Yet Another Radiator Thread (but hopefully updated and helpful...)
 

Okay, so, I'm looking to add an upgraded stock-mount radiator to my FD. I've spent the last two hours reading threads and I've talked to a few of the shops. I'm tracking my car in CA so heat is an issue. Here's where I am:

Although many aftermarket radiators feature multiple rows of tubes, they are all single pass. Which sucks. A rundown:

* Stock: single row, 25mm plastic tank ends. Fuggetaboutit!
* Koyo: single row, or two for the N model, 52mm thick
* Fluidyne: apparently three row, 38mm thick
* AWR: single row (made by Ron Davis), 29mm thick but with excellent tube/fin design
* Greddy: two rows, 48mm thick
* PWR: two or four rows, 40mm (PWR1264) or 57mm (PWR0797) thick
* RadiatorWorld: AL and cooper/brass, one or two rows, 32mm to 52mm thick (I have a suspicion that this is actually a Koyo N model, but I can't be sure.)
* Others I don't have specific info on: ARC, Blitz, etc. (Any I've forgotten?)

(Note: as we all know, not all thicknesses are equal (ha!) and more modern fin design can have a big impact on cooling efficiency.)

So here's what's really bothering me--and this is coming from a guy that used to have a FOUR pass Ron Davis V-mount when I still had a rotary in the car. We have all these aftermarket radiators...and NONE of them are anything but single pass designs. Modifying these rads to run as triple pass without even moving the inlet and outlet tubes would be trivial, but to my knowledge no one has done it. Simply going from a single to dual pass increases the cooling capacity of a radiator by 20-30%. With all the overheating problems--evidenced by the need for air-tight ducting and exotic cooling liquids--you would think someone would have done this.

So I'm looking into either having a radiator built custom for me, or modifying and existing AL radiator to make it a triple-pass. I'm posting here because I'm worried that it hasn't been done for a good reason, but I can't for the life of me think of one.

Also, if anyone knows of a STOCK MOUNT radiator that is a multi-pass variety, I'd greatly appreciate a pointer. Thanks in advance,

-ch

My sources:

http://www.radiatorworld.com/radiato...no=15108&cat=1
http://www.livermoreperformance.com/mazda_engine.html
http://www.fluidyne.com/pl_hpimports.html
http://www.pwr.com.au/radiators_car.html
http://www.blitz.co.jp/products/cool...adiator-lm.htm
http://www.greddy.com/products/displ...SubCategory=31
http://www.awrracing.com/store/produ...?products_id=5

The Koyo N-Flow is a 3-pass design.

Saw your post on it.com forum...I just want to be sure you're right! Do you know of any pictures of this unit? Also, I'm nervous about the Koyo fitment issues--but if it's really a triple-pass then I might be willing to deal with the fit challenges.

-ch

The Fluidyne (at least mine), is a single row of tubes. The core itself is 1.5" thick, the tubes themselves are about 1.25" thick.

There's nothing wrong with a single core... in fact, it's probably better because there's less "waste" of width. In other words, if you've got a 1.5" thick core w/ 1.25" thick single tube, and the you go to two rows of .75" tubes, you're going to end up with a 2"-2.5" thick core. For the same relative core thickness, it's better if you can get it done with a single tube.

The reason that they go with multiple core/tube designs is that they can only make the tubes but so wide, so typically you see up to about 1.5" single core w/ 1" to 1.25" tubes, and then dual core 3" w/ two 1" tubes. Here's a good visual explanation at the bottom of this page:

http://www.alumrad.com/aboutus.htm

The Ron Davis Quad-pass V-mount was done for Knightsports. I'm not sure why they did that, because Ron Davis themselves told me not to (I'm building a V-mount), because it'll put alot of stress on the water pump. It was a 2.25" thick core, w/ 3" endanks.

A V-mount needs to be at least a 2-pass, because the inlet and outlet are on the same side. A stock radiator need only be a single pass, or can be a three-pass so that inlet/outlet end up on opposite ends.

p.s., isn't your car a V8? If so, you won't have any fitment issues with a Koyo, singce you have no IC.

AFCO ALL THE WAY. cost was about $230, biggest radiator that can fit in the car. It is not a bolt in, you need to make some mounts, but it was easy. The company is awesome and the product is phenomonal, the sales person spent an hour and a half on the phone with me trying to find the biggest, best, and most inexpensive one that would fit in there. I have it in my ITS car and never have the temp go over 200* with the stock thermostate. Even at road america on a day that it was 93* ambiant, she never went over 200* I cant say enough about this bad boy, great company and great product, I wouldnt trade it for anything.

IMHO Ron Davis is great quality, but pretty over priced, the modle that is comperable to what I have from afco, from Ron Davis is would have been more than double......FWIW

I've installed one for a customer if that counts. Check out the Racing Beat site. They have a little picture or something.

C., can you comment on the trimming necessary for that particular Koyo?

