EGT's towing light v/s heavy?

[NIsaacs]

Over the years when debating more power v/s EGT's, I have seen comments like; It might get hot on a hot day or with a heavy load.



Using my trucks for an example, they are all fuel modified but the power is usable. As long as I watch the RPM's I can pull hard, hot or cold, high or low elevation and light or heavy loads, I really don't see any difference.



What do you guys say, especially the guys with high HP that need to watch their right foot. Do you see any difference with the above scenarios.



Nick

 

[RVTRKN]

Do you keep your RPM's high when climbing heavy?

 

[Jim W]

I have a slight power increase that has been done to my 6. 7L CTD. I am using the Smarty S67, on CaTCHER level 3 version 23ME. According to Smarty web site this adds about 60HP to the truck. I also tow my 5er at this level and have done so for two years.

What I have notice is if I am going up hill in 6th gear and do to the slower engine RPM's and the engine working harder. The EGT's will rise to 1000F or better, do to less air flow. I will then down shift to 5th gear and the EGT's will lower in temp as the RPM's rise to 2000. Since the engine is turning faster and therefore the turbo is turning faster more air flow is occurring to cool down the EGT's. They will drop back to the 600F to 800F range.

Jim W.

 

[ewcmr2]

Ambient temp makes a big difference. If it's in the 30's or 40's I can pretty much use the power I have. In warmer temps I pull hills based on the EGT gauge.

Empty I don't need to watch EGT. Empty if I push the engine hard enough to have EGT problems I'm going faster than is safe/legal.

 

[CToney]

I notice a bit of a difference with outswide temps and egt. Also the same with rpm and egt. That 2000rpm seems to be the #. Also trannies don't like 1700rpm or less. I could hold the hill in od but usually downshift.

 

[Diesel Gunner]

Is your EGT probe pre or post turbo?



1000 pre turbo is no problem, post turbo your pre temps we be higher and may be running close to a point that you might need to be concerned.



As you can see in my sig my truck is older. I have EGT probes pre and post and always monitor pre when I am doing anything like work with the truck. With only an XZT+ I can easily reach 1300 degrees. I don't run it past 1200 though and then just use a lower gear and my right foot.



I also realize that the '08 can handle higher exhaust temps than my '01.

 

[NIsaacs]

Do you keep your RPM's high when climbing heavy?

Not really, 1600/2100 on the Ford, 1700/2300 '91 Dodge and 1800/2500 '01 Dodge. If I keep within those RPM ranges, I can bend the floor board with a heavy load. Any less or any higher RPM's and I get high temps.



Nick

 

[Midnite]

I also realize that the '08 can handle higher exhaust temps than my '01.

I'm not really up on the newer trucks--what does the '08 have where it can handle higher exhaust temps? Maybe a different kind of piston coating or something?

 

[AH64ID]

Not really, 1600/2100 on the Ford, 1700/2300 '91 Dodge and 1800/2500 '01 Dodge. If I keep within those RPM ranges, I can bend the floor board with a heavy load. Any less or any higher RPM's and I get high temps.



Nick

You have matched your fuel to your air. The trucks that get hot with a heavy load or on a hot day are pushing more fuel than they can cool. It all depends on how you build your setups. You can get more hp out of a turbo for non-towing than you can for a towing setup.

 

[ENafziger]

Towing the 31' TT loaded down with a GVW 20,300 lbs, I was limited to about 500 hp at high altitide. Even with the 62/476 twin turbos pushing a cool 52 psi constant boost, I couldn't keep EGTs cool on a sustained basis much over 500 hp. For me, I don't like to run pre-turbo exhaust temp at more than 1250° with the larger injectors and advanced timing.

The real issue with towing heavy at higher horsepower is the oil system. It seems that in extreme conditions (high altitude, warm temps, slow speed, etc), that the oil becomes too hot at a sustained hp of over 400 - 450. Of course, this is dependant upon the amount of timing advance you are running.

I had to pull over and let things cool down once when oil tempratures passed 260° F. I was running Amsoil HD 15-40 synthetic and probably could've pushed things harder, but I decided to err on the side of caution since I was 5,000 miles from home.

There are not many people that use high horsepower in sustained applications... and in reality, these engines just aren't designed for that. Even with my somewhat heavily modded truck, I would need a larger radiator, better oil cooling system with an external sump, and water injection to sustain a cool 500+ hp. However, while HP is fun, I've yet to see a need to tow with over 350 - 400 hp.

--Eric

 

[AH64ID]

I have always considered 400hp to be the peak of sustained towing hp, based on oil and cooling and its good to see that your data supports that. I agree completely that 350-400 rwhp is an excellent number for towing.

 

[HBarlow]

I'm not really up on the newer trucks--what does the '08 have where it can handle higher exhaust temps? Maybe a different kind of piston coating or something?

