Water-methanol injection can help prevent knocking. Here in South Texas freezing is only possible a few nights a year so that straight water could be used. I'm only considering 9 ish CR.

How much water is typically used?

It depends on how much you are on the throttle. Mid to WOT will be where it gets used. I assume you want to run 87 octane and a small or stock cam? When I drive around normally in my turbo/supercharged Dart I don't use much unless I am having lots of fun. I think of it roughly as needing about a gallon of WW fluid per tank of gas, with some fun bursts here and there.

Note that if you run high CR with low octane, it also may diesel when you shut it off or run a bit hotter. Thoughtful tuning of the timing curve will be needed.

Lou

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Home of Slant6-powered fun machines since 1988

Thanks for the response. I had just watched a YT video on water injection of a turbo motor. The diesel people use it too. - helps clean the injectors . For me, it's not a fail when the reservoir runs dry. I think it falls into the "can't hurt" category, unless too much is used. With the warm days in South Texas, the motor can ping.

Pinging/knocking won't hurt unless you hold down the throttle a while (several seconds or more). If your exhaust is quiet, you can hear it.

Lou

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Home of Slant6-powered fun machines since 1988

What brand of water injection system is the best to use?

I have used the AEM system (for boost) and it works well. So then I have never bothered with an intercooler...

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou, I did not even know they were in the water injection business... I will look them up.

They have a non-boost and a boost version. I bet the directions for the non-boost version talk about strategies for tuning. AEM products have been amazingly good to me.

Lou

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Home of Slant6-powered fun machines since 1988

There is a big disclaimer about race car only installation... I can understand that for emissions relevant vehicles, but for non emissions pre 1966 vehicles.. it would seem that they are exempt?

Almost all aftermarket parts say that. Liability and letters of some laws...

Lou

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Home of Slant6-powered fun machines since 1988

Do you have E85 available? I use it for both fueling and intercooling. Compared to water its benefit is that it burns.

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1966 Dart. 170 cu.in. 200 rwhp.

The application would be a '85 D150 with 904. Under moderate load and 9:1 CR, would water injection be of benefit? What's a safe maximum CR for a truck that might occasionally tow 3,500 pounds? The truck is not rated to tow that much weight, I assume it's a limitation of the transmission. In this thread I'm concerned with fuel and spark timing. It's often 100F here in South Texas

Tim

Unless you're trying to do some sort of lean burn tuning while passing emissions, I don't think water injection would be that much benefit for that build; it's not a lot of compression and does not really sound like you're running it on the edge of detonation if everything is working well. Especially not at moderate load - if it has detonation issues at moderate load but not full throttle, you're running too much vacuum advance.

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Matt Cramer
1966 Dodge Dart turbo / EFI project

Thanks Matt. I searched for welded quench pads and dished zero deck pistons - to push the CR limits on a daily driver D100. I thought water injection could be extra insurance. I mentioned a lower CR because I can't throw money away on something that can't work. I thought I'd start with moderate CR.

I see many lightly abused OBS Chevy longbeds that have high miles but maybe need a transmission. I think I'll give up a couple mpg for a 4.3 v6 or 4.8/5.3 swap. In South Texas these don't rust and many used them for daily commuters so they still look okay.

I love my 3 Dodge trucks, actually five - a Dakota and a '47 1/2 ton. . If I can occasionally tow 5,000 pounds with a slant six that might make me happy. Be fun to see somebody build a welded quench pad S6 in a torque focused truck, maybe with a turbo or M90.

Tim