Amphibious HEMTT

[WaterH]

How many inches is it from the radiator face to that wall?

Havnt measured, but it’s at least 5”. I’m not sure if you are trolling here, but you way off. This is a fan shroud from flexilight. I have been running a shroud like this for 30 years on my Bronco. I think it works.

Note that the corner closest to you is 1” off the rad fins. Is it blocking the air flow? Air is fluid. It can turn very easy. Have you opened the hood of a modern car lately? I doubt you could find a car these days that doesn’t have something with in 5” of the entire radiator.

 

[WaterH]

Yesterday was a long day of climbing in an out of the truck. Didn’t seem to get much done. Of course the shop is like an oven. I had quite a bit of sheet metal fabrication that doesn’t look any different. I’m hoping to make this mod reversible in case it were to be worse for temperature. I had to weld to tabs on my old rad mount to move it 2” out. I just grabbed two small pieces of scrap. One of them was a piece of AR500. I had a hell of a time drilling it. I finally figured out a good way of drilling that stuff. You need to have a hose running on it constant for coolant and a cobalt drill.

I modified the old fan shroud and made some new mounts for the tranny cooler.

I had to cut out the corners of the old shroud to fit around the inlet/outlet. I sure hope I don’t have to go back to the previous set up or I will have to make a new shroud. When I first built the truck, I had hardliners going from the tranny to the “in rad” oil cooler. Later, I switched to this aux oil cooler, but I ran rubber lines for testing. I never got around to replacing them with hard lines. Now I decided is the time to do it. I took one of the old lines and straighten it. Then bent it to the new run. Of course this was a total PITA. After I got done, I wasn’t real happy with it. I went to look for the other line when I found I had a whole roll of new stainless line. So now I can make two new lines that look good. That will be today’s project.

 

[ExWrench]

I’m not sure if you are trolling here,

Not in Tech threads. I was just going by the information you had presented, which made it appear you had some ass-headed arrangement in which you had not identified the flaws.

But "thanks" for the education on fluid dynamics, its obviously one of your strong suits

 

[ThePanzerFuhrer]

Havnt measured, but it’s at least 5”. I’m not sure if you are trolling here, but you way off. This is a fan shroud from flexilight. I have been running a shroud like this for 30 years on my Bronco. I think it works.

Note that the corner closest to you is 1” off the rad fins. Is it blocking the air flow? Air is fluid. It can turn very easy. Have you opened the hood of a modern car lately? I doubt you could find a car these days that doesn’t have something with in 5” of the entire radiator.

We are talking the side opposite the fan it looks to be a solid plate. Even with all the shit packed into a modern car it has the cars motion forcing the air through the engine bay. They are designed to let enough air move through the tangled mess of shit to cool it off properly. You have non of that. You have a solid plate covering your radiator and trying to move enough air with an electric fan. It looks like the air must have to go up or down to get to it.

I might be wrong but that’s what it looks like.
It’s hard to tell from the pictures.

 

[bad zuki]

Havnt measured, but it’s at least 5”. I’m not sure if you are trolling here, but you way off. This is a fan shroud from flexilight. I have been running a shroud like this for 30 years on my Bronco. I think it works.

I think the radiator and fans are cooling as hard as they can, but the hot air isn't going out the side vents. I see you have a duct going into the engine bay, I'd throw some temporary fans to pull air out. Kinda like the Marauder did.

 

[ThePanzerFuhrer]

I think the radiator and fans are cooling as hard as they can, but the hot air isn't going out the side vents. I see you have a duct going into the engine bay, I'd throw some temporary fans to pull air out. Kinda like the Marauder did.

Or an even a scoop from the bottom of the vehicle to clear out the warm air.

 

[WaterH]

I might be wrong but that’s what it looks like.
It’s hard to tell from the pictures.

I agree, it’s hard to see from pics. I assure you, it’s not tight. Here’s another angle. You can see the bed corner is not a big percentage of the rad area.

All the shit you see under the bed is further away.

Or an even a scoop from the bottom of the vehicle to clear out the warm air.

I would think all the turbulence created by the diffs would clear out warm air, but a scoop has been considered. One test at a time.

 

[WaterH]

I think the radiator and fans are cooling as hard as they can, but the hot air isn't going out the side vents. I see you have a duct going into the engine bay, I'd throw some temporary fans to pull air out. Kinda like the Marauder did.

That duct feeds cool air to the intercooler. Once I start blowing hot air in, instead of out, I may have to insulate that. I am worried that the bed corner may get hot running dow the highway. I suppose it won’t be a good place to put a beer cooler.

 

[ThePanzerFuhrer]

Yeah your pictures mean nothing to me. Have no idea what I’m looking at. Need to get one further back.

 

[WaterH]

Yeah your pictures mean nothing to me. Have no idea what I’m looking at. Need to get one further back.

Here you go.

The reason I took this pic is you can see I raised the “cap” to access the rad. I was thinking I might make a new cap this height. It’s amazing how much that few inches makes in getting around in there. If I could “ramp up” the front to the height of the roll bar, it might not look bad.

