Head Compression Ratio

[ippielb]

So with all this talk about the 2009 head and 2010 head compression ratio's. I was curious to see if there's a basic way to judge what ratio goes with what fuel at what psi of boost.

This is what i'm thinking. I know this table could vary a lot, but is there any base numbers? Something someone could go off of to get an idea of what one would need?

Compression Ratio-------Fuel Octane--------Boost------Elevation
12:1--------------------110----------------10---------6000
12:1--------------------100----------------7----------6000
12:1---------------------94----------------5----------6000

The reason i ask is, my head has a 12.8:1 compression ratio, and i'm trying to figure out what fuel i need to run at 7psi, at around 6000feet

 

[mynewuseddoo]

What are the compression ratios of the 2009 and 2010 heads? This will give a clearer baseline to judge from.

 

[ippielb]

What are the compression ratios of the 2009 and 2010 heads? This will give a clearer baseline to judge from.

I do not know the ratio's are, but i have a 700cc with a big bore 800 on it that uses the Cat 800cc pistons. So that's why i'm wondering about the head compression ratio's. And what i can get away with for running 7psi in 12.8:1 ratio.

 

[Crusty82]

2009 Head is 12,5:1
2010/2011/2012 head is 12,8:1
Rktek turbotopp that several people use in Norway: around 10,5:1 (i think)

I was hoping to run
6psi @ 2000ft with 95oct with timing controll on CR 12,8:1

But several people around here say that isn`t possibel. Others say it is.

The alternative is

10psi @ 2000ft on 10,5:1 (rktek) on 95oct without timing. (this is what alot of people around here does).

I just don`t know how the throttle respons will be and if it`s worth it.
People say the throttle respons is good with this head..

 

[ippielb]

2009 Head is 12,5:1
2010/2011/2012 head is 12,8:1
Rktek turbotopp that several people use in Norway: around 10,5:1 (i think)

I was hoping to run
6psi @ 2000ft with 95oct with timing controll on CR 12,8:1

But several people around here say that isn`t possibel. Others say it is.

The alternative is

10psi @ 2000ft on 10,5:1 (rktek) on 95oct without timing. (this is what alot of people around here does).

I just don`t know how the throttle respons will be and if it`s worth it.
People say the throttle respons is good with this head..

That's what i like to hear. I was hoping to get a 3 degree timing control unit on my sled and run the 12.8:1 at 7psi at around 6000feet with 94 octane. Think that's do-able?

 

[Crusty82]

I have no idea. this will be my first turboproject.
My info comes from endless hours reading threads about turboprojects and talking to people here in Norway that have experience with 2 stroke turbo on our elevation.

But yes. I would think that is do-able based on the things I read on the forums, and the experience from other`s that have run similar setups.

But don`t hold it against med if it blows up

 

[mynewuseddoo]

Last year with my 09 head I ran 10 psi on 50/50 av premium from 6000+ feet. I am running a 2010 head now from 10-12 psi and I'm running straight AV. I initially mixed 80% AV and 20% premium to test this and it was working fine. I am running just straight AV now and haven't noticed any hinderance in performance so just to keep things simple I'm not mixing anymore. The 2010 head really wakes up the bottom and mid range I find. It feels more solid on the top end also. I bought the Boondocker 3* electronic timing key. I haven't even installed it yet, still sitting in my house, I don't need to use it. It was a "just incase" purchase as I was going into personally unknown territory with playing with the 2010 head.

 

[ippielb]

I have no idea. this will be my first turboproject.
My info comes from endless hours reading threads about turboprojects and talking to people here in Norway that have experience with 2 stroke turbo on our elevation.

But yes. I would think that is do-able based on the things I read on the forums, and the experience from other`s that have run similar setups.

But don`t hold it against med if it blows up

Yeah, this is my first turbo as well. Built it myself so there's no tech support!

Last year with my 09 head I ran 10 psi on 50/50 av premium from 6000+ feet. I am running a 2010 head now from 10-12 psi and I'm running straight AV. I initially mixed 80% AV and 20% premium to test this and it was working fine. I am running just straight AV now and haven't noticed any hinderance in performance so just to keep things simple I'm not mixing anymore. The 2010 head really wakes up the bottom and mid range I find. It feels more solid on the top end also. I bought the Boondocker 3* electronic timing key. I haven't even installed it yet, still sitting in my house, I don't need to use it. It was a "just incase" purchase as I was going into personally unknown territory with playing with the 2010 head.

So, with running the 2010 head, on 7-psi, 6000feet, with the 3 degree timing controller, do you think one could get away with 94 octane? In theory? One will make sure about it first.

 

[mynewuseddoo]

If the 94 octane fuel is ethanol free, I would imagine you could run without the timing key at 7 psi and 6000+ feet. I've never done or tested it though.