ITS RX-7 FC - Radiator Options

[Bern]

Guys,
Looking for radiator options for our '89 ITS racer. We are trying to keep the car budget minded, but not necessarly on the "cheap"... If you guys could share experience and brands.

Anyone running a universal HOWE Aluminum radiator? Seem cost effective from SUMMIT... if so, dimensions used.

Thanks in advance for sharing the experience!

-Bern

[xr4racer]

I would recommend a Ron Davis radiator, not cheap , but very good. Whatever you do get a good radiator or you will be changing engines, especially in SoCal weather. The best improvement to the system is to have excelllent ducting of the air to the radiator and oil cooler.

Matt

[x-ring]

Here's a second for Ron Davis radiators. RX7s are hard to cool, I'm told. Z cars are too. On a hot (100+ degF) day at medium-high altitude (5000 ft) I saw a 20 degF drop in coolant temperature when I switched from a new OEM radiator to a Davis double pass.

I don't remember it being that expensive. I think it was around $100 more than a cheapie generic radiator from SummitJegs. A lot less than a new engine, in any case.

[bldn10]

RX-7s are indeed prone to overheating, and ducting is absolutely necessary or you will NOT keep the temp under control. I'd rather have a properly ducted Howe or Griffin than some super duper expensive one not ducted. On one of my cars I splurged and bought the $500+ Mazda Comp radiator, that was at that time built by Anthony-something or something-Anthony - it was a thing of beauty but not worth the $ cooling-wise.

[C. Ludwig]

Bill nailed it dead on. A 2-row Howe core setup in dual pass is sufficient. There are a number of places that can set one up to your dimensions. We've had several made by a guy in AZ. Usually about $350. If you take your time and measure correctly they should be a drop in.

[bldn10]

And make sure you take your measurements w/ the sway bar that you will be using. The damn Mazda Comp lower outlet interfered w/ my Speedway bar so I had to cut some of the inner hood out to clear it. :bash_1_:

[Bern]

Guys, the input is much appreciated... sorry for my delayed response. I'm interested in the HOWE option that C. Ludwig mentioned. Do you have any contact info for the guy in Arizona? Again thanks guys for the input.

BTW, long time RX racer and owner, so I'm very aware of the heating issues and ducting issues, I was just wanting to get some practical input on the options for an ITS budget racer.

Thanks again!

-Bern

[JeffYoung]

Questions and comments from a non-RX7 ITS guy:

1. I use a Ron DAvis radiator and saw a 20 degree drop like Ty did. Of course, that was from 235 to 215....lol....High quality, and not that expensive. Mine is an "odd" application (TR8), and it was $600 I believe and was one of the few truly bolt on things I have ever bought. Just dropped right in. Or up acually, TR8 radiators go in from the bottom. Highly recommended.

2. For ducting, on a test day, I simply taped some gaps up and saw another 10 degree drop. My question is, what is legal for ducting? I have some gaps between the spoiler and the radiator that I'd love to put some sheet aluminum on, but don't know if that is legal and it seems the ITCS is silent -- meaning I can't? What do you guys do? I have heard from others that ducting is crucial for RX7s, and it seems to be for me as well.

Thanks again guys, I appreciate it.

Jeff

[C. Ludwig]

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

[Andy Bettencourt]

Jeff,

It is my belief that ducting to the radiator is legal...because radiators are 'free'. As long as your ducting is attached to the radiator - it can be argued that the entire unit is an "Jeff Young Designs" radiator, you are all set. There is no additional rule prohibiting source of air etc like the intake rule obviously.

Same applies to oil coolers IMHO...but use EXISTING holes as there is no provision for creating holes for these ducts.

[Chris Wire]

Andy hit the nail on the head.....it must attach to the radiator since that is the component that is 'free'.

I would also add that you should definately use the splitter rule to the limit. In addition to the handling benefits, having the splitter/undertray under the nose traps the air and forces it into the radiator/oil cooler if it's designed properly. Makes the whole setup that much more efficient.

If you're skeptical, ask anyone who has ever had an 'off' and destroyed the splitter. Then ask if they noticed a temp increase. My guess is that they have.

[JeffYoung]

Got it, thanks Andy. I guess the key issue is "attached to the radiator." Attachments from the spoiler to the radiator mounting brackets probably NOT ok I assume?

Do you guys attach to the radiator with JB weld?? Obviously, you can't rivet or drill, although it scares me that I even considered that......lol.......

[Andy Bettencourt]

Aluminum tape? :D

The same principle applies to 'cold air boxes', intake heat shields, or exhaust heat sheilds. Must be attached to the free intake or free exhaust to be 100%, right?

[JeffYoung]

Aluminum tape it is!

[C. Ludwig]

Since the splitter is free you can attach your ducting to it also. Ducting becomes part of the splitter. That's the way I did it. Aluminum sheet attached to the splitter and then taped to the rad.

[bldn10]

If you're skeptical, ask anyone who has ever had an 'off' and destroyed the splitter. Then ask if they noticed a temp increase. My guess is that they have."

On Sat. at Barber in 7/04 I had a car come across my front end and tore up the splitter (and a few other things).
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I removed the splitter and taped the front up as best I could ...
[attachmentid=752]

(not a bad job - huh?) and started the race on Sun. By the 4th or 5th lap I was running hot. I backed off and puttered around to take a moral victory.

Yes, it makes a big difference.

[Bern]

Interesting topic here on the cooling side... this leads me to another related issue; oil coolers. I've seen many different set-ups and configurations, and even have a few novel ideas, but what type oil coolers, and configs/layout are working for you all? Again I'm trying to keep it budget minded, not cheap, just bang-for-buck.

Love the different rules interpretations for the ducting situation, good info.

I guess we need to turn this thread into overall FC cooling conversation... :023:


-Bern

[Chris Wire]

I removed the splitter and taped the front up as best I could ...
[attachmentid=752]

(not a bad job - huh?)
[/b]

Damn, Bill - nice work indeed!

Love the color-coordinated tape job. Would make those other boys that race on Sunday mighty proud. And topped it off with the requesite MAZDA logo. Nice touch!

[bldn10]

Thanks, Chris. I'm sorry to say but that WAS some of my better bodywork. :(

I fill and sand and fill and sand but never seem to be able to get even close to a perfect result.

[Karl Bocchieri]

Dual pass is the way to go. If your Oil cooler is dirty or plugged up it puts added load on the rad. Get the cooler sonic cleaned and watch your water temp drop.

[HotWheelHolly]

I use a dual pass Ron Davis radiator as well. I switched to aluminum a couple of months back because I needed something that can handle a lot of heat.