Cooling down a big bad v8.

My conquest of stuffing a 1uzfe into this tiny Celica comes to a crossroads on cooling, and I know you guys stuff the biggest engines in the smallest things, so I turn to the hive. The biggest radiator that fits this chassis is a s13 (240sx) aluminum three core. The other two guys I know with this swap have aluminum 2 cores. There is no room between the engine and radiator for puller fans, so I currently have a 14" flexalite s-blade that flows about 1500cfm. I know I'll need a few extra fans maybe two 10"?

So some questions here: do I need the cowling around my pusher fans so they cover the whole radiator, or will that hamper high speed airflow? Those other guys report doing fine in moderate traffic and highway speeds, but rush hour and high speed is when temps creep up.

I'm wondering if I could put the radiator outside the front bulkhead and then have room for puller fans. Ideas? I'm up for just about anything as long as I can use that 240sx 3 core and the 14" fan I already have. Should I create a giant duct to force all incoming air into the radiator, like a funnel?

Forgot- stock 1uzfe. Custom headers. Also wanted to ask if "louvering" the sides of the engine bay would do any harm? I know lifting the back of the hood is bad.

No shrouds for pusher fans. The fans only really need to cool it when you're going slowly, so it shouldn't need a ton of fan. If you can do puller fans, they're generally more effective.

I'd mostly work on getting air through the radiator from forward motion. Ducting air into the radiator will help, but you have to get that air back out of the engine bay. Vents in the hood will do a lot, provided they're not too far back on the hood. Something like the Mustang GT500 vent can move a lot of air. Venting the sides can help too, but you've gotta find the low pressure zones to vent into.

Putting the radiator forward to make room for puller fans is a good idea. They are more efficient than pushers.

You don't want to use a cowling on pushers as it will block air flow at high speeds.

Aside from ensuring there is a sealed duct forcing air into the radiator, there should be a plan for efficiently evacuating that air after it leaves the radiator. This means you need to look at the air flow into the radiator and out of it and through the engine bay.

You may find that putting a vent in the hood, behind the radiator exit, makes the most sense. You can tilt the radiator forward at the top (which allows it to be taller within the same vertical space) to better direct the air flow upward, improving air flow through the radiator. This can also improve front end downforce, especially when paired with a properly designed front splitter.

Agreed, you need to drop the pressure in that engine bay as much as possible. And don't discount the role of fans, you'd be surprised at how little airflow there can be through a rad at speed. WRC cars have fans and massive post-radiator ducting, for example.

You may want to check out the fans from Spal. Some of them have a very narrow profile, but still move an amazing amount of air.

http://www.spalautomotive.com

Tip for looking at Spal (and other fans): look at how much air they pull with different levels of static pressure. Free air testing looks impressive, but it's going to have to pull through heat exchangers, and that means you need torque in the motor. You can use the amperage draw as a rule of thumb, and the slimmer the motor the wussier the fan.

I have never had good luck with a Spal fan. They talk a good talk but they don't move very much air when you have a pressure drop on them.

Look to OEM applications. Apparently Subaru Impreza radiators are way more efficient than aftermarket, and they come with some pretty nice slim fans.

As pointed out look for current draw. A straight bladed fan that will function on one 30 relay is not going to move much air no matter what the marketing department wants you to think. When I was working on a 300C years back and saw that it had two moderately sized fans that required a 40a fuse each, and were dual speed, I knew that I had a winner. Which makes sense - they have to cool a relatively high HP engine in a tiny nose with no good air path in and out (engine is right up against radiator).

These are all great points and ideas! Thank so much guys! Feel free to keep chiming in.

So I could louver the sides of the engine bay? I've never seen that done and didn't want to hack up my engine bay if it didn't work out. I think that would be a last ditch effort anyways. I'll try for the vents in behind the rad first. Also, I love the idea of angling it.

Check your pressure differentials. You only want louvers when there's lower pressure on the other side.

We did some radiator testing a while back. We found some "race" radiators that didn't cool as well as stock. And some that worked much better.

