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Looking good Tuomo- When will _this_ bitch run? John is a hero for even thinking about extracting the current motor from the car with all the additional stuff to be R&R'ed.
Quite correct except it’s two engines that have been extracted and will see this identical bottom end.
The rods came out exactly in the middle of our tolerance range, so we have three race bearing clearance options in the target zone: 0.0018”, 0.0023”, and 0.0028.
The pistons also look like they are the right amount in the hole, see the photo. The second photo is of a semi-autonomous robot that my dad built during the lockdown that apparently follows him around the house with a zippy cup filled with cognac.
The first of my blocks is back from Nikasil plating. John has not detected any Coronavirus infections or other problems anywhere in the block. The cylinder bore centers are still not properly social distancing and have, like #covidiots, remained exactly 122mm from each other:
Same crankshaft and deck height, so very close to the same length from the top of the crown to the center of the big end bore.
Tuomo , are the pistons top thick enough ?
My race shop ( BMW ) had a similar build M3 engine ( 450 NA HP which broke down very quickly due parts that broke loose between the first ring groove and the top.... now we see how thin that top is ! )
Those were USA made pistons.... here is a vid from it .. "still" running ....i may say i helped " a bit" building that car ….
Tuomo , are the pistons top thick enough ?
My race shop ( BMW ) had a similar build M3 engine ( 450 NA HP which broke down very quickly due parts that broke loose between the first ring groove and the top.... now we see how thin that top is ! )
Those were USA made pistons.... here is a vid from it .. "still" running ....i may say i helped " a bit" building that car ….
These Mahle pistons have thicker crowns and wider ring lands than what the conservative Mahle piston design guidelines call for. The top (ring) land of these forged custom pistons is about as wide as that in the diesel-like ‘87 stock 928 S4 pistons. The whole crown area is significantly thicker than, for example, what you find in aftermarket 100mm pistons used in turbo Subarus. The piston is not as light as it could have been design to be, but it’s light enough for our redline rpm.
So you won't be helping to scrape all the protective goo off the bearing journals and blow the mud out of every frickin' hole from the Nikasil process? Whatever John bills you for that part of the block prep, pay it and be grateful.
No, I won’t be doing that. It’s the $hitty part of the plating job, although John’s got a thread protecting process that makes that clean-up work a lot less time consuming than the plater’s standard block masking process.
The lockdown makes people do strange things. I for example, have started writing poetry. It’s slow going, given that I’m fresh off the boat etcetera etcetera but I’ve got the first verse ready for a preschooler investments book:
“When policy sucks,
the chairman prints,
high yield trucks,
and my portfolio sprints."
The pg-13 version with one f-word and more of a hip hop cadence and whatnot:
“When policy sucks,
the chairman prints,
high yield trucks,
and my portfolio sprints,
f?cks
the right up thru the roof,
I testify, that’s your proof."
Originally Posted by Rob Edwards
So you won't be helping to scrape all the protective goo off the bearing journals and blow the mud out of every frickin' hole from the Nikasil process? Whatever John bills you for that part of the block prep, pay it and be grateful.
Did I ever mention that rennlist software can’t interpret edited posts correctly? The quality of software and support here reminds me of the days when I was a young pronoun and working as an assistant professor at H.
Tuomo , are the pistons top thick enough ?
My race shop ( BMW ) had a similar build M3 engine ( 450 NA HP which broke down very quickly due parts that broke loose between the first ring groove and the top.... now we see how thin that top is ! )
Those were USA made pistons.... here is a vid from it .. "still" running ....i may say i helped " a bit" building that car ….
Barry, that BMW M3 engine must have been knocking badly. Was it forged or cast pistons? Regarding the video most rallys taken place here in Sweden and also in Finland are on gravel roads which makes life more interesting.
Åke
Last edited by Strosek Ultra; 04-12-2020 at 04:12 AM.
Ake, don't remember if forced or cast pistons ….but they were crazy thin under the valve pockets . They only had seen it when it broke…..
Yes, here we don't have much gravel roads anymore .. pity. The "Sezoensrally" here is know for some nice gravel stages , i did it once and was indeed fun . Of course due that "we" ( and sure me ) don't have much experience driving on gravel. Most are even forbitten for traffic all year round , just open for a rally.
With the fresh bores, John can measure the distortion in the bores with the deck plate taken off. The bore is round with the plate/head torqued to spec. It goes about 0.0005" out of round (give or take a tenth) without the bolts loading the block.
My conclusion is that if one wants to get everything exactly right, one should use a deck plate boring and honing these blocks, even though it’s an open deck design that doesn’t distort as much as a closed deck design would.
This engine is setup to 0.0026" to 0.0028" piston-to-bore-wall clearance measured at the aluminum and then the Grafal coating Mahle uses adds about 0.0009", so that tiny distortion when the block relaxes can actually be felt on the Grafal.
On other news, I’ve started writing my own “Lockdown Chronicles” which is “A personal account trading manual for preschoolers entering their first hedge-fund internship”. It’s going to be illustrated, with one lesson per page. Example:
Lesson 1:
When policy sucks
The long bond trucks
Until it doesn’t
All those parts look great! What really stands out for me though is how big and beefy the stock rods look - they look like they'll never break.
The early PPF rods and ‘87 S4 thick top pistons can take almost anything except high rpms. Having been run at stock redline and below, we are pulling out new looking pistons and rods from engines that have been run at 20+ psi boost making 800-900 hp at the crank.
Two-valve pistons have fragile ring lands, so those pistons are nothing like pistons from ‘87 S4s. The later cast rods are also weaker, although we haven’t actually broken any first hand.
The ‘87 S4 is the ideal 928 model for forced induction.
...apropos nothing...
Lesson 2:
The emerging markets pro
He’s a leveraged bro
The bro calls you a tourist
But when the tide goes out
It turns out
That the bro’s a nudist
Here are some of the long drill bits for drilling the squirter housings to a non-squirter block. Recall that high rpms require thin rings to prevent ring flutter; thin rings and a lot of power require piston oil cooling jets.
You can see the stock spray location and angle relative to the piston from the second photo.
And now to the after-pre-school special:
Lesson 4:
Your greatest fault is to be conscious of none of them
They say pontificating
If you ain’t sure what “conscious” means
you’ll do better than average in trading
To follow up on Rob’s question about cleaning the head bolt holes after the block comes back from Nikasil plating and boring/honing. We’re planning to use head bolts on the engine, which means that the threads needed protecting. John designed a system that protects them both during the dipping and plating steps as well as during the boring and honing steps. But the proof of the pudding... now that the block is back, no chips, crud, or dust in the head bolt holes, clean and pretty with the same surface that they went in.
Preschoolers ready to ZOOM into their remote hedge-fund internships, pay attention:
Lesson 5:
Without defining
They say no insider trading
Is the reaction you’re going to be fading
Based on misappropriated news breaking?
Usually when you cite the Newman ruling
And show you’re ignoring their fooling
The compliance person goes away
Holds no sway
04-07-2020, 09:46 PM
....i may say i helped " a bit" building that car ….
