Thoughts on increased compression ratio

[Dippy]

I'm not sure what response I'll get on this but clearly there are quite a few knowledgeable folks on here who seem to enjoy discussions about our V6T so I thought I'd try. At present my question below is purely out of interest.

This relates to the CREC engine. I know that there are very few owners of cars with this engine on this forum, but it is a technical matter relating to tuning the V6T. I recently came across SSP 624 which I believe has only been posted here as the Russian version. It was that post which encouraged me to look for the English version which I found here. Now this is an interesting read for those interested in the technical aspects of engines, and it surprised me that the CREC engine has more changes than I originally thought. But there is one change in particular that prompted this post, which is the one about increasing the compression ratio from 10.3:1 to 10.8:1.

Now this prompts the question of if it is correct that the V6T had 10.3:1 through most of its life, because I also have the 2008 SSP for the 285hp version of the engine which shows 10.5:1. This is relevant but not really what interests me. What I'd like to ask is if the increase to 10.8:1 affects the tuneability of the CREC engine. The SSP also states a maximum charge pressure of 1.8 bar. My car with a 2.99 PR develops a peak of around 2.3 bar. But I think I have seen folks on here state that theirs with a higher PR reaches 2.4-2.5? (I believe that in psi with an ambient 1 bar those figures are 11.6, 18.9 and 20.3-21.8 respectively - which makes me wonder if I have seen higher psi figures on the forum?). I believe that in general the consensus on the highest PR for the V6T is limited by the max charger revs of 24000rpm. But I wonder if maybe the CREC engine is more limited because of the higher CR.

So any thoughts?

[JD S4]

High compression + boost + fuel is a beautiful thing. So long as it’s controlled via a tune - “more is more”. Keep your octane up and go build an 11.5:1 with a high PR and ported heads and blower and go start hunting RS3


Sent from my

[Dom991.1]

I'm not sure what response I'll get on this but clearly there are quite a few knowledgeable folks on here who seem to enjoy discussions about our V6T so I thought I'd try. At present my question below is purely out of interest.

This relates to the CREC engine. I know that there are very few owners of cars with this engine on this forum, but it is a technical matter relating to tuning the V6T. I recently came across SSP 624 which I believe has only been posted here as the Russian version. It was that post which encouraged me to look for the English version which I found here. Now this is an interesting read for those interested in the technical aspects of engines, and it surprised me that the CREC engine has more changes than I originally thought. But there is one change in particular that prompted this post, which is the one about increasing the compression ratio from 10.3:1 to 10.8:1.

Now this prompts the question of if it is correct that the V6T had 10.3:1 through most of its life, because I also have the 2008 SSP for the 285hp version of the engine which shows 10.5:1. This is relevant but not really what interests me. What I'd like to ask is if the increase to 10.8:1 affects the tuneability of the CREC engine. The SSP also states a maximum charge pressure of 1.8 bar. My car with a 2.99 PR develops a peak of around 2.3 bar. But I think I have seen folks on here state that theirs with a higher PR reaches 2.4-2.5? (I believe that in psi with an ambient 1 bar those figures are 11.6, 18.9 and 20.3-21.8 respectively - which makes me wonder if I have seen higher psi figures on the forum?). I believe that in general the consensus on the highest PR for the V6T is limited by the max charger revs of 24000rpm. But I wonder if maybe the CREC engine is more limited because of the higher CR.

So any thoughts?

I know that this is an older thread but only Europe got the CREC engines in the 8.5 S4s, correct?