Vortec Thermostat Experiment

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ralmo94

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. No reason to neuter the engine all the time for something that only shows up when it is hot. Also if you do not see a little detonation while dialing in the engine you either have the tune super conservative giving up power and efficiency or a dead knock sensor.
If you haven't yet, you could review your logs and make sure you a4 entering PE soon enough, just changing the thresholds a little might help.
On my 454, I still have the black box, so I am limited on what thresholds I have compared to the 0411, but reviewing closely my loggs while towing, I changed it where it kicks in when needed, only change gave me cooler hill climbs, kr disappeared, towing MPG stayed pretty close, but I think it actually improved, and it feels better.

If I remember correctly mine was set up for throttle and kpa thresholds, and you had to be past both to get PE.
 

Pinger

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In this context, Carnot efficiency is misleading.
As per L31MaxExpress's posts, the cooler the incoming air the denser the charge and the greater the volumetric efficiency. There is also a benefit from lower work taken from the crank during compression and a higher detonation threshold. All practical stuff.

Carnot is theoretical. The upper temp limit in IC engines is combustion temperature - broadly the same for all hydrocarbon fuels so limited there. The lower temp limit is atmospheric temp to which the working fluid (exhaust products) are expected to be expanded to to extract maximum work energy and therefor efficiency. Unfortunately, that final expansion to atmospheric temperature occurs not in the sealed cylinder but downstream of open exhaust valves where no work can be extracted (unless a further expansion device is employed - eg, turbocharger turbine).

The theoretical efficiency of an IC engine is a function of its compression ratio but this too is misleading. In reality it is the expansion ratio that matters as that is where the work is done. That the two are the same allows compression ratio to be cited as the arbiter - but only strictly true if inlet valve closing occurs at the same crank angle degrees after BDC as the the exhaust valve opens before BDC. Miller/Atkinson cycles veer from that symmetry to lower compression work relative to expansion work.
 

Pinger

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Incidentally, Ricardo's conclusion when he researched heat loss to coolant was that the proportion of combustion heat lost was not as serious as frequently imagined.
Heat lost to the cylinder wall was lower than most believed as the expanding gases were already cooling and in any case that far into the expansion stroke it was less exploitable. Where heat loss was critical was with the piston at (or around) TDC when the temperature was highest (not surprisingly) and, when the potential for expansion was at its greatest. Here though, we start to see the conflicts and compromises eg, to employ a higher compression ratio and use squish turbulence to resist detonation when that turbulence will promote heat loss (thinning of insulating boundary layer) and the charge trapped in the squish/quench zones may never burn and contribute to UBHC quite apart from not realising the power available from it had it been burned. The so called crevice volumes (include quench zones) may not appear voluminous but charge trapped in them is at compression pressure so significant fresh charge can be lost to them.

Also, and significantly, a large amount of the temp gain experienced by the coolant occurs as the exhaust gasses pass through the exhaust port heading for the manifold/headers. Obviously, there is nothing that could be done with this heat - it was wasted anyway. But that it appears in the coolant gives the impression that direct heat loss was the cause.
 

0xDEADBEEF

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In this context, Carnot efficiency is misleading.
As per L31MaxExpress's posts, the cooler the incoming air the denser the charge and the greater the volumetric efficiency. There is also a benefit from lower work taken from the crank during compression and a higher detonation threshold. All practical stuff.

Carnot is theoretical. The upper temp limit in IC engines is combustion temperature - broadly the same for all hydrocarbon fuels so limited there. The lower temp limit is atmospheric temp to which the working fluid (exhaust products) are expected to be expanded to to extract maximum work energy and therefor efficiency. Unfortunately, that final expansion to atmospheric temperature occurs not in the sealed cylinder but downstream of open exhaust valves where no work can be extracted (unless a further expansion device is employed - eg, turbocharger turbine).

The theoretical efficiency of an IC engine is a function of its compression ratio but this too is misleading. In reality it is the expansion ratio that matters as that is where the work is done. That the two are the same allows compression ratio to be cited as the arbiter - but only strictly true if inlet valve closing occurs at the same crank angle degrees after BDC as the the exhaust valve opens before BDC. Miller/Atkinson cycles veer from that symmetry to lower compression work relative to expansion work.

