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Few random questions..


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Ah, now I see.... Mopar man when he calls or I call him we jokingly call each other names. It's pretty funny so I was hoping to get a rise is all. Not lately, I think he has lots going on making life a bit less light hearted. I think he needs to go to dieselfutures beer cave for a long visit.

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On 9/9/2021 at 6:38 AM, Silverwolf2691 said:

Does the final drive ratio of 3.55-3.73 also hold true for the gas trucks as well?

 

What I have always looked for when looking for engine performance in a vehicle is, "what will be the engine rpm in a specific gear at a specific highway speed that I would drive at based on a specific engine (gas or diesel).  Engine performance charts are the place to get this information.  At minimum, I would want to know at what engine rpm is peak torque and peak horsepower.  Engines typically perform best just above their peak torque rpm, or at least around their peak torque rpm.

 

For example, my stock '02 Cummins is 245 hp  and 505 lb/ft of torque.  The horsepower rating is at 2900 rpm and the peak torque rating is at 1600 rpm.  This is why engine rpm's between 1800 and 2000 work well with @Mopar1973Man's final drive ratio recommendation.

 

A '99 Ram 5.2 gas engine specs are 235 hp and 300 lb/ft torque.  But the horsepower rating is at 4400 rpm and the peak torque rating is at 3200 rpm..  In general, this would tell me that a rear axle ratio of 4.10::1 would be more suitable because of the peak torque rpm.  Knowing every gear ratio for the transmission and tire diameter will be key for getting this right.

 

- John

 

Edited by Tractorman
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:iagree: TOTALLY AGREE! :iagree:

 

Being I'm in the mountains and do a lot of up and down grades I feel the 3.73 ratio is really optimal for power and MPG wise. Even towing is better. If your more midwest I would still hang towards the 3.73 ratio but not as tight being I've done 27.2 MPG on stock tires and 3.55 gears (Edge Comp, +75 HP injectors, and stock HX35W turbo).

Edited by Mopar1973Man
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First row is gears for a 1500..

 

Steepest grade around here is an 11 or 13% and its less than a half mile long.. otherwise just small rolling hills and flatlands..

 

@Mopar1973Man the custom tuning can still be done on the gassers but its not able to be done on the fly like we can with a Quad. They are are also mostly in for power not economy. No shift on the fly either.. Think smarty S-03.. 

 

Ive gotten 300 miles by half tank once in my cummins. Between the nearly all in town driving, 4.10s, and 285/70r17s im not set up for economy so that felt good.. But i cant seem to get the oil temps where they should be. On a highway run they can start pushing 210*.

Screenshot_20210911-145333_Chrome.jpg

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  • 3 weeks later...

Well I get the dunce cap this time around. :doh:

 

I changed my oil yesterday because I'm at mileage for the change. Well, only a gallon of oil came out.

 

So with the blue smoking at startup and after idling for a bit, and some help on here, determined it was bad seals and/or valve guides. Well I checked the oil a while ago (6 months or so, too long I know) and it was fine. Drained the oil and only a gallon came out. Well sh!t. So I started looking around at some of the issues I made a note to look into after pulling season is done and found that the dampness around the oil cooler is not a re-blown head gasket but is in fact oil being blown out of the exhaust manifold at cylinder 1.

 

My last sled pull is tomorrow so after that I'm going to have to do a long hard look over my truck and make a list. And its already quite long.

 

My engine was only slightly more clackety and engine oil pressure never dropped low low but I thought I sheared the oil to be honest and that's why pressure was low. Possibly my only other indication, and I need to go on a drive to figure this out, was my oil temps were constantly high. Doing 65 down the highway/freeway I would run 210° oil temps, no matter the timing.               

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On 10/1/2021 at 6:08 AM, Silverwolf2691 said:

Doing 65 down the highway/freeway I would run 210° oil temps, no matter the timing.

 

Weird I can run much lower in oil temp but being the oil levels where low it might make a difference. I typically float at 160 to 170*F engine oil temp with the sensor in the test port of the oil filter housing. I know this is the cooled oil from the oil cooler. Typically more advancement the higher my oil temp gets. When I've got my timing right the oil temp falls and drop to this lower levels. 

 

Kind of like my fuel temps are never higher than IAT temp and typically match for temperature after hours of driving. Coolant typically rides at 192*F to 197*F with a 190*F NAPA thermostat. 

 

I must be doing something right for 425 miles at a half tank. 

