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Old 07-26-2010, 04:26 PM   #1
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Default Radiator, Koyo vs CXracing

Speaking of overheating, i'm looking at getting a Koyo 55mm for a track car (turbo), and found this: http://cgi.ebay.com/ebaymotors/CXRac...ht_8663wt_1166

Had a Koyo 37mm in my last car, and it worked really well, so i'm thinking the Koyo 55 is the way to go, but is there any appreciable difference between the Koyo and the CX? Will eventually go fans and shrouding in the future in any case, but their 2" radiator with fans is considerably less than a used Koyo alone...

Also, anyone know if this shroud works with a RB Tubular front sway?
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Old 07-26-2010, 10:14 PM   #2
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I strongly suggest you wait before ordering a radiator right now. We are tweaking fitment on our big dual-row but it will hopefully be out soon.

Nick had it in his SM over the weekend at Thunderhill. 101*F ambient, coolant temps were 167*F with a 160*F thermostat. Can't argue with that.
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Old 07-26-2010, 10:16 PM   #3
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estimated cost? cause i will be in the market for a rad soon....
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Old 07-26-2010, 10:17 PM   #4
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estimated cost? Cause i will be in the market for a rad soon....
$449.

I've been using the rad in my turbo car and I can do full 25 minute sessions at 300whp in 100*F ambient, with coolant temps of 200-205*F. As soon as I lift off the throttle for a cool-down lap, the temps drop to ~170*F.
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Old 07-26-2010, 10:20 PM   #5
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cool, if im gonna drop some coin on a part id rather support a member here first if i can....

do you already have a thread about this rad?
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Old 07-26-2010, 10:24 PM   #6
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Ah, i was thinking that huge radiator on your car wasn't just a Koyo 55.

What before and after temps did you have when switching from the Koyo to your current radiator?

Getting ready for 30 minute sessions in Phoenix, so 30 minutes, 114 degree heat, want to make sure i get the right thing the first time. Even see IATs of 127 sometimes, due to radiant heat from the blacktop.

Also, may have forgotten if you posted it in your build thread, but could you please let me know what oil cooler/trans cooler/diff cooler/intercooler you went with? Don't think you did the trans or diff, but not quite sure.

Oh, and would it work with a standard shroud/would you sell a fan/shroud/radiator kit?
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Old 07-26-2010, 10:24 PM   #7
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Not yet, we've been through a bunch of prototypes so we aren't "officially" announcing it until we have them in stock. We would have liked to have them out 6 weeks ago but the fitment wasn't where it needed to be.

I had a 2" CSF/RadiatorBarn.com radiator in my car before our rad went in (3", 3.25" endtanks). In the summers I never had temps under control, it was always a struggle to keep them in the 230-240 range. With the big rad, CLTs aren't even on my mind anymore, and I've added 50-80whp.

SM guys make the switch from the Koyo55 to the SD rad (similar design to ours but $600) and see a ~30deg difference. The SD rads also used to have problems with random core leaks. They were recently redesigned but it remains to be seen if it was fixed.

There were 3 blown motors at the SFR SCCA regional at Thunderhill this past weekend. 2 were directly attributed to overheating. Most everyone with a Koyo was overheating.

We will do a back-to-back test with my 2" CSF, a 55mm Koyo, and the single and dual row versions of our radiator and document everything. Probably find a 110*F day at Buttonwillow and go hammer on our rental car for a weekend.

Last edited by Savington; 07-26-2010 at 10:35 PM.
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Old 07-26-2010, 10:27 PM   #8
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Quote:
Originally Posted by Savington View Post
I've been using the rad in my turbo car and I can do full 25 minute sessions at 300whp in 100*F ambient, with coolant temps of 200-205*F. As soon as I lift off the throttle for a cool-down lap, the temps drop to ~170*F.
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Not yet, we've been through a bunch of prototypes so we aren't "officially" announcing it until we have them in stock. We would have liked to have them out 6 weeks ago but the fitment wasn't where it needed to be.
Ahh, its the thick *** one thats in your car. i remember seeing pics of it somewhere. im sure you will make a thread bout this as soon as they are ready to go...

exactly how thick is it?
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Old 07-26-2010, 10:36 PM   #9
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Gah, been editing my post during the whole lower discussion. Since it's now out of sequence, i'll repost down here.

What before and after temps did you have when switching from the Koyo to your current radiator?

