AFR Tuning After Adding WI

[cewrx7r1]

My engine is a FD 13B-REW with all the supporting mods for power and reliability. Initial safe tune without any WI was 11.1 AFR at 16 psi boost which has been run for a few years without mishap.

For safety I added 350 cc / minute water only injection back in late 2010. With this, AFRs richen up to about 10.9 and I lose a little power.

I want to now tune to gain that power back or increase power a little. What is a good way to do this? Should I reduce fuel enough to lean out the AFR back to where it was before adding water, go a little leaner?

IN THEORY: If I want to maximise power, would I:
(1) calulate and adjust fuel by: (11.1/12.2) * fuel which would give an AFR of 12.2.
(2) add enough water so that with the above fuel my new measured AFRS would be again 11.1?

[Mazdabater]

As far as I know you tune for the same afr's you normally would. I'm sure rice will pop in with the answer

[RICE RACING]

Originally Posted by cewrx7r1

My engine is a FD 13B-REW with all the supporting mods for power and reliability. Initial safe tune without any WI was 11.1 AFR at 16 psi boost which has been run for a few years without mishap.

For safety I added 350 cc / minute water only injection back in late 2010. With this, AFRs richen up to about 10.9 and I lose a little power.

I want to now tune to gain that power back or increase power a little. What is a good way to do this? Should I reduce fuel enough to lean out the AFR back to where it was before adding water, go a little leaner?

IN THEORY: If I want to maximise power, would I:
(1) calulate and adjust fuel by: (11.1/12.2) * fuel which would give an AFR of 12.2.
(2) add enough water so that with the above fuel my new measured AFRS would be again 11.1?

No short single post answer, you best read my full thread on the water injection site @ Aquamist. You will see the in's and out's of various strategies towards running water at that flow rate and AFR settings and its effects on power.

If you want one line answer, set the AFR to 11.7 to 11.8:1.

[cewrx7r1]

Thanks. The site is great with lots or good info.
I will have to read them over and take notes.

[2gslse]

I have a dumb question. if you tune for H20 injection and the system fails won't you just blow it faster due to being lean?

[RICE RACING]

Originally Posted by 2gslse

I have a dumb question. if you tune for H20 injection and the system fails won't you just blow it faster due to being lean?

^ 100% correct.

The idea with water injection is to increase the power over what fuel enrichment only can achieve. < the practical problem is if you ad it ontop of your fuel only settings and nothing else you loose power, for some people increased safety is more what they are after.

I highly recommend everyone interested in this topic take the time to years my multi year 20+ page thread on Aquamists site. This details all of the pro's and cons of water, WM50, fuel settings to enhance power and durability. Everyone's requirements are different as are rules or circumstances etc. For some people it is just better to run 10.0:1 AFR on gasoline alone and use 20psi boost than it is to fuck around with trying to get maximum power on 16psi at some ideal power AFR setting, the richer and higher boost is actually far more reliable (as well as being more powerful).

Same applies for using water injection or WM50 (forget meth! just follow my BDC and HC commentary threads that show how fucked that ideology is, again its well explained on Aquamists site by me). Far better to run WM50 fluid at a "heavy" AFR and use 30psi boost than it is to try 22psi and some dyno queen SAE figure to save face LOL....

It is not an easy science, if it was BDC and HC would have figured it out by now, but for the smart ones in the room it was all figured out in the 19th century! and applied many times over by enthusiasts and engineers alike.

Best thing you can do is read reputable information on a non for profit web site that is not full of banner adds or paying vendors and also fit applicable cars that actually run and have been tested legitimately in the real world with non intendo MS paint type logs but rather F1 spec/grade equipment TIP: You wont find this information on anyone site that mentions AI LOL!!! or has the URL www.rx7club.com !!!!

[Prodigy]

sorry for slight de-rail....

how much do you charge Rice for say... the water injection nozzle from one of your setups...

I stumbled upon an Austrailain (duh) website that has just your nozzle and fitting on the end for sale for $100...

just thought I would share


http://www.mrparts.com.au/

about 1/4 down the page...



J.

[RICE RACING]

wow ! I dont even remember making that type! (if I did it would be around 10 years ago)....... lots of people claim to have mine or use my name in selling parts or full kits btw.

A current spec RRWEP140 nozzle set up you need to E-Mail me peter@riceracing.com.au

p.s. fwiw I don't really recommend you get the one above even @ $100 since I have no idea (if I did make it) what it was made for! as back then each one was custom made to suit the application.