20210910_175902.jpg

 

Gotta remember all the factory final ratio, tire sizes, rotational mass, etc. All impact the load on the engine. Any heat created in different places is sign of wasted energy that is converted into heat. Any high temps are a lost in efficiency. Even my trans temp is low.

 

 

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Still running too small of a tire for 4.10s technically. (285/70r17) That's part of the issue. My cruise might be too advanced still but I haven't had the time to futz with it. Now that I don't have a sled pull every weekend I can take care of some of the issues that have come up since starting pulling. Finished our season this past Saturday. Looks like I made 3rd overall for work stock in my first year.

 

Running down one of the highways coming back from the pull last Saturday, I was watching my oil temps and they were still slowly creeping up to 210°F. Was running 65mph, which is almost 2100 rpm. Think I was running 21° of timing. Thinking I have to pull that back a degree or two. Thoughts?

 

My oil temp sending unit is in the same spot as your Mike. I tried a run with just my base timing (no cruise advance) one day a while ago and nothing changed. I'm guessing I'm running into the tires being the issue first. But I'm getting the flatland cruise EGTs really low with the advancement right now. Sub 500°F, but hit the throttle and right up to 700-800°. That's not even passing temps. 

 

Over the winter is gonna be a new worked over head, injectors, and a turbo for power. Traction bars, bump stops, and u-joint shields for traction and safety. And new tires because that's where I'm becoming limited more so than power. Thinking of running a road set and a pulling set. Road set would be 35" all terrains and the pulling set would be 33" light mud or aggressive all terrains.

     

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  • 3 weeks later...
On 8/9/2021 at 1:26 PM, Silverwolf2691 said:

2. While sled pulling, in my Quad's datalogs I have found that the canbus fuel is dropping off a bit then back up to 4095. I don't have back downs, and throttle stayed at 100%. The green vertical bars are canbus, the yellow line is load, and the brown/copper one is throttle position. this is my most recent sled pull. It was this past Saturday, the 7th. 200ft track and stupid sandy, no grip. The dip in the middle was me letting off to see if I could get any more traction but I think it cost me distance instead. In the last half of the pull after me letting off the throttle and getting back on the fuel keeps dropping a bit.   

graph.jpg

 

I think I figured out what those dips are. Lines 33-39, and the ones in the latter half of the graph (past line 61) are the computer pulling fuel to keep rpm down. From looking at my other graphs, I think the computer is doing a forecasting calculation to see if the rpms are going high enough to pull fuel to keep an over rev from happening. If not, there is some comparing between RPM, wheel speed, canbus fuel, and throttle position to figure out when to pull fuel.

 

There seems to be no direct correlation between an RPM threshold and it pulling fuel, unless its not visible with the quarter second resolution that the quad has.

 

image.png.64e34e8f460c8c49d07881c997af0605.png

This is why I think that the dips are what I think they are. This was one of my more recent sled pulls (9-17-21). The track was very very hard at the start of the event, and stayed hard all night. This was actually my 3rd place night.. 4th gear low range, this was my test pull, pulled 242.19 on a 250ft track. Sled operator increased the weight after me because I'm the least powered in the diesel class right now. Anyway, where the purple and yellow lines start to dip is between 2850 and 3050 for RPM. With some of the highest rpm where the "lowest" fuel is. I think that the high spot for the rpm was a softer spot in the track. 

 

image.png.22de716212c6bceeedbba1079f8a2bfd.png

 

My second pull that night, same track, 4th low, but faster weight box I think. I also maxed out my wiretap this round as well. The rpm peak was only 3030 and dropped off to 2775. But this one averaged in the 2800 range vs the high 2900 range on the first pull. Pulled to 219.4ft.

 

Both vehicle speeds topped out at 17 mph.

 

I also found that my map sensor is reading correct. I see 35+ on the street while shifting up to speed, but going down the track the boost is only 30 psi (both of these are on my Isspro gauges). I'm guessing its the falling rpm that's building the boost while on the street vs the constant high rpm of sled pulling.

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Theres a saying that i cant remember the exact wording but its something along the lines of 

 

If you dont know what is going on how can you correct, fix, or learn from it..

 

Thats how im learning im maxed out on fuel right now. One of my even more recent runs was on a sandy clay track that had a heavy dew settle on. Turned extremely slick. Thats how i learned that my truck can turn 34-3500 rpm down the track. But track speed was only 9 mph. Wheel speed was 19. Went 2nd high the next time because i got first pull of the class and mph stayed the same..

 

Data is good as long as you know how to read and interpret it.

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