So who has bumped the power on a 6CTA cummins

[Dustinbrwn]

Hello all,
New to the MV thing but picked up a M923A2 a few weeks ago. (still have to get the recovery thread going on that)
I came across this thread and wanted to give the fuel increase a go.
Bought a EGT probe and boost gauge with an auberins dual display. Got it all hooked up today and took her for a short spin.
My max temp was 1300! think max was around 1330 or so. that was pegged with a slight incline gaining speed. it gets up to 1100 pretty quick then climbs to 1300.
I checked the manifold where the probe is located (pre turbo) with a IR gun while idling and it was spot on with the probe. 500 to 550 or so.
My boost was showing 16 to 20 something at WOT but really wasn't paying attention to that.
I looked at the fuel screw cover on the back of the pump and it SEEMS stock. has one flathead screw and then one safety screw.
The truck throws a bit of black smoke while idling. Air filter looks clean. engine temp is around 190.
A few questions.
What are people seeing for temps with stock setup?
What could be causing the high temps, and what could I do to bring them down, if needed?

I do have a MG wix filter and basket mod on the way so I will see if that helps any as well and will report on that.
Tanks in advance!
Dustin

 

[4XDesign]

Hello all,
New to the MV thing but picked up a M923A2 a few weeks ago. (still have to get the recovery thread going on that)
I came across this thread and wanted to give the fuel increase a go.
Bought a EGT probe and boost gauge with an auberins dual display. Got it all hooked up today and took her for a short spin.
My max temp was 1300! think max was around 1330 or so. that was pegged with a slight incline gaining speed. it gets up to 1100 pretty quick then climbs to 1300.
I checked the manifold where the probe is located (pre turbo) with a IR gun while idling and it was spot on with the probe. 500 to 550 or so.
My boost was showing 16 to 20 something at WOT but really wasn't paying attention to that.
I looked at the fuel screw cover on the back of the pump and it SEEMS stock. has one flathead screw and then one safety screw.
The truck throws a bit of black smoke while idling. Air filter looks clean. engine temp is around 190.
A few questions.
What are people seeing for temps with stock setup?
What could be causing the high temps, and what could I do to bring them down, if needed?

I do have a MG wix filter and basket mod on the way so I will see if that helps any as well and will report on that.
Tanks in advance!
Dustin

Ive never seen any factory egt numbers. My truck is intercooled and I have the fuel turned way up with 4K Gov springs. I read a lot on safe egt and everyone claimed 1100-1150. I have babyed the truck to try to keep it that cool. All the time thinking the factory egt had to climb higher. I'm guessing yours is stock based on your observations. Oh and if you do a lot of work to the truck the factory air intake setup even with the MG mods is limiting. The pictures are what a friend of mine did to try to correct that issue after installing an intercooler on his 931. He has not tested it last I spoke to him.
Happy wrenching!

 

[74M35A2]

I have yet to do it, but advancing the timing supposedly lowers EGT. Member grendel has done so and claims some pretty cool numbers, even with wicked up fuel.

 

[Rmtaunton]

Where is G's thread on timing


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[Dustinbrwn]

I might give it a go without the air filter installed just to see if that helps any. I also forgot to mention that I do not have a muffler installed, just the straight pipe. (rotted out)
I have been trying to figure out the timing advance, but looks like without the proper tools its better to just take it in. I might go that route. As stated before on other threads, the motorhome sites have a lot of info on this.
I also might turn up the fuel a bit just to see if it does affect my temps much.
I am new to diesel engines, but it seems if I'm starving for air with the stock plumbing, turning up the fuel might actually bring the temps down?
let me know if I'm backwards on that!
Thanks

 

[nevrenufhp]

I might give it a go without the air filter installed just to see if that helps any. I also forgot to mention that I do not have a muffler installed, just the straight pipe. (rotted out)
I have been trying to figure out the timing advance, but looks like without the proper tools its better to just take it in. I might go that route. As stated before on other threads, the motorhome sites have a lot of info on this.
I also might turn up the fuel a bit just to see if it does affect my temps much.
I am new to diesel engines, but it seems if I'm starving for air with the stock plumbing, turning up the fuel might actually bring the temps down?
let me know if I'm backwards on that!
Thanks

Yes, that is backwards. More fuel is more heat, which can come down with more good air. Good being a decently cool charge. A big problem I've noticed is in the injectors themselves. The pressure is so low they basically inject like a pee stream, not a fine mist. That's just one of the variables to getting EGT in control, bu tone I'm quite certain will make a good drop in temp.

