Dynamometer Results & Comparisons - Troubleshooting low power on the dyno

Guys

I've spent the last 3 months building this 5.3L 70mm powered setup in my 240SX

http://ls1tech.com/forums/conversions-hybrids/1536369-93-240sx-5-3l-turbo-build.html

We got a chance to hop on the dyno over the weekend to iron out a tune, and the results where somewhat disappointing. I'm firing up this thread in an attempt to get some fresh ideas on what (if anything) is attributing to "the numbers"

Setup details:

Engine
5.3L LM7 (miles unknown)
LS6 Cam
Katech Rod Bolts
LS9 Headgaskets
ARP Head bolts
Comp 918 Springs
Comp 7.4 pushrods
LS1 Intake w/F-body accessories
Stock ignition on TR6 plugs ~.032 gap
New OEM wires

Drivetrain
T56 w/Monster Stage 3

Fuel System
FAST Rails
S/D 60# Injectors
Aeromotive 340lph in-tank pump
Aeromotive FPR
-6 Feed/Return Lines

Turbo Setup
Self fabricated exhaust/collector piping
On3 Performance 70mm Turbo
3" turbo back exhaust
Tial 44mm Wastegate
HKS BOV
3" core intercooler
3" self fabricated IC piping


I am working on getting the dyno sheets from the shop. As a baseline pull at 8psi on 93 octane, the car only pulled 260whp and mid 300's tq.

After we settled in on a tune at 10psi. The car was happy with ~14 deg of timing and no knock. We're not showing any mis-fires, but I remember the dyno chart being somewhat "wavy" through the powerband. The dyno reported we made 390rwhp/440tq. The AFR was pretty consistent around 11.8's.

http://i3.photobucket.com/albums/y96/Booztd3/S13%20LS%20Turbo%20Build/Turbo_LS_240_390HP.jpg

I am not sure if I'm simply looking at a dyno thats reading low (Dynojet 210) or if I have a mechanical issue on my hands. I will post the charts when they get emailed to me. The tuner reported some inconsistencies with data collection and that the VE table could not be "smoothed" correctly to make the car happy.

I have yet to do a compression check on the engine, but there was no noticeable smoke to give me an indication of excessive blow-by. The intake system is leak free as well

Here's the video of where the car ended up. You can see it seems pretty "happy"

www.youtube.com/watch?v=H4aIn6Wci9E

Some things I am thinking about going over are:

Flow test the injectors (I bought them used)
Compression Test

Any idea's are appreciated and if anymore information is needed, I'll do my best to accomodate

Ditch the ls1 intake

We're not showing any mis-fires, but I remember the dyno chart being somewhat "wavy" through the powerband. The dyno reported we made 390rwhp/440tq. The AFR was pretty consistent around 11.8's.

I am not sure if I'm simply looking at a dyno thats reading low (Dynojet 210) or if I have a mechanical issue on my hands. I will post the charts when they get emailed to me. The tuner reported some inconsistencies with data collection and that the VE table could not be "smoothed" correctly to make the car happy.

No disrespect to this guy, but I think you need a new tuner.

Also, are you running a MAF?

The tuner knows what he's doing, and I've tuned a number of high (600+) hp import cars to know that. What I meant by inconsistent data is we could make a back to back pull and in some spots the afr error would be a good ways different - which leads me to a mechanical issue that is irratic. Not to mention, with a good AFR, 14 degrees of timing, and 10psi with my mods - I *should* be making a good amount more power

The car is on SD only

Hows your oil look?? Those head gaskets are designed for a motor with a 4.060" bore...not a 5.3L with a 3.78" bore. Not completely sure, but you may have head sealing issues. And for what its worth, my old car with its stock motor blew a head gasket on two cylinders and never ran hot...just a bunch of coolant in the oil.

I have yet to change it since assembling the engine, as it probably only has 300-400 miles on it or so. The last time I checked the dipstick I didnt see anything out of the ordinary.

FWIW I have seen/read several people around (and on here) use those head gaskets successfully on a 5.3 setup

Cool...I wasn't sure but seems like a possibility when you consider the difference in bore sizes. But if people are using them for the smaller motors a lot then I'm sure its fine.

I'm the tuner that was working on this car. For some background, I'm not going to claim to be the best troubleshooter or tuner in the world, but I've been doing this for quite some time and I've got a pretty good knowledge base.

The tuner reported some inconsistencies with data collection and that the VE table could not be "smoothed" correctly to make the car happy.
This car is running OLSD on a 2bar OS. To hit the target AF ratios, the VE numbers on this thing are very funky. As in 70+ values just off idle, and around 2500rpm in low boost regions it is wanting values higher than in the 4800 region. I double checked the scalers in the tune to make sure they weren't set up for a 4.8 or something, but they're all right. This car also peaked in power very early. It has an LS6 cam and it was declining in power by 5700rpm if I recall correctly.

I'm all ears on this one as well, it just acts very strange. If the car ran worse I might think the cam was a tooth off due to the strange VE peak, but the car runs smooth as silk.

I'll try and get you the DRF's tomorrow Andy.

Alyssa emailed them to me earlier. I'll probably get a chance to look at them tonight

Attached the dyno chart

How are yall controlling boost? What spring is in the gate? The dyno graph looks like its about to make good power then just falls off.

