Planning upgrades to cooling system: need input

[pacificdrumma]

Okay so here's the deal. I am planning a center mount turbo build for my truck. I have been stockpiling parts such as exhaust manifolds from a van engine, and a 2nd gen Dodge intercooler. I have also stockpiled some cooling parts, Heath's super cool kit, and a new radiator. I don't plan on using my existing engine because it has blow-by, and I have seen it reach 230* twice, and I wouldn't be surprised if it has some catastrophic failure waiting to happen. So I will likely be looking for an engine and building it instead. I will keep my main build thread going, but use different threads like this for specific areas that I have questions about. That should reduce clutter in the build thread, and make specific topics easier to reference in the future.

The truck is a 96 and has a dual T-stat housing. I ordered the Heath kit for 96+ trucks with dual T-stats. One thing I don't love about the dual t-stat design is how much room it takes up around the IP. Part of my build idea requires making a custom intake manifold similar to a 6.4L powerstroke. This means there is gonna be a lot going on around the IP, and having a large dual t-stat housing would just be another thing contending for limited space. So I am thinking about looking for a single t-stat engine to use. My question is what would be the ideal setup given my situation, and the parts I have on hand? A single 190* t-stat, H.O. water pump, low-temp clutch, and H.D. fan?

 

[Will L.]

Same problem i have with fitting the dual stat in there. Hummer space is worse than pickups. Problem with the desired rare 96 crossover is that it is rare. I have been willing to drop $200 for one a long time now.

On the waterpump- you say H.O. -- get he spin on fanclutch waterpump, not a bolt on type. Best fanclutch is still Kennedy's, that is until Leroy puts hos 100% lockup electric on the market.
Then the dmax fan. It's the best set up out there.

 

[WarWagon]

What are you doing with the truck? Towing in any weather on steep grades is the worst case for cooling need. The other be going all out performance and then towing.

Your cooling system plans should include the exhaust and turbo because that's where most of the heat generated goes: out the exhaust. Restrictive high back pressure turbo's and mufflers can hold heat in the engine and raise the ECT making the power robbing cooling fan come on. The Spool Valve I added overheated conventional engine oil more than anything. (ECT was ok at the max of 210)

So if you are not towing IMO you should be fine with a single T-Stat. If all else fails on your build go dual T-Stat. I run the single towing in the 121 degree heat with the slow Rat-Rod build the 1993 became. Even the Spool Valve 1995 ATT build had the single T-Stat. Only the DS4 with the spool valve started exceeding what the cooling system could handle towing on a extreme heat day out here.

The charge air cooler your plans include helps keep the engine cooler as well.

Oil coolers for the engine and transmission also need consideration. The GM OEM engine oil cooler hoses can't even reliably handle normal 6.5TD engine heat let alone 4.3 V6 gas engine oil heat and were simply eliminated from the Duramax design with the cooler located on the engine with no oil hoses to harden and fail from the heat. Yeah, get better engine oil cooler hoses.

I respect what Heath has done for the 6.5 cooling system for research and fixes. However Kennedy's fan clutch is the only one that locks up at a lower temp. The delay in getting the obsolete spring thermal fan on is what causes spikes in ECT. Go full throttle and the ECT rise isn't going to stop till the fan locks in. This is why the lower temp thermostat and low temp fan clutch are a better choice.

Myself I run the 195 Thermostat as a winter thermostat, and, now that I don't tow so often run the 195 year round. The low temp fan clutch work well with both... But there is better technology out there. When the engine is cold and I need max AC getting a fan on to cool the overheating AC condenser is a challenge. The Spring Thermal krap simply won't do it with a cold radiator in front of it shielding the condenser heat from the fan clutch's thermal spring. Did I mention that I have blown up the high side of my AC system several times out here?

 

[pacificdrumma]

WarWagon, the truck rarely tows. I am not building it to tow, but I don't want to cook it each time I do. In my signature, you will see a couple items that you mentioned have already been addressed: 4" exhaust, S.S. oil cooler lines, and a Holset HX40 hybrid.

My main question here is, I want to eventually run a single T-stat, and I want to use what I can from the Heath kit I already bought... What t-stat should I plan on using?

