Disappointing dyno results w 71mm atmo. Any Ideas?

BBottoms · Oct 7, 2012

Ran the truck at Thoroughbred Diesel's dyno day yesterday and put down 566/1081, which is a bit disappointing for a 71mm Elite atmo and my mods. I've been anticipating putting down 650 +/- 25 whp based on others with similar set-ups (Spartan - 641hp, jdgleason - 673hp, Dustball8504 - 621hp, Dozer - 652hp). I IN NO WAY DOUBT THE 71MM CAPABILITIES as there have been too many good results. It has to be something with my truck.

Truck has 71mm Elite atmo turbo, AFE Intake, 4" down pipe and exhaust, Elite CAC pipe, Flo-Pro EGR Delete and intake elbow, 6.0 manifolds and Elite Up-Pipes, Elite stage 1 valvetrain, AirDog and I was running Gearhead's Race tune. It also has a nearly new HPFP (6k miles) and rail pressure on WOT runs holds ~24.5ksi. I can hit 49 psi boost on the street pretty easily.

Unfortunately I didn't get to do any data logging during the run and they had staff running the trucks so I'm not sure what boost or anything else it hit. They had the exhaust piped outside and i was standing right next to the truck when they ran it and it sounded good. No weird noises or obvious/noisy 100-hp boost leaks. Flashlight inspection under the truck shows no black/sooty places around the up-pipes or manifolds. Filter minder didn't get sucked in.

Their dyno is a Mustang Dyno. I know a DynoJet is preferred, but it is what it is. The dyno graph did look a little funny, it wasn't real smooth like I'm used to seeing. The Corrected and Uncorrected numbers were very close because of the weather (mine was 564/1077 corrected). There were several other 6.4s that ran the stock class with only exhaust/intake/tuners that put down 550ish, so I'm fairly certain the dyno was accurate. There were some torque numbers on a few trucks that seemed squirrel-ly, but most people seemed happy with their results.

Everything seems fine with the truck to me in DD conditions. No CEL and no funny stuff happening. Unfortunately I've never drove another stock 6.4L, more or less a mild-build, so I don't have much to go on with the butt-dyno. The only thing I've noticed is the TC seems to be stalling out a little high, but once it locks up it seems solid and I've never noticed any slipping. Unfortunately I don't have anything to monitor TC slip with at the moment to make sure.

Any ideas? Things to check? I'm going to make a boost leak tester today to make sure I don't have anything leaking and get some WOT data logs on the AutoEnginuity to make sure nothing is obvious.

extreme3807 · Oct 7, 2012

interesting graph...numbers are low no doubt

madman1234509 · Oct 7, 2012

The speed starts off very low compared to other dynos that have speed instead of rpm. Most guys you see dont start their graph until like 80mph and make it all the way to 120. You start off at 60mph, which almost makes me think those drop offs are the truck shifting. I know if I stomped on it at 60mph, 8/10 times my truck will downshift.

My only other question is do you have a waste gate?

BBottoms · Oct 7, 2012

Yeah, mine are definitely low. Like I said though, there were other exhasut/intake/tuned 6.4s there that put down typical numbers.

No wastegate. They did start the automatics running pretty slow, pretty much all of them ended up downshifting then shifting back into 5th. I thought this was odd too, but this is the first time I've ever dyno'd or been to a dyno event. I realize it makes the graph pretty useless, but would this affect my peak numbers that much?

Ipkyss · Oct 7, 2012

I know how you feel, but it falls back to a dyno being a tuning device and not all being the same. I have dynoed 554 on a mustang dyno and 580 at rudys event on Hallers dyno. All while running a 8.1@86mph 1/8 mile at 8400lbs. Which I believe is high 600's by most calculators. My truck just doesn't like dynos it seems. But I run the same track times or better then others with the same set up.

And btw. The only dyno I got to run the truck on. I rolled into the throttle at 45mph in overdrive. was full throttle and almost full boost by 2000 rpms putting down 550hp and 1235 ft lbs at 2050 rpms. stock motor on the 310 tune. My run on hallers dyno was 580/1090 with the 71 and everything else I have now.

Beans71086 · Oct 7, 2012

Have you ran it at the track?

Motostroker · Oct 7, 2012

if it down shifted to 4th. then shifted back to 5th wouldnt that not load the motor enough? When i dyno, i dont lay into it until 75ish mph. it stays in 5th and puts a good load on the motor.

