Fluidyne Radiator

[Hib Halverson]

Originally Posted by A26B

(snip)
A more tangible topic would be discussion of the coolant flow restriction of the thermostat, relative to the rest of the cooling system, and how drilling 1~4 0.125" holes in the thermostat flange can result in significant results.

And a still more tangible topic would be what happens when you run an all-aluminum radiator (Fluidyne, DeWitts, Ron Davis, etc), bump the system pressure up to about 20 psi then either plug or greatly restrict the coolant bypass.

In fact, now that ole "Dynomite" bought my last Fluidyne, that's a great subject for him to test....right....Cliff? Cliff...are you there? Cliff...

[Hog]

Originally Posted by A26B

I don't think such data would exist as hard points for a 160F thermostat that would be relative to anything more than one specific test. Actual coolant temps will be affected more by engine rpm (pump curve & bypass valve), cooling system thermal transfer efficiency and ambient temperatures, than the thermostat.

The only given for the 160F thermostat would be that coolant temps would be above 160F, just as you stated.

Setting up the calibration for an open loop tune with 160F coolant temp could be done, but to what end? The conditions that would have to be present, cold ambient air (WAG~<45F), would restrict use to winter conditions. Besides, how will it affect combustion efficiency? How will it affect the tight clearances already built into the LT5 for 19F higher operating temperatures. Dropping to 160F is going to make them incrementally tighter.

So, for more real conditions of operation, wouldn't it be back to the open/closed loop system? If so, the range of coolant temperature begins at 176F on the low side and 195F on the high side with optimum cooling. How much performance gain will occur from only a 19F differential?

I think there is significantly more gain to be realized from cooler intake air temperature than 19F coolant temp.

In summary, the 160F thermostat makes for a good topic of conversation, but little else.

A more tangible topic would be discussion of the coolant flow restriction of the thermostat, relative to the rest of the cooling system, and how drilling 1~4 0.125" holes in the thermostat flange can result in significant results.

No one here is suggesting setting up a 160º open loop tune, or any coolant temp below any of the stock Closed Loop and Block Learn Temps.
Rather than seeing a straight up power increases from lower ECT's alone, I was thinking more towards the detonation resistance it may provide, but that is a moot point considering the excellent detonation resistance the LT5 head provides. I know this was a trick in some of the aftermarket calibration kits offered for the LT1.

Just enjoying the conversation.

Nice to know that these parameters are adjustable in the OBD1 calibrations as well.

Those extra 1-4 holes in the thermostat would lengthen engine coolant warmup times, I would guess. But if they help overall cooling, that might be a good alternative for some.

[XfireZ51]

Originally Posted by tpepmeie

This is editable in the calibration. I've done it. But why? You really want the coolant temp at 177* (80C) or above, unless you are looking for max power on the dyno.

Jerry said it, all the 160F talk is interesting, but not terribly relevant. I want my LT5 running >180F and <200F on the street. I think you'll find most other tuners do also.

As you say Todd, why do it. If desired, just run Open Loop. No doubt the 80C has its influence on emissions and provides enough heat into the motor to encourage fuel vaporization as it enters the chamber.
So the range of 80C to ~114(check me on that Todd) is the optimum CTS range for the ECM to LEARN and modify the base VE Tables through the process of the
INT(STFT) leading to the BLM(LTFT).

P.S. 114 is too high. I think it's more like 104C..

[Dynomite]

Originally Posted by Hib Halverson

And a still more tangible topic would be what happens when you run an all-aluminum radiator (Fluidyne, DeWitts, Ron Davis, etc), bump the system pressure up to about 20 psi then either plug or greatly restrict the coolant bypass.

In fact, now that ole "Dynomite" bought my last Fluidyne, that's a great subject for him to test....right....Cliff? Cliff...are you there? Cliff...

I am planting corn before it rains on Sun.....

My BIGGER issue was a Thermostat that was restrictive and started to open at 195 deg. And the Old Radiator it turns out had leaks on the plastic ends. Fluidyne is a very nice radiator and did not require shaving the internal fan shroud baffles. (The existing baffles were about 1/8 from touching the thicker Fluidyne.

I installed New Thermostat and also installed Jerry's New Heater Nipple when I had the thermostat housing removed (DO NOT ASK)

Anyway.....I did a run 87 deg ambient and temperature rose to 188 deg on Coolant System.....with a Fluidyne. That AIN'T BAD given before the Fluidyne and Thermostat temps rose to 213 deg on a 80 deg day.