Rear Mounted rad n other trickery!

[Mudgey]

Originally Posted by freebeard

I see two things:

The piping to carry the coolant is subject to corrosion. Water-cooled vanagons have piping that is suitable.

The low pressure wake may not be as helpful as you might think. VW bus owners argue about this. What's more important is the ducting. Maybe you could replace the rear decklid and wing with something Porsche-like with the radiator mounted at an angle, canted to the front. The inlet and outlet can be as llttle as 1/6th the area of the gross dimensions of the radiator itself.

To answer the question, if the internal drag of a sealed engine compartment plus the ducting and radiator (which has a lot of drag just by itself) in back is less you win. So it sort of depends.

Thanks for your reply, the options are:

1. 32mm Alloy pipe, subject to corrosion like you mentioned but only surface corrosion? Unless salt will eat past the surface? Much much harder to route, if I don't go bent and welded there will be an awful lot of connections that could potentiall leak.
2. AN16 hose & fittings, I am a distributor for a brand of hose fittings so I won't be paying full retail but they are still expensive! This will be far easier to route as I can clip them back and there is only the connections at the front and back to worry about.

I have been thinking about radiator placement and airflow, I don't want to chop anything up incase it doesn't work out then I haven't runied the appearance of my car, I will get a 2nd and bumper n chop that up, if it doesn't work I can put it all back to normal and won't have lost hardly any cash! First off I am going to work on a cold air feed and do an ABA test of my car at 70mph as I won't know if any changes will effect the FE if I don't have a baseline figure.

[freebeard]

I remember the pipes as a talking point when the Vanagon was introduced. I don't know much otherwise, as an air-cooled owner I see water as a corrosive agent that's best kept away from the motor. Look at what it does to the inside of tailpipes.

if it doesn't work I can put it all back to normal

That's why I was thinking of replacing the decklid. Is it a low miles, matching numbers example?

A notchback body supposedly has counter-rotating vortexes coming of the roof that increase the pressure on the decklid. The rear-facing part of the lid is really small, but your exit could be between the taillights plus full width up to the wing.

There is probably a lot of structure behind the bumper, how would the air get to it. I do think it would look good to move the license plate up to between the taillights and have the whole bumper look like a front one. The profiles look similar. When you replace the front bumper with a blank piece, you could cut the center out of the old front and graft it into the rear.

[LeanBurn]

How much difference is a CAI going to make when the supercharger increases temps exponentially? Most effective CAI's I have seen give you just a few degrees (at rest, once you get moving air starts to cool quicker in the engine bay) compared to 50, 100, 150 that compressing air produces...Put in a intercooler for most effective and life extending results.

[wyatt]

My old car didn't have AC, so I was able to block half the grill with no fear of overheating, so that's where I started. At the same time, I ducted the flow from the remaining opening into the radiator, so that the air that was coming in would be forced through the radiator. I also put in a belly pan under the engine bay and one from behind the rear wheels to the rear bumper that acted like a diffuser. The gain from this was ~6% better FE, and a LOT less road noise. Once I was comfortable there, I started blocking off more and more of the grill. In the end, I had just a very small opening for winter, and a slightly larger opening for summer. You can see pictures of my mods HERE.
Since you have eliminated the AC, you may be able to follow a similar course of action.
I also did some more work on it, adding a kammback, I don't expect you to do so, especially if you want to keep your stock look, but you may be interested.

[kach22i]

This is a great website for aerodynamic illustrations.

Vehicle Aerodynamics

Ford’s rear mounted transverse engine

Fans improve aerodynamic properties and reduce drag

[cRiPpLe_rOoStEr]

Originally Posted by Mudgey

So in my mind I am thinking about the following ideas:

1. Run a smaller 3/4 width radiator which is also thinner and tucked further forward so I have more room infront of the engine, run a radiator cowl with a 3" bulkhead hose fitting inthrough the other 1/4 width of where the original rad used to be, on one side of the rad cowl would be the air filter (infront and to the side of the radiator), and on the other side a pipe feeding the TB. In total the pipe would be 0.5m long, if that!

2. Split the radiator in two and mount it at the back, run a closed front grill apart from an opening to promote a small amount of airflow through the engine bay and for an air filter box. I like the idea of removing a lot of heat from the engine bay to keep everything as cool as possible. This might also be the best time to run an electric water pump. So the benefits of all this would be reduced front end lift at speed, reduced drag from the large front rad grill opening. Hot air being released in the low pressure region at the back of the car. And if I went electric water pump then less drag from overspinning the water pump when its not required.

As long as you can have the electric fans to induce the required air flow, a rear-mounted split rad with electric water pump might be the best setup. Just make sure to also keep the exhaust flow away from the rads.

[kach22i]

I should mention that I have seen many an interesting radiator set-up for the cars which participate in the 24 hours of LeMons race.

Gallery and Links

The closest to this thread are the ones using a radiator in a Duck-Tail fashion.

I'm not sure why they do this, perhaps to survive front bumper collisions and still keep their cooling system, or the replacement/recycled radiator would not fit the original location.

[niky]

It's 99.9% for collisions. LeMons is an interesting blend of enduro, sprint and demolition derby. Re-mounting the radiators means you can better survive scrapes with muppets on the track.

[freebeard]

LeMons is an interesting blend of enduro, sprint and demolition derby.

Not to mention art.The only entrants I know run a white Dodge van with a 'Soccer Mom' motif.

kach22i -- That sounds like what I was thinking about. can you suggest a specific example to search for on that page?

[kach22i]

Originally Posted by freebeard

kach22i -- That sounds like what I was thinking about. can you suggest a specific example to search for on that page?

It is a course work (college) website, I did a lot of poking around there - many layers.

Not much on any particular topic other than the terms, language and chapter headings and of course the interesting line drawings.

I did get some great "Google search terms" though.

I bet that "Ford" concept car can be Googled if anyone can ID it for you. Perhaps "Ford Concept Rear Engine" will get you some where. I'd say it's a Ghia not a Probe from the looks of it.