ETA pistons

[packratbimmer]

How many stock compression ratios were there on the non-superETA 2.7 ETA cars? ...and, is it a piston height change or a shape change?

Thanks

[estoguy]

The regular Eta engine compression is 9.0:1. The only difference was in the SuperEtas, they were 8.5:1.

[digger]

also euro engines also had 10.2:1 and 11:1 different shape (sjhallower dish or raised dome)

[ak-]

also euro engines also had 10.2:1 and 11:1 different shape (sjhallower dish or raised dome)

[img]http://i.imgur.com/Fc68b0w.jpg[/img

Awesome pic.
What's the significance of piston ring depth (MT) when comparing the SETA to the first listed B25? What's it matter?

[digger]

MT is supposed to be the depth of depression (dish depth) its normally used to adjust compression. it looks like seta has lower dome and shallower dish.

[ak-]

MT is supposed to be the depth of depression (dish depth) its normally used to adjust compression. it looks like seta has lower dome and shallower dish.

Well that was easy to figure out - not sure why I read 'ring' instead of 'top'.

My wrongly read concern was going to lead to the question whether SETA rings differ from B25 rings and if so, how? Can't find good info online.

[digger]

piston rings? iirc the regular eta are different axial width to b25 . as for seta idk someone out there with a piston lying around might help you out and post some numbers.

b25 is 1.50/1.75/3.0

b27 might be 1.50/2.00/4.00 but thats off top of my head

based on real OEM the ring p/n between seta and eta are the same

[ak-]

piston rings? iirc the regular eta are different axial width to b25 . as for seta idk someone out there with a piston lying around might help you out and post some numbers.

b25 is 1.50/1.75/3.0

b27 might be 1.50/2.00/4.00 but thats off top of my head

Okay thank you.
Considering that, would you say one is superior in controlling oil during have vacuum / deceleration?

[digger]

doubt youd notice a difference

[packratbimmer]

Damn! Thanks guys.

I read that the early eta block was a little taller as well.

Anyone ever confirm that?

THX

[digger]

old eta blocks are not taller from what ive measured

[packratbimmer]

Good to know - I was a little skeptical about that.

Thanks again!

[ForcedFirebird]

Pretty sure the seta uses eta rings, made that mistake once when ordering (not sure if they all did, but just measure twice, order once lol). From memory, the rings were thinner on the (s)eta, with less tension to curb friction (just like the cams with less bearings, and softer valve springs).

I have not seen any blocks with varying heights, but then again, I have only seen one block come in the shop that had that weird large freeze plug in the back.

The seta and "i" pistons are noticeably different when next to each other, the valve reliefs give away the compression difference from the top, pin height from the side.

Also, Digger mentioned the compression differences, but remember the seta uses the 885 head and risen/angled squish band (like the b25), the eta used the 200 head and flat squish band.

[ForcedFirebird]

Pretty sure the seta uses eta rings, made that mistake once when ordering (not sure if they all did, but just measure twice, order once lol). From memory, the rings were thinner on the (s)eta, with less tension to curb friction (just like the cams with less bearings, and softer valve springs).

I have not seen any blocks with varying heights, but then again, I have only seen one block come in the shop that had that weird large freeze plug in the back.

The seta and "i" pistons are noticeably different when next to each other, the valve reliefs give away the compression difference from the top, pin height from the side.

Also, Digger mentioned the compression differences, but remember the seta uses the 885 head and risen/angled squish band (like the b25), the eta used the 200 head and flat squish band.