Wow, 3 years have gone by! And still not there (topic titel)…
I think the painfull truth is that there is so much to learn and if you’re not doing this professionally (or on a daily-ish basis), it takes a long time to make any serieus progress…
It occured to me - looking back to the old thread about the 2,2 engine with the original T4 heads made 465 hp in 2018. Granted that was at almost 2 bar boost, tapering to 1,8 or so at peek hp at 6500 Rpm. The turbo back then was really at its end tapering further to 1,7 bar (green line) at 7K Rpm.
My reference point for hp at 4000 Rpm was 200hp on that 2,2 engine.
(Old saved file, sorry for the quality)
8 years onwards, even better flowing heads, 2,4 ltr and a 4-port boostvalve: 474hp at 1,66 bar boost. Not much gain…
I have tried 1,85 bar and although it yielded 598 Nm torque, power fell down quickly. That was also with a messed up AFR measuring due to the wrong PID values in the ecu.
Another issue seemed to have been a very dirty air filter, so for the very first time ever I washed in out and re-oiled it.
Funny to see power at 4K has gone up to 230hp with the 2,4ltr, which is totally what you would expect from a bigger engine. The fact that its also a different cam (much more duration), bigger heads and a little bigger turbine, all that seems almost irrelevant
. Maybe a lot cancels each other out
Anyways, I left out an important part: tuning.
With the billet heads I also now run twin spark, which is nice and gives very good respons and all, but made my knock control unit very irradic. A good friend made the adaptations to use it in twin spark mode, but it has been too sensative (even with the sensitivity knob all turned down) even to the point I had to shut it down. This meant tuning needed to be VERY conservative (timing).
I think that holded me down in power. I did increase timing a bit up top, but that obviously was not enough to make a good increase up top. Most recent runs showed power maxxed around 5K and stayed there.
Very recently I dared to hook the knock control (still J&S) back on. To my delight, it seemed to work better now and an increase in timing gave a nice clear knock signal showing I went too far at low Rpm, but was oké at higher Rpm’s
So, timing up top is now 1,5 degrees higher (still pretty conservative maybe) and the engine lived through it after several runs (at wastegate, 1.0 - 1.1 bar boost).
Also now run the air-air twin-core intercooler inside the deck-lid to make things even more tricky heat-wise, bit its even more sleeper now
Weight distribution is better though and also the intake routing has less bends. I also gave it a little more % W/M injection.
I am very curieus if these settings (and alterations) make it go to 500hp now…
Oh, and this is all on regular 98 pump (US comparitive 93) gas!
