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Ignition starting point for fresh build.

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Hi,

I am in the process of building my rb25 to 600hp and tuning it myself.

I have bought and watched efi tuning fundementals and understanding afr course and countless webinairs. I have also tuned my previous setup myself with a link g4+ succesfully.

The thing that isnt completely clear to me now is what would be a good and safe starting point to set the timing to so i can optimalise the fuel map first without worrying for knock on my build rb25 and any other engine.

I had tuned my previous setup using someones ignition map with similair mods and retarding 4 degrees across the entire map for safety so i can focus on the fuelmap first and after that optimising the timing whilst listening for knock.

Do i now have to listen for knock the entire time i am doing the fuel map just to be safe???

Thanks in advance.

Of course you listen for knock all the time you are mapping. You may pay less attention at low load as you know that with sensible timing you are going to be pretty safe.

If you don't have a base ignition map to go on at all and want to hazard a guess the I would say put 30deg in low load and interpolate that to 10deg with increasing load (full boost) on the rpm side you may with the throw in some advance with increasing engine speed but it really shouldn't matter at this stage.

On a new engine, map low load, low rpm first. I would tend to increase load before moving up rpm but keep boost limited to W/G spring only to begin with.

Alternatively you can limit load and work your way up the RPM first but a new engine will need some load to bed the new rings so don't be afraid to give it some some gentle boost.

By the time you've got to mapping higher rpm, higher load the engine will either be run in or blown up (hopefully the former)!

Once you have a good map start turning the boost up and visit the various rpm sites for this increased load.

Above all, I always say, give the engine what it wants not what you think it should have.

throw race gas in there while you tune basic fueling. Obviously it's not perfectly representative of how the engine would run on a different fuel, but it gives you safety margin if you screw up and it leans out. It's cheaper than a new motor.