as title im thinking 8.5-1 with a 35r any thoughts of the tuners???

 

If you intend to run mainly on pump fuel then i would aim for 8.2 / 8.5:1

More gains to be had from a higher compression ratio, if you're planning on running race fuel.

 

I run 8.2:1 with 27 boost.

 

As above 8.2 or 8.3:1 Static CR

Mick

 

If you want to stay in the past, then stick with standard compression!

 

Should read...."If you'd like to give your engine more chance of staying in one piece, then stick with standard compression! "

LOL

 

Getting the engine built and mapped by someone that knows what they are doing seems to help!!

Moving to High(er) compression does not mean you have to sacrifice the use of normal road fuel. I ran VPower and still managed past 530bhp at over 9:1.

It made 480bhp at a paltry 1.4bar of boost on a standard position AET GT3076 core turbo on a 2.5 build.

As suggested... with Race Fuel it made an awesome difference. With Q16 race fuel it achieved over 600bhp (on the same standard position turbo) at circa 1.8bar, running 12degs more advance.

Obviously caveats may apply, but utilising higher compression even for road use does not mean it won't stay in one piece...... also note all of this was done on OE 2.5 block casings that did over 17k miles at 500+bhp of (ab)use and still going strong to date.

I would say "if" but more likely "when" I do the next big engine build on the current car.... I sure for **** will be going to higher compression again.

 

Depending on the rest of the OP's setup it may not be ideal though - Just because it worked for you, you cant really make a sweeping assumption that it is the way forward.

Sure, it will generally improve off boost performance, turbo spoolup, power output for a given boost pressure etc, but i've seen a few turbo motors that have become very timing limited on pump fuel, due to a static CR greater than 9.0:1 , which would appear to negate any benefit of running at that, in the first place

If you intend on running mainly/exclusively on high quality race fuels, then i would say that it's a worthwhile exercise though

 

Fiestaboy,
My initial post on this thread was slightly tongue in cheek. Probably as much as your statement about "staying in one piece" was I'm sure.... perhaps we are even's then in neither of us actually making sweeping statements that maybe misconstrued as such. Touche!

The fact is it can provide a great benefit...... but as I have not tested the same theory on 2, 2.1 or 2.3 (limited to a 2.5 build) I cannot obviously provide feedback on any benefits or of course negatives on these builds. However... I would be extremely surprised if Subaru's standard CR is optimal and further improvements could not be experienced on these lower capacity volumes without going too crazy.