 

[ExWrench]

Theory

I have mentioned before that my fans maybe be fighting the aero dynamics of the truck because they take air from under the truck and blow it out the side. Possibly at high speed, that air hits an aerodynamic brick wall. This theory is bolstered by my AC condenser on the other side of the truck. That fan pulls from outside and blows under the truck. The AC works great. In fact, I don’t even have both fans hooked up right now because it gets so cold.

Solid theory, and hopefully this crude photo markup helps illustrate it:

At higher speeds, that outer vent set is in a dead zone (blue lines) behind the tire + the flat "wall" of the front fender running blocker, and all that air stacked up on that wall (red squiggles) and held in by the fender lip could be creating a higher-pressure zone right below the rad. area. The rear tire also poses a substantial wall that air could be stacking up against. Just my amateur airflow visualization based on 1 photo, but it supports your results on the other side where flowing out those side vents seems to be more successful.

Taping a few scraps of ribbon to a few surfaces & taking it for a high-speed rip would answer a lot of questions practically rather than theoretically.

EDIT: based on your side-shot in your last post above, that side vent could be a substantial low-pressure area because of all the air displaced by the front fender + tire moving fast across that area because Bernoulli.

 

[WaterH]

Taping a few scraps of ribbon to a few surfaces & taking it for a high-speed rip would answer a lot of questions practically rather than theoretically.

I have played with yarn taped on the side of helicopters before. It was not very enlightening. I think on a model in a wind tunnel it works great. But, It’s very difficult in the real world.

I do feel the AC condenser performance is the best indicator. If this doesn’t work better, I won’t be up set. If it works worse, I will be. lol.

 

[bad zuki]

All the shit you see under the bed is further away.

Yes, but if it produces heat with no air flow, It's not helping at all. I still think It's an airflow problem. I just did some research on the actual HEMTT. They have an absolutely massive radiator mounted behind the cab with sheet metal ducting acting as a funnel.
The easy way to test the airflow theory would be to space the lower panel (pictured) out into the good airflow. That would probably bring in enough air to help without having to change much. Or put some puller fans at the top of the engine bay slats and start pulling air out.

I would think all the turbulence created by the diffs would clear out warm air, but a scoop has been considered. One test at a time.

I don't think that it's pulling any clean air from the underside at all. Do you still have those ballast tanks under there? Those would restrict a lot of airflow, even with the rear propeller.

 

[ThePanzerFuhrer]

Looks like that is not a very favorable spot for a radiator. Needs way more airflow and or may need to get larger by 30%. If you were in the north half the country you probably could get away with that. In Florida heat you are pushing it .

IMO that isn’t enough fan for that location. My stationary gensets which this would be a close comparison of have huge fans on them because they don’t get the traveling down the road help like most vehicles do. I’m talking 10-30hp worth of blades moving air on them.

Your rig needs to be cooled by 100% by the electric fan. It gets zero help from moving down the road.

Where does a military hmmtt have its radiator?

 

[bad zuki]

This is not enough clearance for a radiator, unless it's ducted.

 

[ThePanzerFuhrer]

This is not enough clearance for a radiator, unless it's ducted.

That’s what I think also. I toss a sheet of steel 6” off a genset radiator of mine like this and even with its huge ass fan it would start to overheat. Thats a tight spot. Bigger fan, larger radiator, or ducting or a combination of the above will be his solution.

 

[gt1guy]

I have played with yarn taped on the side of helicopters before. It was not very enlightening. I think on a model in a wind tunnel it works great. But, It’s very difficult in the real world.

I do feel the AC condenser performance is the best indicator. If this doesn’t work better, I won’t be up set. If it works worse, I will be. lol.

Yarn test around the side vents should give you the information you're looking for. 3" pieces of yarn all around the side vents and a GoPro watching while you take it for a spin. If the yarn sticks straight up.....ya got air coming out the vents, if it all gets sucked into the vents....ya got airflow coming in the vents. That should be all you need to know to determine which way you want the airflow going through the rad.

 

[Java230]

Your good with sheet metal, make a quick crude scoop like this and see what it does?

 

[chaplinfj60]

and since we are doing some cool aero tech, the back side of the fender could also be angled back to allow less turbulence of air going to the duct. or even with the duct and the front of the fender could have a angle on it to allow air a easy path around fender besides hitting a flat wall. very interesting for sure. dont give up. this is a really a neat challenge to solve.

 

[WaterH]

You guys need to remember, this truck has never boiled over in 30K miles. So I don’t need giant gains here. If it never gets any better, I can live with it. There definitely is not going to be any changes to the outside body work or the bed. I could put some holes in the engine cover at the front of the bed to let heat out, but that would cook anything I have in the bed. Might be a problem.

I don’t mind the suggestions, but one thing at a time. This motor is known to be cold blooded. There are factory installations that have no fan at all. They only rely on forward motion to cool. The rad I’m using is twice the size of what they use in the bread trucks this engine came in. This is the reason I tried the “inside to outside” direction in the first place. I figured I would be pulling heat out from behind the engine.

