turning up the boost

[Trakx]

What do you think of this?

I have a Corrado G60 TURBO. I'm running 1 Bar boost on a 11.5 AFR. Now i cant raise boost because i get Knock.

I?m thinking on using water injection (JUST WATER). From what i've read i will be able to turn up boost , which will lean my mixture, and
, from what i've read, try to target an AFR of 12.5.

Is this alright? will it work this way?

[nutron]

I would have though 12.5 was a rather high a/f ratio. The leaner the mix, the hotter the engine will run. w/i will bring down the temps but your still playing with fire. If you use water/methanol you will be adding more fuel as well and this will help with power and bring down the a/f ratio so you could add more air. What you need to be careful of is the cylinder pressure. Adding water will increase the cylinder pressure because the water will turn to steam and expand rapidly. If you turn up the boost and use w/i you might over load it. Better to keep the boost where it is and add the water/methanol at that level.

[raddy]

idea of increasing cylinder pressure becouse of steam should be not true....if this will be true, just adding water will increase power, but it is not like this, not at all.

trakx: your idea is just right, I would recommend you to raise boost to knock offset level (first audible knock, without water). Than engage water injection and check that knock has gone-this is effect of water injection. Than turn up boost little bit more (maybe 1.2bar level, with water) and cerefully monitor EGT and AFR and listen for knock. You can try to go to AFR 12.5:1, but monitor EGT very carefully...

[nutron]

I wouldn't increase boost until you get knock then add water, that's asking for trouble...

[raddy]

if knock is clearly audible (or good detection unit is avialable) there is no risk to go to knock onset-rare audible knock at its beginning. Going to detonation treshold and let off gas immediatelly doesnt harm engine. What is important is increasing boost and/or timing in small steps to do not overskip knock onset directly to severe detonation ambient...

[Trakx]

Well, i'm now making my own chips.

I'm trying to run 1.2 bar on 98 ron gas with NO WI.
I?ve got knock a few times, but the knock sensor did it job and retarded ignition. I could feel knock in 4 and 5 gear (it is not a gear related problem but how long you stay at a certain rpm range).
Knock could be seen on wideband log as a ondulated afr. This happens because, in my car, when ecu senses knock it retards timing in 3 degres. Than will star incresing in 1 step degree until it reaches mapped value (on chip) OR knock occurs again.
So, on AFR, a decrease in timing will rich up afr, as timing is gradually advance, afr will lean, and so you see the ondulated afr curve.
I've also have a knocklink but in my car if it lights up (even the first light) i'm already in heavy knock!

Back to water injection.. I?ve managed to run 1.2 bar with 98 ron gas @ 11.5(4500rpm) to 12(6200rpm) AFR but had to drastically decrease ignition timing, from 21 @ 1 bar to 15.7 at 1.2 bar.

Now i?m going to put WI and then will see how it goes.

[nutron]

I'd be more worried about blowing gaskets that knock if you turn the boost up much more

[keithmac]

I mapped my 16vG60 to 12:1 afr on boost (1 bar) aprox 18 degrees ignition timing injecting pure water (1mm jet), I don`t think it`ll be worth your time to run 1.2 bar if you`re retarding the ignition by 5 degrees.

I found on the GTO 75%methanol mix worked a lot better at controlling knock, running 97ron petrol.