12v Tuning advice

[mtm94ramnasty]

https://www.instagram.com/p/BpfSItdF...d=lok95ecxbh7p

Not sure If you will be able to see this video, but here is an 11.7 pass at 117. I tried leaving a little too hard with the s369sxe and spun a bit.I used to shift that around 36-3700 seemed like anything after that power would fall off. With the compounds on the dyno the truck made peak hp around 3250 so I shift it around 34-500. It smoked pretty decent on the dyno and came up decent on boost. I have yet to run the truck down the 1/4 mile with the compounds.
Trying a few different afc springs, hopefully I will update later today with positive results.

[mtm94ramnasty]

https://www.instagram.com/p/BpfSItdF...d=lok95ecxbh7p

Not sure If you will be able to see this video, but here is an 11.7 pass at 117. I tried leaving a little too hard with the s369sxe and spun a bit.I used to shift that around 36-3700 seemed like anything after that power would fall off. With the compounds on the dyno the truck made peak hp around 3250 so I shift it around 34-500. It smoked pretty decent on the dyno and came up decent on boost. I have yet to run the truck down the 1/4 mile with the compounds.
Trying a few different afc springs, hopefully I will update later today with positive results.

[SCHMITTY]

Nice vid

[YOUNG GUNS15]

Originally Posted by jstaylor954

Just asking, but why does everyone say to get rid of afc live? I think on a street truck or tow pig it works great because you can really set it to a cool, smoke free tune and then full fuel with just flipping the switch if you want

Because they don’t know what they’re talking about.

Afc live used correctly, essentially let’s you tune how fast/slow fuel comes in without guessing at springs, star wheel position, pre boost settings.

For the OP, simply sounds like you need to put a plate back in to get your desired results. From what you have described so far it sounds great until maximum fueling is requested by your right foot. Toss a fuel plate in, something like a zero so it doesn’t change your low end fueling curve, leave the afc live alone and set it at about mid position. That’ll get rid of your top end smoke, and from there you can tune in more and more fuel by sliding it forward 1mm-2mm at a time until you have minimal smoke at WOT. In reality your afc live should do this, but since you have it bypassed for racing this will probably be your next best method.

I agree that a 66/480 is outdated, and simply having the 480 updated to something more modern could help you burn the top end fuel and solve your smoke problem. Have it rebuilt into a 488 would be pretty cool. Plenty of air at that point!


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[chad256]

I would start with an interstage boost gauge. Knowing how hard the primary is working will help to see if everything is working right.

[Redrider2911]

Agree on the interstage boost gauge. What about drive pressures? what are you seeing there?

[mtm94ramnasty]

Originally Posted by YOUNG GUNS15

Because they don’t know what they’re talking about.

Afc live used correctly, essentially let’s you tune how fast/slow fuel comes in without guessing at springs, star wheel position, pre boost settings.

For the OP, simply sounds like you need to put a plate back in to get your desired results. From what you have described so far it sounds great until maximum fueling is requested by your right foot. Toss a fuel plate in, something like a zero so it doesn’t change your low end fueling curve, leave the afc live alone and set it at about mid position. That’ll get rid of your top end smoke, and from there you can tune in more and more fuel by sliding it forward 1mm-2mm at a time until you have minimal smoke at WOT. In reality your afc live should do this, but since you have it bypassed for racing this will probably be your next best method.

I agree that a 66/480 is outdated, and simply having the 480 updated to something more modern could help you burn the top end fuel and solve your smoke problem. Have it rebuilt into a 488 would be pretty cool. Plenty of air at that point!


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For what ever reason trying the adjust the afc live since I installed the compounds, I just couldn’t seem to find a sweet spot. I would get it to the point where it would limit rack travel on top end and it’s like an on off switch. I would adjust it one way and it runs clean, but was down on power. I would try to dial in a little more fuel, slightly turn the knob, and boom it’s like I have the full power switch flipped. Any time I would play with how fast the fuel comes in, it would noticeably loose mid range and spool up. This happened with my 69 and I jumnped to a stiffer afc spring and I was able to adjust it much easier. I haven’t had a whole lot of time to play with it.

I knew the 66/80 is out dated, but with my goal of dipping into the 10s. I just figured they would fit the bill to get me there. Push comes to shove once I feel all other options are exhausted (tuning) and I have reached the limit of what they can do on my setup then it will be time to upgrade.

[mtm94ramnasty]

Originally Posted by chad256

I would start with an interstage boost gauge. Knowing how hard the primary is working will help to see if everything is working right.