Bean13, I don't think AFCO makes a part for the FD stock replacement.

ptrhahn, I'm designing something that is in a different direction than most V8 cooling setups. I don't like the setup I have now:

http://i116.photobucket.com/albums/o...7/IMG_0443.jpg

This setup has the air cleaner at the end of a series of 3.5" 90 degree bends and ends in the oil cooler location. This is bad for three reasons:

1) Long, twisty air track is bad, especially for NA cars
2) Air filter is in a location where it gets dirty, and water ingestion is an issue
3) No room for an oil cooler

-ch

Hyperion... sounds like you don't want to dick with a stock FD radiator in the first place... but,

Try that alumrad.com place. They only deal in two-core 3" radiators, and so long as you don't design anything too complicated, i.e.: single pass, can do it pretty cheaply.

FWIW, every radiator vendor I've talked to has told me only to do multiple passes if you need to for the sake of getting the inlet/outlet in the right place.

Trimming neccessary? None. It's a stock drop in.

+1 for alumarad.com if you are wanting to go with a custom rad. Brian is a class act and does great work. I've had him build a couple radiators for me. If you can draw it he'll build it. He uses Howe cores. IMO the Afco, Howe, and Griffin cores are all going to be pretty much similar. So, if you're going that route look for someone that's putting together what you want for the right price.

As far as multi-pass v single, Brian at alumarad is the one that originally turned me on to multi-pass years ago when I was setting up my ITS car.

Peter, the information regarding single-pass vs. multi-pass is incorrect. Let me explain:

The single pass radiator would appear on paper to be a better design: all the tubes in the core see the highest temperature water right away, and thermal efficiency is related to temperature differences.

But what the double pass (and triple/quadruple pass) radiator does is dramatically increase the velocity of the water. Because you reduce the flow area by 2 (or 3/4) the speed rises. This creates or increases the turbulence in the water. Because heat transfers slowly through water, the turbulence helps things by mixing the water and ensuring that more hot water comes in contact with the tube walls--which is how the radiator gets the heat out to the fins.

This effect makes multi-pass radiators about 1/3 more efficient than single pass of the same dimensions.

This is also why multi-pass is harder on water pumps. For my application, the LS1 water pump is the size of a 4-cylinder motor, so I'm not worried. But be assured that multi-pass radiators aren't done for inlet/outlet placement.

-ch

I just talked to Brian at alumrad. Quoted me $460 for a 25 x 15.5 double pass which would fit the stock location. That's not bad, but it means I have to get new fans (two SPAL 12" would do the trick, but set me back another $350) which is a bummer. I need to think this over.

-ch

Afco!!!!!!!!!!!!!!!!!!= $230

Hyperion,
I was just relaying info given to me by Brian at Alumrad, Bill at Ron Davis, and Patrick at Griffin. I've had several convos with each of them.

Nobody had a problem with a 2-pass, but everyone encouraged me not to go with a 4-pass, because of the of the stress to the water pump... they didn't necessarily say it wouldn't cool better to some degree, just that at some point it's a diminishing return.

Once again, just quoting more knowledgeable sources.

I am guessing you are doing this to try to run a intake like this. http://www.swapcartech.com/forum/showthread.php?t=1008

Do you really think that gain will be worth it, the horsepower loss of a snaked intake? Why not run a dual pass radiator standing up with proper ducting. Run a oil cooler on the passenger side and shield the intake from water/derbies.

I was going to run my Ron Davis stock location radiator but it hit the pulley so I decided to run the Howe unit. You might want to check out their units, they are very helpful and reasonably priced although the do not recommend running them at an angle.

A little off topic but talking about stress to the water pump...what kind of stress would it cause if you went from 1.5in hose to 1in? theoretically.

hypothetically sorta thinking in case you wanted to use a rad with 1in ID outlets.

Wicked: I like CMG's approach, but he benefits from having his motor set back another 3" or so (by cutting and welding the firewall). I tried to make that work but there's just not enough room using the stock firewall.

So My approach is a little different, and hopefully unique. I looked at making ducting for the Hinson dual-pass, but you absolutely cannot run 4" tubing with that radiator if you also run power steering (which I do). So then you need to run another rad (like the Howe).

Also, I'm using the driver's side for the cooler because I'm putting an accusump on the left side. Maybe I could switch them but I already have all the parts for the cooler.

FWIW, Mike did an A/B test between 3.5" tubing and 4" tubing on the dyno. Said it was 10-20 RWHP, IIRC.

-ch

Airborne: any restriction is a bad thing, but a 1" inlet is probably not a deal breaker. Probably depends on the application (water pump). I would try to avoid it, but the only way to be sure is test.

-ch

Hyperion,

Thanks for the information, sounds like you are trying to build a track monster. I am sure you thought about it but you could also run the oil cooler right in front of the radiator. I know there is room in front of the howe and you will still have plenty of room for the 4" intake.

Good luck and I hope you do a detailed write up of what you decide to do.

All good points...I'm trying to build something that's going to be rock-solid, servicable, and streetable as well. I'm going to post a few renderings when I get all the details ironed out...

-ch