- Jul 11, 2004
I've had a 30 hp difference in DSMLink's estimation from mild heat soak, just to show how big a difference intake temps can cause. How can you say injecting an extra 40% water/meth gives no increase in performance? It's not like he was flowing so much water/meth that adding more would have gave minimal benefits--a M5 nozzle at 150 psig is only 385 cc/min. There is absolutely nothing that definitively shows that the gains were caused by the M2 being pre-turbo.
You yourself stated that the MAS should still eventually see more airflow from the pre-turbo injection if it is indeed working according to your thinking.
I said that it should show more airflow if you're pushing the compressor off its map (losing boost). It's what that entire aquamist thread that started this whole pre-turbo thing says . That's not happening here.
I can say that injecting an extra 40% of water/meth gives no increase in performance with his particular percentage injection flow to fuel flow because it never has with me with SEVERAL very different cars/setups. I've been doing this water injection thing for a while. There was an increase in power because I tuned for higher boost and more timing. 385cc/min is the IDEAL nozzle size for 750s maxing out at 63% idc. Thats 20% injection flow for unit fuel flow. This would yield the best results without too much water that would actually, possible take power away.
I understand what you are saying. But, wet compression causes the water turn to steam at the compressor exducer. It will never reach the combustion chamber to slow the burn rate if it has already changed states. If you inject enough to leave water droplets remaining for a change of state in the combustion chamber, then your compressor is seeing those droplets at a point of its highest speed (the exducer). I wouldn't suggest it except for the last experiment to do on that turbo. Regrdless there is no way that your experiment can be controlled properly. You'll have to run the exact octane fuel the injection post turbo nets. Or you'll have to know the amount of water is being vaporized in the compressor to know how much will remain for the combustion chamber. . .The test I am running suggesting would actually provide some evidence that the pre-turbo placement is what is causing this change. I mean hell, how do you run ANY experiment without some sort of control? I'm not trying to downplay what you're doing as I think it's great you've got the initiative to actually go out and do testing--that's great! But, adding a control would make your results ten-fold more credible.
It's like saying that meth injection vs. water injection should be teted with using the nozzle flow as the control. If you inject the same amount of meth as reqired for water to be effective at preventing knock, then you'll see likely more knock. But the PROPER amount of meth (3-4 times more) does better than water at charge cooling and provides similar knock retardant.
In otherwords, he's testing a well-tuned (injection nozzle and all) post turbo system VS. the same system that now adds enough water pre-turbo to vaporize competely in the compressor (tiny m2 nozzle).