Melting_pistons build thread

[Melting_pistons]

A couple pics from the event







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[Melting_pistons]

Made it out to the track last night. Wasn’t expecting much, I was mainly looking to get a datalog to see what kind of issue I am seeing on the top end of the track.

I did get a log, and also a new PB. The truck ran 6.81 at 103, still on tune 2. I don’t want to turn it up any until we get the issues lined out. I’ll report back after going over the log with Ryan.


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[Snedge]

This is a good read melting' .. You are all in on the hotrod, that's evident. It's encouraging to see someone thinking on it and not just dumping fuel.

What exactly are the top end issues? I didn't look at your attachments from dragy too closely. ??

I agree the converter would be the link to quicker spool and better 60.

[Melting_pistons]

Cummins street truck goes 6s! - YouTube

Check out this video from my Diesel Truck award recap, and you can see it. Up at the top end of the track I get a loud pop, and the truck is running really clean, but when I get that “backfire” it blows a cloud of smoke. I’m thinking it’s a rail pop. I don’t have a rail pressure gauge, but I think it’s dropping rail... which it shouldn’t be. It’s got dual pumps and the injectors should push a good bit more than they are now. We will see.

And thanks man, I’ve got more than enough fuel to push enough power to destroy this motor. I just want it to run clean and be a steady 6.70 contender.


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[biggy238]

Is that a break in fueling at 0:40 in the video and again at 1:06?

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[Snedge]

I'll have to check out the YouTube link when I get to my pc. Thanks.

[Melting_pistons]

Originally Posted by biggy238

Is that a break in fueling at 0:40 in the video and again at 1:06?

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If you’re looking at the earlier video yeah. There is a better shot of it in the video I referenced in post #164.


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[Melting_pistons]

Well, the spool up issue is resolved. The original converter I had was a a DPC SS. The one we just threw in is a DPC 3000/200.

Originally while spooling I would hit a wall at 1900rpm. I would have to hold 3/4 throttle to get the heat up, then roll forward to free up the converter. Total spool time was around 18-20 seconds (not good).

Now, I ease on the throttle (around 3/4), for about 2 seconds, then I can bring it up in around 5 seconds. Total spool time around 7-8 seconds. MUCH better lol.







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[Melting_pistons]

So I finally got the log from a couple weeks back to Ryan and we went over my issues:

1) the soft launch
The truck is stuck in torque management. He did some wizardry to try to get around that. Hopefully the new file solves that.

2)the top end pop
I felt like maybe I was draining rail and having a rail pop. After looking over the log, everything looks great. The only way we could see the issue is looking at engine speed you could see a very slight dip. Other than that, everything looks great.
The only thing that stood out in the log is that the rail pressure sensor went to 180mpa briefly on a 175mpa command, on a 180mpa max sensor. Not sure if maybe that sensor just isn’t happy, so I’m swapping in a 10bar map and a 200mpa rail pressure sensor and going to see how it runs.

I’ll report back when I try it out.





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[biggy238]

Same engine speed in each log?
Fabricated engine harness or oem?

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[Melting_pistons]

Originally Posted by biggy238

Same engine speed in each log?
Fabricated engine harness or oem?

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Yeah every time it’s done it is around halfway through 3rd gear, and it’s a stock harness... but we just had it apart a few months back and went over every wire and everything looked good.


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[Melting_pistons]

Put in a 10bar map and a 200mpa rail pressure sensor. Leaving fueling the same for now, just seeing if the new sensor helps the top end issue I saw...

I did notice this. The sensor seems to have gotten really hot. Anyone seen this before?




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[biggy238]

Is the rail valve blocked?

The valve opening will create high heat.

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[Melting_pistons]

Originally Posted by biggy238

Is the rail valve blocked?

The valve opening will create high heat.

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You referring to the relief? Nah it’s still a factory fitting. And we aren’t seeing any drop like the valve is popping off


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[Melting_pistons]

Ok guys, been a while since I updated anything on the truck.

Quick Flashback:
Last season my PB was a 1.7ish 60’ due to a tuning issue, but ran 6.81 at 103 on tune 2.

Off-season Changes:
We swapped to a higher pressure rail sensor (thinking the other one having so many miles and being pushed so hard was starting to flake on us a little) and went to a 10 bar map to be able to read boost accurately.
Also, my s*** 60’ wasn’t due to traction. The truck was stuck in torque management. So when the tune was rewritten to accommodate the new sensors, we also addressed that.
The final change we made was we loosened up the converter to -200 looser than stock.

Current time:
We went out for a quick TNT session last weekend. Everything seems to have worked as it should, and it seems (fingers crossed) that we have all the bugs worked out.
First pass we got the 60’ down to a 1.60 and went 6.91@101, still on tune 2. Spun a little on the launch (I think there was some water on the tires due to not being able to get around the water box). Also, I was shifting at around 4K rpm, and I heard the head lift on the 2-3 and 3-4 shifts.
Second pass I turned it up to tune 3, and it just chirped the tires, and did a 1.55 60’, running out to a 6.79@103. Also, I shifted at 4500rpm, and the head stayed down.

I’m not sure why the truck is going slower than last season (down 2mph at similar track conditions), could just be a fluke or due to how I was shifting (fmvb), or possibly the looser converter?... but nonetheless it was a good day.
With the tuning adjustments we seem to have cleared up the launch issues, got rid of the pop at the top end of the track we had seen (hopefully) and cut spool up time by more than in half.