BBottoms · Oct 7, 2012

Yeah, I know dyno's are really just for tuning, especially when everything isn't standardized on how they are run. The big thing that gets me is they ran 4 tuned/deleted 6.4s the same way (downshifted then back up) with just slightly lower numbers than mine (-15 hp/ -30 tq). Maybe mine wasn't getting loaded up enough though.

I'm going to Bean Diesel's event next month. While I haven't heard great things about their dyno either, maybe they'll run it different at least.

I haven't been to the track yet. I was trying to be nice to my transmission for a while since it's still stock. If I get a chance somewhere local maybe I'll try and make a couple passes. I know track numbers are more reliable than dyno numbers.

Motostroker · Oct 7, 2012

Well I'll be at beans also. Both you and I have very similar mods. Should be very close atleast. Then we can take a look at yours is power is still down

BBottoms · Oct 7, 2012

Did a few data logs this afternoon. Rolling into WOT, without a downshift. I did two runs with very similar numbers. Max numbers in 2nd run just before let off were:

2989 rpm
85.9 psi abs EBP (71.2 psi gauge)
52.7 psi Boost
1396 deg EGT
~24.66 ksi FRP (170 mPa)

EBP and EGT were still climbing at let off. FRP had no problem maintaining throughout.

I don't want to be that guy that says "It's not my truck, it's the dyno" but at the moment I'm leaning that way....

Is there anything that can cause a loss of power while still maintaining data like this?

Ipkyss · Oct 7, 2012

Just run it down the track. Dynos have been disapointing and a waste of money for me. My stock trans is still holding fine. Including two truck pulls this year. I keep thinking the next dyno will be better, but they never are. My truck just does not put down good numbers, but its fast

Jeff@Spartan · Oct 7, 2012

Dynojet 248C....done.

bigrpowr · Oct 7, 2012

Yep Dynos are just that. Never know. Track proves everything.

madman1234509 · Oct 7, 2012

I would like to see what your numbers are keeping the tc locked and not letting the truck downshift

WoodBoy · Oct 7, 2012

Your EBP sensor is maxxed out isnt it?

FordPSD64 · Oct 7, 2012

madman1234509 said:
I would like to see what your numbers are keeping the tc locked and not letting the truck downshift

I agree. I don't even hammer it until I'm Doing about 70 or so. Anything less it down shifts. Do you know how much they were loading your truck? I put down 558 a few months ago but I was about 19psi lower than usual.

BBottoms · Oct 8, 2012

Ipkyss said:
Just run it down the track. Dynos have been disapointing and a waste of money for me. My stock trans is still holding fine. Including two truck pulls this year. I keep thinking the next dyno will be better, but they never are. My truck just does not put down good numbers, but its fast

I'm going to run it at Bean's since I'm going anyway and just to see what I put down compared to Motostroker. I do want to find a track to run at though. Couple buddies go down to Bowling Green and run the 1/4 every once in a while, I'll have to tag along next time.

SPARTAN said:
Dynojet 248C....done.

Already been on DynoJets website looking for one. There are a couple right across the river in Indiana, but ones at a stock car shop and the other is a Mustang shop. Not sure how welcoming they are of Diesels though, though mine is pretty smoke free!

bigrpowr said:
Yep Dynos are just that. Never know. Track proves everything.

PMF bars are the next thing on my to-do list then I'll feel safe at the track. I won't worry too much until I find a track and it proves me wrong too, haha.

madman1234509 said:
I would like to see what your numbers are keeping the tc locked and not letting the truck downshift

I would too. It was my first experience with a dyno so I didn't know any better and they were pretty busy trying to get people run through so I didn't have much time to ask questions. Now that I've read more and got some feedback I'll know what to look for next time.

WoodBoy said:
Your EBP sensor is maxxed out isnt it?

The datalog graph shows the EBP still climbing slowly when I let off, so I must not of yet. What's it max at?

FordPSD64 said:
I agree. I don't even hammer it until I'm Doing about 70 or so. Anything less it down shifts. Do you know how much they were loading your truck? I put down 558 a few months ago but I was about 19psi lower than usual.

I've done the same doing data logs. Not sure how much they were loading the truck, but like I said, several other trucks torque numbers seemed low, so maybe they weren't doing it well. Unfortunately they had staff running the trucks and they unplugged my CTS to plug on their OBD for RPM monitoring, so I don't even know if it was pushing full boost.

Sounds like I don't need to worry too much about it until I get it to a track or another dyno. Now I just have try to hold off my buddies since I've been telling them I've got a 650hp truck for the last two months, haha.