4G63 Low Adv numbers

I’ve been tuning my Evo 8 MR on Maxxecu and I’m amazed at low low the timing numbers need to be on these engines! I am approx 7 degrees at 1.0 bar @ 5000rpm and as low as 2 by the time we’re upto 1.5 bar. At first I thought I had my base timing incorrectly set but this has been checked & verified several times, even at sub 10 psi (G25-550 turbo) at moderate rpm I can run into knock very easily.

I’ve learned that this is normal for a late Evo but wondered why! Is it because of the bore to stroke ratio?

Engine is 8.5:1 cr

272 cams on stock head ports etc

Uk pump fuel - shell 99 octane

Smallish turbo

Very low charge temps - IC fairly big

3 inch exhaust

NGK 7 grade plugs now onto 8’s

Have you verified that the timing doesn't change with RPM? When setting the base timing (with a fixed timing), rev the engine and make sure the timing isn't changing with RPM. If it does, it could be an ignition delay that needs adjustment or perhaps an edge polarity on crank sensor setup.

That's because of cylinder head design. Evo's head design is very efficient in terms of mixing air and fuel (good combination of swirl an tumble) that makes it very homogeneous and allows to compress it and ignite late on compression stroke to burn af mixture very fast which helps two things: less power loses during compression stroke and lower knock threshold since af mixture burns fast and evenly. Toyota and Ford repeated the same thing on their modern small displacement engines and it gave them additional 20-30 hp just by optimising mixture burning rate.

But you are 100 percent correct, ignition timing values usually are very small comparing to other engines and can be even negative depending on the engine load and RPM.

David Ferguson - I am starting to think the same in terms of ignition delay. Very good point

What is your current ignition timing map? If you can post it I'll tell you if it's ok or not.