Temp goes up to high as 206 only highway cruising. Local 188 190 ish after pull still staying 190 ish. Highway cruising 206 and do pull goes up to 212. But temp doesn't come down if I stop let it idle. Do I need better radiator? Just installed mishimoto 2 core rad. I have fully built ek hatch b18c turbo 600whp.
has mishimoto 2 core with mishimoto fan. New.
Also put 170 fan switch.. I also wrap manifold and downpipe... heak soak?

 

Check for air in your lines

 

This. Bleed the coolant system with the front end raised. For future good measure, consider making an air diverter plate. To help force air through the radiator and not around it. I made my with clear leaxn i had laying around.

 

Sounds dumb but also check the fan is blowing the right direction...i may have done that myself a looooong time ago and chased similar issues lol.

Wires were switched.

Wrap won't hurt but I would start with a shroud.

 

Sounds like heat soak to me. It sounds like you've already wrapped...add a turbo blanket if you haven't yet.

Which manifold are you running? The top mount tubular manifolds have a LOT of surface area. The more surface area on hot parts, the more likely you are to heat soak your engine bay.

Which Mishimoto fan - what is the CFM rating? I recommend upgrading to a Spal 30102029 that is 1328 cfm. Set it up as a puller fan (not a pusher) with a shroud, and ensure it's wired correctly.

Are you running it on stock wiring with the 15A fuse, or are you running it on a relay with large gauge wiring and a 40A fuse? If you upgrade to the Spal fan, you'll want to upgrade the wiring so the fan can draw all the current it needs.

What are the cooling protections set up like in your tune? OEM turns the fan off at anything over 35 mph. I recommend resetting this to having the fan come on at around 185F and stay on until the car is over 90 mph. This should keep it on for most highway cruising instead of just relying on forced cooling.

 

Overhead shot of the engine bay would be nice to see.

 

I’ve commonly seen coolant lines plumbed wrong cause this issue