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Alcohol Injection - Questions and Answers - Tech Info

 
automotivejtm-#001
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Posts: 1076
Joined: 08/06
Posted: 08/29/06 02:47 AM

This Information was submitted by Trunkmonkey. Some of this information is written to be STI specific, but alcohol injection can be beneficial to all FI cars.


What is Alcohol Injection?

Alcohol injection injects a mist of alcohol directly into the intake stream, this has the effect of massive "chemical intercooling" along with greatly raising the octane level of the air/fuel charge. On 93 octane pump gas, the general consensus is that when the system is spraying, you are at or around 110 octane.


So what does that do for my car?

Well higher octane and a MUCH cooler air charge means a MUCH higher detonation threshold. It will take a LOT more to make your car knock.  

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automotivejtm-#001
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Posted: 08/30/06 02:45 AM

My car isn’t knocking now, why do I care?

Because one spot of bad gas can make it happen. And where "stage 2" wrx's last forever, there have been quite a few "stage 2" STI’s blow up. You want as little chance to detonate as possible. With alcohol injection, it’s less likely to detonate. And if you don’t tune super aggressively, you can pretty much set the car up to where it’s almost impossible to cause it to knock in any driving condition, with any weather change.



What Benefits are there other than the above?


POWER. You can tune leaner, running up to 12-1 under full boost. I run 11.7-1 at 19lbs and never see det. Your EGTS typically go down up to 200 degrees too. Mine are about 75 deg lower than pre alch. You can also run up to 5 degrees more timing and 2-4 more lbs of boost. Want detonation free 21lbs of daily driving boost on a stock STI turbo? You got it. It will be hard on the turbo, but those are cheap enough
Typically I would say running 2 more psi boost, 20% less fuel under boost and 3-4 more degrees timing would be a "normal" alcohol injection tune.
It also has the effect of "steam cleaning" the engine from the throttle body to the exh ports. No carbon buildup on the backs of your intake valves, and the domes of your pistons stay much cleaner, which means there is less chance of developing "hot spots" which cause detonation.

But that sounds expensive to run Alcohol, in 1 gallon cans is about 7-11 dollars per can.  

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automotivejtm-#001
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Posted: 08/30/06 10:14 AM

Wow that’s nuts, how long does 1 gallon last?

Well the SMC kit uses your washer bottle, that’s 1 gallon. Most people get 2 to 3 tanks of gas out of 1 fill up. I average about 2 1/2 tanks of gas for each alcohol fill up.
When you are tuning your car, it will go MUCH faster as you are spraying a lot more often. At a track day, it will REALLY go fast. I haven’t done a track day with it yet, but I would suggest you plan on AT LEAST 1 tank per session. If you use a 1 gallon tank, it MAY not even last the entire 20 min run session, or it might, you would have to talk to someone that has run it at a track day. Best bet, if you are going to try it, is have EM that you can switch maps on the fly. That way if it runs low (watch for the light) you can switch to a non alch injection map on the fly. It may not be an issue, I have no honest idea. If you run a bigger tank, you shouldn’t have a problem. If you are going to do a lot of track days and want to run this, you should consider buying the 12L Spec C tank and using that as your tank. SMC will install the pump in that for you if you would like.

Can I mix the alcohol with anything to stretch my dollar??

YES!! Many, in fact, in the Subaru world, most ppl run a 50/50 mix of distilled water and alcohol. The difference in what the alcohol injection does for your car is small. Figure if straight alch would yield you a 110octane charge, figure 50/50 would net you 108ish. I am totally talking off the top of my head, but I use those numbers to illustrate how small the difference is.
Also, if you mix, you end up with 2 gallons of mix. Which means for about $13 max, you get 4-6 tanks of gas worth of alc injecting goodness. That drastically lowers the cost to run this.  

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automotivejtm-#001
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Posted: 08/31/06 04:24 AM

What kind of alcohol??

Where do I get it? Home Depot is one of the most common places people get it. The type is "Denatured Alcohol". Rubbing alcohol can be used too! If you are tuned for denatured, and you cant find any for some reason, you can stop at any grocery store, or drug store, and buy rubbing alch, dump it in, fill that bottle with water, and dump that in. I did that just the other day, it worked great



What about Methanol?

Works great. Tune will be SLIGHTLY different than denatured.
* Methanol might be harder on the seals in the pump than Denatured, so before running it you should check with SMC (or whoever's kit you choose) to be sure their pump and such will be ok with it. I will email SMC and ask about it and update this as soon as I hear back from them.



