4bt Cummins Dyno Session

Big Blue24

Comp Diesel Sponsor
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Jan 5, 2008
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Recently Todd and I had the opportunity to help tune and modify the 4bt Cummins powerplant inside a Dodge Dakota land-speed Bonneville race truck owned by Tom Sauter.

The fueling setup is a 13mm p-pump built by DPE before Seth Farrell left and started his own shop. With the guidance of Seth over the phone, we made some modifications to the pump holders and springs while it was still on the truck. The 5x.018" injectors originally built by another shop were modified in-house at Power Driven Diesel with custom needle work, and raised pop pressures to take advantage of the 13mm pump. We also swapped out the small delivery valves for some Power Driven 7mm +100 cc DV's.

Todd spent the better part of a day chasing boost leaks and touching up old leaking welds with his tig welder as well as installing a prototype Power Driven in-cab fueling adjuster and panel mounted knob so fueling adjustments could be made on the fly at the dyno and also mid-run at Bonneville. We also advanced the timing another 7 degrees prior to hitting the rollers.

After spending a couple days giving it the once-over, we headed down to the Big Rig Taylor Water-Brake dyno at PDI in St George, UT for some simulated 2-3 mile long runs. We weren't trying for short term max power like you'd want on a drag strip, we were tuning for one to two minute long full power runs where high EGT results in a melt-down.

It was a challenge getting the relatively big 66mm turbo to spool on the little 4bt, didn't really make boost till 4000 rpm and would often fall under the charger on the WOT 3-4 gear shift. Towards the end of the dyno session we started making headway in the tune-up after the instrumentation started working and providing valuable EGT, Boost, and Drive pressure information. Our several hour dyno session was ended short when an injection line broke at the #2 injector but we still were able to get a few glory pulls in between the max useable power tuning.

The best run was 477 HP on this known to be stingy Semi-Tractor Trailer dyno so this little 4bt is making good peak power, just too hot without the water injection to help keep things cool on the combustion side and airflow to keep things cool on the engine coolant side.

The video is a little rough but it's better than nothing.


[ame="http://www.youtube.com/watch?v=SvudM8YxWpc"]http://www.youtube.com/watch?v=SvudM8YxWpc[/ame]


This truck is the current record-holder in it's class with a 152 MPH speed record. We hope the current setup will be enough to raise the record another 10-15 MPH and then future plans include a compound turbo setup with a goal for 650-700 useable HP, enough power to push this Dakota into the 200+ MPH range.
 
Where do you have the pump set at? What was your timing? The only two passes I got out of my 4BT Dakota this year at the drag strip she went 110mph through the traps with a 4500lb truck. I just have a Columbus built 12mm P-pump but twin turbos. My pump was set to min (not sure on cc, but max is 425cc) and the timing was 23 degrees.
 
Cool! They should call those old water brake dyno's for semi's dream crushers....LOL
 
Where do you have the pump set at? What was your timing? The only two passes I got out of my 4BT Dakota this year at the drag strip she went 110mph through the traps with a 4500lb truck. I just have a Columbus built 12mm P-pump but twin turbos. My pump was set to min (not sure on cc, but max is 425cc) and the timing was 23 degrees.

We had to set the pump to the minimum fueling setting to hit those 200-260 rwhp runs. I don't have the pump flow data but I did verify that it's a 13mm and it seems to have PLENTY of fuel. When DPE built it, they set it up with 131 DV's in an attempt to limit the fueling. Injectors are modest sac 5x018" 155* with some needle work and typical edge filter removal. Timing was set to 33-34* range on the higher HP passes, then we dropped it back down to 28* or so to see if we could get a little better EGT control.

The head has over-sized valves from Mountain High Performance that were installed and set-up by the truck owner's local hotrod gasser machine shop in Lake Havasu, AZ. It has a custom valve spring setup that the machine shop came up with. The head has a removed intake plenum and ZZ-Fab side-draft intake with a fully ported head. I believe the cam is a 188/220 or something close to that. Turbo is a custom Garret BB T04z with a billet 66mm compressor. It has a modest sized Frozen Boost water/air cooler and there is an icewater tank in the bed that was circulating 60-70* water. It's amazing how much ice that little 4bt can consume when you really lean on it at 50 psi...

The motor has stock rods, I'm unsure of the rod bolts, but likely has upgraded rod bolts. Typical wide bowl marine pistons, etc.

We were just starting to make some headway on the tuning after 4 hours of blind tuning with the truck's flukey AEM data logger, flukey EGT probes, etc. We finally installed some test probes from the dyno's data logging equipment and only got 2 or 3 more test runs before a broken injection line ended the fun....
 
Cool! They should call those old water brake dyno's for semi's dream crushers....LOL

I had no idea what to expect till the dyno operator came running in and ended the first run short because he was concerned the little 4bt was about to explode when it held 420+ HP for 15 seconds and spiked to almost 500 HP.... he's used to factory-rated 500-600 HP big rig motors that rarely show those numbers in stock form.....
 
I'm glad that dude got hooked up with you guys. I've seen that truck a few times at El Mirage, and I always thought it had way more potential than was being realized. I'm sure you were seeing some scary EGT numbers on some dyno runs!
 
I'm glad that dude got hooked up with you guys. I've seen that truck a few times at El Mirage, and I always thought it had way more potential than was being realized. I'm sure you were seeing some scary EGT numbers on some dyno runs!

Part of the problem was that the scary egt numbers were fake. We figured out half way through the day that his gauges were not good. An old gasser gauge he had. We were trying to keep it below 1500. When we finally got the dyno egt probe installed we find that it took about 1000 degrees to bury bus 1500 pyro!
 
I know antrims water dyno has crushed alot of pickups dreams. Id say 477 is very impressive on one of those bad boys.
 
Thanks for the details Will. I've talked to the owner before over on 4btswaps, pretty sweet truck he built.
 
That's definitely cool you guys are helping them out! I surely see it making some GOOD headway with you and Todd helping them out! I'd like to see that thing rip! I'm sure it sounds un-Godly at 4000k RPM!

Waterbreak dynos are brutal old dinosaurs for sure. My best friend's dad was just up at PDI about 3 months ago and surprised the **** outta them when his W900 laid down 741hp, after a little more tuning they got her to 780hp. He also trumped their asses, they kept saying their turbo would make more power and cooler EGT's than his billet S483, they swapped em around, his still made the big number, they were bitter. LOL
 
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