Willie

I need opinions from those who've experimented with water/alky and total advance. With these two variables, which do you hold constant first?

1) Turn the water injection on at a preset boost, then start conservatively on the timing, advancing it a couple of degrees at a time until detonation, then backing off, or

2) Set the timing using the same method as above but with the water turned off, then experiment with when and how much water to inject?

And one more question. I always assumed that by running water, I could get away with NOT retarding timing, i.e. timing would be equivalent to an NA setup??? Am I wrong?

I'm asking all this because I just learned upon disassembly of my engine that it has obviously seen detonation. This detonation was NOT picked up by my knock sensor! I was running 34 degrees total advance at 14-psig boost (intercooled) with a 40/60 mix of denatured/distilled. I received an opinion from ASSC Racing that 34 degrees is WAY too much timing, that I should be somewhere around 22-24 degrees, even with water.

Willie

rskrause

I don't know a simple answer, but have a couple of comments. 34 degress is a lot of advance for a blower car, unless it's operating at sky high rpm. Obviously, exact timing requirements depend on a huge number of variables. Examples: Mine's currently at 27 degrees (15psi LT1 set up for 100 octane unleaded, water, no intercooler). My buddy runs SBF stroker with 22psi and an icewater cooled intercooler with C16 (117 octane) and no water. He runs 26 degrees of total advance. No evidence of detonation on either setup. If you are running street gas, I would agree with the 22-24 degrees.

In both of the examples, the cars were tuned for max hp. There was minimal to no advantage with more timing.

Rich Krause

Willie

I appreciate your input as always, Rich. I asked the questions because of a recent development with my engine. Due to a balancer that cracked and destroyed my crank snout, I had to disassemble the engine. In doing so, I discovered evidence of detonation. My steel-ringed head gaskets were elongated and there was metal transfer on my main bearing caps. The odd thing is my knock sensor did NOT pick this up. (New sensor is definitely going in when I reassemble.) So in a way, it was a good thing that my balancer cracked.

I really need to know the proper sequence in correctly timing my car so this doesn't happen again. I'd appreciate if you could elaborate on a couple of points about your car:


Examples: Mine's currently at 27 degrees (15psi LT1 set up for 100 octane unleaded, water, no intercooler).

I'm assuming you run 100 octane at the track only? If so, how do you compensate for the difference in octane on the street? Limit your boost, I imagine? Personally, I'd take this approach because I don't need anywhere near the power I have on the street and see maybe 5-psig max.


I would agree with the 22-24 degrees.

I feel the conservative approach in tuning would be to turn the water on and start at 22 degrees. Then bump it up 2 degrees at a time and check my plugs after each pass, maybe maxing out at 26 degrees or so.

I guess my presumption about water was incorrect. You cannot run any more timing even with it. But as you said, you saw no advantage to doing so anyways.... Sometimes you learn lessons the hard way.

Willie

rskrause

I have a "street" program with a bit less timing, a bit richer, and I don't use more than 5,000rpm when running pump gas. This has the effect of keeping the boost down. But to tell the truth, I have been running the 100 octane a lot on the street. Last year, I put ~4,000miles on the car. Probalby 300galoons of gas, so the cost of the 100 octane isn't all that high compared to engine parts.

As far as tuning goes, I add water until is lays down, then back off a little on the water. Currently I as using a nozzle sized for 24gph.

Rich Krause

Willie

At what boost level does your water turn on? I have mine turned on at 3-psig, which might be too soon. I have not experimented with nozzle size, but currently run a #10.

Willie