I have to pull the plumbing and install a fitting so that I can tap into and read the interstage boost. I know I need those readings to appropriately set the gate on the 66.
As for the drive pressure, I traded my old t-4 manifold for a used t-3 stainless diesel one and as luck would have it the 2nd plug is seized in the manifold. I have everything to install the drive pressure gauge, but I just need to get that plug out or swap it temporarily where my egt probe is. Those #’s will come this weekend most likely when I get time to swap everything around.

As for the afc. I sourced a common rail valve spring from my brother and trimmed it to size. Once installed, full rack travel is now right around 80psi or just before. I tested on the bench real quick with shop air. Threw it on the truck and went for a quick test ride. Once warm I was able to jump on it. The fuel comes on what feels/looks like perfect now. Over all boost is right at 90 psi, egts start much much cooler climb nice and slow bounce around 1750-1850 max. Seems to have picked up mid range, visible smoke from low to mid range is now just a consistent heavy haze to full boost and remains that way. Probably only 1/4-3/8 of what smoke is seen in the video with the s369 at the track.

[WUnderwood]

Just clarifying, but are you running a T3 exhaust manifold?

[YOUNG GUNS15]

Originally Posted by mtm94ramnasty

I have to pull the plumbing and install a fitting so that I can tap into and read the interstage boost. I know I need those readings to appropriately set the gate on the 66.

As for the drive pressure, I traded my old t-4 manifold for a used t-3 stainless diesel one and as luck would have it the 2nd plug is seized in the manifold. I have everything to install the drive pressure gauge, but I just need to get that plug out or swap it temporarily where my egt probe is. Those #’s will come this weekend most likely when I get time to swap everything around.



As for the afc. I sourced a common rail valve spring from my brother and trimmed it to size. Once installed, full rack travel is now right around 80psi or just before. I tested on the bench real quick with shop air. Threw it on the truck and went for a quick test ride. Once warm I was able to jump on it. The fuel comes on what feels/looks like perfect now. Over all boost is right at 90 psi, egts start much much cooler climb nice and slow bounce around 1750-1850 max. Seems to have picked up mid range, visible smoke from low to mid range is now just a consistent heavy haze to full boost and remains that way. Probably only 1/4-3/8 of what smoke is seen in the video with the s369 at the track.

Sounds like you have it figured out. Afc live might be more useful now with that heavier spring. However if the top end fueling isn’t as thick as it was before, it for sure is cutting back from full fuel, even just slightly. Might keep that in mind when you have more air and become fuel-limited.


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[mtm94ramnasty]

Originally Posted by WUnderwood

Just clarifying, but are you running a T3 exhaust manifold?

Yes it’s a t-3

[mtm94ramnasty]

Originally Posted by YOUNG GUNS15

Sounds like you have it figured out. Afc live might be more useful now with that heavier spring. However if the top end fueling isn’t as thick as it was before, it for sure is cutting back from full fuel, even just slightly. Might keep that in mind when you have more air and become fuel-limited.


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Top end fueling I had an issue with before was corrected by changing out the open holders / full cuts to stock holders off my 160pump and comp cuts. That took top end fuel from heavy smoke not cleaning up at all to a heavy haze, reduced egts, and actually seemed to pick up a little power. I still had an issue with low/mid range fueling being extremely excessive. It would only clean up at peak boost wot. I was running pdd’s stiffest spring. With no preload it was at full rack travel by 45 psi. Now swapped out to the common rail valve spring it’s a constant heavy haze through out the power band. Just a little bit lazy preboost smoke.

[YOUNG GUNS15]

Originally Posted by mtm94ramnasty

Top end fueling I had an issue with before was corrected by changing out the open holders / full cuts to stock holders off my 160pump and comp cuts. That took top end fuel from heavy smoke not cleaning up at all to a heavy haze, reduced egts, and actually seemed to pick up a little power. I still had an issue with low/mid range fueling being extremely excessive. It would only clean up at peak boost wot. I was running pdd’s stiffest spring. With no preload it was at full rack travel by 45 psi. Now swapped out to the common rail valve spring it’s a constant heavy haze through out the power band. Just a little bit lazy preboost smoke.

That makes a lot of sense. I didn’t see where you listed open holders and full cuts, must’ve skipped over as I read. Comp cuts definitely pull fuel and duration out compared to a full cut. Hence the smoke and egt reduction. Have you tried the comp cuts with the PDD afc spring?





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[mtm94ramnasty]

Originally Posted by YOUNG GUNS15

That makes a lot of sense. I didn’t see where you listed open holders and full cuts, must’ve skipped over as I read. Comp cuts definitely pull fuel and duration out compared to a full cut. Hence the smoke and egt reduction. Have you tried the comp cuts with the PDD afc spring?