Thanks, I think I have a better understanding now.
 

yevgenievich

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I get considerable power differences 185 vs 200. Been playing with a tune to see if can get away with less timing reduction, but still feels more alive around 185
 

AuroraGirl

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The high flow a slightly larger hole in the center and thicker coils on the spring. When it is hot, the valve portion opens noticeably further than the standard stat. Otherwise, they look pretty much the same to the casual eye. Both have jiggle valves to bleed the air.
you do NOT want high flow in your coolant system. if your truck is having heat problems, you need to flush your cooling system with an aggressive flush and use a green coolant as apposed to a silicate free(for a while at least) and you need to get your radiator cleaned/replaced, and new fan clutch and ignition timing under control. your cooling system is designed to be sufficient and resistant cavitation by having flow restriction and pressure differential on each side of the stat. i suggest installing a bleeder valve in you t stat housing before doing mods outside of just refreshing components.
 

L31MaxExpress

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Adding flow IS what you want to do if you want the cooling aystems capacity to be increased. My cooling system has to shed nearly twice as much heat as the factory installed 350. I have a high flow pump as well that is more balanced bank to bank. The stock pump is just ugly in flow distribution. While it will get grannys 140 hp 305 wagon to the groccery store and back it has no place on a performance engine. Also my cooling system is new and it is clean. Green coolant will not be going anywhere near it. I ran Nissan Blue for years then with the 383 and new radiator switched to semi truck coolant. Both are far better at protecting aluminum. The semi truck coolant is actually better at transfering heat. It was designed to better withstand high temperatures found in diesels with water cooled EGR coolers. The engine in my 1980 Corvette did not even have a thermostat, just a restrictor ring. The car was never driven in cold weather so it was not a problem to run it that way. The water outlet angle on a Vortec does not trap air and the hose is uphill all the way to the radiator. I use a Lisle burping funnel to purge the cooling system of air.

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tayto

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I saw more consistent coolant temps going to a flowkooler "high flow" water pump in my squarebody w/ diesel rad. i also would avoid traditional coolant, the newer long life formulas last 5 years/100,000 miles. no brainer IMO.
 

Erik the Awful

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you do NOT want high flow in your coolant system.
Adding flow IS what you want to do if you want the cooling aystems capacity to be increased.
Both true for different reasons. There's a misconception that if you have too much flow the coolant doesn't stay in place long enough for the heat to be transferred to it. That's bad science. The heat is going to transfer to whatever coolant the hot surface is in contact with. The problem with flow comes when you pump coolant near its boiling point too fast, and the localized drop in pressure on the draw side of the pump causes it to boil. The water pump can't pump vapor, and it cavitates until the coolant cools down, changes back to a liquid, and can be pumped again. You get a temperature spike that can cause detonation.

This is also why manufacturers raised the cooling system pressures back in the '90s. It allowed them to run hotter coolant temperatures without cavitating the water pump.
 

AuroraGirl

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Both true for different reasons. There's a misconception that if you have too much flow the coolant doesn't stay in place long enough for the heat to be transferred to it. That's bad science. The heat is going to transfer to whatever coolant the hot surface is in contact with. The problem with flow comes when you pump coolant near its boiling point too fast, and the localized drop in pressure on the draw side of the pump causes it to boil. The water pump can't pump vapor, and it cavitates until the coolant cools down, changes back to a liquid, and can be pumped again. You get a temperature spike that can cause detonation.

This is also why manufacturers raised the cooling system pressures back in the '90s. It allowed them to run hotter coolant temperatures without cavitating the water pump.
as well as flow restrictors, such as reduced openings on ports in legacy designs (Like the old SBC thread in kind) or flow through brackets(like 3800 with plastic elbows) and of course thermostats themselves.

This is why I said you do not want high flow, no thermostat is just asking for cavitation and thus hotspots/boiling. The flow can be restricted without a thermostat, and then you would eliminate my concern. but these are more common on racing where they want to reduce drag and use propylne glycol from what I can tell, , so not spinning the hp on the pump against a thermostat but also cooling sufficiently in a WOT pull situation, from what i gather
 
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