How much to inject for 20B at 15psi (50/50)
 

Like the title says, my car with 20B is currently still worked on, I'm trying to figure out how much to aim for.

Previously, it was dyno'd at 702hp at 16psi, with mostly water being injected, around 500cc or so (will verify). Mechanic said that he had to switch to race plugs to be able to get the ignition working ok with the amount of water being injected. This is with the std ignition of the Tec3r.

My question is, for the near future, as I plan to switch to 50/50 water meth mix, what's the ideal amount to be injected for my setup, mostly as an additional safety measure, as I don't plan to run the car more than the current amount of boost.

TIA!

50/50 at your boost level... 500cc's is pretty ideal for your setup. Maybe look into some better coils possibly so u can run the race plugs. Id run 10's all around for heat range plugs also.
Congrats on the numbers thats very high #'s with so little boost. tell us more about your build.

It's my 911 20b project here, dyno chart on page 5:
https://www.rx7club.com/20b-forum-95...-815969/page5/

The dynapak used reads like dynoject, probably will show less on mustang or dyno dynamics. It's going through another round of changes, aiming to get it back by 7Stock.

The water injection is one from the now defunct leBonte (same roots as Snow Performance). It does have a nice fail-safe inline device, which powers down the Boost Controller if the flow is ever less than the configured minimum amount..

The true answer is enough to reach your AFR targets.

But your starting point will be based on calculating the minimum fuel flow differences for the new fuel blend to match your old fuel blend.

1 gallon of gas will produce about 116,090 BTU.
1 gallon of methanol will produce about 57,250 BTU.

Calculate how much total flow with 50/50 meth/water you will need to provide the water you want. From that you can calculate how much meth flow you have from it, and the BTUs it will produce. Then reduce your gas flow by that amount of BTUs. That would be a rough estimate starting point.

There is no other way to approximate your starting point.
Your tuner can do the math!

Thank you for the advice, however, I don't think just reaching the AFR target is the only key, that's over simplifying it. Please don't take offense, really.

i.e. the AFR target can be met by compensating the fuel map to accommodate for either 50cc of AI or 500cc of AI.

What I'm after is how much AI is needed to keep things cool enough w/ my situation to give me the safety margin that I'm looking for.

waterinjection.info - Powered by vBulletin

the only legit place for info reguarding water/meth injection.

Since the car is aleday tuned with "with mostly water being injected, around 500cc or so",
the change over can be calculated as I stated.
Since you are not sure with the current amount means you did not tune it.
Thus let your tuner do it all.