 

[Rmtaunton]

That's backwards


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[brakejay]

My max temp was 1300! think max was around 1330 or so. that was pegged with a slight incline gaining speed. it gets up to 1100 pretty quick then climbs to 1300.

I also have, what I believe is, a stock 8.3L 1990 M931A2. I have almost same EGT results. 1200+ easily on a long accel, touch 1300 on a slight grade, all unloaded. I was surprised. I'll be turning up fuel gradually. Interested in how everybody is keeping EGT in check.

 

[74M35A2]

Where is G's thread on timing


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It is just a mention, but he says 1100F. Post #61 on his "Fixed Wrecker Boom" build in 5t mod dept. Sorry my phone is not copying the link.

 

[Dustinbrwn]

I guess my thinking on the more fuel was to cause a rich condition, in which would hopefully bring the temps down. again, new to the diesel thing.
I did just turn the fuel up a bit (about 10 turns out) and took her for a short run. before my temps were around 1330, an now it peaked at 1400, just for a sec before I backed off and keep them under 1200. Boost was about the same, around 26psi. It didn't seems to help acceleration in first, but seemed to get up and start moving well once it started running through the gears, but again, at 13 to 1400.
I'm thinking about turning the fuel down further than what it was to keeps temps under control. I have a pretty good pull into town, about 10 miles worth and would like to know I'm safe.
Ill keep posting my results with temps and boost as I play around a bit more.
Thanks for the replies!
D

 

[74M35A2]

I guess my thinking on the more fuel was to cause a rich condition, in which would hopefully bring the temps down. again, new to the diesel thing.
I did just turn the fuel up a bit (about 10 turns out) and took her for a short run. before my temps were around 1330, an now it peaked at 1400, just for a sec before I backed off and keep them under 1200. Boost was about the same, around 26psi. It didn't seems to help acceleration in first, but seemed to get up and start moving well once it started running through the gears, but again, at 13 to 1400.
I'm thinking about turning the fuel down further than what it was to keeps temps under control. I have a pretty good pull into town, about 10 miles worth and would like to know I'm safe.
Ill keep posting my results with temps and boost as I play around a bit more.
Thanks for the replies!
D

With a gasoline engine, yes more rich = cooler EGT. Diesel is opposite.

 

[4XDesign]

It is just a mention, but he says 1100F. Post #61 on his "Fixed Wrecker Boom" build in 5t mod dept. Sorry my phone is not copying the link.

I can't find a shop that will touch the timing job. I would love to give it a try I just want to get someone else to do it first.

 

[74M35A2]

I can't find a shop that will touch the timing job. I would love to give it a try I just want to get someone else to do it first.

Bring it up, I'll do it. Trade you to mount my full size Volvo charge air cooler in my 925A2 like you did on yours.

I have not done the timing on mine yet, but I worked out the procedure and had others check it for approval. Read up here:

http://www.steelsoldiers.com/showthread.php?143521-Cummins-6CTA8-3-Injection-Timing

 

[Dustinbrwn]

