Speed UTV - discussion

[RiverDave]

I would definitely try reversing the fans before I got all crazy and shit.

The hot air coming through it right now into the cabin at speed (with a windshield on) is insane.. You want to actually wire the fans to blow it in there?

RD

 

[dirtslinger2]

The hot air coming through it right now into the cabin at speed (with a windshield on) is insane.. You want to actually wire the fans to blow it in there?

RD

I'm hoping you try the jerry rigged plexiglass rear window soon, and see what happens.

 

[LargeOrangeFont]

I'm hoping you try the jerry rigged plexiglass rear window soon, and see what happens.

Will be really interesting to see if that helps or even fixes the radiator airflow issue.

 

[dirtslinger2]

Will be really interesting to see if that helps or even fixes the radiator airflow issue.

A guy in Utah, Vent racing, did it, but he never posted anything after that, I PM'd him on FB, but he hasn't even read it yet.

 

[LargeOrangeFont]

A guy in Utah, Vent racing, did it, but he never posted anything after that, I PM'd him on FB, but he hasn't even read it yet.

I’ve been really thinking for awhile I want a rear window on this car because of the hot air wash from the radiator will be pulled into the car.

I was planning to talk to @dspracing to get something put together almost immediately. He is right down the street from RD.

Alternatively Dirt Warriors is near me, they do windshields, rear windows and full enclosed cabins.

A window above the radiator outlet should help make more of a vacuum to hopefully draw air through the radiator.

 

[Bigbore500r]

Somewhere as we speak - there's a redneck with some random electric fan just itchin to zip-tie it to the other side of the radiator and hotwire it direct to the battery without a fuse

 

[LargeOrangeFont]

Somewhere as we speak - there's a redneck with some random electric fan just itchin to zip-tie it to the other side of the radiator and hotwire it direct to the battery without a fuse

The fan direction isnt the problem. The cars are not overheating while idling

 

[Bigbore500r]

The fan direction isnt the problem. The cars are not overheating while idling

That ain't never stopped no redneck with an extra fan layin around

 

[rivermobster]

Somewhere as we speak - there's a redneck with some random electric fan just itchin to zip-tie it to the other side of the radiator and hotwire it direct to the battery without a fuse

I'm wondering how much air those fans even move! They look Awful damm small. Do they even have a part number and brand on them?

 

[Bigbore500r]

I'm wondering how much air those fans even move! They look Awful damm small. Do they even have a part number and brand on them?

All the cars have the same fans, and the ones without a windshield don't get hot.

 

[LargeOrangeFont]

That ain't never stopped no redneck with an extra fan layin around

It did when they stick their fingers in the fan .

 

[rivermobster]

All the cars have the same fans, and the ones without a windshield don't get hot.

So maybe they are just strong enough to move air easily, but not strong enough to move air when the Really need to?

Just like with the brakes...

So many possible issues in play.

 

[LargeOrangeFont]

So maybe they are just strong enough to move air easily, but not strong enough to move air when the Really need to?

Just like with the brakes...

So many possible issues in play.

Fans are useless when the car is in motion. This is a 100% airflow and management issue at speed with the windshield.

 

[hallett21]

Fans are useless when the car is in motion. This is a 100% airflow and management issue at speed with the windshield.

This part has me scratching my head.

No windshield, the wind comes through the cab and passes the passengers and through the radiator right?

With a windshield I understand there’s no airflow in the cab but shouldn’t those fans draw cabin air through the radiator?

The cab can’t be under a vacuum otherwise you couldn’t breath lol.

Otherwise are the fans just to cool the radiator at idle?

 

[LargeOrangeFont]

This part has me scratching my head.

No windshield, the wind comes through the cab and passes the passengers and through the radiator right?

With a windshield I understand there’s no airflow in the cab but shouldn’t those fans draw cabin air through the radiator?

The cab can’t be under a vacuum otherwise you couldn’t breath lol.

Otherwise are the fans just to cool the radiator at idle?

Correct.

There is just some dead spot at the radiator air intake (behind rear seats) with the windshield installed that is altering the pressure and not letting enough air pass through at speed.

Since the thing works perfectly without the windshield, the challenge is to move that low pressure zone behind the windshield rearward so it works for us, not against us.

A rear windshield will move that low pressure area from the cabin area into the bed area and that *should* redirect air through the radiator. Is it enough? I have no idea, but I do know that I don't want the hot air wash from the radiator being sucked back into the cabin while I drive. Nor do I want to make the puller fans pushers and pump that hot air into the cabin. Maybe in the winter my kids will like it, but in the fall and spring they will sweat their asses off lol.

So I am running a rear windshield on this thing almost for sure.

 

[hallett21]

here ya go lol

 

[Socalx09]

I don’t have much knowledge here. I just know we had this issue with the YXZ after a windshield was added. It would overheat quickly. We checked if the fans were reversed, which I guess is a common Yxz problem. YXZ OEM windshields were also causing the car to overheat, so it wasn’t just a bad aftermarket design. We tried a scoop, and it didn’t work. We now have the fans turn on sooner than the factory settings. One day Robert took off the cover and ran it. It worked. He had a custom cover made with holes. I doubt this will help, since I know you guys are way more savvy then I am about these issues, but it’s not the only sxs that doesn’t run well with a windshield when it’s hot outside. We still have the bigger fans we were going to install, but haven’t needed to do that yet since it hasn’t overheated with the new cover

 

[LargeOrangeFont]

I don’t have much knowledge here. I just know we had this issue with the YXZ after a windshield was added. It would overheat quickly. We checked if the fans were reversed, which I guess is a common Yxz problem. YXZ OEM windshields were also causing the car to overheat, so it wasn’t just a bad aftermarket design. We tried a scoop, and it didn’t work. We now have the fans turn on sooner than the factory settings. One day Robert took off the cover and ran it. It worked. He had a custom cover made with holes. I doubt this will help, since I know you guys are way more savvy then I am about these issues, but it’s not the only sxs that doesn’t run well with a windshield when it’s hot outside. We still have the bigger fans we were going to install, but haven’t needed to do that yet since it hasn’t overheated with the new cover View attachment 1282591

Something simple like that will end up being the fix.

 

[SKIDMARC]

Ghetto as heck, but what if you go buy a 90 degree piece of 2” pvc electrical conduit. Zip tie it where I circled. Maybe one on each side.

If it works at least you know how much air you need.

View attachment 1282589

I wonder if that black plastic part at the bottom of the windshield can be removed or modified to allow air to pass through? Or maybe speed just needs to make a half windshield, that would work.

 

[LargeOrangeFont]

I wonder if that black plastic part at the bottom of the windshield can be removed or modified to allow air to pass through? Or maybe speed just needs to make a half windshield, that would work.

Half windshields suck. Removing the bottom may help, but probably not enough. It provides some airflow so you aren’t baking behind the windshield though.

 

[Taboma]

Correct.

There is just some dead spot at the radiator air intake (behind rear seats) with the windshield installed that is altering the pressure and not letting enough air pass through at speed.

Since the thing works perfectly without the windshield, the challenge is to move that low pressure zone behind the windshield rearward so it works for us, not against us.

A rear windshield will move that low pressure area from the cabin area into the bed area and that *should* redirect air through the radiator. Is it enough? I have no idea, but I do know that I don't want the hot air wash from the radiator being sucked back into the cabin while I drive. Nor do I want to make the puller fans pushers and pump that hot air into the cabin. Maybe in the winter my kids will like it, but in the fall and spring they will sweat their asses off lol.

So I am running a rear windshield on this thing almost for sure.

From my experience, the area behind the rear window on a truck seems to be a negative pressure area, or dead air space, unless you open the rear sliding window and the air blows back into the cab from the rear. Is this what you're striving to achieve ?

 

[SKIDMARC]

Half windshields suck. Removing the bottom may help, but probably not enough. It provides some airflow so you aren’t baking behind the windshield though.

I like my half windshield, it blocks enough cold air in the winter and is tall enough to deflect the rocks. I've never been a fan of the full ones, they always get dirty and hard to see out of. But just personal preferences.

 

[LargeOrangeFont]

From my experience, the area behind the rear window on a truck seems to be a negative pressure area, or dead air space, unless you open the rear sliding window and the air blows back into the cab from the rear. Is this what you're striving to achieve ?

