1jz efr 7163 compressor surge at full throttle

[toy4speed]

Hello All, just wanted to ask for some feedback on my 1jz surging at full throttle situation. Noticed in 2nd gear as it is an autox Mk2 supra. Specifics currently:

1jzgte stock internals
BW EFR 7163 .80 a/r, T4, internal WG, internal BOV, high boost WG canister set 3 turns preload. Turbo compressor inlet is 2.5" with an old cone filter (not same filter used with GT3076)
SDS standalone
TruBoost controller, wired to the EFR solenoid for IWG
Misimoto IC with 2.5" piping
Quick Spool Valve
3" DP with 3" exhaust, single muffler.

Just swapped in the EFR 7163 to get more response, powerband lower in the rpm range for autox. Had a GT3076 that worked fine, no issues, ran on gas then later on E85 (currently too).

The turbo hits about 21 psi max, on low setting with the TruBoost. Don't want more boost till figure out the surge problem. It is very pronounced on full throttle. No datalog yet, may try to get something later if possible. I believe it happens mostly above 4000 rpm. Boost from 3-4K feels pretty good and smooth. Not tuned much yet so hoping there is more response and power, especially if the surge if corrected.

My thoughts: I don't think the turbo is too small for the 1jz motor. Boost is not too excessive or too quick, my impression. Have yet to check spark plugs but not a miss, more of a surge. It feels something similar to when I first set up the motor with too small of an intercooler, and the airflow was too low, like choking the flow. Just my impression.

Perhaps my cone filter is too restrictive or too dirty, which I am hoping is a simple thing. Next chance I will take the car out without the air filter, just open the inlet to turbo, see if better. Pretty new to turbos, so didn't think a filter could choke down a turbo inlet, but saw a few posts.

I can also swap back in my Tial WG 38mm and bypass the internal wastegate of the EFR, for testing. Can also bypass the internal BOV of the EFR and use my Tial BOV. Left all my flanges intact on the motor just in case.

If anyone has some experience with the EFR turbo on the 1jz, please offer some thoughts! Looking for ideas! Thanks!

 

[toy4speed]

Update: Played with the spring pressure setting on the Tru Boost. It is variously referred to as "wastegast crack pressure", "gAE", "spring pressure". On my GT3076 with external WG with a 1 bar spring, the suggestion is to set this spring pressure to about 2-3 psi less than the WG spring. I ran the spring pressure on that setup at about 12 psi and it worked ok. With the high boost WG canister on the EFR turbo, I really had no idea what the relative spring pressure was on the canister, so I varied the setting from about 12 psi to about 17 psi. According to some AEM videos, setting the spring pressure on the Tru Boost too high, or higher than the WG spring rate can result in oscillations or surging as the turbo is somehow trying to reach boost levels not possible at that time. I believe this was my issue. I set the spring pressure down to 8 psi, thought it was somewhat better, am now at 4 psi and the turbo spools up smooth. With some time, I can fine tune the setting some more to improve the spool up response but hopefully not encounter the surging problem of the turbo again. I also found that the EFR turbo responds well to the Tru Boost duty cycle settings, whereas the GT seemed to be much less responsive. I set the duty cycle at 10% on the GT, it hit about 22 psi, I didn't want more, never increased the duty cycle (10% is minimal setting). On the EFR, 10% duty cycle gave me 14.7 psi, 20% duty cycle also gave my 14.7 psi. I am up to 45% duty cycle now and reached 19.5 psi. Will try 55% duty cycle next, trying to reach 22 psi.

Feeling pretty good now with the progress, need a bit more boost and a little quicker response on the turbo. It already has quite a bit more boost from 3-4k rpm than the GT3076. Will make for comfortable 3rd gear parts on the autocross course which formerly felt pretty flat.

 

[te72]

Just wanted to say thanks for updating your post. Having a similar issue on my 1j, although with a completely different setup. This gives me some confirmation of ideas I had...

Question then, did you give up any power in the mid range to get away from the surging? I'm thinking of setting my wastegate spring setup to around 18psi, then playing with the boost control settings to get me back up to the 20 to 21 psi that I am currently at on the spring, but... I don't wanna give up any torque if I don't have to.

 

[toy4speed]

Ended up with a truboost spring pressure of 11.5 psi, working fine. Haven't tried bumping it up any higher. Mid range power is strong, no sacrifices. My goal with the 7163 was to get earlier boost, and it definitely succeeds. Top end is plenty strong as I am at about 23.5 lbs boost now, not looking for more. Still needs some fine tuning, haven't been on a dyno, all street tuning myself.

 

[seoul4korea]

interesting read.... I'll have to remember this for mine later.

 

[KenHenderson]

Are you sure the compressor map for the 7163 EFR is compatible with the 1JZ's ability to ingest air. I assume you have stock cams with your statement indicating you have "stock internals"? Typically, to get all that turbo has to offer, a set of bigger cams may be required, although that could negatively impact your autox power band from your perspective. Playing with the wastegate may help as you've noted but, in my experience, that is more of a band aid fix than a solid resolution of the problem.

Given that you autox, your current arrangement may work well for you, though your low to mid-range boost setting may have to be artificially low because of the surge issue you described in your OP. I am unfamiliar with OEM 1JZ cams, but you might find a mild set of aftermarket cams, such as HKS 256s or 264s might enhance the response of your set-up, provide more power all over and eliminate the surge problem in the part of your power band where you spend the most time at autox events.


Ken.

 

[toy4speed]

Ken: no expert on turbo compressor maps, but what I have read and seen the 7163 EFR is good for about 500hp, which is my general goal also. Yes, my 1jz has never been opened up (by me), so stock original since purchased. I have no doubt some cam, head/valve work can better numbers, but the gain in my desired rpm band may be less significant (2.5-4k rpm). Not familiar with other electronic boost controllers, as the TruBoost is my first and only. Just to be clear, it's not the wastegate or wastegate spring rating that gave me issues, but the TruBoost "wastegate crack pressure" that I had to figure out a good setting. Too low (2 psi) and the spool up may be slow, too high (17 psi) and I may get compressor surge. The EFR has an internal wastegate, which differs from my original external 38mm Tial WG previously used. So really just my own failing, of tuning the engine to run well. I don't pay a shop to build or tune, so it tends to take me a bit of time to figure it out.

 

[te72]

After some discussion with some more experienced folk, I've come to a different conclusion in my case. The exhaust housing of my turbo is a bit on the small side. The turbo spools up hard, stuffing the head full of air, but due to the smallish size of the exhaust housing, it has a bit of trouble getting out. Will be stepping it up to the next size housing and experimenting with that. Will update then, but we're talking next spring sometime, don't hold your breath.