I am wondering about making a couple of mods to my H2 and wonder if it will really make an appreciable difference or if I might be better off leaving well enough alone.

1) Coolant Bypass Kit (tube) - $19.99

2) 172/178 Degrees High Flow Thermostat - $69.99

I know, I sure am jumping in head-first. Just call me Mr. Risky!

Ed

I am wondering about making a couple of mods to my H2 and wonder if it will really make an appreciable difference or if I might be better off leaving well enough alone.

1) Coolant Bypass Kit (tube) - $19.99

2) 172/178 Degrees High Flow Thermostat - $69.99

I know, I sure am jumping in head-first. Just call me Mr. Risky!

Ed

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TheGoodHummerMan:
I am wondering about making a couple of mods to my H2 and wonder if it will really make an appreciable difference or if I might be better off leaving well enough alone.

1) Coolant Bypass Kit (tube) - $19.99

2) 172/178 Degrees High Flow Thermostat - $69.99

I know, I sure am jumping in head-first. Just call me Mr. Risky!

Ed<HR></BLOCKQUOTE>

I did the coolant bypass on my new Corvette. I doubt you will feel the difference but in theory it makes sense.

----------------------------------------------------------
2002 Vette; Vortex Intake, Vortech S/C, Stage II heads, comp cam (220/220/114/.581), 3.90 gears, 14 inch cross drilled rotors, 170 stat, NGK TR6, B&M Ripper Shifter, Autometer Boost & Fuel pressure gauges on a-pillar, Hotchkis Sway Bars, HRE 543 wheels (F:265/35 R:295/35), Z06 titanium exhaust, RK LT headers, Magnaflow x-pipe, Programming by Morgan Motorsports, 5% tint, AA Frame & Rocker Savers, TB Bypass, Lowered 2", Custom Audio;570 RWHP Dyno Here

2003 H2; 37 inch tires, Manik Off-Road pkg., Airaid Intake, Custom Audio

Yes they do work, but not you're not going to feel a difference. The difference is minute, only a few HP.

-Grim

2003 Sunset Metalic Orange H2 - Breathless Stage 2B, HID's, Gobi Rack & Ladder.

2003 Millenium Yellow Z06

I was wondering if reducing the engine cooling system's operating temperature by 14 to 20 degress would actually have any affect. Since the engines were designed to operate with the coolant at 192 degrees --- does dropping this temperature by 7 to 10% really help prolong engine life?

I remember back when it was common for carburated engines to have 160 degree thermostats and now these have been increased to 192 degrees. Maybe for a good reason?

The more I think about it, the more I think it might be a waste of time, effort and money to bother with these mods. Unless someone has something else to add?

Thanks, Ed

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> I was wondering if reducing the engine cooling system's operating temperature by 14 to 20 degress would actually have any affect. Since the engines were designed to operate with the coolant at 192 degrees --- does dropping this temperature by 7 to 10% really help prolong engine life? <HR></BLOCKQUOTE>

NO!

Think of it this way ED.

Temp is only an indication of how hot the coolant is. Heat is measured in BTUs (1 BTU is the amount of heat it takes to raise 1 pound of water 1 degree farenheit).

Now your engine still makes the same amount of heat from the combustion process and you are passing a lesser amount of heat to the cooling system because you are not heating the coolant to as high a temp. So where is the extra heat at? You guessed it... still in the engine block.

However, in theory you should make more power because you are not passing as much heat to the intake air passing through the intake manifold, thus a denser intake charge.

Don

Don,

But why then does the ad on the Breathless site state: "Prolong engine life and increase HP by lowering you engines operating temperature " Oh, maybe to aid in selling these things?

The way I see it though, which might be all wrong, is that the lower range thermostat simply allows the engine's coolant to recirculate more rapidly whereby it is cooled more by the radiator, thus actually reducing the engine's (latent) operating temperature.

As I recall, British Thermal Units (Btu) is the precise measurement of energy required to raise the temperature of 1 pound of water 1 degree Fahrenheit when the water is near 39 degrees Fahrenheit.

The engine's coolant transfers the excess energy created by the engine during the combustion process and then re-transfers it from the coolant into the air while being pumped through the radiator...

The thermostat simply controls the flow rate of the coolant through the engine and radiator, which determines how much "cooling" is achieved?

One other thing... If the heat is still in the engine block, why would the intake manifold be cooler?

Maybe this is just way beyond my inferior abilities? It has been a LONG time since I studied physics... Don't judge me too harshly!

Ed

Ed...

I will agree with you that the lower thermostat will reach full coolant flow sooner, but both will reach full flow. I have seen demonstration in cooling system seminars where temp readings were taken on the sides of the engine block. The higher temp thermostats actually yeilded lower readings on the block. Same vehicle, same day, the only difference was we changed thermostats. Why?