The window open on the back of the truck is what we are dealing with in a UTV with a windshield only.

That is the problem all the air is sucked back into the cabin.

Same truck, close the back window and open the side windows, you get a bunch of air in the cabin and no air being drawn back in. That air will get pulled through the radiator in a Speed car instead of swirling around in the cab..

 

[LargeOrangeFont]

I like my half windshield, it blocks enough cold air in the winter and is tall enough to deflect the rocks. I've never been a fan of the full ones, they always get dirty and hard to see out of. But just personal preferences.

A DOT glass windshield is nice. All the plastic ones are miserable and attract dust like crazy.

But yes it just depends on what you like. We go on long rides and the wind sucks over hours and days.

 

[Outdrive1]

Plastic windshields are horrible, they attract dust and if you clean them they scratch.

 

[Taboma]

The window open on the back of the truck is what we are dealing with in a UTV with a windshield only.

That is the problem all the air is sucked back into the cabin.

Same truck, close the back window and open the side windows, you get a bunch of air in the cabin and no air being drawn back in. That air will get pulled through the radiator in a Speed car instead of swirling around in the cab..

I just recall that with that rear window slider closed, leaves will swirl vertically in a vortex and end up at the front of the bed, won't blow out.
Not knowing the precise positioning of the Speed radiator and intake, that may be what you're trying to achieve ?

We've had windshields in all our various SXS, had to use a rear window in order to keep from becoming a cabin full of silt. Now with the half windshield and just a netting across the rear, problem solved, yet the air flow is directed primarily up and over our heads and I can see driving into the sun in the late afternoon, which many times prior I couldn't.
Given, we don't ride in caravans you do, so we're not getting dusted from in front of us.

 

[LargeOrangeFont]

I just recall that with that rear window slider closed, leaves will swirl vertically in a vortex and end up at the front of the bed, won't blow out.
Not knowing the precise positioning of the Speed radiator and intake, that may be what you're trying to achieve ?

We've had windshields in all our various SXS, had to use a rear window in order to keep from becoming a cabin full of silt. Now with the half windshield and just a netting across the rear, problem solved, yet the air flow is directed primarily up and over our heads and I can see driving into the sun in the late afternoon, which many times prior I couldn't.
Given, we don't ride in caravans you do, so we're not getting dusted from in front of us.

Keep in mind the bed in the truck is solid. There is a pass through to that bed area via the radiator in the Speed, and the beds themselves are mostly full.

We are trying to get the air coming down off the roof of the car to pull the air through the radiator as it passes over the bed.

With some simple experiments we can figure out if this works or not.

 

[LargeOrangeFont]

I had my rear slider open on my standard cab truck cruising down the freeway and spit a lugie out the window and it came back in the back window and hit me in the side of the face, scared the shit out of me then I had to pull over so I wouldn't crash because I was laughing so hard

Exactly..

 

[grumpy88]

Half windshields suck. Removing the bottom may help, but probably not enough. It provides some airflow so you aren’t baking behind the windshield though.

I disagree . My half windshield puts the air right over my head and keeps the dirt blown out of the car . Also my sxs does not overheat even with a rear mounted radiator .

 

[Taboma]

Keep in mind the bed in the truck is solid. There is a pass through to that bed area via the radiator in the Speed, and the beds themselves are mostly full.

We are trying to get the air coming down off the roof of the car to pull the air through the radiator as it passes over the bed.

With some simple experiments we can figure out if this works or not.

So the heated air exits out the bottom of the radiator and flows under the truck ?
Interesting discussion, zero experience with a radiator behind the cab.

 

[LargeOrangeFont]

So the heated air exits out the bottom of the radiator and flows under the truck ?
Interesting discussion, zero experience with a radiator behind the cab.

Air enters the rear firewall area of the vehicle and exits above the bed.

 

[DLow]

This isn’t a knock on the car, but that’s the worst place these cars can have the radiator, and the current angle puts it parallel to any airflow over the top of the car instead of perpendicular. I see two additional options that haven’t been discussed… fans on other side in addition to stock to push and pull air, which would put a huge load on the charging system, or running a small additional radiator at the front of the car as a kicker. It seems they are close on cooling now, and it may be just enough to keep it cool with the windshield in place.