I do have Viking dual adjustable shocks on the rear set at 8-10, and the tires had a lot of air (25 front 30 rear). Next time out I plan to air down just a tad. If it still spins a little I may bump up the compression setting a couple clicks. It seemed like the truck transferred really good, but once the weight went back it allowed the front tires to unload. I’ll also be doing 625s very soon so that the head lifting will be a thing of the past...

Anyways, sorry for rambling. Feel free to check out the link below for videos of everything. Skip ahead to about the 12:40 mark for pass breakdowns, the first half is just videos of other cars out there.

First Track Day of the Year! - YouTube




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[Melting_pistons]

Well, took the truck out to Diesel Truck Wars last weekend. If you haven’t already, you need to check this event out. It remains to be my favorite event every year.

I ran in 6.70. First pass (qualifying) I accidentally bumped through the lights, so that pass was trash. Also, the truck had the same fuel pop I had heard before... back again! I feel like an idiot, but I think I figured it out. I had been running the truck at just under 1/4 tank..... with a draw straw lol. So I think it’s been running out of fuel. Idk why it wasn’t showing anything on the log, but I threw 5 gallons in it and it did fine the rest of the day.

Second round qualifying, I did like I should. .02 reaction time, 1.55 60’, 6.79 at 103. Ended up qualifying #3 in the field.

E1 I got lane choice... and chose the wrong lane. Several people had issues that round in right lane, which is the lane I had picked. Not sure what the deal was, but I launched the exact same as the previous round, and this time blew the tires off. It spun 1-2, and when I hit 3rd it pulled the rpms down and blew the head gasket. I guess 1000-1100 is a little much for arp2000s haha.

New head gasket and 625s came in today, and will be going in this weekend. Since the last track day, where I had a little traction issue, I made a small shock adjustment to try to help. It didn’t really.... so I’m going to adjust more, then I’ll also start to mess with air pressure some and see what we can get done at Rudy’s.

Unfortunately, I don’t have a roll bar in the truck yet. So 6.70 is out for me... I guess I’ll just fall in ET, unless I can get it to slow down enough for 7.70.

Anyways, here is an event recap video. First half is event coverage, second half is a pass breakdown. Feel free to check it out.

Diesel Truck Wars Spring 2021 - YouTube


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[Melting_pistons]

Well, we changed the gasket and threw in the 625s. Went through heat cycles, retorqued, and all seems well!

Previously, tune 1 has netted me a 7.1 at 99 in Mexico on the dragy. So here was my plan for Rudy’s. I can’t run 6.70 since I don’t have a cage... so I’m going to try to slow it down for 7.70. My plan was to leave on practically no boost, tune 1, and run no lockup.

First run I left at 10lbs and went 7.9... second I left at 15 and went 7.6... so it’s in the neighborhood. Afterwards, I got looking over videos, and noticed the truck was extremely smoky. Found a busted boot... so all the testing went out the window. Lol. Video link below of the weekend.

Rudy’s Truck Jam Prep! - YouTube


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[Melting_pistons]

So Johnny Gilbert at Stainless brought me a new boot to Rudy’s and we swapped it out Thursday night. Friday was a huge waste of time where we just sat around to wait. Not sure what the deal was... anyways.

They weren’t having ANY tnt at this event, so I had no idea what to do to make this thing slow down for 7.70. They did have a gamblers race that night, with 3 qualifying rounds...so the guys talked me into running in that to get a few more passes on the truck (a guaranteed 4 passes) to figure it out.

I knew there was no way I was going to slow down that much without a revision, so as I was in the staging lanes I decided to wipe off the 7 and change it to a 6, so my dial in was 6.70 and I’d just run my normal passes and see how far I could make it.

The full nights break down is below... long story short, in a field of 43 trucks.... I WON! Lol I couldn’t believe it.

Rudy’s Truck Jam! Gamblers Race and Pro Qualifying - YouTube




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[Melting_pistons]

We went into Sunday at Rudys on a fresh track. I decided to drop 7.70 and get into ET so I could keep my 6.70 dial in after the outcome of Friday night.

I’m not sure why, but in Q1 I blew the tires off. So I came back, dropped some air, and went up a couple clicks on compression.

There was only one qualifying round, so we went straight into E1. Long story short, I had to sit on the converter waiting on the other guy to stage, got frustrated, and left a tad early at a -.006.... so shot that race all to crap before it ever started.

To sum up the weekend.

Positives:
Won the gamblers race
No major damage to anything
Set a new PB 60’-1.51, ET-6.77 on brakes, 105mph

Going forward:
Practice more consistent 60’ and RT
Replace broken leaf spring bushings
Set up a staging limiter

Full breakdown and info below!

Rudy’s Truck Jam Eliminations! - YouTube




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[Melting_pistons]

So the first step to being more consistent is to set up the staging limiter... so I did some datalogs, sent them to the nerd, and bought a switch. The switch I got is a momentary button from motion raceworks that has a 6’ wound cord. I made a mount that attaches to the top of the cruise control switches on the steering wheel, and ran the cord through a grommet in the dash to keep it looking clean. It’s not perfect... but it will do for now.

On my next set of days off I’ll try to finish wiring it up and try out the new launch file.








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