PVX build thread: one view from the slope

[panzerfaust]

+1 ... epic build. im wondering why more arent built with watercools than LS1's?

[75 911s]

^Expense and complexity I'm guessing. Amazing build.

[Tremelune]

This thing is bananas. I'm impressed that a car with this drivetrain still looks classy.

Still turning laps?

[earlybroncoguy]

Are the radiators custom, or off the shelf units for some other vehicle (UTV, motorcycle, etc)? I'm doing a water cooled motor swap and need a radiator, but don't really want to cut open the front trunk area and lose the factory gas tank and spare tire space, hadn't considered dual outboard mounted units but they seem a great alternative,

[Andy Somogyi]

Love those radiators, great design.

Are they hooked up serial or parallel? I wonder how much of a difference it would make if the radiators were serial or parallel?

[Andy Somogyi]

Any chance you might have specs on your radiators, or who made them?

I figure if these will cool that monster engine you’ve got, I’m sure they’ll cool the N/A Subaru 2.5 that’s going in my 912.

[Walt Fricke]

Andy

If Carrol Smith (RIP) is to be believed - and there certainly is no reason not to believe a genuine engineer who worked on race cars and wrote books about the engineering basics of it - you want radiators to be in parallel if you can. Because heat transfer efficiency increases as the temperature difference between what you want to cool and the cooling medium (air for the water in your WC system)increases.

In parallel, this delta is highest in both radiators. If you run things serially, the first radiator (assuming about equal cooling air flow) is more efficient than the second, and the water returning to the engine is hotter. This doesn't mean a serial system can't be made to cool adequately, but given a choice, why not go parallel? A little more plumbing, but better cooling.

[Bill Verburg]

Here's how the cooling for 991GT3, Cup, RSR etal is setup

[Andy Somogyi]

Thanks for the info Walt and Bill for the info. I worked out the math last night, and a parallel system is, in fact, has a higher cooling capacity for the same sized cores. There's a reason why Porsche decided to run all their radiators in parallel.

It seems that serial systems are easier to plumb and easier NOT to screw up because you're guaranteed uniform flow through all radiators. Challenge here is the higher pressure drop, which can push the water pump out of it's operating efficiency range.

Parallel radiators are more efficient but easier to screw up if you don't balance the flow correctly, and more complex to plumb.

I'm just starting to design the radiator system for 912 swap that I'm planning. I'm going to use petevb 's radiator design, but plump them in parallel. I figure, if his design, even in series can cool a 400 hp 3.8 M97, they'll easily cool the 175 HP Subaru twin-cam 4 cylinder that I'm putting in the 912.

[-Levi-]

Subd

[pkabush]

“ Thanks all. I guess everyone who thinks water is heresy is holding their tongue “
Nobody said that. Some of us still believe in purity though.
That said, bad ass build.

[rennch]

Originally Posted by petevb

Ken, vs a 993 VRam you're looking at ~48 lbs empty, ~56 lbs including water weight within the motor...

Hey Pete,

Sorry to resurrect the thread with something that might have been asked, but I'm doing my twin turbo Subaru EZ30R Flat 6 build (Sounds like a pissed off GT3) and am wondering about your radiator overflow tank. Looks like you mounted it on the engine on the driver's side? I've basically "duplicated" the oil tank in aluminum and am going to use that one in the stock location. Do you have a "1 in, 1, out", or just a single line running to the tank? How do you check fluid levels? Or is it not necessary?