Doesn’t alcohol eat rubber?

Yes a little, but that doesn’t matter as this never touches any rubber.  

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automotivejtm-#001
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Posted: 09/05/06 03:24 AM

Alcohol is flammable, will my car catch on fire??


If its straight alcohol, and you get hit hard enough to puncture the container, yes it could. But at that point, sorry to say but your car is most likely totaled anyway. The fire will just prevent the insurance company from trying to fix it and leaving you stuck with a car that has been in a BAD wreck and was repaired. If you run a 50/50 mix, it will not catch fire as the 50/50 mix does ignite. At least when several of us have tried to ignite it, it just will not light, so if you run 50/50 you are 99.99999999% safe.



So is this dangerous for my motor??


Well if you are boosting hard, and it fails, there is a very high chance your motor will blow. However, this is ULTRA rare, in fact I have yet to ever hear of a single case where it has failed. I know it HAS happened, but so far, not in the Subaru world, and from what I have heard and read, the cases where it failed, were bad installs. One guy with a VERY early SMC kit had a pump go bad, but his motor was fine.



So how does this work??


Ok so, you have a few parts. This is standard with all the kits, some have a couple differences, but here are the basic parts.
Tank
Pump
Controller
Nozzle
Some kits have a single stage or dual stage controller that sprays at either a constant flow rate regardless of boost pressure, or sprays at a higher rate after a given boost pressure.
Yet other kits, such as the SMC kit or the Devils own kit use a progressive controller. This is by far superior. It starts spraying at a predetermined boost pressure, that YOU can set and ramps up to maximum spray at another, higher predetermined boost pressure that YOU set. The SMC kit, and I THINK the devils own kit come set to kick on at 7PSI, and max out by 15 PSI. This doesn’t mean it doesn’t spray past 15PSI< it means it is a constant rate past 15 PSI. And you could make it 20PSi if you wanted to; you aren’t limited to 15PSI, that’s just the default.
Some people set it to only kick on at say 15 PSI or so, which saves a TON of juice, but you lose all the benefits of lower boost spray. 7PSI is great because then it will just kick on when you are at part throttle boost.  

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automotivejtm-#001
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Posted: 09/19/06 03:04 AM

More details please!

(The info here is based on a progressive controller) Ok so you are cruising along, you hit the gas, you hit 7PSI and the spray control unit kicks on. It turns on a high pressure pump that sends the mix down a hose to the nozzle which is typically located 2-3 inches in front of your throttle body. TMIC people usually drill a hole in the bottom front of their tmic and put the nozzle there. FMIC guys typically put it in the pipe, again, 2-3 inches in front of the throttle body.
As boost increases, the pressure from the pump increases, which causes more to be sprayed into the intake stream, up to the max point (default is about 15PSI)

IF YOU DO NOT HAVE A KIT WITH A PROGRESSIVE CONTROLLER> It will begin spraying at a constant rate at whatever boost pressure it is set to, many times this is not adjustable and is determined by what pressure switch it uses. This kind of kit still works, but it isn’t nearly as nice and not nearly as tunable as one with a progressive kit. I would recommend staying away from these, and at least getting a kit with 2 stages. However if you are just going to have it spray at or about your max boost, this kit should be fine. However be aware that there is a good possibility of a "hesitation" like feeling at the point that it kicks in, no matter how much you tune.


I live where they only have 91 octane, will this help me out??


In those cases, you are helped out EVEN MORE than the 93 octane people. You will have a lower overall effective octane, but it will still be well above the equivalent of 100 octane. Your power and detonation resistance gains will be more dramatic than the people who can get 93.

So this is like running race gas? Yes and no. Its better than 100 octane(and MUCH cheaper) but its no C16 (which is 116 octane) Its a heck of a lot more economical, because lets face it, you don’t need high octane when you are cruising around off boost, or even at 1-4 PSI boost. Heck I drove my WRX around on 89 octane and waste-gate boost with no issues for awhile just to test that theory. Think of this as race gas when you NEED it, and cheap pump gas when you don’t.  

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jwracing
New User
Posts: 1
Joined: 03/08
Posted: 03/06/08 09:38 AM

I was just curious if SS was going to be doing an article on  alcohol injection any time soon?  I was thinking about buying a kit threw DevilsOwn  www.alcohol-injection.com   so im looking for pro cons etc.  

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