Im curious, does anybody think reversing the airflow will completely cure water temp issues? I’m not saying it will, but I have high hopes. My thinking is the air temp behind the engine is probably 10 degrees or more higher than ambient. On a 95 degree day, that could be a big difference.

 

[WaterH]

Yarn test around the side vents should give you the information you're looking for. 3" pieces of yarn all around the side vents and a GoPro watching while you take it for a spin. If the yarn sticks straight up.....ya got air coming out the vents, if it all gets sucked into the vents....ya got airflow coming in the vents. That should be all you need to know to determine which way you want the airflow going through the rad.

I should have done that with the fans unhooked. That would tell which way it “wants” to go.

Your good with sheet metal, make a quick crude scoop like this and see what it does?

I’m sure this would work after I reverse the flow. But I’m not going to do this because of aesthetics. So there’s not much sense in spending the time.

 

[gt1guy]

Im curious, does anybody think reversing the airflow will completely cure water temp issues? I’m not saying it will, but I have high hopes. My thinking is the air temp behind the engine is probably 10 degrees or more higher than ambient. On a 95 degree day, that could be a big difference.

From what you've described, I'd say it will help. Completely cure, who knows, all depends on the amount of airflow change there is through the radiator.

If you're getting less airflow through the rad the faster you go, it really sounds like you're trying to move the air in the wrong direction.

I should have done that with the fans unhooked. That would tell which way it “wants” to go.

Absolutely.

 

[Dethmachinefab]

I had to duct the buggy rad because it got no airflow at speed even with a good shroud and high performance fan. Just was a dead spot working against the fan there. Fan is below pulling air down here.

I think a duct from somewhere and venting out the side is the best bet. Do the coach buses with the side mounted rad have any ducting?

 

[elbekko]

Solid theory, and hopefully this crude photo markup helps illustrate it:

Agreed with that. An easy gain for the turbulence and wall off air coming off the front wheel and fender could be to slot the top/back of the fender, like many modern cars have.
Potentially even straight from the fenderwell into the radiator, but with a very fine mesh screen so stones don't destroy it.

 

[Bebop]

We are talking the side opposite the fan it looks to be a solid plate. Even with all the shit packed into a modern car it has the cars motion forcing the air through the engine bay. They are designed to let enough air move through the tangled mess of shit to cool it off properly. You have non of that. You have a solid plate covering your radiator and trying to move enough air with an electric fan. It looks like the air must have to go up or down to get to it.

I might be wrong but that’s what it looks like.
It’s hard to tell from the pictures.

I'm just out of a 45mn meeting on the aerodynamics of the relocation of a PS cooler by 3 inches.

We don't wing it and hope for the best because the air is a fluid that can turn easy...

 

[WaterH]

I'm just out of a 45mn meeting on the aerodynamics of the relocation of a PS cooler by 3 inches.

We don't wing it and hope for the best because the air is a fluid that can turn easy...

I’ve worked with lots of engineers in the helicopter field. The thing I learned from them is you “math it” out all you want, but testing is the final authority. The FAA loved tons of paperwork, but it wouldn’t approve something until you tested it for X amount of hours.

In the case of aviation, testing is far more expensive than paying some engineer. So they have a tendency to over think everything. In this case, it just cost my time and small money. It’s also kind of fun.

 

[Bebop]

I’ve worked with lots of engineers in the helicopter field. The thing I learned from them is you “math it” out all you want, but testing is the final authority.

100% true and I wouldn't argue otherwise.
The thing is, over the course of years and experience, we are able to model a lot of the behaviors of known factors and do computer testing vs actual testing. We would never build a prototype dedicated to airflow testing for a radiator when CFD testing is providing a statistically relevant answer for a much lower cost and timeline.

The FAA loved tons of paperwork, but it wouldn’t approve something until you tested it for X amount of hours.

In the case of aviation, testing is far more expensive than paying some engineer. So they have a tendency to over think everything. In this case, it just cost my time and small money. It’s also kind of fun.

Yup. Apples to orange. And I think that you're going in the right direction with the approach you're taking in solving your issue. Fresh air in vs trying to push the hot air out. Curious to see how it turns out.

I wouldn't be too concerned about the lack of airflow, but it's very dependent on fan performance. That's another topic.

 

[arse_sidewards]

We don't wing it because between the cost of tooling to make millions of these things, paying off regulators, paying lobbyists, UAW fuckery and all the other overhead the margins are real thin and we make money on volume so we kinda gotta get it right the first time if we want to make a buck.

Fixed.

You're making the same mistake(s) every twat who foams at the mouth over inconsequential "factory performance parts" makes. Only worse because you should know better.


Floridaman is likely better served by just re-working it until it does what he wants.

Edit: Floridaman beat me to it.

 

[Bebop]

You're making the same mistake(s) every twat who foams at the mouth over inconsequential "factory performance parts" makes. Only worse because you should know better.

Please explain, cause I don't know any better

 

[SLOWPOKE693]

Please explain, cause I don't know any better

This should be a good one.....