Yea I agree it looks like its about to make some nice power then just falls off. Since the a/f and timing seem to be in line id start looking at restrictions. Id start with that ls1 intake, I doubt it fixes the huge drop off but it needs to be done anyway. Are the valvesprings new?

I agree. sounds like it has a restriction in it. if its intercooled id start there. not sure if you have done any leak checks yet. it should be making alot more.

I'll answer the last couple questions since I asked them the other day.

Brand new comp 918 springs.
Brand new Monster Stage 3 clutch (no clutch small on the pulls).
Boost gauge was rock solid at 10psi, and the map sensor agreed.

That cam falls off at around 5500 so thats normal, sounds more like an ignition issue

Yea I agree it looks like its about to make some nice power then just falls off. Since the a/f and timing seem to be in line id start looking at restrictions. Id start with that ls1 intake, I doubt it fixes the huge drop off but it needs to be done anyway. Are the valvesprings new?

Thats a pretty normal reaction with a wastegate. Its a single Tial 44mm wastegate on a 10psi spring with no boost controller. Looking at the dyno logs I can see we reached target boost right at the exact time the curve leans over.


The car trapped 126mph today, which is pretty close to the power levels we're seeing on the dyno and factoring in the weight of the car.

Its not the LS1 intake or the LS9 gaskets, I can gaurantee you that.

Whats the turbine wheel size in that 70?

May want to drop that plug gap a tad down to around .026 or so.

Id say its a tuning issue.

We had a little discussion while on the dyno about ignition. It was dismissed due to the fact we were not seeing any misfires. I'm not familiar of the mis-fire detection strategy but on other applications I've played with I'll usually get an audible mis-fire.

I dont have much info on the turbo other than whats on the website

Cold Side:
.70 a/r
4” Inlet and 2.5” Compressor Outlet
Inducer- 70.15mm
Exducer- 94mm

Hot side
A/R - .68
Inducer- 64.5mm
Exducer- Unlisted

I would bet the turbine is too small for the combo. Also did you try more timing? The 5.3ls will take more timing then the 5.7s and 6ls. That is the reason the graph is wavy and the engine doesn't seem happy yet.

Tiny backside!!!

I would bet the turbine is too small for the combo. Also did you try more timing? The 5.3ls will take more timing then the 5.7s and 6ls. That is the reason the graph is wavy and the engine doesn't seem happy yet.
Thanks for weighing in here, I know you've got a lot of experience with boosted 5.3's.

We didn't get crazy with it, but he only picked up around 4rwhp with 1 more degree of timing. We quit there since that's not on par with where the gains should have been if it was happy. I'm not saying it couldn't handle more, we never saw any knock anywhere, and the knock sensors were tested and working. Perhaps that backs up the theory of the exhaust housing being too small?

Had a talk with some turbo guys here at work and one of them is thinking that the wastegate spring is potentially too "soft" for the application. The wastegate opens and over compensates and then enters a cyclic pattern of over/under correction.

After that conversation, I went into the datalog from the street and I can see (upwards of) a 5kPa swing and what appears to be some cycling of pressure.

http://i3.photobucket.com/albums/y96/Booztd3/S13%20LS%20Turbo%20Build/Boost_Log.jpg

The guy I talked to earlier suggested moving to a smaller wastegate to combat the "waves" were seeing on the dyno. The frustrating part is that its unlikely that will do much for my low power issue.

Thats where i was going with asking what spring was in the gate.

Its got two springs in it from Tial that equate to 10psi, which is inline with what we see. I can tell you that it doesnt feel "soft" when putting the wastegate back together after putting the springs in.

One thing I am curious about is still the intercooler being a restriction. I am pulling the wastegate reference line post-IC. If the IC acted as a restriction it could potentially pulse air which could in turn pulse the wastegate - somewhat of a cyclic pattern.

I've been thinking about moving the wastegate reference line to pre-IC just to see how it reacts

MAP holds steady, so its not a boost issue in my eyes. The waviness does look like it wants more timing, or has a valve spring issue.. I would not recommend adding more timing on pump gas.

If you can try a different turbo, you may want to try that as well. On similar builds with a 76mm turbo, it will usually pull smooth to 58-6000 using a manifold kit like what you have. And that is using the basic LS9 HGs, LS6 style cam, but always with dual valve springs vs the single 918s. On one where the springs had some miles the power curve looked similar to what you have, changed out the worn out dual gold springs for new ones and the power jumped back up gaining over 100rwhp.

MAP holds steady, so its not a boost issue in my eyes. The waviness does look like it wants more timing, or has a valve spring issue.. I would not recommend adding more timing on pump gas.

If you can try a different turbo, you may want to try that as well. On similar builds with a 76mm turbo, it will usually pull smooth to 58-6000 using a manifold kit like what you have. And that is using the basic LS9 HGs, LS6 style cam, but always with dual valve springs vs the single 918s. On one where the springs had some miles the power curve looked similar to what you have, changed out the worn out dual gold springs for new ones and the power jumped back up gaining over 100rwhp.

Any way to validate whether or not I have a valve spring issue? Not sure if a simple compression/leakdown is going to give me the data I want

Additionally, I'm at a crossroads with the turbo. I'm not aware of anyone that has a "test" unit I could at least try out which means shelling out coin for a new turbo, and then deciding if I even want to go down the "chinese manufactured" route again