Audi R10 (and other Audi racing TDI engines) bore and stroke?

[chernaudi]

I suspect that I'm chasing a question with no good answer here, but was the bore and stroke of the Audi R10's V12 TDI (or the R15's V10 or any of the R18's V6s) ever declared or discovered?



I've never been able to find a good answer, though I did read on this forum a long time ago that Peugeot did run something like an 84x82mm bore and stroke. Given similar displacement, did Audi run something similar, at least on the V12?

[Gerard C]

Road going engine was 83x91'4 Is what I found on the net. Sorry, don't think it's the answer you're looking for.

[bhtooefr]

Old post, but I was searching for if anyone had calculated it, and I think it can be roughly calculated for the V12 and V10.


Race Engine Technology issue 24 states this much as a fact:

Baretzky admits that the R10 TDI cylinder bore is in the region of 82 mm-84 mm.

Combine that with this from Baretzky (which the Race Engine Technology article references, but this paper makes more clear): https://pics.tdiclub.com/data/500/R10_tech_paper.pdf

The V8 4 litre production engine of the Audi A8 was mainly modified to achieve the same bore stroke dimensions of V12 concept. Crankshaft, con rods and pistons were designed and manufactured

This implies an upper limit on the bore - 88 mm bore spacing on that engine, minus whatever wall thickness you want. VAG only ever went up to 81 mm for production diesel engines in that bore spacing, and 82.5 mm for gasoline, but that's for sale to the public with different durability requirements. It also implies a lower limit of 81 mm, as that's the bore of the 4 liter engine, but Baretzky admitted that it's bigger than that.



The Race Engine Technology article goes ahead and assumes 83 mm in a lot of places, partially based on the 4.2 V8 TDI moving to 83 mm bore (it also moved up to 90 mm bore spacing) - that makes a lot of sense, especially in light of Baretzky stating elsewhere (regarding the head gasket) that "our philosophy is to keep as close as possible to production", but it's not confirmed. (It also assumes an 84.75 mm stroke as a result, but that's very slightly too long to comply with regulations, it practically needs to be under 84.710 mm. I'll just use 84.7 because that's already more significant figures than anything we're working with.)


Additionally, https://paulsf1.wordpress.com/2012/0...the-v6-engine/ claims 0.98 bore/stroke ratio without a source. Honestly wouldn't be surprised if this blog got it from Race Engine Technology.


For my calculations, I'm using the FIA definition of Pi as 3.1416. I will round normally, but will mark values that are rounded up and that after all rounding (of both bore and stroke) would put them above the displacement limit with an asterisk.



So, a range of 82.0 x 86.8* to 84.0 x 82.7, most likely 83.0 x 84.7 for production commonality and being in the middle of the range.


But, now, a bonus: the R15.


Racecar Engineering stated in their 2012 Le Mans issue that the R15 had a different bore and stroke, and that it was 9% longer stroke than the R10.


Well, that's easy, if we assume it's exactly 9%, and that they then went to the maximum displacement - this produces a range of 86.0 x 94.6 to 88.1 x 90.1, most likely in the ballpark of 87.1 x 92.3 (if you like rounder numbers, 87.0 x 92.5 also works). Note that all of this is approximate, and based on unconfirmed numbers for the R10, though.