As for the intake manifold, without the coolant bypass tube I doubt it would be cooler if the block is hotter.
Don

[This message was edited by Hummie2 on 06-03-03 at 08:10 PM.]

One of the reasons the manufacturers run the higher temp is to reduce emissions as it helps cook it away. I have always changed my thermostat to a 160 because it just lets more coolant flow. I did the bypass I believe it is a 1/4" tube. I did mine for about 3 bucks. My t-stat came of the previous Yukon XL. I bought it for 50 bucks online.

Black H2 Adventure Series+ all other options.

Todd...

The flow rate will still be the same ( given the same size opening of the thermostat). Both will flow at full flow when the coolant temp stabilizes at the operating temp of that particular thermostat. The lower thermostat will reach full flow sooner, but you are not rejecting as much heat from the engine as you are not heating the coolant as hot.

Don

I understand what you are saying. I just need some time to absorb it. Tell phyllis hello, I got distracted with a nephew and my wife and did not see her the rest of the day.

Black H2 Adventure Series+ all other options.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Hummie2 said: "I have seen demonstration in cooling system seminars where temp readings were taken on the sides of the engine block. The higher temp thermostats actually yeilded lower readings on the block."<HR></BLOCKQUOTE>
If you go to "cooling system seminars" I think I will just shut up and listen to you! Your description doesn't make any sense at all to me though. I thought that the higher temperature-range thermostats restricted coolant flow resulting in higher coolant temperatures. Something has to be happening to cause the coolant to be cooler? If not increased flow, what is it?

TBarrow: Thanks much for the comments! A 1/4" tube and a couple of clamps... Ka-ching! Strange that your Yukon XL had a 160 degree thermostat... I am a REAL sucker for "If a little is good, a LOT is even better". Why go with a 172/178 degree thermostat if I can get a 160 for less money?

Thanks a lot guys!

Ed

It is actually a hypertech part.
http://www.hypertech-inc.com/powerstat.html
The part fits the 4.8 / 5.3 / 6.0 motors.

Black H2 Adventure Series+ all other options.

Guy...

Its been a while since I have been to the seminars and I also didn't believe the hotter thermostats would result in better cooling when I was first asked the question. We made temp crayon marks all over the block and ran the vehicle on a dyno with a 195 thermo. Next we changed the thermostat to 160 and ran everything the same, the crayon marks melted and ran down sides of the block with the lower temp thermostat.

Todd, Phyllis says she understands. It was a busy day indeed. Hopefully we will see you at some other events.

Don

You will see us at other events for sure.

Black H2 Adventure Series+ all other options.

Great, while surfing the `net I came across a site that said that running an engine with a computer set for a certain temperature would get REDUCED gas mileage if the temperature range were lowered because the engine would run too rich.

Now what the heck is THAT all about?

If the computer is sending a set amount of gas into the engine based upon an expected temperature range, how would reducing the temperature REDUCE the mileage? I can see where it might be possible (MIGHT) to reprogram the computer to get increased fuel economy, but not how it would hurt just to lower the engine's temperature?

I am getting a headache.

Ed

Ed...

A lower operating temp might give cold enrichment fuel setting. The computer might be fooled into thinking that the engine was't warmed up yet.

Don

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Hummie2:
"...the crayon marks melted and ran down sides of the block with the lower temp thermostat.'<HR></BLOCKQUOTE>

I guess theory is all fine and dandy, but your description seems to PROVE the fact. I don't understand electricity either, but I don't doubt that it exists.

Thanks, for your patience, Don.

Ed

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by TBarrow: "It is actually a hypertech part."<HR></BLOCKQUOTE>
Do you have a Hypertech Programmer? Do they make it for a Hummer H2's 6.0L engine/transmission?

Hypertech states emphatically that lowering the thermostat temperature range results in lower engine operating temperatures.

Something is fishy, huh?

Ed

Ed...

I agree there seems to be a contradiction of information somewhere.

The information I based my statments on came pretty early on in a week long class presented by AC Delco and after that demo they had my full attention for the rest of the session.

Their position was all things being equal (ambient temp, load, fuel rate etc) reducing the operating temp of the coolant by going to a lower thermostat did not result in more heat being rejected by the engine. It did,however, result in more cooked seals and gaskets as well as increased emissions.

A poor old mechanic don't know who to believe anymore, but if I can't feel a performance difference in the seat of my pants, why bother with changing something that was engineered to perform to a certain standard.

Sorry, I didn't mean to start a big controversy, but only to pass along some info that was presented to me a long time ago.

Don

[This message was edited by Hummie2 on 06-04-03 at 07:45 AM.]