problem with overheatin

ive got a 91 camaro RS came with a 3.1 5 speed I converted it to a stock 350 with a 350 turbo ive installed a new radiator to fit a z28 so it should cool the engine. the electric fan runs constant but any time the engine is over 1800 rpm it tries to run hot. It runs cool in town and at an idle but you can be setting still or going down the highway and if you get the engine over 1800 rpm and im turning 2800 at 55mph. the temp starts to climb it has new radiator hoses and new thermostat help me out guys anything you can think of that could be causing this let me know

if anything it should actually be running cooler when youre moving.. do you have air dams that direct air through your radiator? no collapsing hoses, im assuming since you changed it..

ive got a 91 camaro RS came with a 3.1 5 speed I converted it to a stock 350 with a 350 turbo ive installed a new radiator to fit a z28 so it should cool the engine. the electric fan runs constant but any time the engine is over 1800 rpm it tries to run hot. It runs cool in town and at an idle but you can be setting still or going down the highway and if you get the engine over 1800 rpm and im turning 2800 at 55mph. the temp starts to climb it has new radiator hoses and new thermostat help me out guys anything you can think of that could be causing this let me know

Your posts would be easier to read if you used good grammar structure, but anyways ...

Does it have a power falloff while it's getting hot? If so, you could have an exhaust restriction, such as a plugged cat or bent/crushed pipe.

I so want to say there is no spring in the lower radiator hose and it's being sucked shut.