Getting ready for 30 minute sessions in Phoenix, so 30 minutes, 114 degree heat, want to make sure i get the right thing the first time. Even see IATs of 127 sometimes, due to radiant heat from the blacktop.

Also, may have forgotten if you posted it in your build thread, but could you please let me know what oil cooler/trans cooler/diff cooler/intercooler you went with? Don't think you did the trans or diff, but not quite sure.

Oh, and would it work with a standard shroud/would you sell a fan/shroud/radiator kit?
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Old 07-26-2010, 10:51 PM   #10
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Here's my opinion: If you're not going to shell out the extra ~$250 for Sav's double pass radiator (at least I think it's a double pass), then just buy one of the chinese radiators from mishimoto, godspeed, or cx racing for $200 shipped.

This is one of those "go big or go home" items. I know it's on my wish list. Ignoring coolant temperatures because I trust my coolant system is a certainly a dream.
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Old 07-26-2010, 11:02 PM   #11
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I would overheat with a koyo 55mm after 3-4 laps.

I have one of Savs radiator, (3 inch i believe) and i don't pass 190* temps. This was last ran in April, IIRC ~65*F at the time.
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Old 07-27-2010, 12:25 AM   #12
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Well FM's race rad costs the same as Sav's. This would be a toss-up if I was in the market at the moment for a race rad.
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Old 07-27-2010, 12:47 AM   #13
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Quote:
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Well FM's race rad costs the same as Sav's. This would be a toss-up if I was in the market at the moment for a race rad.
How is it a toss up? Your going from the standard radiator design like everyone else sells to a much larger dual pass unit from Sav..... One of the MT.net track gods
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Old 07-27-2010, 12:51 AM   #14
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Quote:
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Well FM's race rad costs the same as Sav's. This would be a toss-up if I was in the market at the moment for a race rad.
Yes Fagatron, because the price of a product determines it's effectiveness.

AFAIK, FM's is the same design as a Koyo unit. Great for an HDPE track ****, not great for higher horsepower levels combined with incredibly aggressive driving and/or high ambient temperatures.
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Old 07-27-2010, 01:05 AM   #15
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Quote:
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exactly how thick is it?
It's twin 1" cores. I believe the endtanks are 3", maybe a touch thicker than that. Triple-pass crossflow so you get the benefits of a crossflow radiator as well as factory hose locations. The lower radiator hose lines up perfectly, I have a NAPA part number for the upper radiator hose. It's also designed to touch the factory belly pan, vs. the gap that the OE radiator leaves.

One of the nice benefits of the triple pass is that the radiator inlet is moved over, offset from the OE throttle body location, which makes reroutes MUCH easier to install.

I'm sure the FM radiator is a nice upgrade over stock, but it isn't even in the same league as our radiator. It's not cross-flow, let alone a triple-pass cross-flow.
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Old 07-27-2010, 01:10 AM   #16
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Holy smokes! I didn't realize you were doing a triple pass unit. I thought it was a dual pass like the PRC unit.
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Old 07-27-2010, 01:36 AM   #17
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Quote:
Originally Posted by Savington View Post
It's twin 1" cores. I believe the endtanks are 3", maybe a touch thicker than that. Triple-pass crossflow so you get the benefits of a crossflow radiator as well as factory hose locations. The lower radiator hose lines up perfectly, I have a NAPA part number for the upper radiator hose. It's also designed to touch the factory belly pan, vs. the gap that the OE radiator leaves.

One of the nice benefits of the triple pass is that the radiator inlet is moved over, offset from the OE throttle body location, which makes reroutes MUCH easier to install.

I'm sure the FM radiator is a nice upgrade over stock, but it isn't even in the same league as our radiator. It's not cross-flow, let alone a triple-pass cross-flow.
Wow
Btw do you have any weights - empty and full of water?


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Old 07-27-2010, 02:20 AM   #18
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We will get weights, both dry and full of water, on the final production pieces.

BTW, we are doing all fitment work on cars with RB tubular bars and RB sway bar braces for a worst-case scenario.
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Old 07-27-2010, 02:40 AM   #19
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Quote:
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BTW, we are doing all fitment work on cars with RB tubular bars and RB sway bar braces for a worst-case scenario.
That's awesome news! I'm excited for the final product!
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Old 07-27-2010, 04:22 AM   #20
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Pic to show inlet:

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