Diagnose These Dyno Graphs

[Strik3r]

Went to have the car tuned on monday and ran into some problems.

I wont go into details - rather let the dyno graphs speak for themselves, but in essence

1) Can't seem to hold/maintain higher boost pressures. We had the actuator duty cycle set at 65 to produce the high boost plot you can see in the graphs below. When we set it to 75 or 85 it made no difference to the plot (for reference, 85 should have generated about 1.8bar of boost). This COULD be related to the HKS EVC settings. I've since checked the manual and there is a 'Boost Offset' setting that may help us sort this out, but it may not be the problem.

2) Loses power dramatically at *about* 7krpm (someone confirm what 155km/hr in 3rd is ?). You can see a 120hp drop from peak at 145km/hr to about 340hp by 8500rpm. The only thing that was noticed was the CAS sensor output starting to wiggle a bit after 7krpm... but it was staying on the same 2 MAP points and wouldn't pull through them. The 2 map points were VERY similar in terms of inj duty and timing, so its not as if one of them is causing it to go backwards.

Car mods:

Fully built rb26 (all forged good bits including n1 block)

Garret t04z turbo.

3.5" turbo back exhaust with external wastegate venting to atmo (not exactly sure on size of gate - HKS job)

Tomei pro cams (270degree, 10.2 lift (i think))

Tomei lifters

1000cc Sard injectors, Sard Fuel rail, Sard FPR.

2*044's from surge tank to engine - PLENTY of fuel.

HKS EVC V boost controller

Splitfire coils, HKS Twin Power CDI system

New NGK Copper plugs - heat range 7, 0.8mm gap (had them at 1.1 but took them down to eliminate that as a cause).

and finally PFC Djetro so there is no issue with AFM's here.

more mods but i dont think they are relevant...

Onto the graphs:

the plot that ends up slightly richer in the AFR graphs is the high boost graph.

Obviously the car should be making a lot more power (i'd expect to see 550-600hp at 1.7 bar), but what is interesting it that the boost drop off happens long before the big power drop., making me believe its 2 seperate issues although it could be one causing both symptoms. You'll notice that on the low boost (1 bar) run, it held boost all the way yet there was still a big power drop at the end.

Any ideas ?

[666DAN]

Who did the rebuild? And do you have just cams or adjustable gears as well?

[tridentt150v]

What spring rate is in your wastegate, I'm betting its a 14psi [light blue colour] or similar. So your wastegate is bleeding too early.........just a guess.

[Adriano]

What sort of ignition timing is it runing up top?

[2rismo]

Check the spring in the gate.

[Guilt-Toy]

Check the spring in the gate.

I don't think its the spring in the gate, the turbo is holding the boost as normal.

I just think the turbo or turbo's are running out of PUFF.

Possibly be a boost leak as well.

can you post a map trace of any of the runs ? a screen shot ? also a screen shot of your timing map ?

[tridentt150v]

I don't think its the spring in the gate, the turbo is holding the boost as normal.

I just think the turbo or turbo's are running out of PUFF.

Possibly be a boost leak as well.

can you post a map trace of any of the runs ? a screen shot ? also a screen shot of your timing map ?

I thought he said it was only holding boost OK at 1 bar [which roughly would be around the 14psi spring rate], but they couldn't increase boost above this without problems. Maybe I misunderstood???

[666DAN]

Yeah but his power still drops like a rock even at stable boost and reasonably stable AFRs.

looks like the power delivery is right off, that's why I was asking about the cams, have they be installed out of whack?

[R31Nismoid]

Yeah i agree not wastegate related, you can see boost is holding while power drops off.

I'd drop the exhaust from the dump pipe, do a run and see what happens.

It looks as if its hitting a brick wall, which likely to be back pressure or something flow related

[dano4127]

Hey Gman that's pretty much the same sort of power it made before you got it aye, I wonder if the previous owner had something similar happening and that's why it never went further? Might pay to give him a call (if your on speaking terms)

From memory he had said it made 400kw @1.4bar but didnt go any further cause it was a "quick" tune, im guessing they had a similar prob and that's why it was never pushed any further?

Since then it has had a proper rebuild, more fuel system added and the ignition upgrade so you can take that part out of the equation.

T04Z should be up to the task.

Seems flow related so exhaust or manifold???

[Strik3r]

Who did the rebuild? And do you have just cams or adjustable gears as well?

Dan from ERD did the build. I'm actually not sure if it has adjustable gears or not, will find out.

What spring rate is in your wastegate, I'm betting its a 14psi [light blue colour] or similar. So your wastegate is bleeding too early.........just a guess.

yea its a 14psi wastegate. The boost controller obviously controls this. im going to check the vac lines running to/from the stepper motor to make sure they arent dirty and will replace the filters too.

