your boost pressure / cr
Turbo Mini Forums

random question here, what boost are you all running? and what cr?
not fussed about power or spec, just getting the feel what your all running cheers :)

Yes i moved to the darkside

Instagram @jdm_brett

about 8.1:1 ish and around 17/18 psi

8.7:1 & 20psi maybe more

9:1 and 12psi

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

9:1 and seemed happy at 25psi.

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

8.5 and 23psi highest logged

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

8.7 10 psi

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

8:1 ish and 18psi

9.4:1 and 16 psi blew the ring lands on No 4 piston on the van using a 26 cc chamber volume and 8 cc piston bowls (which I thought were 10 cc - moral of story: never trust what you're told when in comes to someone else machining piston bowls - check it yourself before engine assembly).

I'm doing the rebuild using a new set of Omega cast 10 cc +.020 pistons and an extra 2 cc in the chambers (28 cc) and am aiming for 8.4:1, still running 16 psi.

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

spot on guys anymore?
Im getting 8.25cr and aiming for 20 +

Yes i moved to the darkside

Instagram @jdm_brett

used 9.4/10 psi, making a nice boost ramp on a large kkk k16 and a nice road engine
hearing det at 16 when fuel isn't up for the job...,never tried this set up a lot as engine was "quicker" at 12 psi ( not more powerful, quicker.

8.5:1 and 15psi on the hillclimber (planning to run upto 20 though, hopefully this weekend!)

9.3:1 ans 12psi on the sprint

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

7.5:1 and 1bar, planning on 25psi+ wen it gets running again

rick

i thought my cr was abit high for the boost i want to try but it maybe spot on, Richard, thats the same as my engine but im having pistons about 0.5mm down the bore ( more if i can get away with it) currently at about 0.7 but i need to skim it

Yes i moved to the darkside

Instagram @jdm_brett

8.1 as currently built but only test run, not on the road yet. Boost will be up to 1 bar (15psi).

Block has 0.5mm spare to deck which would take me to 8.3

I'm way too low as I'm playing with the siamese injection and want it to stay in one piece when I get it on the road for mapping, but Paul has already proved a lot higher is safe if the mapping is right.

My choice of 8.1 was based on a very common OEM setup (sitting on my drive) which uses an old fashioned T3 and will take lots of abuse at well over 1 bar. The whole of my plenum, injectors and intercooler is copied from that OEM setup, only the 5 ports and siamese code being different.

Schrödinger's cat - so which one am I ???

8.9.1 10psi

8.6ish:1 and 14 psi no probs, hoping for a few more psi when I get things sorted.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

8.6:1 20psi but not for long.

In the 13's at last!.. Just

8.4 11 PSI no problem, your Dynamic cr will make a differnce depending on the cam you use.

BTW - I took my buddy VTEC Pete out for a spin this weekend, and even though I am running her in, he gave it a name, the "Brocket"...cause I'm a brocket maaannn, nah nah nah nah nah nah nah nah nah nah nah....

Build thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7483

Katy Mini Owners Club Thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=505552

Let's make sure you embarrass at least one VTEC MINI today !

https://www.facebook.com/groups/17557298589...096464253807802

Yes i moved to the darkside

Instagram @jdm_brett

Brett,

I have taken some of the info from this link:



The dynamic or effective CR is the CR of the cylinder at inlet valve closure (including the contribution of the turbo) which is further influenced by the cam advance, lobe centre angle(s), duration, lift, rocker ratio, pressure ratio and the CR the octane will tollerate within that particular pressure/volume cycle, which in turn also depends on the bore and stroke of the engine.

Also, octane is very sensitive to temperature of the incoming air. It is quoted at a series of 3 standard temps, the lowest of which is 77 deg C. If you can cool your intake air to 40 deg C then you will pick up almost one extra point of tollerated effective CR for 105 RON and half a point on 98 RON if using an efficient intercooler

As a rough guide....

I used the first chart from some one who posted it up here a while ago and is based on empirical values.



The chart shows the maximum compression ratio for a given boost. The three curves relate to the inlet closing point of the chosen cam. For example an SW5 has an inlet closing at 48 Deg ABDC and the MG Metro, 56 Deg ABDC so a bit of interpolation is required.

Less than 20 degree inlet closing angle has little effect on the dynamic compression ratio.

The chart assumes an efficient intercooler.

And 95 RON Unleaded.

Obviously if you want to run a higher octane fuel, you can run more boost, you can use the table below (UK values in the white boxes) as a rough guide and apply the relative offset to the curve on the table above.

Hope this helps.

Edited by Brocky on 8th Oct, 2010.

BTW - I took my buddy VTEC Pete out for a spin this weekend, and even though I am running her in, he gave it a name, the "Brocket"...cause I'm a brocket maaannn, nah nah nah nah nah nah nah nah nah nah nah....

Build thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7483

Katy Mini Owners Club Thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=505552

Let's make sure you embarrass at least one VTEC MINI today !

https://www.facebook.com/groups/17557298589...096464253807802

cheers brocky, that is perfect :)

Yes i moved to the darkside

Instagram @jdm_brett

But a bit dated :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Can't beat digging up old posts lol :)

BTW - I took my buddy VTEC Pete out for a spin this weekend, and even though I am running her in, he gave it a name, the "Brocket"...cause I'm a brocket maaannn, nah nah nah nah nah nah nah nah nah nah nah....

Build thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7483

Katy Mini Owners Club Thread - http://www.turbominis.co.uk/forums/index.php?p=vt&tid=505552

Let's make sure you embarrass at least one VTEC MINI today !

https://www.facebook.com/groups/17557298589...096464253807802