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Two schools of approach. Big boost means low CR as a general rule. High CR then you stay low boost but get off boost response. Fairly simple but off boost I get wheelspin in second out of corners. Haven't seen knock over 12 on the logger with 7 psi and fooling around with the tune and timing.

Question... Using Autronic SM4 in my 33 GTSt (not fitted yet). Looking at my old computer/loom, what needs to stay??? Does the std ecu have to stay connected for a/c, dash, any other ancilleries or can I just cut the loom out all together? I seem to have other wires coming from my std loom going to wiper motor (and some other little orange box back there) not to mention that wires head back from the loom towards the fuse box etc. Anyone else have any of these issues when changing computers?? Cheers for any ideas.

Two schools of approach. Big boost means low CR as a general rule. High CR then you stay low boost but get off boost response. Fairly simple but off boost I get wheelspin in second out of corners. Haven't seen knock over 12 on the logger with 7 psi and fooling around with the tune and timing.

What does one classify as 'big boost'?

Theres 2 people i know of that are running on or very close to 9:1 and 22+psi boost. (michael & noel).

Maybe gone are the days when that rule of thumb doesnt really apply anymore? Food for thought...

you will find they will be running very little timing.

9:1 is great for a street engine running less than 18psi

8.5:1 is good if you plan on running anything over that

8:1 is really a bit low for a street driven car I think

with high CR and high boost you are walking a much finer line. water/methanol injection can be used to supress detonation whilst keeping a nice timing map.

Good points. A decent tuner will work with what he has and extract the maximum from that. Used to be anything over about 20 psi was considered a high boost situation, but that is going up.

Ultimately it is all relative to peak combustion pressures and mean effective pressures (MEP) in the cylinders to calculate the available torque and power.

A classic example is Honda tuners throwing a low pressure turbo on a stock motor and then using that to improve power. Still has good low down, and builds a whack of power up through the rev range. Still a Honda though :thumbsup:

9:1 is still a decently high compression too. Consider the big lump of 5.4L V8 in my BA ute. Only runs 9.5:1 CR and is cammed for reasonable high rpm power.

A MASSIVE cheers to everyone that helped put together the RB30DE .PDF file!

Its taken me a while to find it (after reading 50 pages of this thread) but its all been worth while!

If i bump into the boys who put it together.. Ill have to buy them a beer!.. or 20!

Thanks again fellas!

:yucky:

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