Thermostat and Tuning question(s)

[mccartam]

I have a '05 5.3L V8. So far the only mods i've done are to install a 57 series K&N intake and a Magnaflow (kit 15794) exhaust. Other that that the truck is completely stock and it hasn't been reprogrammed. Admittedly i'm a newbie when it comes to the automotive scene, however after these two upgrades it seems that I have caught the 'mod bug'.

I've read quite a few posts about putting in a lower temperature thermostat. Logically it makes sense that running the engine at a cooler temperature would be good for it, but what does it mean in terms of performance for the engine? gas mileage? engine longevity? What are the disadvantages? What type/temp rating thermostat would you recommend?

Secondly, i've also read many posts talking about tuning the PCM. Again, i'm a newbie so I don't have a comfortable understanding as to the advantages of retuning other that if something is wrong it can really screw my truck up (not really a good thing as this is my daily driver). With the mods that I currently have is it necessary to reprogram the computer? If so, what settings need to be changed and what effect will they have on gas mileage, performance, etc?

[badassstroker]

With a lower temp thermostat you are going to gain a little power, i mean little because the engine is going to be cooler so the air and fuel mixture will be cooler. Cooler air and fuel means more can be packed in the combustion chamber. more fuel and air in the combustion chamber means a bigger boom which gives you more power. This will hurt your mileage a little bit.

as for if it is better for the engine or not i think it is a little better.

it helps a stock engine to get a re-tune. the factory is very conservative in their tune and does not tune it to run at its peak potential. since it is fairly stock i think you could get a internet tune to work pretty well

[redneck]

i thought 5.3 liter motors like to run a little hotter than most motors...also, if there is not many mods on the motor, no point in running a different thermostat but I could be wrong

[ice2500HD]

a lower temp t-stat is gonna hurt your mileage and make your truck run like ass, unless you get the pcm tuned for the temp change to take advantage of the cooler temps. As for the pcm go with justin at blackbear or nelson, westers or wheatley, all have outstanding reps with the chevy world and will help wake up your truck.

[MeanGreen95]

Get a tune before messing with thermostat. Your tuner may want you to change thermostats depending on the amount of timing added, type of octane the tune needs, etc.

[Atomic]

Dont waste your time with a lower t-stat unless you plan on running forced induction. These engines are designed to run at around 200, lowering that temp will shorten the life of the engine.

[badassstroker]

^^^^ how do you figure it will shorten the life of the engine? my obs 99 tahoe had a 160* in it and when i sold it the odometer read over 200k. same with my 92 buick regal.

[2500ak]

Lower temp stat will allow the tuner to advance the timing more with less occurrence of detonation. Engines that run significantly cooler than the intended operating temp may experience more wear, the metal doesn't expand to where it should. And anything lower than 180 can give you reduced heater performance if it is really cold.

That is my understanding at least.

If you're planning on tuning and your stat is bad or are planning on a flush then I'd switch it out. But if its working properly then it's almost not worth it. For some reason, probably emissions or something, they moved the stat to the water pump and removing it is really awkward and you loose a lot of coolant. Not hard though.

[Atomic]

^^^^ how do you figure it will shorten the life of the engine? my obs 99 tahoe had a 160* in it and when i sold it the odometer read over 200k. same with my 92 buick regal.

yea yea yea and my friend's cousin's uncle's brother-in-law's best friend has a blown 572 on the 4l60e with 100k miles with just a vette servo and never had a problem.

Fact is, on average it will shorten the life of the engine and the benefits do not outweigh the costs. Most likely you wont keep the truck around long enough to notice, or youll break something else before then, so I guess it doesnt really matter.

[2500ak]

Some engines don't take well to running cold, I recall hearing somewhere on jeepforum if one of those 4.0L i6's gets a stuck stat it will wear out 3x as fast. That happened to my roommates jeep, he drove it like that all last winter. Now he has between 0-3 psi oil pressure at idle, not much more at higher rpms. Running cold messes up the clearances, a lot of wear occurs during warm up and if it never warms up, its rather hard on it.

That said I don't think a 160 degree stat is going to be the death of your engine. These engines just prefer 180-195 stats.

[Atomic]

160 tstats usually run around 180 anyway. Cruising on the highway my temps are right at 190 with the stock tstat.

[mccartam]

Thanks for all the input. I'm not planning any other upgrades to the engine so from the sound of it it doesn't appear that I'd have too much to gain by putting in a cooler tstat.

I would like to explore the potential behind getting it tuned. How much does it normally cost to have a custom chip made?

[Atomic]

Where are you in alabama?

[mccartam]

Huntsville

[MeanGreen95]

Get a tune first. Justin at Blackbear Tuning can take care of you. From what ive seen his work is awesome.