EGT's Seem Too High

[BrianX128]

So on my 85 6.9 about two years ago I put a new pump and injectors in from conestoga. Truck smoked a lot more than it used to, but it's a non turbo. I didn't think much of it but put a pyro on it just to be safe and the truck always seemed to run a bit hotter than my 7.3 but it really was never near dangerous levels but I'd see 800-900 empty on hills that my 7.3 runs at 600 all day on. My 7.3 is also way heavier, and in overdrive instead of 4th (zf vs t19). The pyro on both is the same (isspro) and mounted in the same location.

This isn't a perfect comparison with all the factors, but I'm hoping some of the factors will help me decide what to start messing with first. My 7.3 (though non turbo) has a factory turbo pump turned up 3 flats with 80k from a totaled 94 bucket truck. It has the banks powerpack which is basically a different bigger intake in the grill area, the giant soup bowl that takes the bigger filter that says "banks power pack" you see on ebay, and the Y pipe is different than factory. I don't know that it was this way from banks, but it looks less terrible and also is 3" out instead of 2.5" out. I have it fed into a straight pass muffler that actually is a great mix of deep sound but cutting out the obnoxious noise. I'm not a stack guy but the 7.3 has a stack because our camper was changing colors. This truck tow a 6500 pound camper and it will get to 1100 on hills, but I can shift my way around it and keep 55 most place unless the grade is crazy and then 3rd and 45 is the limit. There is one 2 mile stretch that's all uphill and easy to maintain 55 to compare egt's and the 7.3 can stay at 55mph in overdrive and be + or - 950 towing the camper.

It just seems odd that I can drive the same hill in my empty 6.9 and see nearly the same egt's unloaded that the other truck has loaded. The 6.9 doesn't do worse if it is loaded either. It's just kinda like that's where it is no matter what I do.

This makes me think it's either timing or the exhaust on the 6.9 is killing me. When I got the 6.9 it had the factory exhaust the whole way, but the muffler had a hole and the previous owner gave me a 2005 super duty exhaust. I only have the muffler on it because it all fit perfectly and I spliced things together with an adapter right about where the bed and cab meet. It's a 3.5" exhaust and there's probably 3 feet of the old factory pipe from the y pipe into it.

I'm also wondering if this muffler is killing me, I never had the egt gauge with the stock setup to compare. It is pretty quiet by comparison, but I don't want to rip all that off for no reason. It just seems so odd that I hauled a pretty heavy trailer and my vac last year with the truck on the same hills and the egt's barely changed from what they are unloaded..

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[snicklas]

If it's a muffler from a 6.0 Superduty (3+ inch) that shouldn't be a restriction unless it's plugged. A 6.0 moves A LOT more air than an IDI does, especially an N/A IDI. That banks powerpack is helping on the other truck. More air in, and that y-pipe that flows better is helping. To test the air in theory, on a damp day, or just after a rain, take the air filter completely off and take it for a quick run (I'm recommending these conditions because that would have the least amount of ambient dust in the air) and see what your temps are. I bet they will be lower. If you're really adventurous, pull the y-pipe off the manifolds too. That would make it so the only air restrictions would be "inside" the engine.

It may be you are getting more fuel from the Moose pump, or timing. I remember Wes @Thewespaul making a comment that even an 80cc pump is an upgrade over a stock pump because they max out at something like 60ccs....... So 60ccs in the other truck and 80ccs (or more depending on pump) and you are going to make more heat, period.

 

[Dane Rickford]

Thanks for all the recommendations, if you have any questions about your projects let me know! FYI... Stock pumps are actually calibrated to 67cc peak and 58cc at hp peak, so even an 80cc pump is a good upgrade from stock.

This is what @snicklas is talking about

 

[BrianX128]

It's just strange I get so much more black smoke from the truck that runs with the lower egt's (the 7.3) then what I'm getting out of the 6.9 with the moose pump and injectors. The 7.3 sounds more advanced timing wise when your standing with your head in the engine bay, the "rattle" is more high pitched. I'm not sure how much of that has to do with different intakes and exhausts though. The air filter is new on both.

I'm wondering if it would be a bad idea to bump the timing a dime both ways and see if anything changes on the 6.9. Even the throttle response is a bit "laggy" in comparison. The 7.3 feels dangerous for half a second when you floor it until reality sets in, the 6.9 I can practically hear it sigh when I floor it yet it can still do things, you just gotta peak at that stupid pyro a lot.

 

[Dane Rickford]

It's just strange I get so much more black smoke from the truck that runs with the lower egt's (the 7.3) then what I'm getting out of the 6.9 with the moose pump and injectors. The 7.3 sounds more advanced timing wise when your standing with your head in the engine bay, the "rattle" is more high pitched.

If it was me I would definitely bump the timing up. From my experience with 7.3s, when the timing is advanced you will have more black smoke and lower temps. And when the timing is retarded you will see less smoke, or if it’s way to retarded, I’ve seen grey and white smoke because a great deal of combustion is happening in the exhaust instead of all of the combustion being in the cylinders

 

[BrianX128]

Bumped it up a dime, it's down 100 overall roughly. Helped for sure, but it holds high temps differently than my 7.3 still. Same hill the 6.9 got to 65 and could hold it at 950 instead of 55 at 1050.

Maybe my 7.3 is just in the perfect suite spot for this, but once I hit 65 on this hill unloaded it will slowly drop from 950 to 850 after it's done "accelerating" through it. My 6.9 doesnt do that at 65 or 55 on this hill even after the timing adjustment.