 

[riverroyal]

I like my half windshield, it blocks enough cold air in the winter and is tall enough to deflect the rocks. I've never been a fan of the full ones, they always get dirty and hard to see out of. But just personal preferences.

I'm a big fan of my half lexan. No issues

 

[Terminal Velocity]

what about a Gurney flap on the back lip(spoiler). Or make that spoiler an air foil style to smooth the air over the top of the car which might accelerate the air and move the negative pressure more towards the tail gate?

My thought is that with what has been mentioned almost no airflow in the cabin, the air over the top is essentially turning down as there is no air on the bottom to reconnect to. (my explanation is probably gibberish, but it seems good in my mind)

 

[Racer56]

With Robby's extensive background in racing and the fact the car was designed in the heart of Nascar country, you would have thought they would of spent some time in the wind tunnel.

I ordered a windshield on my car (#792) and if someone else hasn't fixed the overheating issue by the time I get my car in December I'm going to fix it myself.

 

[hallett21]

Another dumb question.

Porsche has rear end motors. When the wing comes up on the freeway is that ramming air into their radiator?

Maybe a little too complicated for a fix.

Or does the shape of the car naturally ram air into the radiator?

Talking new cars not 60s air cooled ones.

 

[hallett21]

There is a negative pressure zone in the cabin.. it would take a lot to not be able to breathe.. lol

Any idea on what the CFMs are on these fans?

I have no idea how you calculate that while moving at 50+ mph. I’m used to fixed buildings lol.

Just seems like 3 fans at full throttle could/should draw enough air.

Which circles back to my confusion. What the hell is the point of fans in general if the radiator always needs “ram air”? Everyone seems to suggest either opening the windshield or raising the radiators. Either option increases “ram air” so it seems like the fans are only good for idling? Or low RPM running?

I’m very curious and interested is how you fix this. Yarn on the car seems like a good first step.

 

[Racer56]

Any idea on what the CFMs are on these fans?

I have no idea how you calculate that while moving at 50+ mph. I’m used to fixed buildings lol.

Just seems like 3 fans at full throttle could/should draw enough air.

Which circles back to my confusion. What the hell is the point of fans in general if the radiator always needs “ram air”? Everyone seems to suggest either opening the windshield or raising the radiators. Either option increases “ram air” so it seems like the fans are only good for idling? Or low RPM running?

I’m very curious and interested is how you fix this. Yarn on the car seems like a good first step.

The windshield is causing a negative pressure zone in the cab keeping the fans from pulling the required amount of air thru the radiator.

 

[Terminal Velocity]

I have another thought of how to possibly introduce air off the windshield to the existing air scoop on the roof, but I’m not at my computer and my typing skills aren’t good enough to explain LOL.

 

[Bpracing1127]

The windshield is causing a negative pressure zone in the cab keeping the fans from pulling the required amount of air thru the radiator.

Yep, if the pressure was null, the fans should be able to move the required amount of air through the system to keep cool at any speed

But because the pressure is negative. You are trying to convert the negative pressure to positive pressure and the fans are not big enough to overcome that difference.

No one has said it but for the windshield, the cooling system is too small. Not big enough radiator nor fans. Without a windshield it’s just fine.

So you have two options, redo the cooling system to put bigger fans (cfm) and radiator (maybe try 1 at a time will work)

Or eliminate the negative pressure from the windshield. That’s what RD is trying to do.

If it were me, maybe put ducts in the triangle of the a/b pillar. Like a nascar. Force the air in the cab. That with the roof vent might actually work.

Something like these

 

[Racer56]

Yep, if the pressure was null, the fans should be able to move the required amount of air through the system to keep cool at any speed

But because the pressure is negative. You are trying to convert the negative pressure to positive pressure and the fans are not big enough to overcome that difference.

No one has said it but for the windshield, the cooling system is too small. Not big enough radiator nor fans. Without a windshield it’s just fine.

So you have two options, redo the cooling system to put bigger fans (cfm) and radiator (maybe try 1 at a time will work)

Or eliminate the negative pressure from the windshield. That’s what RD is trying to do.

