Radiator vs. intake sprayer on NA engine

Driving through the mountains in our motorhome last year(26' E450 gas V10) while watching temps on the Scangauge, I could see both the coolant & trans temps were climbing close to their limits, despite keeping our speed low & ambient temps only in the upper 70's. 
 

I had the trans rebuilt last spring, and it has a higher capacity pan. So I think it's increased temps might be just general heat soak. Plus the temps still remained a bit high after we descended & never really cooled back down. 
 

So I'm thinking about repurposing the parts from the "hydrogen injection kit" that was on it when we bought it, and building a sprayer to help cool things down the next time we're mountain climbing. Unfortunately I can't find any concise info regarding whether spraying the radiator, or directly into the intake tract, would be more effective. 
 

What does the hive say?

Spraying into the intake might help cool the intake charge, but it won't bring the coolant temp down. Might have the opposite, it might increase power output and thus heat generation.

We did some experimentation with an intercooler sprayer about 20 years ago and it definitely worked. The IC was cool to the touch after coming off track. I've also seen the water temp gauge on my Land Rover drop 10 degrees just by driving through a puddle and soaking the rad. So I'd be hosing down the heat exchangers.

In reply to Keith Tanner :

Thanks Keith!

Radiator water spray is a much harder solution to get wrong, and if the problem is a lack of cooling capacity, would address the problem more directly. The facts that it only happens on long climbs and that the engine doesn't recover suggest that cooling capacity is the biggest issue. If the engine cooled well otherwise and only had temperature problems under sustained load then I'd lean more toward injecting the water into the intake.

Setting up water injection for the engine does sound like fun though...maybe you could do some of both? Spray one nozzle at the radiator and another into the intake?

I used to use a garden sprayer to hit the radiator and TMIC on my Mazdaspeed3 between autocross runs. They suffer bad from heat soak on short hard runs. I could hose the radiator down and watch temps drop 7-10-degrees over the next 2-minutes. I would definitely consider a modified intercooler sprayer for your situation. 

Pete, you need to watch more Roadkill!

Draguar,  I believe, they hooked up a sprayer on the radiator to keep it from overheating 

Can't have any external spayers on most tracks. I'm sure that was the eventual plan for the motorhome?

Intake tract spraying is meant more to decrease detonation by cooling the intake charge and hopefully clean out carbon deposits in the process

In reply to mr2peak :

Yes, definitely read the class rulebook first before modifying the motorhome :)

I, for one, fully support your motor home racing efforts!

In reply to aircooled :

The next street takeover is gonna be lit!

Spraying the radiator will work, at the risk of rapidly increasing the rate of corrosion.  Think aluminum pan in the dishwasher kind of corrosion.  Not apocalyptic, and it won't happen in a month, but not the greatest solution (pun intended)

I'm also a big fan of set-and-forget.  I hate having to add crap, and [insert whatever supply] always seems to run out at the worst times.  I would vote for more radiator or increased air flow.  I want to get in and drive, no stress about where I can fill up an additional tank.  If I get in a motorhome and put my foot down on a hill and it overheats, I want to fix the problem instead of making a work-around.  I realize I'm maybe different than others in that aspect.

It's why I would rather do forced induction instead of nitrous.  It's why I won't buy a diesel that requires DEF (for multiple reasons other than just the DEF).  I want the vehicle to do what it's supposed to do without conscious effort on my part.  If you don't mind it, go for it.

In reply to Curtis73 (Forum Supporter) :

To some extent, a very fine spray shouldn't have quite the expansion/contraction issues as a stream of sloppy spray. If you can ramp up the flow rate over the first (guessing) 20-30 seconds you'll probably be okay. 
 

would corrosion be an issue? I know the radiator won't hit boiling temp but it's still hot enough to burn off the water isn't it? As long as you don't shut down immediately I imagine it would be okay for quite a while. 
 

Arm chair quarterback here

Curtis73 (Forum Supporter) said:

Spraying the radiator will work, at the risk of rapidly increasing the rate of corrosion.  Think aluminum pan in the dishwasher kind of corrosion.  Not apocalyptic, and it won't happen in a month, but not the greatest solution (pun intended)

I'm also a big fan of set-and-forget.  I hate having to add crap, and [insert whatever supply] always seems to run out at the worst times.  I would vote for more radiator or increased air flow.  I want to get in and drive, no stress about where I can fill up an additional tank.  If I get in a motorhome and put my foot down on a hill and it overheats, I want to fix the problem instead of making a work-around.  I realize I'm maybe different than others in that aspect.

It's why I would rather do forced induction instead of nitrous.  It's why I won't buy a diesel that requires DEF (for multiple reasons other than just the DEF).  I want the vehicle to do what it's supposed to do without conscious effort on my part.  If you don't mind it, go for it.

I'm also very much not a fan of adding more systems with their own finite supplies that need to be topped up...an upgraded radiator could be a huge investment, but adding a junkyard motorcycle radiator or "heater core on the outside" setup could be a cheap way to improve cooling capacity.

In reply to GameboyRMH :

That's what I did with my classic Mini. It's got an electric fan that triggers off coolant temp plus an auxiliary radiator. Made a big difference.

