As ambient temperatures rise as we move closer to summer, I've had to open up more area on my grill block to increase the air flow to keep the engine temps from rising above normal. At 85F while travelling at 65MPH on rolling terrain, I need a total grill opening of 4" X 3" to keep my engine at a normal temp. I figure that by late June I should have a good idea exactly how much grill area I need to operate normally under the hottest conditions I can get around here. But the main problem from the standpoint of drag reduction is that for most of the time I am driving, I don't need that maximal grill area and that extra grill area is just unnecessary MPG-wasting drag. I could go and tape over this unneeded grill area in the winter or when night driving, but this is a fairly cumbersome and crude method for adjusting the radiator's intake/drag to the current engine cooling requirements.

But we can steal another idea from the aircraft industry to solve this problem. Designers of piston powered aircraft have long known that increased cooling equals increased drag and install cowl flaps (for air cooled engines) or radiator doors (for liquid cooled engines), so the pilot can reduce cooling-related drag to the minimum level needed to maintain proper engine temperature. So once I know how large a grill opening that I need, I plan to design a replacement grill block for my car with a cable-actuated radiator door built into it so I can adjust the grill air intake from my seat while driving. Of course, the ultimate version of this would be an electronic controller that monitors the engine temps and automatically adjusts the grill air intake to keep it from rising above normal.

__________________
]
aerocivic.com

How about another hood release cable or something like that, pulls it back but it's on a spring so it can snap back shut!

I plan on completely blocking off the front and mounting some aftermarket radiator somewhere else. I've considered a water/water heat exchanger and a water/oil heat exchanger, both plummed to a smaller radiator mounted in the rear somewhere.

__________________
Anger is a gift!

- Zack de la Rocha

Ohh I should mention, the reasons I plan to do this are:

1. Aerodynamics

2. Thermal Efficiency - No reason to have a cooling system that could handle 300hp when I'm only making 92. Less water to haul around and to heat up means less time spent warming up and a lower curb weight.

__________________
Anger is a gift!

- Zack de la Rocha

Just curious Bunger. What are the stock 88-91 Civic radiators rated for? They're pretty freaking big, and I'm wondering if I just should find a smaller one to clear up some space.

Makes me wish I would have gotten that radiator out of the 93 civic I saw months ago in the junkyard.

I'm not sure what they are rated for, but I had a HUGE FMIC infront of my stock Si radiator on my turbo setup, and it was able to cool about 400HP without issue. I was running water wetter, stock cap and stock thermostat. I didn't run it hard in the summer though, so I'm not 100% sure if it would have held up under 105 degree ambeint temps.

Those 1/2 size radiators out of the EG civics are a good deal lighter, but also taller, so don't plan on just tossing it in there. Considering a single core one of those is able to cool 250HP (in my experience)... imagine how small of a dual core unit you could run only cooling 100HP!!!

Another thing we should consider is really how often are we asking 100% out of our motors??? When you aren't burning much fuel, you're not producing too much heat. You really put your cooling system to the test at road race events, which is where I can back up my claims as to what radiators are good for what HP.

__________________
Anger is a gift!

- Zack de la Rocha

Maybe I should look for a radiator out of a Metro or something like that. These huge radiators not only take up a lot of space, but they are a LOT heavier (as you mentioned).

Radiators are only $10 at my junkyard, so hopefully I'll get lucky soon.

I've been looking for 500cc (or around there) motorcycle radiators. I just can't decide if I'm going to do my accusump/remote oil filer/oil-water heat exchanger/water-coolant heat exchanger idea or not. It would be nice to pre-oil the engine. I've even considered cooling the engine through the heater lines, just need to figure out if that will have a negative effect on coolant flow overall and how to engineer a thermostat of sorts.

I just like to complicate things =)

__________________
Anger is a gift!

- Zack de la Rocha

maybe you already have a thread about this...
but size and shape of the radiator hole i would think would make a difference...
as in tall & skinny only cooling a few runners
and wide/narrow cooling a little of them all

__________________
BE ZEITGEISTED

My grille block opening is at least 6" from the radiator surface. The opening is meant to allow air flow. The air can flow to a much larger area of the radiator compared to the area of the opening. If the grille block was laid against the radiator, then your statement would be more accurate.

