Cramming a flat six where the old lump was requires some creativity. Mostly in the cooling department thankfully. I have a hole about 24x14 that I have to slide a radiator into. AND I'm a cooling system beginner.

FACTS
the stock turbo radiator core was/is 26x16x1 = 416 cu inches of water holding goodness.

If I double the core thickness but go to a smaller frontal area, say a core 13x18x2 = 468 cu inches of H2O capacity. Think that would cut it?

or perhaps a slightly larger 16x19x2.25 = 684 cu in. <---- that one is cheaper too.


I'll cut holes in whatever I need to to get airflow and of course have a fan on it. Thoughts? Tips?

Which engine are you using? EG33? Or one of the EZ30 variations?

Be aware that the EG33 tends to run hot due to some design issues. Not bad if left under 6500 rpms, but above that (and especially at high sustained loads), they have problems. Radiator size doesn't matter either...

I ran into a lot of problems with my friend's EG33-swapped Impreza that he road races. He's twisting 8200 rpms and making about 415 hp and we had to re-engineer the entire cooling system. It's still marginal, but at least it doesn't puke coolant 10 minutes into every race anymore.

I JUSt read about these issues on another forum. Seems like guys are enlarging the lower tubes and pump inlet to reduce cavitation when the motor is at high revs. They said to bump it to 50mm and relocate the t-stat to the upper hose with an inline unit.

I think I'll get the big radiator anyhow. 179 didn't seem like too bad a price for a alum rad from griffin.

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biggreen96
I JUSt read about these issues on another forum. Seems like guys are enlarging the lower tubes and pump inlet to reduce cavitation when the motor is at high revs. They said to bump it to 50mm and relocate the t-stat to the upper hose with an inline unit.

I think I'll get the big radiator anyhow. 179 didn't seem like too bad a price for a alum rad from griffin.

Yup, I'm on that forum as well, I'm well-versed with the subject! Do yourself a favor and design-in a surge tank as well, that seemed to help a lot with the dispersion of air pockets.

You can also put a bigger pulley on the pump to underdrive it and keep the pulley RPM down. That will also help prevent cavitation.

That's a good idea but getting the timing belt on is hard enough with the stock pulleys.

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Dazed_Driver
You can also put a bigger pulley on the pump to underdrive it and keep the pulley RPM down. That will also help prevent cavitation.

The pump pulley also serves as a tensioner for the timing belt. Unless you can also get a new longer belt with the exact length needed to retain correct cam timing AND fit the new pump pulley OD, even just trying to fit it in place would be a problem.

There are other issues at hand, one of which is bad coolant flow through the 2 rear cylinders, and a pressure differential issue at the suction side of the pump.

My friend's EG33-powered race car uses a remote electric pump, and while it helped it did not cure the cooling problems. Basically, the higher you rev it the more it aerates the system, regardless of the pump configuration. You need air bleeds drilled into the heads and a new upper crossover pipe doesn't hurt either, as well as a large surge tank. This is all in addition to the aforementioned larger OD radiator outlet.

Oh lame, it doesn't have a seperate tensioner pulley Boo.

Errr. I'm not too excited about that. So tell me, if I do nothing to the cooling system besides putting this aluminum radiator in, and then go to a stage rally, and rev the car to redline each shift.. how far will I get?

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biggreen96
Errr. I'm not too excited about that. So tell me, if I do nothing to the cooling system besides putting this aluminum radiator in, and then go to a stage rally, and rev the car to redline each shift.. how far will I get?

Well probably at least a couple of miles, that's more than some..

I know of two rally cars with H6 engines. The infamous Anders Green as well as a Colorado guy named Max Johnson. Max's I know is a newer 3.0L. But was checking it out last week and saw nothing crazy on it. He's not done an actual event, but he's done a ton of testing at a facility that at least on my car is harder on the cooling system than a rally.

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NoCoast
I know of two rally cars with H6 engines. The infamous Anders Green as well as a Colorado guy named Max Johnson. Max's I know is a newer 3.0L. But was checking it out last week and saw nothing crazy on it. He's not done an actual event, but he's done a ton of testing at a facility that at least on my car is harder on the cooling system than a rally.

Anders has a 3.0 litre as well. In fact his car and his website build was the inspiration for my friend Jack's Impreza (he had the Impreza and an old junky SVX, I talked him into the swap). The 3.0 is substantially shorter than the EG33, and uses chain-driven camshafts rather than a belt. They don't overheat either AFAIK.

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Errr. I'm not too excited about that. So tell me, if I do nothing to the cooling system besides putting this aluminum radiator in, and then go to a stage rally, and rev the car to redline each shift.. how far will I get?

Early on, my friend's car would overheat within 12-15 minutes of a 20 minute sprint race. Backing off the throttle and letting the rpms drop to 4500 or so would let it cool sufficiently, but by then he was losing time.

With the current cooling mods he can run a complete race, and only the last 2 laps or so does the temp climb, but not enough to go into limp mode. Of course, he started off with 210 whp and 6500 rpms max, and he is now making 318 whp and running 8200 rpms. So while the cooling has improved the power and rpms have risen appreciably at the same time. If you kept the rpms to 6500 and did some of the cooling mods, you should be fine.

So do the aluminum radiator with a custom 50 mm lower output hose to the pump, and add the surge tank. I think you'll be fine with the stock redline this way.

Ok. Thanks for the insight.

I picked up this flat six because I wanted something more reliable and cheaper than a turbo motor to start with... haha, at least the sound it will make is nice.

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biggreen96
haha, at least the sound it will make is nice.

You got that right!

Ok summitracing has a good selection of rads but the price jumps radically when going from a 16in high unit to a 15 or 14in unit. Id prefere a 14x24 but it is 3x the price of a 16x24.

Anybody know of a another ok place to get rads?