I've read a few different times that the Subaru EJ20 is pretty easy to cool.

The inlet/outlet size from the motor is 1-9/16" ID. The Radiator I have is 1-1/4" ID. I have a bunch of 1" ID hose that I could use, but I'm wondering if there's a down-side to going a little smaller so I can make it fit through the tunnel easier. I upgraded the water pump in the motor when I got it so theoretically I'm pushing more water through the motor now.

The radiator I have is an all aluminium 2-pass out of a VW Scirocco, and it fits quite nicely. I have 2 fans that most would consider overboard for the application.

My question is: Can I get away with a smaller ID hose than 1"? I could adapt the 1-9/16" outlets from the motor down to 3/4" ID and then expand back to 1-1/4" at the radiator. This would give me a lot more flexibility in getting the hose through the tunnel.

So....what am I damaging/risking by going to 3/4" ID to get through the tunnel?

(Not saying I will....just weighing my options right now.)

My guess is that even with the pump upgrade you wont be able to push enough coolant though that length of 3/4" hose. I ran this silicone hose through the tunnel using the 1 1/4"ID w/ 1 5/8 OD to and from the radiator. It's a snug fit, but I only have one adaptor for the temp sensor on one end. Less connections reduce the chance of problems. YMMV
http://www.mcmaster.com/#silicone-coolant-hose/=rjs1yv

The Silicone tube is a good idea. That has a much smaller sidewall and I'll bet a little better at bending around the corners.

I just ordered 2 12' pisces. I'll let you all know how it goes. Should be here tomorrow morning so I can get that part all plumbed up in the evening. Tonight I need to finish the brakes.

The parts fairy just dropped off a box for me!

I'm going to run 1" through the car. If I need bigger later, I can work that out then. For now, this will get me rolling. Hell, 1" was enough for the V8 I pulled out of there.

Nice. FYI I just ordered 50 feet of 7/8"gates green stripe... WHY??? It was $30 which was the same as 15 feet by the foot. Figure a few people might need some and I could help 'em out. In case you don't like the fit of two 1" lines and the car is cooling well I can send you some to try. Should be here next week.

If 1" works, I'll just leave it in there.

The silicone 1" ID is quite a bit smaller OD than the 1" ID rubber I have now. I have a feeling this is going to work perfectly for my needs. I'll need to get a few pieces of 1" OD Aluminium or stainless for the 1.5" to 1" joints.

OK. I have to cal BS on this one. I'm a pisces and can tell you that NONE of us are 12' tall.


Did you buy an open box deal off of ebay? That's what I did and saved a bundle. Now get back to work on your car, Chris.

I did sir. If you need any you know who to call....Yeah I'm back at it!