vt951

I’ve seen LS swap guys run with a new stock 951 rad with 350 to 400 whp on street and track. I don’t know anyone who has tried it with higher hp than that. They are good radiators, but the problem is the lower hose connection is on the wrong side.

I have a radiator spreadsheet at work that I could use if you want me to plug in a particular radiator. Need core dimensions, number of cores, fin size and spacing, tube size and spacing, and altitude. I can just plug in 1000 ft for altitude, guessing that would cover most tracks in US.

senior_squishy

Right, so I'm guessing it will be up to those of us using that rad to figure out the plumbing for it 🤔

senior_squishy

So this will allow us to remove the stock heater valve that is inline with the core, and use this as like a junction from the back of the 07k to the heater core and radiator, correct?

vt951

We actually found a pretty good setup for Mikes car using formed hoses from Autozone. I believe we still have all the stickers on the hoses so we can share the part numbers to save you some time. Now I just have to remember to get those numbers next time I’m at PE!

vt951

Sort of... Two ports on the h-valve get connected to the heater core ports in the firewall, one gets connected to the smaller of the two large barbs on the rear coolant flange, and one goes to the bypass pipe coming out of the thermostat housing. We will document all this when we put my car together.

Cjar

Good to know the 951 can handle 400 no problem. Any data we can put to use is helpful. I have not found any good off the shelf option with cooling ports both on left aside from the Griffin that V2 suggested. If we can get the cooling performance from an available 951 rad (wizard, etc.) I think plumbing one long hose is a good trade off to save a few (or many) hundred bucks.

Any idea how the coolant flow rate of a 951 compares to a 07k? If the 07k is considerably higher then we have a head start there.

senior_squishy

That would be great!! I was not looking forward to forming my own hoses 😅. Did they all mock up nicely with no adapters?

senior_squishy

Okay, I think I understand now. So at the very least I might be making a bracket to hold the H-valve in place so the cable doesn't just push the thing around under the hood? Or maybe the hoses will be stiff enough to hold it in place...

RoyaleWithCheese

I have been running a Davies Craig electric water pump and controller on my 944 engine for a few years now. If possible I would like to keep that setup on the new engine as I have had zero issues with it.

From what I can see I will need to create a block off plate for where the water pump bolts up, remove the thermostat, and cap some ports on the thermostat housing and port on the rear of the engine to cut off the engine-only loop so that it will always flow through the radiator.

Does anyone see any issues with that? Removing that and the heater loops from the equation looks like it should simplify things quite a bit for me in terms of coolant piping. Another benefit is that with no power steering, AC, and water pump it looks like the only thing left that's belt driven is the alternator so hopefully it has a tiny bit less parasitic loss.

senior_squishy

I'm guessing the reasoning for the stock 944 engine water pump bypass was the inconsistency of the 30 year old technology. I don't know much about the 07k water pump, but 30 years vs 5-10 years is enough put any worries of mine to bed.

I've read some articles showing the load from the alternator compared to the power requirements for turning pulleys is negligible. Meaning, belt drive power loss is comparable to the power loss from the added load on the alternator. On that note, if an electric water pump works for you, by all means go for it. Sounds like you've got it figured out

Cjar

I am leaning toward this setup as well. It’s not necessarily more efficient, but does give good flow at low RPM when needed at high loads. I also wonder how well the stock 07k pump flows, as the TTRS has a pump that is quite a bit larger. I like the idea of only one level of belts, since I don’t have power steering a 2-row idler just to run the stock water pump and alternator seems like extra work. The electric pump will double as an after run pump, so that simplifies the plumbing.

For no heater you probably can do away with the stat and just run the Davies Craig pump controller. If I went this route I was thinking the thermostat housing could be replaced with an adaptor and use an inline stat, like from a BMW 2002tii or Mustang. I want to keep some minimum level of flow so my heater works and keeps the turbo from becoming a hotspot.

RoyaleWithCheese

Ya I originally did it for reliability on the 944 engine. I had my original pump seize up and luckily saw the car was overheating before the belt burned through on the pulley. I have driven it with the electric pump in weather ranging from 30*F at high altitude in Colorado, up to sitting in traffic in 115*F in Vegas and it has always handled it just fine. If I lived in a place that wasn't 70+ all the time I would probably get a size down from the pump I bought since it takes a while to get up to temp when it's cooler out.

I never expected to get much, if any, additional power from swapping to it but the simpler belt routing, coolant line routing, and low rpm flow make it nice to have. One of the best features is that the controller keeps the pump and fan running for a few minutes when you shut the car down to prevent heat soak which is nice after running it really hard.

Cjar

Which model pump do you have?

RoyaleWithCheese

I have the aluminum EWP115. It looks like on their site that it is the recommended size for a 2.5L so maybe I was wrong about going a size smaller if you live in a cooler climate.

I do have an old model of controller and I think the new ones have much better control over the pump. My controller is basically an on/off switch and pulses until the engine is warm and then runs continuously. It looks like the new models have variable speed control and better temperature management so the warm up times I'm seeing in cold weather are probably less of an issue.

V2Rocket