What sort of ignition timing is it runing up top?

about 20-21 degrees i believe.

I don't think its the spring in the gate, the turbo is holding the boost as normal.

I just think the turbo or turbo's are running out of PUFF.

Possibly be a boost leak as well.

can you post a map trace of any of the runs ? a screen shot ? also a screen shot of your timing map ?

*could* be a boost leak, but if you look at the graph, it holds 1.4 bar near the end.. If it was a leak, i know the HKS EVC would just make the turbo spool more and more to try and get the pressure on the intake up to the desired amount. Might measure the pressure output at the compressor wheel and see if we are getting any big pressure drop off. That being said, its still holding 1.4 bar right through to the end, and its holding that boost while the power plummets. Dunno if i can get a screenshot of the maps/timing or not... might chase it up.

As far as the turbo running out of puff.. Garret t04z is definately not running out of puff at 1.4 bar .

Yeah i agree not wastegate related, you can see boost is holding while power drops off.

I'd drop the exhaust from the dump pipe, do a run and see what happens.

It looks as if its hitting a brick wall, which likely to be back pressure or something flow related

Ya, will prob try dropping the exhaust to confirm its not an issue.. but the exhaust has nothing in it.. no cat, single rear muffler, and the external gate is quite large too, so the effective exhaust size up top is pretty huge.

[Strik3r]

Hey Gman that's pretty much the same sort of power it made before you got it aye, I wonder if the previous owner had something similar happening and that's why it never went further? Might pay to give him a call (if your on speaking terms)

From memory he had said it made 400kw @1.4bar but didnt go any further cause it was a "quick" tune, im guessing they had a similar prob and that's why it was never pushed any further?

Since then it has had a proper rebuild, more fuel system added and the ignition upgrade so you can take that part out of the equation.

T04Z should be up to the task.

Seems flow related so exhaust or manifold???

prev owner said 400awkw @ 1.4 bar.. but it wasnt a quick tune.... He spent some $2k on tuning.. including running the engine in on the dyno. Said it was a 'safe and rich' tune cause he had had experiences where there was no 'good' fuel available at some track locations. Theoretically i guess if the dyno he was on was reading happy he could have been making what I am now..... still, something has to be holding it back.

[dangerman4]

i would be looking at cam / valve related issues.

[2rismo]

There is still a problem with the boost climbing to 1.6 bar and dropping off to 1.45-ish. Poor boost controller setup more likely. Now I've had a better look at the graphs as a whole and not just the boost curve, I say have a close look at the exhaust but fix up the boost curve and intake air temps too.

[Guilt-Toy]

few other things to look at....

what air temp is the temp getting up to ? have you checked that and referenced it to your air temp ignition correction table?

Boost leak could be causing this as well, ive seen boost leaks do some weird things in the past and it IS possible for the leak to cause this.

When you have a boost leak, the turbo is working sooo much harder that the air temp would go through the roof and also cause ignition retard...

Can you send me a log of the dyno run from the datalogit ? the text file with all the values ?

post them up ?

[MBS206]

Cams not set right?

Valve float? You haven't mentioned springs that are being used...

It looks like it ramps up quite nicely, and just noses over... As if the cams are set for response...

[Strik3r]

few other things to look at....

what air temp is the temp getting up to ? have you checked that and referenced it to your air temp ignition correction table?

Boost leak could be causing this as well, ive seen boost leaks do some weird things in the past and it IS possible for the leak to cause this.

When you have a boost leak, the turbo is working sooo much harder that the air temp would go through the roof and also cause ignition retard...

Can you send me a log of the dyno run from the datalogit ? the text file with all the values ?

post them up ?

not sure on air temp. Am going to do a pressure test of the intake side of the engine to check for leaks soon. I can't get a log of that run, but if I go back I'll make sure I have my USB stick so I can dump some log files of any future runs.

Cams not set right?

Valve float? You haven't mentioned springs that are being used...

It looks like it ramps up quite nicely, and just noses over... As if the cams are set for response...

Fairly sure it has aftermaket valves/springs/etc. Am going to confirm and also check what the cams are set at. Will update this thread once I know more.

[666DAN]

Yep my thoughts were it made power too early in the rev range for a TO4Z, then looked like it an out of puff....so was thinking the cams were out of whack bringing the power band forward.

[The Dan]

It's a full Tomei head. Lifters, valves, springs, cams etc. You are right on the cam specs Gerv.

It does have adjustable cam gears. These are set at 0 and 0. I left that part for the tuner.

I don't think the power is coming on too early for a T04Z. It pretty much makes 1 bar at 4000rpm from memory.

Can you post up a pic of that dyno night run you showed me? or send it on Skype to me.

[The Dan]

Keep in mind, also the dyno runs were done in 3rd so 4000rpm is only about 100k's I think