If timing is supposed to help so much with egt's then why are people that are towing with the TST having to run at such low levels. I did a search and even people running 1x2 and 2x3 are having to watch egt's. I'm not trying to start an arguement since I'm considering one also, just trying to understand since I tow heavy ALOT. What HP and TQ would these compare to or equal in other boxes?

-Richard

 

It's simple-- the TST adds a LOT of fuel. All the timing in the world won't magically conjure up the air needed to burn the fuel.

If you have high EGT because your fuel is STILL burning on exhaust, then maybe timing will help a little.

But if you have high egt because there's not enough air, the timing will only help a little bit at certain rpm.

justin

 

I've towed several thousand miles with my TST, some on 2x2 and 3x2. The max EGT's I've seen with 2x2 was 1050, 3x2 was 1150. These were at fairly low altitudes and on a hot, humid summer day.

I did a neet experiment going up a long steep hill where I had it on 1x2 floored and noted the EGTs (950), then switched to 2x2 and the EGTs went to 1050, then switched to 3x2 and watched the EGTs go to 1150. On the 1x2 I could just maintain my speed, on 2x2 I gained a few mph, and on 3x2 I was still accelerating when I crested the hill.

I do have a 4 inch exhaust with a high flow muffler and the Home Depot air box mod. I put my gauges in shortly after I installed the TST so I don't know what my EGTs were pre-TST, and pre intake/exhaust mods.

 

So what will push the temps to the 1250 limit? 4x2? 3x3?
Back to Gypsyman's question, what kind of HP and TQ improvements is the box giving at these levels?

 

why is there a 1250 limit when we all know in stock trim the truck pushes 1300 to 1350? I am sticking with 1300 all day...

 

I read a post on here the other day where a guy ran a test with his 03 HO truck. The truck was stock except for the guages he installed. Towing hard up hill the truck would reach 1160 MAX and then the truck would de-fuel to keep it there. Another post said the pistons start to "melt" at 1250. Not sure what he meant by that - maybe the metal starts to fatigue due to overheating at that temp. So I dont know about running 1300 all day- maybe short burst.
Maybe a metallurgist out there will chime in.

 

If you live above sea level, you will see an increase in EGT. Compound that with the size of our mountains out here...11% climb at 11,000 feet with a little wieght or a lead foot and you can easily see temps above 1300. Heck..make it a 100 degree day too!

Pistons are cast...my guess is there melting point is over 2000. Weaker alloys of aluminum melt at 1300 or so, cast iron is around 2300, low carbon steel is 2500, stainless is above 2600, chromium is 3000, and straight carbon is over 6000. So depending on the exact alloy of the piston, we are safely above 2000. Most metals become harder after heat tempering, but can become slightly more brittle.

 

That motor doesn't have some of the new oiling passages and other refinements that the new 600 motor has. People with only gauges have seen 1300+ on their 600's in stock form, so I really doubt that's much of a problem. I plan to use 1300 as my "safe zone" number when I start modding... oh yeah after I get another truck heh

 

My truck would go just over 1300 going through mountain passes. Needless to say, being a wimpy SO, I have driven for miles through the passes with the pedal to the floor and pyro at 1300 or above the whole way......stock.

 

I was wondering where the 1250* figure came from also. Did some checking on the web and all of the sites that I found state the melting point of Aluminum as 1220* !!!

-Richard

 

What are these new oiling passages that the 600 has ion additon to what the 03/04 HO engines have? i'm aware the HO trucks have more oil passages for cooilng the piston bottom ends over the SO engine.

 

Yeah, AK, that doesn't surprise me. I think the ~1250 numbers are conservative and carried over as a 'better safe than sorry" number from older gen motors that ran cooler in stock form. I'm sure as EPA requirements and demands for more power in stock form have required higher EGTs, Cummins has taken whatever means neccessary to make sure their motors remain reliable in a muriad of real-world conditions. Honestly, we'd probably be OK using 1400 as a safe pre-turbo number on the later models, but it might take a while for me to "not care as much" about the longevity of my hard earned $40K toy... so I'll keep the better safe than sorry mentality. Looks like twins will be the only way to get in the ~500HP range with towing in mind... I better start saving now... or maybe in 5 years when the beast is paid off.

 

But our pistons aren't Al. They're an ALLOY... not sure exactly what alloy although I think it's been mentioned on here before... but I'm positive the melting point of our pistons is well above 1220F.

 

I meant to add that I wish I knew for sure what the true make up of the components we're worring about is. Got cut short by a phone call. Anyone know for sure...

-Richard

 

Hmm.. dunno exactly what they're made of, but maybe you can ask these guys