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Yes, that was the setup before swapping in the valve spring. I couldn’t get the tuning right with the afc live for my life. Fuel either came in too fast or too slow with that spring playing with the adjustment. I couldn’t find a happy medium. Hopefully now this weekend I can get everything set up to dial in the compounds. From there I will try to get back on the same dyno asap to see what the results are.

[zachu812]

Originally Posted by mtm94ramnasty

As for the afc. I sourced a common rail valve spring from my brother and trimmed it to size. Once installed, full rack travel is now right around 80psi or just before. I tested on the bench real quick with shop air. Threw it on the truck and went for a quick test ride. Once warm I was able to jump on it. The fuel comes on what feels/looks like perfect now. Over all boost is right at 90 psi, egts start much much cooler climb nice and slow bounce around 1750-1850 max. Seems to have picked up mid range, visible smoke from low to mid range is now just a consistent heavy haze to full boost and remains that way. Probably only 1/4-3/8 of what smoke is seen in the video with the s369 at the track.

Glad to hear the spring worked out. Just out of curiosity, did you trim it to the length of a stock spring or longer? I have mine trimmed so it's barely compressed with preboost all the way out and the starwheel all the way towards the front of the truck. With just a few clicks and no preboost I'm able to stage the truck by flat footing it, still only get a nice haze and thats with a 13mm pump. I cut up a few different springs before finding whats best, it sounds like you're close.

[97rada]

Something to keep in mind, my truck never dynos well. First setup I strapped down only showed like 880 or so. Boost never got over 90 psi ect. Timing was 32 degrees. Take the exact same setup to the track and it runs 10.01 and makes 155psi boost and mphs were showing much closer to 1250hp. Current engine is the same way. It did 1200hp a few months back much lower then track times. I also found going from 32 degrees to 38 was worth 200 hp as was 38-42 worth about 80 hp out in the curve and about 15 at peak.
All that said, don’t live and die on a dyno with a mechanical truck.


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[mtm94ramnasty]

Up date. Got the interstage boost gauge hooked up. Looks like I’m seeing peak 45psi at about 88-89 psi with the out side temp being 71*. Aside from the peak numbers as boost builds to about 85 psi and slowly climbs to peak, interstage goes right up to 40 and climbes to the 45.
I will have to move the gauge I have to the drive pressure once I get everything set. From those numbers I am guessing things are fairly decent? If anything I can dial back the gate a little and drive the 80 a little bit harder if the drive pressure is too high?

I have the valve spring set up in my afc exactly as you do. Star wheel is full in towards the front with no preload, smoke screw is flushed with the housing. My afc is slid full forward. That combo seems to be the ticket for me. Thank you for reccomending that spring!

I certainly think I need to get the truck to the track and see where the mph is. That will be a good indication of where it’s at power wise.

[mtm94ramnasty]

Unfortunately today I had a run of bad luck. It seems as if my stock intercooler finally decided it didn’t like life anymore. Some of the welds on the passenger side tank had split. Lucky for me xdp is about a 50 min ride so I got my hands on a new Mishimoto unit. After getting that installed I had my passenger side lower boot blow off twice. I finally got that to stay on by double clamping it. After that ordeal I laid into it yet again for the cold pipe boot to burst. These compounds are a side mount setup and the turbine housing on the 80 sits close to the cold pipe boot on the 66. Apparently my turbo blanket on the 80 worked it’s way down and it heated up that boot so it was nice and soft causing it to burst. Hopefully I’ll have it fixed tomorrow and I can report back with the drive pressure #’s so long as everything holds together.

[mtm94ramnasty]

Quick update. I finally get all the intercooler boots to stay on. I thought it was a little weird boost dropped with new mishimoto intercooler (down to 86psi) . I am guessing this is because I’m measuring boost at the intake on the cylinder head and the intake air temps are much lower then before. Before I would put my had on the intake side of the intercooler and it would be hot, now with the mishimoto it’s nice and cool after wot pass. I never got the drive pressure hooked up, but I did get the truck down the track. Went 11.66 leaving easy 1.81 60ft @ 117.6 mph and an intercooler boot burst as I passed through the traps. Looks like the truck didn’t change at all from the s369sxe going to the compounds �� egts are still hot 1850-1900. I have checked and re checked for boost leaks. Capped the intake off on the s480 and capped of the intake horn pressurized it up to 90psi and no leaks. I’m kind of at a loss. I am starting to wonder if my old Colmbus 12mm pump is just worn out. The other issue is with the pump I don’t have a timing chart for the cam. I’m going off info from about 5 years ago when my brother called cds for timing measurements.

[95cummins5.9]

Do you know where it was pinned? Sounds like some timing would help.