 

[WarWagon]

I am saying there is a performance line I haven't crossed out there where dual T-Stats can become a factor. I never could burn all the fuel from a DS4 with the NA precups I had to work with. The Single T Stat restricts the HO water pump flow period. (Rare 1996 items I haven't tested.) Given the extreme temps here and hard use I gave mine the single T-Stat worked fine in combo with a 4 bolt HO water pump and KD fan clutch on a 180 T stat. (The OEM cooling system: 6 blade fan and low output pump went to the scrap yard attached to the engine it let scuff a piston.) So in context of where you live with summer temps below 100 and no major grades I suggest there is a larger margin of cooling to get you by with a single T stat setup.

 

[pacificdrumma]

To clarify, I am not proposing to use a 96 single t-stat, but rather a 92-95 engine with the factory single t-stat. I am confused where you say that a single t-stat restricts H.O. pump output, but that you run a single stat with an H.O. pump and it works fine? Your conditions are much more severe than mine btw.

 

[Will L.]

The theory goes :The single thermostat can't handle the volume of the HO pumps. So there is some pump cavitation to start with. The rare 96 with the block off recirculates the water through the engine rather than just stopping flow and causing worse cavitation. When the stat is closed. The dual stat housing flows more coolant than the single through the radiator.

If you have the rare 96, run it. Otherwise the dual stat does better than the other single stats.

 

[ak diesel driver]

there's actually more flow capable with 2 stats, more surface area. Whether it actually does has been hotly debated

 

[WarWagon]

I run a 1993 single and ran a 1995, both with HO water pumps. Couldn't afford a dual t-stat upgrade at the time and getting it to fit around the DB2 throttle/cruise bracket was another reason holding me back. I don't have a heater core restrictor at the t stat crossover that may let some of the flow out, but, I close the heater completely off in the summer.

Apparently by dumb luck the single T stat works for me. About the only non-bad-luck I have seen. Now GM disagrees enough to spend the money and put another part into production with the dual T-stats. GM doesn't do this unless they have to. And that's a period. Sometimes GM's testing gets it right and the results make it past the bean counters. I am not clear if GM did the entire cooling upgrade for 1996 with the 9 blade fan or if that came out later with the dual t-stat.

Consider GM never went back to a lower temp fan clutch. This changes the equation for me vs. what GM's testing had to work with.

The 1993 and 1995 single T-stats have built in bypass blockers on the thermostats themselves. Heath Diesel makes a flow restriction for the dual T-stat setup because the dual setup doesn't ever block the water pump bypass. (I question how well this bypass restrictor works during an aggressive engine warm up, but, another debate.) So dual t-stats not only can flow more they allow the bypass path to stay open for even more flow. The other side of the debate is the hot coolant return to the pump from the bypass always open isn't cooling the engine like a single stat housing that is putting 100% of the hot coolant flow to the radiator. (This be the reason Heath makes the restrictor.)

Yes, the only worse conditions than I get are found in the Desserts of Iraq combined with the tilted Hummer cooling stack.

So in summery I don't see a need to run a dual T-Stat setup.

 

[Will L.]

Fitting the dual stat housing is my issue also. Db2 with cruise is bad enough, but the van intake manifolds are hug and inthe way

 

[jrsavoie]

Same problem i have with fitting the dual stat in there. Hummer space is worse than pickups. Problem with the desired rare 96 crossover is that it is rare. I have been willing to drop $200 for one a long time now.

On the waterpump- you say H.O. -- get he spin on fanclutch waterpump, not a bolt on type. Best fanclutch is still Kennedy's, that is until Leroy puts hos 100% lockup electric on the market.
Then the dmax fan. It's the best set up out there.

I didn't know the 96 single stat crossovers were rare or desirable. I had access to a couple of them this year

Or are you just talking for Hummers?

 

[GM Guy]

@jrsavoie yes, the pickup/SUV application 96 single t-stat is desired for folks that want to run a single in the 96-00 trucks, as that s the only year to do it.

 

[jrsavoie]

@jrsavoie yes, the pickup/SUV application 96 single t-stat is desired for folks that want to run a single in the 96-00 trucks, as that s the only year to do it.

I sent a message to a guy that ended up with some stuff. But he's big on scrapping everything. Kind of annoys me

 

[Will L.]

I have $200 just sitting waiting for the rare '96- part #23500374. The casting number is on them. Not from any hummer btw. Hummers never had a good single stat.

