Cummins 6CTA8.3 Injection Timing

Updates?

Also what year was the volvo intercooler? Was it a d12 or d13

Nope. Spin your timing to 16 and let us know what happens. Too cold to do it here in MI right now.

Volvo charge air cooler that 4xdesign used is part number is 8181250. Used with a Detroit Diesel Series 60, but other engines also in the same chassis (WIA).

One thing to consider, increased timing causes increased cylinder pressure and temps. Also you can't gain without taking. You'll give up bottom for more top with timing changes. (But given the gearing it might not be a bad trade off)

74M35A2 said:

6CTA8.3 uses head bolts.

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Which can be replaced with studs, which can handle more cyl pressure. (Course the HG becomes the weak link.)

nevrenufhp said:

Yes, exactly. The head bolts make a distinct sound as they pop thru the hood.
I mean the cackle (clatter) as you hit the pedal from idle.

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You can get a rough idea of timing based on sound. But underway these trucks are so noisy that it might be difficult to hear them.

Given the mass of these vehicles, I'd rather adjust fueling than timing. But you'd certainly be safe increasing the timing a little in these trucks from the 8*.

Thanks for input and agree to all. Deep study of RV boards (same root engine) shows up to 16 degrees is safe for stock sealing architecture. I'm willing to try it, and will post results when it happens.

Need to consider you're making a apples to orange comparison. There's weight differences between an RV and MVs. As well as a greater difference in driveline mass.

I disagree 50%, but, let's see what happens. If it blows the pistons out the bottom of the pan and the head gasket is hanging out the sides of the block, then I will come crawling back with my tail between my legs. I don't think anybody here has done it yet. That is the exciting part.

Ive always seen truck carnage as forced upgrades. I just watched the timing video today, i might give it a try tomorrow. All the numbers kinda made my head spin tho.

patracy said:

Need to consider you're making a apples to orange comparison. There's weight differences between an RV and MVs. As well as a greater difference in driveline mass.

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Got to disagree with you on the weight of rv versus mv most of the rv's with an 8.3L are huge, no way they weigh less than my 931A2.

Good point about loosing power on the low end of the operating range when advancing timing. Maybe it's set to 8deg for emmissions, and advancing it won't have any negitave effect on performance.

Seems like a bunch of us have turned up the fuel rate, now we're going to move on to advancing the timing, next will be turbo and injector upgrades and so on. I'm thinking we have plenty of scattered motors amoung us by the summer, and will be discussing performance rebuilds or swapping in "bigger" power.

By the way, My old jaloppie of an RV outweighs my 923.

Yep yep. I'm waiting until I have my EGT installed, so we can actually quantify if EGT's are reduced. I also want to try to do a timed acceleration run on a marked or otherwise known portion of road to be able to have more than a "feels better" opinion. The RV guys says it really helped their fuel economy most, and then other add on's took better hold because the engine ran more efficiently.

To add to the bigger benefits of hiking up timing... #1, better mpg. #2, lower EGT. #3, less torque on the low end is less strain on the trans and ujoints. The trans will survive longer with more rpm.

Jason O said:

Good point about loosing power on the low end of the operating range when advancing timing. Maybe it's set to 8deg for emmissions, and advancing it won't have any negitave effect on performance.

Seems like a bunch of us have turned up the fuel rate, now we're going to move on to advancing the timing, next will be turbo and injector upgrades and so on. I'm thinking we have plenty of scattered motors amoung us by the summer, and will be discussing performance rebuilds or swapping in "bigger" power.

By the way, My old jaloppie of an RV outweighs my 923.

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74M35A2 said:

Yep yep. I'm waiting until I have my EGT installed, so we can actually quantify if EGT's are reduced. I also want to try to do a timed acceleration run on a marked or otherwise known portion of road to be able to have more than a "feels better" opinion. The RV guys says it really helped their fuel economy most, and then other add on's took better hold because the engine ran more efficiently.

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Ive been looking at upgrading the turbine and compressor wheel in the hx. I'm ready to follow your tutorial on the timing...!

I think we would just move from the HX40 to an HX50, HX52, or HX55. Buy a genuine used one from a truck parts yard and put a seal/bearing kit it in. Test and tune kind of thing. On the 300hp and higher, I believe they use an HX50 stock.

I didn't do the timing bump yet, so don't follow me too closely. I just did the math based upon damper diameter and the timing procedure based in the Cummins service manual posted on their free Quickserve web site (anybody can register for $0 and it itemizes all parts and procedures based upon your engine serial number).

I'm excited to see what kind of results you guys are going to get! I want to do some of this stuff too

Go first. Take pics.

I talked to a friend that messes with a lot of smaller cummins. He asked if the pump has hydro advance and I did not know. But thought I'd throw it out there to make sure it was thought of or considered. If more rpm equals advanced timing it could over time the motor with an advanced pump. It was a rotary pump that he was referring to not the 7100.

Our 8.3 IP's are Bosch MW pumps, which are similar but not same to Bosch P7100 pumps. I believe they do not have any advance mechanism within them. The 16 degree "sweet spot" I reference is taken from the RV boards where they are equipped with the P7100 pump.

74M35A2 said:

Go first. Take pics.

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wuss.

Says the guy who's engine is spread all across his garage floor. Mind you I drove my truck for an hour last night, and you worked on yours for an hour. You should put your engine parts in milk crates and then call it a crate engine. Ha ha ha! I thought you were supposed to be pulling your other 5 low compression pistons, not stalking me!