11:1 Compression ratio on a VR

[double-6s 0]

Hi

 

Would raising the CR on a VR engine to 11:1 be asking for trouble?

 

Would the engine die a lot sooner?

 

And is there any way of lowering that back to a reasonable level to add a charger at a later date?

 

Thanks

 

Will

[gaz the geezer 0]

i wouldnt do it will, standard cr is 10:1 on the vr, if you turbo the engine you will probaly have to lower the cr, it may well be a good idea to pm kev haywire and sound him out, he knows the score

[double-6s 0]

I've pm'd him mate :)

[gaz the geezer 0]

I've pm'd him mate

 

i`m sure he`ll be able to sort it for you fella, he seems quite clued up :thumbleft:

[Kevin Bacon 5]

That 'cup' block has been 'machined' to 11:1 mate. The only way to drop it back to 10 (or lower) would be with spacer gaskets. But that block would kick arse and almost certainly rev way past 7K with solid lifters in the head - if you like that sort of thing ;-)

 

I don't know if OBD1 would be able to cope with the extra work the knock sensors would be doing with that block and you'd definitely need race fuel in it, it would pink more or less all the time on 95 unleaded.

 

It's a good engine for it's purpose, but no use for what you need it for ;-)

[double-6s 0]

Poo

[olly elworthy 0]

with higher compression you would really be wanting a remap to make the most of the engine and determine a suitable ignition curve

[Chris VR6nos 0]

As always there's lots of conflicting words and theories!

 

I've had experience of higher C/R VR6 engines and this i can say:

It's perfectly fine to raise the C/R to 11:1 and yes you will need to run Optimax all the time and no it shouldn't pink unless you have something dodgy going on.

You SHOULD use longer duration cams, there is a good reason for this, not wanting to get too boring about engine dynamics but....

There are TWO types of C/R to consider if you are building something special!

1. A STATIC C/R

2. A Dynamic C/R

These are completely different though are inseperatelly linked.

You really need to work out both of these to make an engine work correctly or more to the point, make it work to it's potential and be stoichiometric!

 

Not being dismissive but by virtue that you are asking this very question you don't have enough info to go out and start dismantling your engine and rebuilding it using blind luck.

There's so much info out there to gleen that you should go on the hunt for some ideas then re-address this article.

Reading and doing are a far throw apart and take years of experience to do it right.

I'm not saying don't have a go, more like use baby steps rather than dive straight in.

 

 

Chris

[double-6s 0]

You implying i'm going to be rebuilding it mate? Fek that. I'm looking at one thats already built to race spec with 11:1 CR.

 

Tomorrow i'm starting my space shuttle project ;)

[Chris VR6nos 0]

Well, done right it'll be just fine, but as previously said by olly elworthy, you're advised to get a remap as with any mod it's essential for optimal running.

 

What is classed as a 'Race' engine anyway?

 

 

 

Chris