Diggs24
Autocross Champion
- Location
- de plains! de plains!
- Car(s)
- 2015 GTI
2015 GTIs must have sensitive knock sensors then....
7
Hoon's DIYish Engine Build Thread
- Thread starter Hoon
- Start date
billbadass
Drag Racing Champion
- Location
- your moms house
doesn't look like it on the head but if was sucking in some oil from turbo or PCV then that of course doesn't help octane too
Hoon
Autocross Champion
- Location
- Rhode Island
More updates to the process...
The head is complete with the exception of 1 valve, because IE sent a retainer that was only partially machined and def can't be used. The QA department must have had the day off.
.007" was milled off the head to get it flat and true. The valves were seated .010" deeper into the head (seats had to be recut) and the stems were machined to keep OEM geometry. Piston to valve clearance is therefore increased .003".
The machinist measured the bores and found a .004" taper on cyl 1 (think of an ice cream cone), and noted that they are egged out in addition to being tapered. .004" is a huge amount of wear in engine terms. IDK what the stock piston to wall clearance is, but it is likely less than that, so clearances have more than doubled on the #1 cylinder. The others weren't as bad, but did show the same issues (oval shaped and tapering outward at the top). The oval shape comes from the load on the piston during the power stroke, which is uneven (the rod doesn't go straight down) and wears the bore unevenly over time. This is accelerated by high boost pressures, and my right foot spending too much time on the floor.
What is very odd about this to me is that the crosshatch looked normal...but i guess that's why visuals don't mean a whole lot at engine tolerances.
My usage was definitely very severe and high heat, but i didn't expect the block to be significantly worn. He expects it to need about .3mm to get it back to a straight cylinder, so 83mm it is.
The machinist is very thorough but this process is taking about 2x as long as the timeline we initially established so i plan to switch from JE pistons to IE because of the lead time (4-6 weeks vs off the shelf).
Time to order the bottom end
The head is complete with the exception of 1 valve, because IE sent a retainer that was only partially machined and def can't be used. The QA department must have had the day off.
.007" was milled off the head to get it flat and true. The valves were seated .010" deeper into the head (seats had to be recut) and the stems were machined to keep OEM geometry. Piston to valve clearance is therefore increased .003".
The machinist measured the bores and found a .004" taper on cyl 1 (think of an ice cream cone), and noted that they are egged out in addition to being tapered. .004" is a huge amount of wear in engine terms. IDK what the stock piston to wall clearance is, but it is likely less than that, so clearances have more than doubled on the #1 cylinder. The others weren't as bad, but did show the same issues (oval shaped and tapering outward at the top). The oval shape comes from the load on the piston during the power stroke, which is uneven (the rod doesn't go straight down) and wears the bore unevenly over time. This is accelerated by high boost pressures, and my right foot spending too much time on the floor.
What is very odd about this to me is that the crosshatch looked normal...but i guess that's why visuals don't mean a whole lot at engine tolerances.
My usage was definitely very severe and high heat, but i didn't expect the block to be significantly worn. He expects it to need about .3mm to get it back to a straight cylinder, so 83mm it is.
The machinist is very thorough but this process is taking about 2x as long as the timeline we initially established so i plan to switch from JE pistons to IE because of the lead time (4-6 weeks vs off the shelf).
Time to order the bottom end
shovelhd
Autocross Champion
- Location
- Western MA
That's a ton of taper.
Hoon
Autocross Champion
- Location
- Rhode Island
I still have a somewhat in depth video I need to edit and get posted for the teardown process, which has a lot of good info. I've been working a ton of hours and haven't had much motivation to get the video editing done but it's on the list.
It's a walkthrough recorded after the teardown itself. The teardown was a bit if a scramble, we had limited time to get it down to a bare block and get it out the door.
Yeah considering the stock clearances on many engines are .002" or so, an additional .004" is a big deal.
It's a walkthrough recorded after the teardown itself. The teardown was a bit if a scramble, we had limited time to get it down to a bare block and get it out the door.
Yeah considering the stock clearances on many engines are .002" or so, an additional .004" is a big deal.
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shovelhd
Autocross Champion
- Location
- Western MA
AnyHoon, Continue?
SugarMouth
Drag Race Newbie
- Location
- Nevada
well it's not a good iron if it warped
Hoon
Autocross Champion
- Location
- Rhode Island
Won't have an issue after machining, even if it was off from the factory. They'll square everything up ?
Cliff p.
Drag Racing Champion
- Location
- El Paso, TX
- Car(s)
- '17 Golf R DSG
Should be assembled in another week or so. Think the machine shop now has the parts and has started the process.
Hoon
Autocross Champion
- Location
- Rhode Island
They're soooo slow.
If the block isn't done next week I'm going to lose my shit, pay them for the head and take the block to another shop.
They've had the thing since mid-late November and we're going into March for fucks sake.
Cliff p.
Drag Racing Champion
- Location
- El Paso, TX
- Car(s)
- '17 Golf R DSG
Well if it's not done by the time I get home, send me your injectors and I'll send you some when I get them in.
Hoon
Autocross Champion
- Location
- Rhode Island
I know they do good work but man I'm getting frustrated. The lead time is unreal