The heater hoses have a bit of a preformed shape to them. You can try to use straight rubber hose but it may cause a weak spot at any given crease point, depending on the type of hose you use.
Here's a little story of my experience with the oem heater hoses and heater core
- as my car sat dormant for years during the build, I had replaced nearly every oem rubber hose in my car to an alternate braided teflon, silicone or higher quality rubber item. I knew when the car got on the road I was still running oem heater hoses, the one-way check valve vacuum hose to the brake booster and also the power steering hose.
The first good hot day in Summer I had my car on the road one of the rubber heater hoses split at the clamp and left me sitting on the side of the road with some steam escaping out the bonnet... grrrr.... So out with the toolbox, cut the heater hose a little bit shorter, reatached it, got some water from a local resident in the street and off I went again. That was a good indicator that the oem rubber heater hoses had past their use-by date lol. I also didnt like the oem piece of **** plastic elbows coming out of the firewall from the heater core either so I wanted to replace those too. (later found out that the oem heater core was blocked from corrosion from sitting around for 8 years! - I know a lot of people dont think about checking/replacing them in long term builds so here's a heads up for you guys lol)
Anyhow, in the end I fit a larger EVO heater core, a pair of custom built longer stainless heater core elbows, and bought some 16mm ID wire reinforced silicone heater hoses to replace the oem ones. The wire reinforcement stops the straight heater hoses from kinking plus it adds to the strength and longevity of the hose. Its not cheap, but its reliable (I think it was about $40 just for the 1m worth of hose back then).
I felt much more confident taking the car out the next Summer and on a 30+ degree day drove from Newcastle to WSID in Sydney (over 170km each way), ran 10 passes down the track in stinking hot weather, then drove the car back home again. The heater hoses and core survived that test so they get a thumbs up of approval :thumbsup: . I used normal hose clamps at the time and it was fine, but I've since learned that for the wire reinforced hoses they recommend dual wire spring clamps as they fit between the reinforcement and hold hoses on better - so who am I to argue not to upgrade the clamps as well
You can be creative and spend a bit making custom pipes with AN fittings etc too.. hmmm.... why didnt I think of that back then? lol :lol:
