dennis50nj

CyberGS

point 1: we agree that a high flow pump would NOT flow too fast, that's good.
point 2: I have some doubt, but assume you wouldn't lie and in fact have proven to yourself that your car runs cooler with a Tstat than without. I am willing to believe it tho' I have the exact opposite experiences. Also, I have to assume others, back in the day, found they had to run Tstats to stop the car from overheating or the lore wouldn't exist.

BUT, your link only serves to prolong the wives' tale, there is no proof whatsoever of the statement made of why having a Tstat keeps an engine from overheating. Instead, as you state for yourself, you "think" you know why it overheated and they, like yourself, are making statements but provide no facts to support the conclusion. I am not out to call you a dumby or anything like that, but everyone has limitations, and you don't know the fundamentals of thermal dynamics to actually draw an accurate conclusion. You have to assume things. I wouldn't have an clue how to replace my roof (hail damage so pending issue for me ) but I wouldn't assume or think I would know how to do it, let alone start telling others on a forum about houses how their roof "works" if you catch my drift.

Your conclusion is wrong, that's all, not the end of the world. Whether or not running a Tstat showed cooler temps on your car doesn't automatically equate to a reduction in flow or slower water speeds. It also doesn't mean I can assume it didn't work for you, again, I believe it did in your case. The "why it worked" is what is questioned.

My road race car runs the exact same temps whether I have a Tstat or not, the only difference is the transient state before it gets to constant temp - it heats up slower without the Tstat, so given I tend to run 20-30 minute session on the road course, I prefer having all of the water flowing immediately and the thermal mass to keep the car cooler overall while I am running it for those durations. By the next session the water is still pretty warm and gets to temp pretty quick, but it would with a Tstat just the same. When I run an enduro, it gets to the same temps and just stays there constant.

An efficient and well designed cooling system (like our modern cars) should not run any hotter with or without a Tstat, but without a Tstat they may actually run cooler due to not forcing the water to stay at a Tstat regulated temp. But if your car runs 220 degrees on the road course, it should do that with or without the Tstat, or your system is flawed. Period.

That old Mustang I mentioned actually ran cooler without the Tstat, the whole time it was the rad, but I had tried everything because of point 3 you made - I didn't have much money other that what I wrapped up in my love of cars (nor a degree, I sold that car a few months later to have money to go back to school for my ME degree) so without money nor knowledge of thermal dynamics, I tried changine the Tstat, three of them with different temp ranges (IIRC it was 195, 180 and a 160, the typical ratings you find in Tstats) because they were cheap, then I just left it out altogether. And I promise you, everyone told me that wouldn't work for the exact same "reason" you have stated, time in the rad. Once it was moving it would actually run cooler, like 200 on the freeway v. around 210 with the Tstats. All 3 Tstats ran the same temp on the freeway as well. It overheated at idle and slow speeds as I stated - no matter what I did including beating the steering wheel and begging it to cool down.

I have both a degree in Auto Mechanics and worked as a mechanic for years before I went back and got my Mechanical Engineering Degree - they are NOT the same thing, and having been surrounded by both groups of "pros"... the difference is mechanics assume they figured something out or assume to know something and engineers have to prove it. It is a big difference. Point is those guys on your link are mechanics that haven't a clue how the cooling system actually works to convect heat, all they know is what they have heard as an excuse.

Dan Wendling

I think we are getting pretty close to letting this thread die.

I do have one more point to consider.

Off the forum I had someone comment that there should be some caution on using a higher performance pump regards possible risk of damage to a heater core. The idea being that the heater core is not designed to support the higher flow rates and may become damaged at high rpm.

My view is that this is also a bit of BS. The pressure in the system is controlled by the pressure cap and since the fluid is not compressible the pressure throughout the system is the same. Higher flow makes no difference.

PS> My biggest issue now is that I have not found many aftermarket suppliers of a performance pump for a 2010 6.2L. Seems that the design changed between 2008 and 2009. The only source I have found is GM Performance p/n 19180610. Have not been able to find any data on its performance.

Anybody got a lead on a performance pump?

dennis50nj

just the EWP

glass slipper

While I agree with your stance in regards to the heater core rupturing with higher flow rates being BS, I would ask that you reconsider your reasoning. While the fluid is in fact incompressible, it does have resistance to flow meaning the pressure does indeed need to be different at different points throughout the system in order for flow to occur...unless you've happened upon a perpetual motion machine. The heater circuit uses much smaller lines which act as an orifice to the circuit protecting the heater core. The pressure cap actually sees the pressure on the inlet side of the water pump therefore it only limits the highest pressure at the lowest pressure in the circuit...not the highest absolute pressure.

The C4 ZR-1 LT5 DOHC engine is a prime example of too high flow rates causing problems. When designing/developing an engine, Lotus uses a 25 GPM/100 HP design criteria for the water pump which put the water pump at 100 GPM for the LT5. GM fought Lotus on many design points along the way but Lotus prevailed on this one. The L98 was no where near this number and radiators promptly started rupturing during development due to excessive pressures on the inlet side of the radiator. (It should be noted no problems occurred with the heater core.)

BTW, GM's solution was to design a bypass circuit in the cooling system where the thermostat doubles as a pressure relief on the inlet side of the radiator. At about 6000 RPM when flow/pressure has increased to a certain point, the thermostat begins to "close" and divert a certain amount of coolant back to the inlet of the water pump. This was not part of the engine and not the responsibility of Lotus...GM chose the cheap way out so they could use the same radiator as the L98. With that said, the design sucks but that was par for the course...GM had their hands in several other facets of the engine design/development and a lot of their decisions sucked. If GM had kept their hands out of it, the Corvette would have had a 500 HP engine in 1995...and that was from a 5.7L (although it is heavier than an LS7). However, there are plenty of NA 6.8L+ LT5s running around with 600+ HP on stock cams that idle so smoothly at 500 RPM, you could balance a nickel on the plenum.

I do have a few more links and more discussion I think dennis50nj may like but I don't have time right now. Hopefully this thread will still be open later today...

dennis50nj

that would be great Rich

CyberGS

glass - that's some interesting info to know. Whenever I upgrade a cooling system I do radiator first now, so I have never had, nor have I seen, any issues with blowing a rad or heater core. Again one of those things I have heard of, just haven't had that or seen it myself.

'Course my race cars haven't had heater cores, but have upgraded a few DDs with aftermarket pumps and not blown a core.

On the circle track cars I crewed for back in the late 90s into 2Ks we would run water pumps with similar HP/gpm values of 100HP/25gpm as that was a pretty known ratio for performance stuff. So many of the aftermarket belt driven race pumps would have low rpm flows around 30gpm but at 7000 rpm would have 125-ish gpm flow rates. Of course we had high quality radiators in the cars as well so never blew a core, and no heater core.

Dan - Haven't looked into any cooling stuff for the new Vette as I don't need anything yet - bone stock on this car thus far. When I go to a supercharger setup I will update the cooling system and be looking then, but I agree that Craig Davies pump is available for everything since it is an in-hose pump. I have talked to Craig a few times at big industry shows but haven't tried his pump... on my current race car I have a remote mount 55 gpm Meziere pump.

Skunkworks

Interesting thread... I agree with all of your posts. In theory more mass flow will always result in more cooling capacity, no ands ifs or buts about it (within reason and there is a point of diminishing returns). In practice there maybe exceptions as pointed out, but this does not negate theory. Pump cavitation, well poor design with high NPSH (net positive suction head), cooling cores bursting, again homework not done as pressure differential to attain XXX flow is somewhat straightforward.

On your supercharger project, you will find that intercooler blockage and changes to air flow path are two big killers. Car will pretty much run on fan with the exception of say 40+ MPH cruising. EWP most skip then on FI (forced induction), also your alternator maybe pushed over the edge in the summer.


Mike

CyberGS

Taking this a bit off topic, but that is good to know about the EWP... I wouldn't have expected GM to have the alt near maxed as is, because if adding that booster pump can pull enough current to tax the alt too much with A/C going, fans running, etc like a hot summer day, then GM didn't think that one through too well Those pumps don't pull that much current.

I am only looking to get HP back plus a little with the Vette I am down about 20% on power at my altitude here in CO, so I really only expect to get up around 500HP, maybe a bit more with a 599HP E-Force kit with smaller pulley so I will only be adding about 70HP over what others have stock at sea level. I may not even have to update any of the cooling system, but I hear you about planting the intercooler heat exchanger in front of the radiator and messing with airflow, as well as the temp of that airflow, to it.

Skunkworks

Well the E-Force seems to be a good kit and preserves factory air flow better then most. I have a centrifugal so results will vary a bit.

It's really not uncommon for supercharged cars to get service charging system (or something like that) messages, then also have AC issues. With the additional blockage to cooling stack and heat load, fan has to work much harder. Some upgrade alternator and don't laugh but some bump idle RPM +100 to cure this. In 95+ degree days my voltage can dip under 12V in heavy stop and go traffic.

Don't let this get you worried as it's a minor issue compared to return of being blown. AC, some remove a bit of refrigerant (I did not and only had hot air blowing once). Just get a good tune as this seems to be key to longevity.

Oh, stop by FI section if you have any questions as I don't want drag this too far off topic.


Mike

carpe dm

Yes! Moovy too fast no cooly.