Actually, all Cummins B engines used in Dodge Rams since the '04. 5 HO was introduced have been able to run safely at a sustained 1400 to 1425* egt in factory stock condition. I don't remember all the improvements that contributed to the improved tolerance but improved valve and valve seat metallurgy were part of it.

Even the '01 HO/six speed I had was capable of 1300*. I always allowed it to climb long grades at 1300* with full throttle if rpm did not drop below 1600 rpm or egt climb above 1325*. That same truck runs fine today with 352,000 miles showing on the odometer. It still produces full boost and pulls strong.

Those engines are tougher than some give them credit for IF unmolested.

 

[Midnite]

Harvey--that's interesting stuff. Sounds like I'm pretty conservative with my 1250 deg. limit on my '00.

Eric--you raise a good point about oil cooling, and it's something I've been wondering about for a while now. I don't have an engine oil temp gauge, but I've been thinking about getting an oil cooler. For my truck, since I have a manual transmission I don't have the transmission cooler mounted in front of the radiator. I was thinking I could get one of those and plumb it into an oil line, perhaps the return from the turbo maybe. My thinking is that cooler oil might give a larger margin of safety. However, I just don't tow heavy, so the whole thing is really just academic for me.

 

[AH64ID]

Actually, all Cummins B engines used in Dodge Rams since the '04. 5 HO was introduced have been able to run safely at a sustained 1400 to 1425* egt in factory stock condition. I don't remember all the improvements that contributed to the improved tolerance but improved valve and valve seat metallurgy were part of it.



Even the '01 HO/six speed I had was capable of 1300*. I always allowed it to climb long grades at 1300* with full throttle if rpm did not drop below 1600 rpm or egt climb above 1325*. That same truck runs fine today with 352,000 miles showing on the odometer. It still produces full boost and pulls strong.



Those engines are tougher than some give them credit for IF unmolested.

The key word is stock. The reason the 04. 5+ trucks run so hot is the retarded ignition timing. It puts less heat into the cylinder and more into the manifold for emissions reasons. That heat is why the valves had to be upgraded. By no means can you run a truck with advanced timing at 1450* sustained and be safe!

 

[NIsaacs]

Eric, thanks for the info, I never thought about oil temp getting hot with high power. I don't have a gauge but I do use a laser temp gun when I tow and they never seem to get over water temp. AH always has good info, thanks.



I have been to numerous local dyno days and see 400/600 hp and 900/1300 trq and always wonder how they can tow with them. My oldest has an '06 with 437/1019 and can't use it with a load. I always tell him some day I will catch him when we are both loaded and I will spank him, that always gets him going



All three of my trucks have been on the dyno and show low hp but good trq. The Ford is 242/655, '91 is 263/708 and the '01 is 335/852. All have stock intakes, exhaust and turbos, but dang they will pull hard.



Nick

 

[ENafziger]

Eric--you raise a good point about oil cooling, and it's something I've been wondering about for a while now. I don't have an engine oil temp gauge, but I've been thinking about getting an oil cooler. For my truck, since I have a manual transmission I don't have the transmission cooler mounted in front of the radiator. I was thinking I could get one of those and plumb it into an oil line, perhaps the return from the turbo maybe. My thinking is that cooler oil might give a larger margin of safety. However, I just don't tow heavy, so the whole thing is really just academic for me. <!-- google_ad_section_end --> <!-- / message --><!-- sig -->

I wouldn't do it from the turbo drain... it needs an unrestricted path back to the oil sump. I think a better way would be to get a remote mount oil filter kit and put in the cooler in series.

By no means can you run a truck with advanced timing at 1450* sustained and be safe!<!-- google_ad_section_end -->

Exactly!!! While 1450° F is safe under stock conditions, advanced timing and larger injectors both give good reason to lower that limit significantly. In addition, with the air flow balance problem both on the intake and exhaust side, there can be a 50 - 100° deviation in cylinder-to-cylinder exhaust temp. I'd rather err on the side of caution!!

I don't have a gauge but I do use a laser temp gun when I tow and they never seem to get over water temp. AH always has good info, thanks.

I am measuring oil temperature at the filter head. Under sustained high hp loading, the oil temperature will exceed the water temperature significantly... by at least 20 - 30°, and sometimes more.

--Eric

 

[AH64ID]

I am measuring oil temperature at the filter head. Under sustained high hp loading, the oil temperature will exceed the water temperature significantly... by at least 20 - 30°, and sometimes more.



--Eric

I don't monitor oil temp (yet), but I do monitor pressure. My psi sender is above the ECM. On a long hard, hot (215* coolant, 1300* EGT) pull my oil psi will drop from 55 to 38-45, so I know its getting up there in temp.