20V CQ Tidy Up

[Error404]

OK lets play a little game of spot the difference

A


B

[jsws3]

No numbers stamped on the top of the piston ?

[Tony Stark]

The dishing/piston crowns look different?

[rxl]

you skimmed the pistons so the numbers one the piston are gone.

[twoqu]

Does look that way. I guess you effectively get a set of 4 and they knock another up to make it 5. Stick it in the middle and we won't tell anyone.
By the way isn't it better to measure piston protrusion along the axis of the pin rather than at 90 degrees otherwise the reading is effected by piston rock!

[andy10v]

Dropped compression ratio?

Changed squish?

No writing and machine marks around the top, and in the bowl.

[Error404]

Yup I had the pistons skimmed
I was worried about the squish clearance as it was only 0.65mm - caused by the deck being resurfaced quite aggressively due to the condition of the block. Robin yes in that pic I was measureing the range of rock and then halved it to get an average which I used to work out the above deck height
I spoke to a few folk and the general concensus is about 1.00mm is a safe bet allowing for some rod stretch and some carbon build-up. So I stripped them out and got them machined down by 0.35mm. The machinist modified some vice jaws to hold them so they didn't damage the skirt coating
CR is back to just over 8.5:1 so almost as it should have been with these piston in a virgin block.

Bottom end is all build up again now, will put the head back on next over the next few days, then I can stop worrying about it all

[Error404]

Not had much time on the old beast recently, but last week I started on the downpipe.
It's getting serious now





Just got to fish-mouth the wastegate pipe and then I need to get some bits to back-purge so I can weld it up

[terrybullwon]

Looks good.

Tin foil, elastic bands and blue tack work a treat

[Error404]

Good tip MrBullwon
I have been using an old kitchen roll tube thus far, it's the same diameter as the wastegate pipe.
Looks like I've got some filing to look forward to

[quattrostyle]

Great work!

[andy10v]

Looks good.

Are you notching the pipe by hand?

How are you building the downpipe out of the car?

[Error404]

I also have a mocked up engine in the car using an old 7A block and a spare head

Yeah going to do the rough cuts with power tools and then hand file the rest to get a nice tight fit-up

[Error404]

After 4 hours of filing I ended up with this:





I couldn't have cut it with a tube notcher even if I had one as it meets the downpipe on the bend and sort of wraps around it - should flow nicely









Just got to cut out the downpipe now where it meets

[rynaqui]

That is super sexy work Alex