Interesting To Say The Least Dyno Result Rb30det Hx35

[menthol369]

Hey guys,
i have a rather odd result from the dyno today.
Setup is as follows
stock 30 bottom end ( rings and bearings done)
660cc jecs injectors
100mmx600x300? trust FMIC
z32 AFm
20det ecu with latest nistune firmware
FF Freddy plenum
VCT s2 r33 head
45mm hyper gate (did runs with 14.7 psi springs and new 10 psi springs, no change)
Greddy profec b2

HX 35 with this supposed trim
7 blade
a/r 0.89
Comp inducer 56mm
comp exducer 76mm
turbine inducer 69.5mm
turbine exducer 60mm
Turbine trim 75

Now whats happening is that the boost falls off quite fast above 5K rpm, no matter what we did we couldnt get it to boost above 12-10 psi above 5k.
Tested the following
Leaks in the intake ( sealed the turbo intake and pressurized to 20psi, no leaks
Gate - changed to new springs (14.7psi OLD 10~ new)

completely sealed the gate exhaust- would stack on boost down below 5k ( didnt over boost so dont worry) crept revs up to 5 k and slowly put foot into it- foot flat and gate closed the boost would still fall off down to 10psi at 6800rpm

completely unrestricted the exhaust, ran from dump and screamer not plumber back to check for blocks, no change

Basically we tested every single aspect we could to try pin point the problem, and by the looks of it its asif the turbo is running out of beans with such high flow.

Thoughts? there should be the final dyno results attached.

Cheers,

Dan.

[menthol369]

https://scontent-sin.xx.fbcdn.net/hphotos-xap1/v/t1.0-9/s720x720/11134045_10153102376977850_3608340679872147921_n.jpg?oh=bb9b30057ea7b5b2737d4d26211a14f1&oe=5570D321

[menthol369]

[menthol369]

oh and the rear housing is 12cm ( i think, it has 12 164 on the housing)

[KiwiRS4T]

No idea what to expect from that turbo. Are you able to measure boost before and after the fmic in case it is somehow blocked? When you pressurized the turbo intake could someone read the boost gauge to see if it was getting the same reading?

[menthol369]

Yeah boost was measers at the comp outlet and the mani exactly the same @ WOT

[Ben C34]

Is cam timing confirmed correct?

[Dale FZ1]

Daniel from your initial post about the "supposed" turbo spec: Have you had the housings off to inspect and/or measure? What engine does this particular HX35 spec get fitted to, and at what power rating?

The boost curve indicates the thing gets up and boogies nicely down low but it's falling from 4200rpm onwards. That's 1000 engine rpm through which it is delivering max boost. Presuming the engine setup is all correct, and your search for boost leaks appears thorough.

Looking like a restriction or flow efficiency issue with the turbo system. eg. no stray rag in the intercooler, pipe work not nasty, and it may be a big presumption that you have a 12cm housing simply because of what might be a part number. To me it looks like what you'd expect with (just picking a number) an 8cm housing on those quoted impeller sizes. (Not likely because your unit would have come from a diesel with focus on turbine flow efficiency).

Probably little to no chance of getting a different turbine housing to try, so is there any other variant of the HX35 you can get onto for cheap if nothing becomes evident?

You've got a head-scratcher there, and some of the suggestions seem basic, but when identifying cause of problems I tend to start with the basics.

[menthol369]

Cam timing is correct ( albeit not perfect as it was done as you do on a 25)
Egts are not high and the turbine housing doesnt get mega hot with back to back runs, the mani glows red but that is normal.

I did some research and the stamped "12" indicates it is a 12cm rear.

i have a mate who works with alot of trucks and buses that use holset so it may be easy to go to a 14 or 16cm housing

checked intercooler for rags, pipework is nice.

one of the tests we did was hook pressure to both ports of the waste gate and clamped the top hose so it didnt recieve pressure and the gate operated nomral.
did a full power run and when it go above 5K let the crimp off so the gate (should) close

it recieved a 3-4 psi spike ( which should cause a significant increase in power) but didnt increase power where the spike occured.

