Bobczar

I recently came into possession of a 94 z28 and am not familiar with f-bodies or lt1 engines. My car has an issue with overheating with casual cruising. The car has a built engine with a single 66mm turbo. I know it has a high flow waterm pump (cam driven), water wetter, and propylene glycol coolant, and dual 10" pusher fans. I did notice however that radiator has plastic end caps so I'm assuming that is stock. What is a recommended radiator that I should install? Also, is there anything else I should do so I don't run tells of 230+?

Injuneer

Are you running the Evens NPG/NPG+ coolant? If so, water contamination has reportedly led to system corrosion problems. For some applications, Evans recommends a larger radiator.

http://contrails.free.fr/temp/ECS_Instructions.pdf

Radiator sounds stock.

Are the high temps specific to any particular operating conditions? For example, if the plastic air dam below the front bumper is not installed, temperature will start to climb on the freeway, the faster you go.

Where are the fan on/off temps set in your tune? Stock is first fan (or both on low speeds for late 94 production) on at 226*F, and second fan (or both on high, late production) at 235*F.

Pusher fans are less efficient than pull-through fans, but I assume you have space limitations behind the radiator.

What temperature thermostat are you running?

I'd be interesting in learning more about the "high flow water pump"..... have not seen or heard of one of those in the 20+ years I've owned my LT1.

Bobczar

Unfortunately the previous owner(a good friend of mine) does not remember which brand of coolant he is running, just that it is a 60/40 mix.

The car stay at about 225 during highway driving and climbs during city driving. <50mph

The car is tuned to have the fans come on at 160. It also has a hypertech 160 thermostat

The gauge is the stock gauge in the instrument panel

He doesn't know which water pump he installed but the only one I could find was the Tuff Stuff brand which pushes 30%(so they say)

I don't have much room to work with due to the turbo being so close. I plan to change water pump to the Meziere HD when I get time to tear it down along with a new radiator at that time. Until then I'm looking to see if I can lower temps so I can drive longer than 20-30 minutes. I live in Oklahoma and the weather here is 90+ degrees with heat index at 110+.

Here is the build of my car 94 Z-28 Turbo

Injuneer

A buddy of mine had a 97 30th SS convertible, with a Vortech S/C 383ci LT1, making 1,125HP at the flywheel. He used the stock water pump, the stock dual electric fans, and a BeCool LT1 aluminum radiator. He had no problems with cooling. My setup is only 800HP at the flywheel, but again, stock water pump, stock dual fans, and a Griffin LT1 aluminum radiator (by direct comparison, the Griffin was superior to the BeCool). No cooling problems. We both had outboard, fan assisted trans coolers, because both of us started with the M6 manual trans, and the radiators we bought did not have the trans cooler. Had to add the fan assisted cooler for the auto trans conversion.

The shop that built and installed the engine would not use an electric water pump, since they did not feel it provided adequate flow at max RPM/HP levels. I've seen some discussion on at what RPM the stock water pump runs into cavitations problems, but whether the shop modified the stock pump, or the cavitation problems were not there, the stock pump successfully cooled the 1,125HP engine, operating close to 8,000 RPM.

I would be concerned by the indication of a 60/40 "mix"..... mix of what.... PG/water, PG/EG?

With the 160*F t'stat, and the fan on temps set at 160*F, you are essentially running the fans all the time, since the t'stat only starts to open at 160*F.

Bobczar

PG/water mix is what is in it.

I figured it should be fine for city cruising with the stock radiator.

The only things I can think of is either hoses or that the turbo needs to have a blanket installed since it sits so close to the radiator.

I have done some research and I was thinking of getting the Ron Davis radiator. Stock dimensions as well as 18 fins per inch. Thinking the extra fins per inch will be beneficial since I'm running pusher fans. Correct me if I'm wrong on that statement.

Injuneer

50/50 EG/H2O has a higher heat transfer coefficient, maybe 8% better.

The problem with a pusher is it blocks the incoming air flow. Add to that what sounds like the close proximity of the turbo components to the back of the radiator, plus any heat the components are radiating, and air flow and cooling are going to be a problem. While more fins per inch increases the heat transfer surface, it also increases resistance to air flow. Hard call on whether it will fix your problem.

Is the back of the hood scoop open, allowing hot air to escape from under the hood, and relieving pressure buildup?

Are the pusher fans fully shrouded to the face of the radiator, preventing the air from flowing off the face, and not through the radiator?

Might be a good problem to post on the "Forced Induction" forum, to get input from the guys who are running turbos.