So the radiator on our restoration 85 fb is shot and literally falling to pieces. Should I do an aluminum new one with elwcteic cooling fans or keep the stock belt driven fan

 

up to you! the stock fan is nice because it works and you already have it

 

One word of warning with the eBay aluminum radiators. They work well, are priced right, but most have one flaw and that is the top bung for the low coolant sensor. It's the wrong size. They make the with a size if 1/4 npt. Many will have a drain petcock plugging them for that bung.

The Champion radiator is also aluminum, but last one I bought had the correct bung on top. Done know about now. They have been out of stock for a long time but I see they have them again.

https://www.championradiators.com/Ma...ator-1983-1985

You'll never find a cooper rad for these now. Everyone stopped making them.

 

Ok ill look on amazon and keeep an eye for the coolant sensor location

 

The location is the same, but the bung size is wrong. I really like the Spectra radiators but can't be had now. Don't remember if its the CU97 or CU701.

https://www.summitracing.com/parts/sgt-cu701

 

Very happy with Koyo. I have one on my turboed ‘80 as well as my son’s GSLSE

 

I've heard that an electric fanned radiator will give back some power. How woukd you wire them up to come on with temp of coolant? Also shoyld I use an electric coolin fan. Don't think I wsnt to use the stock belt driven fan

 

technically, they do. i don't think the power refund is that significant though.

that said, it's entirely up to you as to whether or not you should convert to electric. out of curiosity, why don't you want the stock fan any more?

anyway, you would need to get a thermo switch to control when it comes on. i don't know which brands or types are best for our cars, so someone else would have to chime in on that detail.

something like these:
for the fan, you're going to need something that pulls a lot of CFM. i know the Taurus 3.8 fans are recommended in terms of things you can buy or get from the bone-yard. in terms of aftermarket stuff, i know Black Magic (i think?) was the brand everyone (or many) recommended back when i was new here. i'm not sure if that's still the case.

here's a thread that might help:
https://www.rx7club.com/1st-generati...an-12a-751835/

Edit: the brand is actually Flex-A-Lite and i guess they have a series called Black Magic.

 

I suppose I could use the stock fan I just was looking for a little bit more power but if it's not going to give me much then I'll just reuse it the new radiators I think have less clearance than the old one the new ones are thicker and The Originals were thin so I don't know if they'll be enough clearance

 

You biggest bang for horsepower is the exhaust.

This book "How To Modify Your RX-7" is a good read on hp gains.

https://www.foxed.ca/rx7manual/manua...20your%20rx-7/

Here is the exhaust chapter: https://www.foxed.ca/rx7manual/manua.../02Exhaust.pdf

 

If you have a MotorTrend subscription check out the Engine Masters episode on cooling fans. On their test engine (a V8) all of the engine driven fans sucked up HP. Some were worse than others, especially the ones that didn't have a clutch. If you do use the OE fan, make sure the clutch is working

Which ever direction you go, spend time making sure that air coming through the grill goes through the radiator/oil coolers and not around them. Air will take the path of least resistance.

 

Ok and I have a beehive oil cooler

 

As additional info to KCRepu's. With a stock port 12A (in a Pro7) it was possible to get about 118WHP. Same engine with a RB collected header (and relatively little downstream restiction) I got 135WHP. These were both with stock (but stripped and minor jetting mods) Nikki. Mild street port 12A with stock Nikki was 135WHP. Same mild street port with Nikki primaries bored to 24mm (and jets modified accordingly) was 145-150WHP. As KC said, the exhaust is the quickest bang for the buck. The modified Nikki is great on track, but I would prefer the stock Nikki for daily driving.

Carl

 

So I also need a new radiator, what did you go with Pauliboy72?

I see the Champion radiator that KC was mentioning is in stock, I think. There are 2 options, a 2 row ($204.98) or 3 row ($234.98). Warranty is lifetime but failure due to corrosion is not covered so it looks like it's 12 mo. from purchase.

RA has the Liland Global brand, all alu, and similarly priced at $237.79 with a 12 mo. warranty.

Richard Miller, who/where did you get the koyo rad. from? Was it priced around these mentioned above?

Is one better than the other?

 

I just bought a used one

 

Thanks for the reply. I think I'll pick up an aluminum just because.

 

The Koyo is model HH063146 and will be in the $350 range. I'd google the part number for the best price.

 

Thanks for the model# j_tso

 

Do all aluminum radiators require the use of an aftermarket fan, or are some of you with the al. radiator reusing the oem fan and shroud?

 

I used the factory fan with the Champion rad.

 

KOYORAD, factory fan, fan clutch, and shroud; temps never go about 1/4 on the gauge. The shroud is a critical element to cooling. Without a shroud for the fan, almost zero air gets pulled through the radiator by the fan.

I live in the Sonoran Desert, so I should know.

 

Thanks for the feedback guys.

In case anyone else is looking for the Koyorad, cheapest I've seen online is from Evasive Motorsports, $285.48, with free shipping. The cap is an extra $36, all together it's still a great price.

https://www.evasivemotorsports.com/s...da-rx-7-83-85/

 

I wouldn't bother with the higher pressure cap. It could be fine but I don't think the coolant seals don't need more stress.

That all depends on fitment, like if the radiator mounts are in the wrong place or offset somehow towards the back that causes interference.

 

Future readers should recognize that the KOYORAD coolant cap is proprietary to the KOYORAD and your stock radiator cap isn't going to fit. Further, while expensive at $36, the KOYORAD cap has a silicone (vs. rubber) gasket and is rated to a slightly higher pressure for better flow and cooling effect. I bought a spare radiator cap just to have a spare, but doubt I'll ever need it...

 

Koyo uses the standard "mini" cap. Stock FB RX-7 cap won't fit, but one from most newer OEMs will. That's what I'm running on mine.
Mazda switched to that style on the FC.

Higher pressure raises the boiling point of the coolant.