Heat issues with bigger horsepower

GregAgrest · #1 (**permalink**) 09-23-2013, 04:23 PM

I'm going to change engines out, going from a 35w 350hp to a 351w 408 stroker, 515hp. Is this higher hp engine going to create lots of additional heat, create an overheating problem etc?? Would appreciate advice and experiences from those of you that have made the jump from mid to higher hp.

Greg

vector1 · #2 (**permalink**) 09-23-2013, 05:18 PM

Only if you run it hard.

RallySnake · #3 (**permalink**) 09-23-2013, 05:52 PM

I made a similar swap a few years back. Used a hydraulic roller cam and made lots of horsepower and lots of heat. So, at the same time I installed the engine, I also installed a triple pass radiator like this one: http://www.summitracing.com/parts/aaf-all30045

I had a couple of problems with overheating after that. The worst was because the intake manifold bolts loosened and allowed air to be sucked into the intake. I suggest that you use Indian Head Shellac to seal your intake gasket and check every so often to make sure they stay tight.

The other problem was caused by the thermostat being too small (only on a hot day). I had to find a larger one, I believe that I ended up with 15/16" hole.

I also found that water mixed with the most expensive Prestone antifreeze allowed my engine to rust internally. I flushed all that out and use 1 and 1/2 bottles of Redline Water Wetter and distilled water only. After I purged all the air out of the system, it stays cool unless I am creeping slowly, like in traffic.

My electronic thermostat starts the radiator fan at 200 degrees and is able to keep it there. I have tried to locate the temperature sensor probe for the fan switch in different places. I have found that the best place is near the outlet tube at the bottom of the radiator. If you put it near the input, it runs too much. It will even run your battery down if you don't shut it off when you park. At the outlet works much better and I actually wired it so it does not run when I turn the engine off.

These are lesson that I learned the hard way, I hope that they help you.

GregAgrest · #4 (**permalink**) 09-23-2013, 09:57 PM

Thanks for the info RallySnake. Which engine did you change from and what engine did you install?? Also, I already have a Griffin aluminum radiator. Any opinions on whether that will be adequate??

vector1 · #5 (**permalink**) 09-23-2013, 11:11 PM

I have a 351w and a 351/408, identical cooling systems. You are wise to correct any deficiencies now. I use the Stewart stage 4 water pumps and high flow thermostats. Their website has some good information. Idling and cruising around both engines use similar amounts of hp, higher rpm and acceleration is when the cooling system should see more heat.

RallySnake · #6 (**permalink**) 09-25-2013, 01:45 PM

Oh, I forgot to mention that the Redline Water Wetter absolutely stops rust.

RS

RET_COP · #7 (**permalink**) 09-25-2013, 05:12 PM

351w -HP in the high 400s and no heating issues. I did have to spin the Edelbrock Victor water pump a little faster to stop my temp creep at idle. I have a real good Griffin radiator and 16" electric fan. 180* temps

GregAgrest · #8 (**permalink**) 09-25-2013, 05:32 PM

Hey Ret Cop

Which Griffin do you have. I already have one. Its 26x19 dual pass I think. Am I close?

Greg

RET_COP · #9 (**permalink**) 09-25-2013, 05:57 PM

I believe its the muscle car radiator. Mine is 24 wide 20 tall 2.50 thk.
Like this
http://www.summitracing.com/parts/gr...-fxx/overview/