Two other cheap ideas - by all means, run Redline's Water Wetter. It's a heat transfer agent you add to your coolant. I've seen as much as a 15 degree pull-down in a tow vehicle. Esp effective in big V-8's. Secondly, you could shim up the back edge of the hood a bit with some washers between the hood and hinges and get some extra air flow that way. Every little bit helps - and air is free

The shims only work if you have lower pressure at the base of the windshield than you do underhood. Not always the case, I did some testing on a "cowl extraction" hood one time and found it was a "cowl intake" instead.

Exactly. Some kind soul posted a wind tunnel chart for this car a long time ago, it's positive at the base of the windshield. http://www.celica-gts.com/forums/index.php?topic=26359.0

Good point! Thanks for that.

But in that link I posted, I noticed the big -6 at the start of the hood, and that makes me think vents should go there. But to pull that off I'll have to move the radiator forward more... Then again, the OP comments the engine/trans placement is off for the pic and should be scoot d back.

One thing that I have noticed is to control air under the car at the radiator. If you use an air dam or something along the plane of the radiator will create higher pressure in front and lower pressure behind the radiator. Just go look under a modern car or truck and you may spot a plastic piece added on for just this purpose.

Google radiator air dams for examples.

Bruce

Plus 2 on adding some type of airdam under the nose of the car. Fox Mustangs have an OEM air dam to keep the 5.0 V8 cool. I have read many posts on Mustang forums where someone posts that their Mustang is overheating and when someone asks the poster if they have the OEM air dam in place they almost always answer that they either removed it or it was removed on a parking curb.

if you need to put vents in the hood further back.. but them towards the edges of the car. Centre right infront of the windshield is a high pressure area that will push air into the vent rather than pull it out.. but if you move them to the "corners" of the hood, the air flow off to the sides of the car will pull air from under the hood.

you may also want to consider some sort of inverted wing under the engine. Pull it tight to the front of the bodywork and try to get it to continue under the engine and beyond it slightly if possible, this should create a low pressure area under the car that will help pull heat from engine bay..

If you can, put a flat plate that extends from the front of the rad forward at the bottom. That way the air that is destined to go thru the rad actually does and doesn't just sneak under or around it. Lots of old British cars had ducting extending forward to funnel the air thru the rad because they were located so far behind the grill.

In reply to Trackmouse:

Notice that he says the readings were taken down the centerline of the vehicle. Usually, but not always, you will get slightly better numbers towards the outside edges of the hood in those forward locations.

Based on that I would try to lean the top of the rad forward and either put two vents in the forward location towards the outside edges or one long vent across the front.

It would be interesting to see how much pressure differential there is behind the wheel arches, similar to where the second gen T/As had their air extractors placed.

I'd say get a manometer and do some testing to find out where your best feasible locations would be. I would want to see what the pressures are doing under the hood as well. Back next to the firewall, up near the radiator, down low and up under the hood. If you find a localized spot with high pressure in the engine bay and low pressure on the outside of the bodywork, BAM, you need to put a vent there. The person who made this is at a good starting point, but is missing the whole picture IMO.

That illustration shows that the wing was completely useless

Here's a view of the first three Miata generations. I took the NC numbers, Perryrace took the NA and NB ones. Shows trends, anyhow.
https://www.flyinmiata.com/support/instructions/misc/louvers.pdf

On the inlet side your funnel doesn't have to be metal. Many Roundy round cars use rip stop nylon to form rectangular funnels so when they wreck the rad lives. So times its easier to work with other time a pain but it help funnel the air.

tr8todd wrote: If you can, put a flat plate that extends from the front of the rad forward at the bottom. That way the air that is destined to go thru the rad actually does and doesn't just sneak under or around it. Lots of old British cars had ducting extending forward to funnel the air thru the rad because they were located so far behind the grill.

I was just going to mention radiator ducting. Basically you want to get as close to having a square duct extending from your radiator to the front bumper as possible:

(this guy would've been better off if he plugged the gaps around the sides of the intercooler)

Here's another example:

Don't forget copper radiators are far more efficient than the fancy aluminum ones.