. 6.5, and 86.15 vs.86.5) which should net me almost .5cc volume gain over the Mahles
36cc chamber volume.

Just need to do the math to figure out what this translates into in terms of revised static CR :)

EDIT: plugging the numbers into Steve's formulas I get:

5.232cc pop up volume
.925cc ring land volume
2.1cc flycut volume
36cc chamber volume
8.961cc HG volume
400.831cc cylinder volume

So, all that translates into 443.585 BDC volume, 42.754 TDC volume = 10.375:1 static CR.

I'm concerned that the increased pop up of .89mm translates into .61mm / .025" clearance, allowing for 1.5mm / .059" crushed HG thickness. This is NOT good, based on this post and this one

Checked head alignment dowel depth again. Measured TTY head bolt insertion depth; even though they are longer, they still have .25"/6mm clearance in the block. I used the hardened washers anyway.

25mm

X19_0073ca.jpg


Bolt bottomed in head

52.5mm

X19_0073cb.jpg


59mm

X19_0073c.jpg


Put putty in the flycut to check valve clearance (valves have been further recessed to increase chamber volume);

X19_0127f.jpg


installed original thickness HG, torqued to 20ft/lb
after:

0EC375C8-4C1F-403F-81BF-894CB7EAA7FA_zpsfoiw3owq.jpg


no contact at all, so no worries there.

Engine mostly back together. TTY bolts torqued in 4 stages: 14ft/lb, 29ft/lb, 90º, 90º.

4B4D7347-653A-4F11-B26A-13F82E53676F_zpscwgqkeun.jpg


7A905986-C42F-49B9-B070-0363DEA4C91D_zpshp9vtj9c.jpg


Still have to weld a boss on the oil pan to provide a 2 point bolt down for the crank position sensor, so that will hopefully get done tomorrow, then I have to finish up the revised exhaust.
 
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Wait a minute.
Are you putting the engine back together with a squish height of 0.6 mm?
As Clint said: "do you feel lucky?"
 
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