ABOUT: Lower Compression Pistons

 Lower compression pistons were tried in later model GM 6.5 in an attempt to lower piston temps and reduce pistons from 'grabbing' the cylinder walls when hot. For a manufacturer or engine builder it is easy to change pistons you just change the ones you are using in the parts bin, for those of us with them already in an engine it's a lot more involved and to be done correctly an engine rebuild is required. The cost of such is prohibitive and even if you are doing a rebuild the prices are typically way over those of stock ratio pistons.

 I have found the best thing to do is to use water-mist-injection, this keeps piston temps down acts as an air-charge cooler and also helps to keep the combustion chambers and engine oil cleaner.

 We do not want to hear of more people falling victim to marketing 'scams' diesel pages or forums to buy over priced parts when they don't need to, so we tell you other ways IF you still feel you must lower compression, and this can be done other less expensive ways than the guys trying hard to sell you on their (or their friend's) pistons will tell you,

 TECH TIP: To lower compression in GM 6.2/6.5 Diesel engines, you can either use thicker head gaskets or if you are getting new pistons, get stock ones that have some material milled off the top, the small amount milled off will make little if any difference in the strength of the piston, however lowering compression should reduce power output and efficiency of the combustion process. 
 The higher compression that can be run safely without overheating and detonation then the better the efficiency and power output, the key is to keep things cool

  We do offer quality pistons and rings and have lower compression available, sometimes they take longer as they are not a popular item. 

 It is bar far more wise to keep your properly running engine together by using the water-mist-injection to keep it cooler  to help it stay together.

 Then BEWARE, another tactic of those pushing the low compression 6.5 pistons is to then push "splayed main caps"...

Our recommendations for cooling the GM 6.5 Turbo-Diesel What one website recommends as modifications for cooling the GM 6.5 Turbo-Diesel
Water-Mist-injection (WMI) $449.95, (plus tank avg. $75.00) 
Only basic hand tools and basic skills are usually required to install.
18:1 Low Compression Pistons $1000.00+ to supposedly reduce cylinder temperatures.
NOTE: Requires additional and very expensive engine disassembly, cleaning, machine work and reassembly. 
NOTE: Read Notes above about that product.

nothing else needed with WMI

Intercooler $1500.00+ to reduce intake are temperature (IAT) 
NOTE: requires a fair bit of mechanical skill and more than basic tools to install.
nothing else needed with WMI '97 cooling upgrades $325.00+ adds more flow to current system
NOTE: they recommend a gear-drive timing set at the same time. 
NOTE: requires a fair bit of mechanical skill and more than basic tools to install.
nothing else needed with WMI Gear drive timing set $310.00+ 
NOTE: requires a fair bit of mechanical skill and more than basic tools to install. 
nothing else needed with WMI Earlier engaging fan clutch $250.00+ 

WMI kit is Only $449.95 and tanks average about $75.00 in most areas.

TOTAL $3,675.00+ PLUS the added cost for expensive engine work to install the pistons.

 So as you can see from the above chart the site pushing products for GM diesels recommends a large bill of goods to reduce the cylinder temperatures and keep the 6.5TD running cooler, and then when your being sold on that stuff and need the engine work for the pistons you'll be advised to get splayed main caps and other nonsense you don't need and that can even be detrimental to the engine.  All that nonsense is recommended by them when one simply needs to use a quality water-mist-injection system to keep the 6.5 running cooler. 

Please Beware what you read at some so-called "information" or "resource" sites on GM diesels, often they sell the parts they're pushing, click here to read the WARNING.

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