This doesn't sound like something the system would rely on, though. We're not talking water injection to keep a supercharged car from blowing the head off or something. It would be to help the stressed cooling system when the vehicle is operating under the hardest conditions. The vehicle never actually overheated even during mountain climbing. Having a sprayer spritz the coolers above a certain extreme threshold wouldn't be that hard to keep working, and the failure mode would be the vehicle acting exactly as it does now. Sourcing some water (especially if you're in a motorhome!) is not as much of a challenge as finding DEF.

Interesting thread. 

1) It's a big heavy duty motor home.

2)It makes lots of heat going up mountains.

Questions:

How do you get more airflow through the cooling system? 

Is there a way to add vents/outlets to let heat out of the engine compartment?  Vents in the fenders or hood?

Does it have a large transmission cooler?

In reply to Curtis73 (Forum Supporter) :

I was initially looking into a dual core radiator vs the single core it currently has, but I discovered the transmission line connections are different between the two. So at that point I'm paying someone to do the work, but unfortunately all the local  places & mechanics that work on RVs don't do that type of work. 

Since I already have most of the components to build a sprayer, it'll be a quicker/cheaper solution I can have in place for our summer travels. 

Noddaz said:

Questions:

How do you get more airflow through the cooling system? 

Is there a way to add vents/outlets to let heat out of the engine compartment?  Vents in the fenders or hood?

Along the thought line of airflow . . . is there anything that has changed airflow-wise? Something added (transmission cooler, bike rack), or removed that may have changed the airflow ahead of or past the rad?

The part where it doesn't return to normal suggests airflow to me.

spandak said:

In reply to Curtis73 (Forum Supporter) :

To some extent, a very fine spray shouldn't have quite the expansion/contraction issues as a stream of sloppy spray. If you can ramp up the flow rate over the first (guessing) 20-30 seconds you'll probably be okay. 
 

would corrosion be an issue? I know the radiator won't hit boiling temp but it's still hot enough to burn off the water isn't it? As long as you don't shut down immediately I imagine it would be okay for quite a while. 
 

Arm chair quarterback here

Arm chair here as well.

I'm quite certain it will boil.  The whole point of adding glycol and a pressurized cap is because the coolant reaches higher than boiling, so the aluminum in the radiator is probably within a couple degrees of the coolant.

I would imagine using distilled water would help, but all the minerals in tap water might cause galvanic corrosion, or at the very least leave clog-ish deposits over time that would block airflow.  I know if you get an aluminum pan really hot on the stove and put water in it, the pan has pretty permanent staining on it after the water evaporates, and I know that putting that aluminum pan in the dishwasher (which isn't really fair because it has pretty strong detergents) it comes out looking like it's 10 years old.

Pete Gossett (Forum Supporter) said:

In reply to Curtis73 (Forum Supporter) :

I was initially looking into a dual core radiator vs the single core it currently has, but I discovered the transmission line connections are different between the two. So at that point I'm paying someone to do the work, but unfortunately all the local  places & mechanics that work on RVs don't do that type of work. 

Since I already have most of the components to build a sprayer, it'll be a quicker/cheaper solution I can have in place for our summer travels. 

What motor is in it?  One would think it's one of about three different connection types which all have adapters.  I also like Gameboy's idea of adding an aux cooler in the system.  Like scavenge a small radiator from a junkyard Prius and stash it somewhere.  You could run it in series with the heater core.

Could you ratchet-strap a neighborhood kid or Mrs Gosset to the hood with a bucket?  Beep the horn when you need some water poured in the grille?  Now THAT'S grassroots.

I don't see anything wrong with your sprayer idea, I'm just curious if it will kill/clog the radiator in three months or 30 years.

Is it a clutch type fan or electric?

If it's a clutch fan you may be able to adjust when it engages so forced airflow increases before things start to get uncomfortable. 

GRM fan clutch thread

You may need to do some googling, but I would start with trying to get the fan clutch to engage at a lower temp to help with airflow before adding water sprayers. 
 

You want it to boil (vaporize). It's the phase transition that pulls heat out of the heat exchanger. 

I think it's a low effort bandaid that's worth trying. You're not going to need to run it constantly, just under certain high load situations. Long term, it might leave deposits but based on what our hard water leaves on our swamp cooler pads with nearly constant use, I would not be too concerned about the actual amount. Distilled water would help a lot. 

I used to live in a province with a hill that is famous for overheated tow rigs and motorhomes.

Your heat is coming from your transmission. 

The built in cooler in the radiator can only handle so much before it just starts adding heat to the coolant.

Every blown-up dodge at the top of the hill didn't have an extra trans cooler.

I've always added an extra trans cooler to my tow rigs and never had an ounce of trouble with overheating on long climbs.

Replace your fan clutch with a heavy duty unit as well. The original is probably shot by now anyway. If you can't hear the fan roar when the engine heats up, it's time for a new one.

Adding a separate trans cooler is a great idea - it's an engine cooling + trans cooling increase 2-for-1 deal, plus it can open up more radiator upgrade options.

In reply to Pete Gossett (Forum Supporter) :

Grab the windsheild washer bottle from a junkyard Subaru Impreza Wagon. They have two pumps, one for the front and one for the rear. Swap it in for your existing washer fluid reservoir and use the rear washer pump to spray down your cooler.

2002-2007(?) Impreza sedans and wagons use basically the same reservoir. The pumps nest into a molded areas on the side of the tank. The wagons get two pumps but the sedans only get one.