In magic happy land, I would hack together 2 of them for massive flow and both having the blockoff to send all coolant back, and when open it could dump all the flow possible. Best of both worlds. Seriously thinking about making to inline housings that use two of these http://leroydiesel.com/products/ac-delco-195-tstat/
Tied in parallel. If I had a lathe still...

 

[n8in8or]

What about going with a universal inline thermostat holder and getting the bulky housing out of the way altogether? Here's an example of one. I have no experience with one and have no idea on the specs that you would need to make sure it would be sized appropriately, but I just wanted to introduce the idea....

https://www.summitracing.com/parts/wsn-500321/overview/

 

[FellowTraveler]

I have $200 just sitting waiting for the rare '96- part #23500374. The casting number is on them. Not from any hummer btw. Hummers never had a good single stat.

In magic happy land, I would hack together 2 of them for massive flow and both having the blockoff to send all coolant back, and when open it could dump all the flow possible. Best of both worlds. Seriously thinking about making to inline housings that use two of these http://leroydiesel.com/products/ac-delco-195-tstat/
Tied in parallel. If I had a lathe still...

This be what you want!

http://www.ebay.com/itm/6-5L-GM-GMC-CHEVY-6-5-DIESEL-COMPLETE-THERMOSTAT-HOUSING-PART-NUMBER-23500374/112281547283?_trksid=p2047675.c100011.m1850&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=20140602152332&meid=98755d35d4e94f90bc36cde880fab9ca&pid=100011&rk=1&rkt=2&sd=261242399611

 

[WarWagon]

I have $200 just sitting waiting for the rare '96- part #23500374. The casting number is on them. Not from any hummer btw. Hummers never had a good single stat.

In magic happy land, I would hack together 2 of them for massive flow and both having the blockoff to send all coolant back, and when open it could dump all the flow possible. Best of both worlds. Seriously thinking about making to inline housings that use two of these http://leroydiesel.com/products/ac-delco-195-tstat/
Tied in parallel. If I had a lathe still...

I fail to see the difference in this rare housing. Is the thermostat bigger in diameter? Sure the angles of the head to T-stat housing pipes are different, but, I still see the bypass on it that is blocked by the secondary thermostat valve when hot on the older models. Put a thermostat in the older ones without the bypass blocker for the same effect?

What about going with a universal inline thermostat holder and getting the bulky housing out of the way altogether? Here's an example of one. I have no experience with one and have no idea on the specs that you would need to make sure it would be sized appropriately, but I just wanted to introduce the idea....

https://www.summitracing.com/parts/wsn-500321/overview/

You have to be careful with alternate designs to actually get the hot coolant in the area to open the thermostat before it boils locally somewhere in the engine. The bypass keeps coolant moving in the engine, and most important, the warming up coolant is going past the thermostat wax container also heating it up. Note the bypass is just below the thermostat making sure coolant is moving past the thermostat wax container. I find the peak ECT is slightly higher if I block the heater flow off before the thermostat pops open for the first time during warm up - Usually stomping it for a 65 MPH zone. So any remote location of the thermostat has to be in the coolant flow to prevent ECT spikes from getting out of control.

Long time ago I attempted to put a thermostat kit on a 454 jet boat. It didn't have enough flow past the thermostat to heat the 160 thermostat before it got too hot and steam locked the cooling system. The second short lake trial had several bypass holes drilled in the thermostat. After listening to the 454 sound like a boiler for the second time the thermostat itself is in the bottom of a lake somewhere. What a waste of money that ill designed kit was.

One last consideration to cooling system design is "cold shock" from the cold coolant in the radiator suddenly flowing in. Shocking a very hot engine with cold coolant can contract the cylinder enough to scuff or seize the hot pistons because it simply runs out of clearance. (On a 6.5 this would first be the #1 cyl. due to the most coolant flow hitting that bank first.) Thermostats move gradually mixing the coolant at first making use of the bypass before going full open. it's like adjusting the hot and cold tap water to get warm to wash your hands. This warms the radiator up and keeps the temps from extreme swings. Modern cooling systems with the low mount thermostats are even more precise at temperature control keeping the temperature swings to a minimum. This precise temp control is done out of need for tighter emissions control and CAFE not concern for the wide temp swings itself.

The above bypass description with thermostat controlled bypass blocker is one reason I do like the single thermostat design over the dual T-Stat.

