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Sept 28, 2023 18:53:03 GMT
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I have a fiat 850t van with a rear mounted engine and rear mounted rad. The cars can just about cool themselves with the aid of vents mounted above the engine. The van however has no such luxury and most owners report cooling issues of one kind or another ranging from catastrophic boiling over to fuel vapour lock etc
The route cause of most is the inadequate cooling.
Are there any other water cooled rear engined cars that don't have these issues?
I have space to move the rad 90 degreed and even intall a bigger one if necessary.
The only thing I cant do is front mount one.
Any and all creative cooling solutions greatfuly received
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Sept 28, 2023 18:58:11 GMT
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Here you can see just how tight it is. The theory is that the fan pulls air through the side vents into the rad. This is then blown (by the same fan) through a small vent under the van Visible hear on the right. The engine bay is effectively sealed to help this air flow, however once sitting still (like in traffic) or under slow moving heavy load (like going uphill) the heat given off by the engine also has to escape through that little vent. It appears to be a bad idea, poorly executed.
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Sept 28, 2023 19:28:27 GMT
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The only two that spring to mind are the Hillman Imp and Simca 1000, both work the other way round (I think) pulling air from under the car and out through vents. I can't help but think that sealing off the bottom of the engine bay and then drawing cooling air through the engine compartment is a bad idea - can you reverse the flow of air (electric fan?) and take off the plates across the bottom of the engine bay to allow more air ciculation?
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Last Edit: Sept 28, 2023 19:29:18 GMT by cortinaman
Old Fords never die they just go sideways
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Sept 28, 2023 21:00:11 GMT
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I guess anythings possible. I believe the theory is to draw in clean, dry air but it still seems odd.
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Darkspeed
Club Retro Rides Member
Posts: 4,688
Club RR Member Number: 39
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Sept 28, 2023 21:52:11 GMT
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Does it not draw air in from a plenum behind the rad that gets air from beneath the car and then expel it out of the side louvres?
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jimi
Club Retro Rides Member
Posts: 1,816
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Sept 28, 2023 22:00:33 GMT
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The only two that spring to mind are the Hillman Imp and Simca 1000, both work the other way round (I think) pulling air from under the car and out through vents. I can't help but think that sealing off the bottom of the engine bay and then drawing cooling air through the engine compartment is a bad idea - can you reverse the flow of air (electric fan?) and take off the plates across the bottom of the engine bay to allow more air circulation? I'd agree, my MR2 is mid engined (with a front mounted radiator) also has a side vent to the engine bay. The airflow in the engine bay is from underneath up through the engine bay and out through vents in the lid, on the move it's that strong it will lift an unlatched engine bay lid up. When stationary there's an electric fan that draws air in from the side vent across the engine and out of the lid. I have a vague recollection of reading about someone reversing the airflow on and imp to improve cooling (might have been on here) It's all about airflow, the more air you get into and out of the engine bay, the cooler it will run, venting under the car isn't helping I.M.O.
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Black is not a colour ! .... Its the absence of colour
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jimi
Club Retro Rides Member
Posts: 1,816
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Sept 28, 2023 22:17:22 GMT
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Does it not draw air in from a plenum behind the rad that gets air from beneath the car and then expel it out of the side louvres? If it's not then that's the way it should be đź‘Ť (I.M.O.)
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Black is not a colour ! .... Its the absence of colour
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Sept 28, 2023 22:22:12 GMT
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bigger rad with a more efficient fan
when i used to help out grass track racing they used to run export fans on their mini’s that had different blades angled /bigger ? that pushed/sucked more air
or run a modern electric fan with a bigger rad change the air flow as per other posts
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Last Edit: Sept 28, 2023 22:23:56 GMT by redratbike
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Sept 29, 2023 10:27:59 GMT
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Does it not draw air in from a plenum behind the rad that gets air from beneath the car and then expel it out of the side louvres? You'd think that, and like many others so did I. It's been known for people to ditch the undertrays to allow more air in but all it actually does is pump its own hot discharge air back into the already hot engine bay. The radiator is quite small and they're known to clog the fins, both inside and out so I guess the idea of drawing dirty air from underneath seemed counter productive in the design phase. This way of doing it dates back to the fifties and was installed in all manor of rear engined fiats right up to the eighties, but almost all other varients have bonnet louvres or vents to help. There is more space around the radiator than you'd find in a modern front engined car and yet they seem to cool themselves whilst sat still. Could it be as simple as a chronically undersized radiator?
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In engine cooling air flow is king. A mechanical fan generally shifts more air than an electric fan once you are on the move and the engine revs are up. It might be worth calculating your fan speed in relation to engine speed with those pulleys. Adding an electric fan to the other side of the rad will help low speed/idling.
Water flow is next. Is the pump working efficiently, getting the most flow for engine rpm. Darkspeed has done a lot of work on flow from different imp pumps. You might be able to use this information to asses your pump.
The radiator has to be of good design and in good condition. In a modern aluminum rad, it’s not having lots of fins that’s important. If you go too dense the air won’t want to go through it. A rad with less fins per inch (fpi) can often work better. Likewise, if you make the radiator too thick it will hinder airflow and reduce cooling. Once the air going through the radiator has picked up all the heat it can, the rest of the radiator is just reducing airflow. A thin radiator can work better than a thick one.
The fins have little slits or louvres in them the angle of these louvres is really important. A small change can make a big difference on the radiator’s cooling ability. If you buy a new radiator that is a reproduction, the chances are it won’t perform as good as an oem item as these are not developed to the same standards. The manufacturer doesn’t have the vehicle manufacturer scrutinizing everything and setting standards. The same goes for companies making bespoke radiators. They generally use old technology cores. All this isn’t so important when your rad is at the front with all the ram air, but you don’t have this luxury.
So I guess what I’m saying is get the biggest surface area, oem modern radiator you can. Make sure you can get as much air and coolant through it as possible
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Good post jonesy. To add to that modern radiators aluminium radiators use oval tubes. This gives greater surface area for the same cross sectional area. It's getting the heat from the water to the air that's the harder part, surface area matters in this. If the tubes are bigger than standard then you will almost certainly need more flow to prevent laminar flow (laminar flow reduces heat transfer). Don't listen to stories about slowing the flow down to improve cooling, it's bollards.
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Proton Jumbuck-deceased :-( 2005 Kia Sorento the parts hauling heap V8 Humber Hawk 1948 Standard12 pickup SOLD 1953 Pop build (wifey's BIVA build).
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