[menthol369]

This is a dyno sheet of an rb30et with the same turbo
runs e85 400hp on a steady 20 psi

could valve float cause this? stock 20 year old springs...

[jay-rod]

Try see if you can get another turbo to test.
Because it certainly looks like the turbo's fault from all your tests.

[Dale FZ1]

+1 for further checking of the turbo and/or replacing it with a known good unit.

The plot on post #10 is interesting. That setup holds 19psi but power flattens and it's basically holding 350hp from 4250-5250rpm before tapering. I'd be looking at that as a fair indication that the compressor really can't efficiently push more air.

400hp on E85 from a 30DET at 19psi is not what I'd consider outstanding results, although this spec looks like it would be quite good on the road.

[GTSBoy]

Another thing to ponder is whether the turbine side is wrong. Let's say it has a big housing, but a small turbine that can't extract enough power. Then you'd get low back pressure (good) but also not get enough power to drive the compressor to the required air throughput.

[menthol369]

mate of mine who i got the turbo off has already ordered a 16cm rear for it haha. ( ill add that this turbo is brand new)
ive now spoken to a couple of guys that have gotten 400hp out of these turbos on 30e+t

Gtsboy. that would return the opposite of what is happening. It stacks on boost real quick at lower rpm and maxes out real quick.

Dale it was a 30et, not det ( not that it makes much difference, head flow and lower comp however would come into play) but all signs are indicating that this turbos rear housing is too small.
I know its a disel purposed turbo, but you would think for a peak of 220~ rwkw it would come on earlier than it does.

ill just have to wait for this rear housing to turn up,

[GTSBoy]

Gtsboy. that would return the opposite of what is happening. It stacks on boost real quick at lower rpm and maxes out real quick.

I appreciate that it seemed to be coming on boost OK. I was willing to give some credit to it being a 3L for that. I would have thought that a 12cm2 housing wouldn't be too small though. And if it was too small, not so massively too small that it would start killing the fun 1000rpm after it came on. Just looking for alternative ways that it could be f**ked up.

Edited April 4, 2015 by GTSBoy

[menthol369]

appriciate it, because i certainly have NFI!
also being 12cm^2 divided twin scroll housing its probably a fair whack less than the stated 12?

[Dale FZ1]

Now there is more information not initially provided.

Split pulse housing.

What manifold are you using? Pictures too please.

[XR Pilot]

Figure I'll fill in some more information here as I'm the one that tuned it. Timing/fuel/dwell has all been checked, no problems there (Though to be honest I haven't checked timing scatter with a light but I doubt it is a problem here - engine responds to timing how it should) and ignition timing is about what you'd expect - it's not overly sensitive to timing as a lowish comp motor on low boost as you'd expect. Timing sweep under load shows minimal change. AFRs are on another sheet but are sane around the mid-11s, low 12s mark. Pressure drop across the cooler was minimal. We tried dropping the exhaust from the dump back and made around 4-5rwkw more.

Basically aside from not being able to get the thing to hold boost (even with full boost pressure applied to top port of gate it made 12-13psi peak up top) it behaves as you'd expect. I have asked Dan to put a pressure tap into the collector on the manifold to check back pressure when he gets time. Cam timing may not be spot on - it's aligned to the backing plate marks - yes, it's not going to be spot on being a 3L block - but I can't see how that'd cause a problem with it not holding boost, just shave a bit off the top end power figure if it is a bit out. VCT is connected and works as expected, changeover sweet spot is around 5K.

Finally, before anyone asks the RPM scale is incorrect and I kept forgetting to tell Dan. The end of the run is just off the rev limiter at 6800. I kept forgetting to reset the derived RPM scaling as I had other things to worry about.

Edited April 4, 2015 by XR Pilot

[GTSBoy]

Need to measure the compressor exit temperature to get an idea how far off the efficiency island it might be.

[XR Pilot]

Unfortunately I left my thermocouples at home on the day but I can lend them to Dan to check discharge temperature later. Lack of compressor flow is a possibility but personally I'm leaning to a small turbine housing causing a restriction. From what I know of the HX35s the compressor supposedly flows around the 55lb/min mark; you'd think that'd be enough flow for at least somewhere around the 300rwkw ball park.