Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
7/30/20 8:20 a.m.

The premise behind water injection is simple: Squirt a mixture of water and methanol–windshield washer fluid, basically–into the engine’s combustion chamber to cool the intake charge and prevent detonation. 

A few factors decide a given fuel’s detonation point: intake air temperature, ignition timing and cylinder pressure combination. Cylinder pressure can be developed by compression ratio, supercharging or turbocharging. If you can reduce one of the three variables, then you can increase one or both of the other two.

The water/methanol mixture vaporizes and cools the intake charge significantly, allowing you to increase the timing and boost. In layman’s terms, water injection can produce the same effects as high-octane race fuel–but without the cost or complexity of finding it at the pump. 

This technique has been around for decades, but it has only become a mainstream modification in the past few years. Credit more precise engine control systems with making water/methanol injection durable enough for everyday use. Additionally, companies like AEM now offer turnkey, all-inclusive kits for less than $500. 

Okay, so water/methanol injection is relatively easy to add. But is it really necessary? Here’s a handy guide to making that decision.

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MrFancypants
MrFancypants Reader
7/30/20 8:54 a.m.

Has anyone tried running E100 through one of these systems?

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) Dork
7/30/20 9:07 a.m.

You are better off using pure methanol or a blend from an evaporation, octane and detonation resistance point of view.

z31maniac
z31maniac MegaDork
7/30/20 9:15 a.m.
MrFancypants said:

Has anyone tried running E100 through one of these systems?

Why not just tune the car to run on E85 then? 

From what I understand most engines can already reach MBT with ~E60, so going all the way to E100 isn't really necessary. 

MrFancypants
MrFancypants Reader
7/30/20 9:29 a.m.

In reply to z31maniac :

Ahhh, fair point.

MrFancypants
MrFancypants Reader
7/30/20 9:30 a.m.
Paul_VR6 (Forum Supporter) said:

You are better off using pure methanol or a blend from an evaporation, octane and detonation resistance point of view.

So my thought about ethanol is that if you live you can get it at the same place you buy gasoline, making it super convenient.

slantvaliant (Forum Supporter)
slantvaliant (Forum Supporter) UltraDork
7/30/20 10:04 a.m.
Vigo (Forum Supporter)
Vigo (Forum Supporter) MegaDork
7/30/20 10:29 a.m.

The thing i always think about when trying to explain detonation is all the bomb-camera footage from Vietnam. You could pretty clearly see the pressure wave moving away from the center much faster than the actual flame front. I went ahead and edited out my political statement from the middle there before posting. 

Another thing that's interesting about a draw-through turbo setup like that Oldsmobile, or water/meth injection in general, is that at low-ish charge temps your ability to vaporize liquid in the fast-moving charge air is somewhat limited and you are generally just adding a 'safety margin', but as your charge temps go up you can actually vaporize so much liquid that you can stop using an intercooler. Seems kind of counterintuitive! There are a lot of really fast drag cars that inject a huge proportion of their fuel pre-turbo and drop their discharge temps from 500f to 200f roughly. Of course, 200f isn't a great number for a street car on pump gas, but if you're running high octane fuel and can only floor it for 6 seconds at a time without dying, it seems to work out! 

frenchyd
frenchyd PowerDork
7/30/20 10:31 a.m.

In reply to MrFancypants :

That has been my policy. Tune and  Run E85 with a back up of washer fluid for times when the E85 you get is less than 85% Ethanol. ( E85 can be as low as 51% ethanol at the pump)

 

  At those times  if you have a EFI system where you can dial back timing with a few key strokes, that's what you should do. But if like me you're dealing with distributors and carburetors you need a crutch. Hence windshield washer fluid.   
My Luddite solution will be to simply drive knowing the restriction and avoid high boost situations. If that's not possible I flip on the toggle switch and using a Kinzler  dial -a-jet  squirt in the proper mixture of WW fluid 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
7/30/20 11:21 a.m.
Paul_VR6 (Forum Supporter) said:

You are better off using pure methanol or a blend from an evaporation, octane and detonation resistance point of view.

-Paul - 1992 Corrado SLC 3.6 VR6 11.38@120 ALLMOTOR kptuned.com ig:@needavr6

Pure water is itself an anti detonant, up to 2x the amount of gasoline injected in highly forced induction applications.  Ricardo was running incredibly high BMEP while lean of stoich, with the main limitation being the stength of his test engine and the limits of his dynamometer.

Methanol does a wonderful job of reducing charge temps (I have heard of 30+psi turbo engines on carbureted methanol with iced over intake manifolds after a pass) but because it is also a fuel, ultimately it CAN detonate.  What water brings to the party is that it is inert and interrupts the detonation process, similar to EGR.

Apexcarver
Apexcarver UltimaDork
7/30/20 11:30 a.m.

Did some looking into it when researching blower stuff for my Mustang. 

 

Reasons to not go straight ethanol or methanol is that the mix they are using in those isnt combustible on its own, so you dont have to worry about it as much from a safety perspective. Saw a lot of articles on testing percentages of methanol and mixing to get it right, most of the washer fluids need a kick up.  Tuning is interesting as you are adding more fuel, so if you tune for it you run lean if you run out and could damage your motor. 

