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HELP! Way down dyno figures (185kw 19psi GTX2867rGen2)

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Hey all.

Looking for opinions on those who would know what is wrong - if you look at the dyno, it is just not good.
Mostly validate if I need bigger size cams, etc.
S15 Jap Spec-r.
Running GTX2867r with 86 rear housing. (brand new Gen2)
Stock cams.
850cc Injectors (JECs side feeds, flow tested), splitfire coils (blue ones). Blirtz Spec-r boost controller.
Custom hard intake pipe (3inch?)
455L Walbro Fuel Pump. Z32. BKE7 something spark plugs (new and the correct ones).
Kakimoto Regu 06&R with resonator removed. High flow cat, tomei 3" dump. FMIC (generic).
As the dyno results show - no power. People like to blame the housing, others the tuner. The tuner is good, those who he is all agree. The figure is way down regardless of the housing size. I don't believe the housing is the issue either. Just a LITTLE more lag.

The timing was not advanced further due to detonation.
FYI comp test is fine (135 to 145 across all 4 from mem).
Leak test done - no boost leaks.
The car had the T28 before and would move even at 6th gear at 100km/h, my old S15 had a 2871r 0.64 and moved still without a tune more at under 5kRPM. 
Again, No boost leaks, injectors have been tested. 
With no cat and exhaust it made 192kw. So that eliminates the exhaust.

I want my bottom end back and my 260kw I should have.
Tuner is saying E85 and cams are needed as some SR20s just don't make power.
I am hoping not to rely on E85 to make her move again.

With all the above info, WHAT THE HECK IS WRONG?!?!? :( 

Thanks all. :) 


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Is the only change the turbo or were other mods made at the same time?

Have you checked spark plugs to see what colour they are?

Is turbo internal or external wastegate? what boost pressure you running? What is the actuator rated for?

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In short all at the same time. The intercooler though was what was on the car originally.

The plugs are new but I will recheck them. Tuner though has said he has checked them and my splitfire coils (swapped them out for troubleshooting).
Internal gate. Actuator is rated for 14psi. Boost controller set for 14 and 19psi (185kw at 19, 145kw at 14psi).

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"JECs side feeds, flow tested"

Did you get them flow tested, or were they the cheap "high flowed JECS flow-tested remanufactured" injectors off eBay? Those $250 eBay JECs injectors are notoriously bad, either due to inconsistent flow or poor atomisation, so get them tested yourself or replace them with oem-quality injectors like Nismo 750s, a top-mount rail with Bosche injectors (Taarks sell conversion kits for top mount injectors), etc. If you have access to a spare rail with something better than what you have, it could be worth testing. I'd also suggest you check your pump and FPR with a fuel pressure gauge, to confirm that you don't have an issue there. There's a reason the eBay injectors are less than half the cost of reputable gear.

"splitfire coils (blue ones)"

Try some OEM coils if you have access to any. I'm not that trusting of Splitfires, heard too many bad reports in the past, but they might be absolutely fine like your tuner said.

"BKE7 something spark plugs"

Those are one grade colder than OEM which is correct for your power goals. It could be that the spark is blowing out, in which case gap them down to 0.7 or whatever. Search and you'll find threads on that situation.

"In short all at the same time. The intercooler though was what was on the car originally."

Check your intercooler pipes to ensure there aren't any rags lodged in them from the turbo installation. It's happened before.

"The timing was not advanced further due to detonation"

Get hold of a graph of AFRs vs RPM at peak power. If the car is detonating, is it leaning out or running rich? We need more information to diagnose the problem that that dyno sheet.

My money is on the yum-cha JECs injectors, looking at how it ramps up on the graph, holds constant boost, then power goes down, up and all over the place. Do some reading on modified JECs and you might think the same. For example:




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Thanks Pmod. I appreciate the massive effort you put into your reply. I really do :)

I did have the injectors  tested at Unigroup myself and they said "they're ok but they could atom better" so I reckon you are right. Everyone blames the turbo 0.86 housing and I have read so much to flat out disagree. A little l"ag" is not a missing 70kw

I have been already coincidently lookings at the Taarks set (bosch) and am thinking I may go for the 1200cc  too and go for a retune. Do you think I should get the Tomei poncams (256/256) in at the same time for the bigger turbo and go for gold?

As for the spitfires and rags in intercooler. They checked that as they were baffled at the lower power output too and did a heap of troubleshooting.

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No probs man, we've all been stumped by strange car problems at some point lol. If you're considering cams, then go for broke and do them too. I've driven on non-VCT poncams and they were alright... probs have to do it myself if I find the SR20DE cams don't cut it for me with my compression ratio.

If you haven't already, do some research with regard to cams/springs and VCT, since you don't want to delete VCT (you'll lose some response), and the wrong cams/springs can pose a problem. The best people to ask for advice on these forums will be Johnny (Does Pipe Stutututtutu on here and SAU) or Stao (Hypergear on NS and Performance Forums) of Hypergear Turbos. Stao has a thread for Hypergear detailing his testing and the results people got with their combinations. Lots of good info to be had:


To be honest, I don't understand why anyone would blame the .86 housing... makes no sense considering power is a peak figure, and bigger housings are aimed to make more power at the sacrifice of response. If anything, a bigger exhaust housing should promote stability by helping to evacuate gas more efficiently, so you should experience fewer problems at the top-end than with a smaller housing.

More confusing is that they would point to housing size as being the cause (i.e. boost comes on too late to make power, so it's just starting to hit peak efficieny at your rev limit), yet power on your dyno graph clearly stops ramping up at 4700rpm when the wastegate is opened by the EBC, power dips sharply at a point where boost is still climbing, then power barely ramps up across 2000rpm at the top-end! Even running N/A it should make a little more power after 5000rpm.

Obviously the .86 housing is not ideal for your SR20, as you get virtually no boost before 4750rpm, however response is an entirely different topic to detonation (i.e. the real reason for the imposed boost limit and that bizarre plateau) and boost ramps up quite smoothly. My understanding is that when turbos limit power it's due to a small turbine housing choking up flow at high rpm, or a small compressor housing failing to generate any more boost in the top end.

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Cams will only push the power further up the rpm. I would be checking that the z32 afm is genuine. Guessing it has a nistune? If so look at installing a hpx afm. 

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