__________________

If you are planning to replace your stock radiator with a smaller sized aftermarket radiator, one way you could shrink your radiator even further is to install a system to spray water onto the radiator to get some evaporative cooling going. Some of the modified P-51 Mustangs at Reno air races use this system to augment their cooling systems. You could probably adapt a windshield washer system to this duty. Of course, this system would be more effective in Arizona than in Florida.

__________________
]
aerocivic.com

Ohh, you know about the Reno air races? 2 of the guys at work fly in those races, one in the unlimitied class and one in the T-6 class. Its always fun to watch and even better if you get to go up with one of them. =)

Ohh and back to the subject at hand. You could spray some water for better cooling, but then you've gotta carry more water around. I'm just looking to replace it with something that JUST about right... maybe 125% of the needed capacity, just in case.

__________________
Anger is a gift!

- Zack de la Rocha

the radiator off the civic VX and crx HF are both half size,
as long as you keep the fins clean, and straight, a half size should cool plenty.

I've thought about useing heat pipes to cool my engine, make a manifold with one end of the heat pipes stuck in it, and the coolent running past the base tip of each of them, as heat pipes have only a small amount of fluid in them they would be lighter, and your engine coolent can then flow in a straight line, and would be less restricted, and if done right, the heat pipes would most efficently cool only to a pre set temp, below that temp they stop working, so if the fluid cools to the ideal temp by the time it's half way thru the mainfold, past half the heat pipes, they stop absorbing as much heat, and your engine is not over cooled.

I didn't know that eh HF had a half size radiator. That's one more thing for me to look for this week at the junkyard.

I wouldn't go as far as calling an HF radiator a "half size"... its more like a 7/8th size. Its about 2 inches more narror than the dx/si rad and not much lighter, but I guess if you have a choice between the 2, get the HF, ohh and don't forget the drivers side upper mount, its different than the dx/si one.

__________________
Anger is a gift!

- Zack de la Rocha

Ok, I've looked at the coolant passages, and I don't see any negative effect to completely blocking off both the upper and lower radiator hoses and using the heater lines to cool the engine. This will eliminate the stock thermostat, and a large amount of the system coolant. Now all I need is an electronic way to modulate the flow or amount of air the new radiator sees. In winter months, the heater alone may be enough to cool the engine. The cool part about this is if I can modulate it well enough, I can experiment with different operating temps to see which one yields the best mileage.

Any input on this?

__________________
Anger is a gift!

- Zack de la Rocha

is this relocating the heater core to the front bumper area...???
or just leaving it in the car...?

i dont think it would cool enough left inside the car
even on the front bumper i think thats pushing the system...
but who knows
experimentation
this is definatly something i would see if you get working before trying it...

__________________
BE ZEITGEISTED

I'll keep the heater core where it is, but will be adding a second radiator to cool during summer and to add the heater core in the winter. I'm going to try to move the radiator somewhere the will optimize the airflow over the car, if thats the the front, then so be it.

__________________
Anger is a gift!

- Zack de la Rocha

maybe a little scoop right from under the car and in thru the firewall...
if you altered the firewall that is...

__________________
BE ZEITGEISTED

Ok, I think I've got it! I'm going to mount 2 radiators (one for oil, one for coolant) inside the front fenders. I've thought of using these aftermarket pieces:



Or constructing my own. The radiators of course will have to be protected, but this will allow the entire front end to be blocked off and the now wasted air flow which is normally caught, increasing drag, will be lessened and useful!

Input??

__________________
Anger is a gift!

- Zack de la Rocha

Yeah, my 92 Civic radiator never had a problem keeping up with my 240 whp. We could probably get away with some tiny radiators.

why not use aftermarket radiators, instead of from a different car.

Some altima people use aftermarket radiators instead of buying oem from different companies and it saves them gas.

__________________

I think most aftermarket radiators are rather expensive, and if I can get a smaller radiator for $10 at the junkyard, I'm definately going to go that route.

bunger i think you are asking for a lot of dirt/debris/bent fins with a wheelwell mounted heat exchanger...
close to the ground behind or in front of the engine could use the air under the car which is a bit accelerated with less chance of damage

__________________
BE ZEITGEISTED

Ohh I agree, I would of course screen the thing off, which is no guarentee that its not going to get punctured, but I was thinking of it as a 2 fold deal. Vent a high pressure area and use that venting to cool the engine. I just need to figure out how to work in a fan for when I'm not moving.

__________________
Anger is a gift!

- Zack de la Rocha

SPINNERS !!!

:P

__________________
BE ZEITGEISTED

bwahahahaha