 

The show stopper for me is that SCCA flat bans it for autocross. I suppose they worry about someone torturing the alternative fuel possibilities of it and making a flammable mixture?  Either that or just plain rules creep, the alternative fueling could provide a performance advantage that would make it a "need to have to be competitive" thing. 

frenchyd
frenchyd PowerDork
7/30/20 12:13 p.m.
z31maniac said:
MrFancypants said:

Has anyone tried running E100 through one of these systems?

Why not just tune the car to run on E85 then? 

From what I understand most engines can already reach MBT with ~E60, so going all the way to E100 isn't really necessary. 

The problem is that E85 can have as low as 51% ethanol in it from the pump. Modern sensors can detect and adjust automatically ( if properly programmed)  but on carbed engines or older EFI  that's not possible. 

MrFancypants
MrFancypants Reader
7/30/20 12:38 p.m.
frenchyd said:
z31maniac said:
MrFancypants said:

Has anyone tried running E100 through one of these systems?

Why not just tune the car to run on E85 then? 

From what I understand most engines can already reach MBT with ~E60, so going all the way to E100 isn't really necessary. 

The problem is that E85 can have as low as 51% ethanol in it from the pump. Modern sensors can detect and adjust automatically ( if properly programmed)  but on carbed engines or older EFI  that's not possible. 

I was more curious than seriously considering it. Just seems like an interesting supplement for those of us whose fuel systems can't move enough fluid to take full advantage of an E85 tune.

I've been considering a water only injection setup to avoid having to install an extra 20 lbs worth of aftermarket intercooler so far forward on the car. Obviously the water pump and reservoir have weight, but I can place those anywhere I want. Given that I have a nose heavy FWD car I'd prefer the reservoir to at least be located aft of the front axle.

z31maniac
z31maniac MegaDork
7/30/20 12:56 p.m.
frenchyd said:
z31maniac said:
MrFancypants said:

Has anyone tried running E100 through one of these systems?

Why not just tune the car to run on E85 then? 

From what I understand most engines can already reach MBT with ~E60, so going all the way to E100 isn't really necessary. 

The problem is that E85 can have as low as 51% ethanol in it from the pump. Modern sensors can detect and adjust automatically ( if properly programmed)  but on carbed engines or older EFI  that's not possible. 

True on carb'd vehicles. 

But I've been driving since '98, the only thing I've ever owned with a carb is a lawnmower. laugh

mikeatrpi
mikeatrpi HalfDork
7/30/20 1:36 p.m.
Apexcarver said:

The show stopper for me is that SCCA flat bans it for autocross. I suppose they worry about someone torturing the alternative fuel possibilities of it and making a flammable mixture?  Either that or just plain rules creep, the alternative fueling could provide a performance advantage that would make it a "need to have to be competitive" thing. 

Sorry, what is banned by the SCCA?  I thought as long as you are <49% methanol and the mixture was outside the passenger compartment it was ok?

CAinCA
CAinCA Reader
7/30/20 1:37 p.m.

What is the car in the picture? 

Apexcarver
Apexcarver UltimaDork
7/30/20 1:46 p.m.
mikeatrpi said:
Apexcarver said:

The show stopper for me is that SCCA flat bans it for autocross. I suppose they worry about someone torturing the alternative fuel possibilities of it and making a flammable mixture?  Either that or just plain rules creep, the alternative fueling could provide a performance advantage that would make it a "need to have to be competitive" thing. 

Sorry, what is banned by the SCCA?  I thought as long as you are <49% methanol and the mixture was outside the passenger compartment it was ok?

Solo rules 3.3.3 (safety inspections) B 22."Alcohol may not be used in manifold injection or spray bottles"

 

Rallycross rules 3.2 R. "Nitrous oxide and methanol/alcohol injection systems are prohibited."

 

Street prepared does allow straight water injection though. You just cant use Meth. 

Apexcarver
Apexcarver UltimaDork
7/30/20 1:48 p.m.
CAinCA said:

What is the car in the picture? 

Factory Five 818, its a kit car

https://www.factoryfive.com/818/

 

 

CAinCA
CAinCA Reader
7/31/20 12:00 p.m.

Thank you Apexcarver. 

frenchyd
frenchyd PowerDork
7/31/20 12:43 p.m.
mikeatrpi said:
Apexcarver said:

The show stopper for me is that SCCA flat bans it for autocross. I suppose they worry about someone torturing the alternative fuel possibilities of it and making a flammable mixture?  Either that or just plain rules creep, the alternative fueling could provide a performance advantage that would make it a "need to have to be competitive" thing. 

Sorry, what is banned by the SCCA?  I thought as long as you are <49% methanol and the mixture was outside the passenger compartment it was ok?

Can't be a fire issue because even relatively small amounts of water will prevent burning. At The Indy 500 they have buckets of water every few feet to throw on fires.  One well aimed bucket will put out a alcohol fire easily. 

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