So after re reading most of this thread, again, I decided to leave the full fuel screw where Its at, a bit less than stock and adjust the top fuel screw out a bit, as well as my governor springs in 3 clicks.
I have not gone for a spin yet due to my only road is a main hwy and its holiday traffic but, that thing smokes like crazy now! its just when I first give it throttle from idle, blows a cloud and then clears up. I actually turned it back in a bit. If I'm on the throttle just a bit, maybe 800 rpm and give her throttle its clean. So ill give her a few runs and see if I can live with it.
with the governor springs in 3 clicks I'm jumping up to around 26, 2700 rpm, then it settles down to 25 to 26.
So another question. Will running a bit higher rpm at WOT bring down the EGT above the stock 21 to 2200 rpm? After turning down the full fuel screw I did notice it was a bit more sluggish but my temps were still in the 1200 range.
I'm wondering if mine is a fluke or what, because others have been cranking them up all the way out with no EGT probe and have yet to hear of a failure. at least not reported here. I'm just wondering what temps they could be running at.
Ill try and get a run in tomorrow and report back on temps and boost again.

 

[Ford Mechanic]

So I just turned the rate screw, pre boost screw, and gov springs. I don't recall what the before temps were. So mine won't get above 1160F unless I'm lugging it. It will pull WOT up a grade as long as you keep the rpm above 1800 it normally runs 23-25 psi. Anything below 1500 rpm up a significant grade is lugging it, pull it down a gear. We just got back from the Graves rally, it's in the mountains. I had no problem up there, but I would drop a gear sometimes 2 if we were in grades to steep or if I just didn't have enough rpm. Now mine throws a big coal cloud if you slap the pedal to the floor but I cranked on that pre boost screw to get exactly that.

Rpm is key in my experience

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[4XDesign]

Bring it up, I'll do it. Trade you to mount my full size Volvo charge air cooler in my 925A2 like you did on yours.

I have not done the timing on mine yet, but I worked out the procedure and had others check it for approval. Read up here:

http://www.steelsoldiers.com/showthread.php?143521-Cummins-6CTA8-3-Injection-Timing

If Michigan were to change places with North Carolina you may have a deal. My truck is in a state of disassembly adding the sleeper/ pretty far back burner...

 

[Ford Mechanic]

Pre boost adjustment!

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[adamsoffroadperformance]

So far I have done the 4k springs, cranked the fuel, straight pipe, air cleaner baffle removed, Mrap radiator with top mount Intercooler, built a custom intake the get rid of the aftercooler, and the plumbing from the turbo to intercooler to intake is all 4" except for the short section of elbow coming off the turbo to the intercooler. The intercooler made a huge difference on egt's but I can still push them up if I'm cranking on it. I try not to get over 1250 on a hard pull. next step is 5" exhaust, bigger turbo, and bump up the timing. I'm doing the same mods to a buddies truck right now but it's getting the bigger exhaust and bigger turbo now.

 

[4XDesign]

So far I have done the 4k springs, cranked the fuel, straight pipe, air cleaner baffle removed, Mrap radiator with top mount Intercooler, built a custom intake the get rid of the aftercooler, and the plumbing from the turbo to intercooler to intake is all 4" except for the short section of elbow coming off the turbo to the intercooler. The intercooler made a huge difference on egt's but I can still push them up if I'm cranking on it. I try not to get over 1250 on a hard pull. next step is 5" exhaust, bigger turbo, and bump up the timing. I'm doing the same mods to a buddies truck right now but it's getting the bigger exhaust and bigger turbo now.

Do you have any pictures of the radiator intercooler?

 

[74M35A2]

So I just turned the rate screw, pre boost screw, and gov springs. I don't recall what the before temps were. So mine won't get above 1160F unless I'm lugging it. It will pull WOT up a grade as long as you keep the rpm above 1800 it normally runs 23-25 psi. Anything below 1500 rpm up a significant grade is lugging it, pull it down a gear. We just got back from the Graves rally, it's in the mountains. I had no problem up there, but I would drop a gear sometimes 2 if we were in grades to steep or if I just didn't have enough rpm. Now mine throws a big coal cloud if you slap the pedal to the floor but I cranked on that pre boost screw to get exactly that.

Rpm is key in my experience

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I'm surprised you can lug it. Mine does a forced downshift. I could not lug it at 1400rpm no matter how hard I tried. Maybe you need to adjust your modulator cable? Mine seems adjusted almost all the way out, but it shifts great like that, doesn't lug at all.