 

[n8in8or]

I fail to see the difference in this rare housing. Is the thermostat bigger in diameter? Sure the angles of the head to T-stat housing pipes are different, but, I still see the bypass on it that is blocked by the secondary thermostat valve when hot on the older models. Put a thermostat in the older ones without the bypass blocker for the same effect?



You have to be careful with alternate designs to actually get the hot coolant in the area to open the thermostat before it boils locally somewhere in the engine. The bypass keeps coolant moving in the engine, and most important, the warming up coolant is going past the thermostat wax container also heating it up. Note the bypass is just below the thermostat making sure coolant is moving past the thermostat wax container. I find the peak ECT is slightly higher if I block the heater flow off before the thermostat pops open for the first time during warm up - Usually stomping it for a 65 MPH zone. So any remote location of the thermostat has to be in the coolant flow to prevent ECT spikes from getting out of control.

Long time ago I attempted to put a thermostat kit on a 454 jet boat. It didn't have enough flow past the thermostat to heat the 160 thermostat before it got too hot and steam locked the cooling system. The second short lake trial had several bypass holes drilled in the thermostat. After listening to the 454 sound like a boiler for the second time the thermostat itself is in the bottom of a lake somewhere. What a waste of money that ill designed kit was.

One last consideration to cooling system design is "cold shock" from the cold coolant in the radiator suddenly flowing in. Shocking a very hot engine with cold coolant can contract the cylinder enough to scuff or seize the hot pistons because it simply runs out of clearance. (On a 6.5 this would first be the #1 cyl. due to the most coolant flow hitting that bank first.) Thermostats move gradually mixing the coolant at first making use of the bypass before going full open. it's like adjusting the hot and cold tap water to get warm to wash your hands. This warms the radiator up and keeps the temps from extreme swings. Modern cooling systems with the low mount thermostats are even more precise at temperature control keeping the temperature swings to a minimum. This precise temp control is done out of need for tighter emissions control and CAFE not concern for the wide temp swings itself.

The above bypass description with thermostat controlled bypass blocker is one reason I do like the single thermostat design over the dual T-Stat.

Great info and points WW. I think my posting was too simplistic. What I am envisioning is a remote thermostat system that moves the functions away from the physical location they are in right now, but maintains all of the function of the current crossover system. So it would likely end up being a bundle of snakes plumbing system or if not a bundle, it would be some hoses run to various parts of the engine compartment....all in an effort to keep everything working as a proper 6.5 thermostat system would as a 1 piece casting. It would take lots of planning to be sure. One possibility is that an oversized thermostat could maybe be used so you could get more flow through the thermostat, but with only 1 thermostat and not two. Or maybe 2 thermostats of different sizes and even different opening points could be utilized to create a system that opens more gradually (if that's desired). I just think that if some specific goals couldn't be attained with the existing GM bits, there may be options to make a thermostat system that meets all goals....even if that only goal is to not have a thermostat crossover in the way of a desired intake system. You are right though....it could be playing with fire so any of this would have to be done with a good understanding, a watchful eye and a willingness to abandon/change the design.

 

[ak diesel driver]

My understanding of the 96 is the actual housing for the stat is angled differently than the early ones and clears things such as db2 linkage.

 

[n8in8or]

I also forgot another cooling element that I think is often overlooked and has some real merit with our trucks: getting hot air out of the engine compartment or maybe just having air circulation through the engine compartment period. I think @Paveltolz did a good job of this with the hood louvers he installed. I think there is really something to the hot air being able to get out of the engine compartment. If the hot air can get out, then the cool air can follow in behind it through the radiator. Or maybe I'm not describing that correctly.....if the engine compartment is jammed with air from the grill already and can't get out so it's a relative high pressure zone, then it would keep new air from coming in through the radiator and doing the job of removing heat from the radiator. I really like the idea of hood louvers and plan on doing some myself at some point. I want to put them above the space directly behind the radiator and in front of the engine. In my mind that would be a high pressure zone in the engine compartment and a lower pressure zone above the hood, unlike the area below the windshield that is a high pressure zone. I also like the idea of outlets high and back on the fenders, though the path for the air wouldn't be as clear as the former suggestion. Also with where I have proposed putting louvers, if water drips in, I'm thinking it shouldn't be as harmful as water dripping directly on the engine, though yes, there would be some back-spray onto the engine from the fan. I think that would only happen when stopped or at low speeds as at road speeds there should be enough air moving through the grill to force water out of the louvers, not in. It's all just theory though.