If it were me, maybe put ducts in the triangle of the a/b pillar. Like a nascar. Force the air in the cab. That with the roof vent might actually work.

Something like these View attachment 1282654

I agree . I think the car needs a little bit bigger dual pass radiator and bigger fans. Small single pass radiators never seem to get the job done unless you are running alcohol.

I think the car needs some vents around the windshield, a Gurney flap at the back of the roof and a real radiator.

 

[LargeOrangeFont]

Another dumb question.

Porsche has rear end motors. When the wing comes up on the freeway is that ramming air into their radiator?

Maybe a little too complicated for a fix.

Or does the shape of the car naturally ram air into the radiator?

Talking new cars not 60s air cooled ones.

Another dumb question.

Porsche has rear end motors. When the wing comes up on the freeway is that ramming air into their radiator?

Maybe a little too complicated for a fix.

Or does the shape of the car naturally ram air into the radiator?

Talking new cars not 60s air cooled ones.

The water cooled rear engine Porsches have radiators in the front of the car.

 

[hallett21]

The water cooled rear engine Porsches have radiators in the front of the car.

Well shit lol

 

[Terminal Velocity]

Not sure this sketch will translate well. But if there was a formed piece incorporated into the light bar, that directed the air more to to the shape of the roof and towards the existing air scoop, would it introduce air into the cab, and therefore create airflow and negate the negative pressure at the back and help exhaust the stagnant dirty air in The cockpit Then again it might force dust in from the front but hopefully the airflow would help and be a less static dust cloud.

 

[LargeOrangeFont]

Yep, if the pressure was null, the fans should be able to move the required amount of air through the system to keep cool at any speed

But because the pressure is negative. You are trying to convert the negative pressure to positive pressure and the fans are not big enough to overcome that difference.

No one has said it but for the windshield, the cooling system is too small. Not big enough radiator nor fans. Without a windshield it’s just fine.

So you have two options, redo the cooling system to put bigger fans (cfm) and radiator (maybe try 1 at a time will work)

Or eliminate the negative pressure from the windshield. That’s what RD is trying to do.

If it were me, maybe put ducts in the triangle of the a/b pillar. Like a nascar. Force the air in the cab. That with the roof vent might actually work.

Something like these View attachment 1282654

Fans are not even needed when the car is moving at speed. If they are turning when the car is at speed they are a restriction.

The cooling system is sized appropriately, because it seems to be fine when there is no windshield. If you put in a thicker radiator core, you need air to cool it.

You can’t fix an airflow problem with a bigger radiator. And you can’t fix insufficient cooling capacity with airflow.

If I tape off the front grill of my car, and it overheats… I can’t fix that with a bigger radiator.

This isn’t a lack of air problem. If it was you’d suffocate in the car. This is a pressure differential and air management problem. It is an air through the radiator problem. Directing air into the front of the cabin is not going to do it unless you get enough in to negate the negative pressure behind the windshield.

If you were gonna use NACA ducts, you’d want them plumbed to a shroud on the front of the radiator. You’d want the radiator completely sealed so the air was forced through the radiator.

I’d love to see what happens with a rear window forcing air over the car and drawing air out of the cabin area.

That’s where some flaps on the roof might make a difference.

 

[Raffit78]

mesh rear window can be an easy test?

 

[LargeOrangeFont]

mesh rear window can be an easy test?

Some thick corrugated cardboard would do it.

 

[Terminal Velocity]

Spitballing here. What if the roof scoop was inverted. The “intake” on top was inside the cab underneath and the roof shape created a Naca duct to “suck” the air out of the cockpit. I’m not sure with the windshield, it’s not just sending the air to high. But something that came to mind.
I’m just a lowly civil engineer, I make sure poop flows downhill and water doesn’t go uphill

Edit to add: I don’t know about any of you, but sometimes I find a solution to a problem, but it causes an unknown problem elsewhere. Then I chase that problem not knowing my other solution is what caused the new problem for a while. Only until I realize that, I can go try and rectify the original problem without causing the new problem, and the rabbit hole begins again LOL.

 

[whiteworks]

Wire the fans up 24V, should double your air flow

 

[hallett21]

Wire the fans up 24V, should double your air flow

At least once