alcohol injection = rich

[zerosoul]

I dynoed my car yesterday to see how alcohol effects the car.
previously my A/F were about 12:1 across after 4500rpm-redline.
with same mods +alcohol (on 91 octan) this time my A/F drops below 10:1 after 4500rpm. I turned off alcohol and A/F stayed around 11:1 all the way.
can anyone help expain why alcohol injection would make car run rich?

thanx

 

[blackbuick87]

Probably because it sounds like you are not increasing boost or timing with the alky. You cant just turn on the alcohol and expect it to not richen the mix. Add timing and boost and you can get back to 12:1

 

[zerosoul]

no I did not add boost nor timing, my main goal with this alcky set-up was to prevent detonation. since my turbo are already maxed out at the boost I'm running and I dont have any timing control device.
what I really want to know is why the car would run rich with alcohol injection?

 

[blackbuick87]

Because you are adding fuel and no air. Its like adding a 7th injector. What turbo, boost, and chip do you have

 

[tminer]

Just run water instead of the alky. Water is actually better at knock suppression.

Alky adds fuel and makes for an easy setup to increase boost (which requires more fuel), but in reality you can increase the boost more with less alky and adding gas (which you don't even need).

I added a 7th injector (gas) and reduced my alky mix from 100% to 40% and could run the same boost with a lot less alky flow! This was just a test, the best bet is a chip and injectors to handle the fuel and spray water (maybe some alky for winter driving so water doesn't freeze).

Tom

 

[bruce]

In theory in a perfect world you should be able to make max HP at Stoich..

The reason to run richer then stoich is for in cylinder cooling.

If you add X mass of water, you can remove the same mass of fuel.
Or,
run more boost, or timing since you've increased the engines capacity to resist detonation.

Juggling Alky/water percents is to change the inflenece of wither your combo likes the mix as being more atomizing or vaporizing.

These are real distilled answers, google thru NACA papers for a few hundred pages of explainations for the above.

 

[Turbo__Tim]

Try a 40 percent water mix. You will need to turn the pump speed down, and maybe even raise your turn-on point somewhat. this will allow the cooling you want, without the rich condition.

Injection is meant to lower cylinder temps. If you read MrURL's alchy information page you will se the egt's are lowered 200 degrees with alchy injection. (intake temps are lowered somewhat as well)

A 10 percent richer mix has been reported using alchy, so that is in line, and normal.

Adding alchy acounts for about 10 percent of the mix that hits the cylinders, so that should explain some of it.

If you can't manage to tune a 50-50 mix, then your nozzles are too large. 3-4 1 mm nozzles from Aquamist will work.

See how much delivery you have when running the pump for 12 seconds. 5 ounces is in the ball park...

 

[zerosoul]

thanx guys!

I have been watching my EGT ever since I had the alcky kit installed and my EGT has not changed a bit. I was expecting EGt to drop though...the only thing that dropped was my A/F. strange.