astonmartian

About time I post about the silvia I've had for almost 2 years so figured posting up the dyno results from last week would be a good start.

Bit of background on the car: Came to US 3ish years ago stock, save for an aftermarket exhaust and now sits, imo, as a solid street car. All parts were bought new save for a few things here and there. Early 1991 production factory two-tone manual with SR. Now sits with ~100k miles on it.

Major Mods:

Tomei m7960 w 11lbs spring
Nismo 740s
z32 AFM
Enthalpy ROM tune (16 psi)
Greddy FMIC/airnix intake
Tomei turbo outlet, 3" downpipe, hi-flow cat, HKS sport exhaust
Blitz id-color dual sbc
Greddy FV bov recirculated
DW 300LPH pump, Tomei FPR
Stock unopened engine, stock HG and cams

The car has been laggy as sh*t since I've had it (same for PO) but once it's above 4-4500 rpm it pulls with a vengeance. Needs cams badly though to really make this turbo shine as it kinda huffs and puffs off boost up top.

On to the pull:

Mustang dyno, 60 degrees, 57% humidity and running 15 lbs of boost.



Results were 266 and 268 whp with 253 and 257 torque respectively. As you can see, the spool is pretty pathetic, with full boost at about 5000 rpm (on the street; had gopro setup in cabin but tuner's hat blocked it).

- The boost spikes about 2psi thus the hump around 5250
- There's a drop in power, then acceleration around 4-4200: Is this because the EBC is opening the wastegate at that time? May be able to turn gain up to get some additional area under the curve.

AFR's in-car on my gauge read upper 11's, leaning out a bit towards redline, no doubt due to fuel pump not being hardwired. Dyno tailpipe shows low 12's for afr

Sent graph over to Martin and he said there's something wrong with the wastegate most likely and that he's tuned a bunch of 7960's that start cooking in high 3k rpm. But I've done pretty extensive researching online and looks like the tomei just spools like poo regardless. On the highway in 4th, I get 5psi at 3k, 10psi at 4k and 16psi at 5k, consistently. I dunno. First SR/tuner turbo car I've owned.

This setup will fall out of boost when shifting WOT to WOT in 3rd 4th to 5th and when the boost comes back on, it hits hard (literally sends shock through drivetrain). Very fun setup on the highway but driving it anything more than a third throttle below 3k rpms is so uneventful I just putz around when off boost. Probably worst setup I could have for a car that's driven most frequently in downtown Boston but I like the Doctor Jeckyl and Mr Hyde personality.



Cheers

RalliartRsX

The turbine wheel is an almost a 30 year old design


Not surprised it spools like crap lol

astonmartian

Yeah truth. I'm kinda torn internally over upgrading to a 'modern' turbo. The lag feels so ... period correct

Dboyizmlg

If you are looking for a fun set up with superior quick spool and just as good top end as that 7960, you should upgrade to a GTX2863r it will be an extremely fun car to drive!!!

You also need some 256 cams

silviaks2nr

Those numbers seem so low. Have you compression tested your engine? I honestly think the real answer is just tossing that internet tune and getting a real EMS/dyno tune.

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RalliartRsX

I have an efr 6758 that may pique your interest on a stock manifold if you want to dump the tomei lol

slider2828

He is on a mustang dyno... Those things always read really lol... That is normal

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RalliartRsX

The Mustand dyno should have no effect on spool readings now?? Power output yes (in comparison to say a dyno jet).

I guess the Mustang just loads it up differently. However, the mustang dyno is a much more real world interpretation, so unless you want bragging rights, one would probably want to load up a dyno jet for instance like a mustang.

deolio

yeah those tomei turbos are junk. sounds like what you need is an s15 t28.

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RalliartRsX

^^ Those are also junk. The Tomei turbo is based off the same ol tired haggard out wheel as all those garrett GT25, GT28, etc turbos that came on the silvias. 30-40 year old turbine wheel.

No thanks

It would be a step back...….

silviamang

Congrats on getting the car dynoed and your setup all done. Seems like you put a lot of thought and effort into the car.
But man.... those numbers do seem pretty low and your description on how the car drives doesn't sound right either. Was the turbo brand new? And is the engine healthy? I think that "Martin" guy you mentioned in your post might be onto something.

e30gangsta

I just installed their new mx8270 with the billet wheel. I pray to god its not as horrible as this lol.

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deolio

doesn't take 4k rpm to spool to only make 260...

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S14rebuild

4k spool what rear ar is on that turbo....dam

astonmartian

That seems to be a great ticket. Would love to drive a car w one (or 67 trim). Feel like it would be night and day. Cams going in this winter. Stock runs out of breath pretty badly up top.


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astonmartian

I haven’t It’s been more a thought and I will soon. Engine runs like a sewing machine but I guess still could be down on comp?

Saving up for standalone She runs well now and has been very reliable. I want more failsafes and efficiency tho. Some quicker spool on this turbo would be nice too but the flexibility to retune


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astonmartian

🤤 everything I’ve read EFRs are the jam. Buddy just sent me a Zilvia FS listing... would make a solid winter makeover but I’d want/need to change EMS too so cost doubles quick ... not sure if I’m at that point yet!


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astonmartian

Steady/static state dynos are beat for tuning/real world imitation for sure. Bragging rights not so much lol I don’t know what effect it could have on spool characteristics or at least the interpretation of the spool. Big bummer I don’t have the in car footage of the boost and afrs


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astonmartian

S15 would be a great daily option. I’ve driven and ridden in a few. Loved how snappy response was. Wouldn’t argue that the same or similar spool PLUS big power could be achieved with a more modern turbo.

@deolio It would be a seemingly comparable power wise as current setup and definitely spool light years faster. Not sure id trade off the top end potential though ... I do like hanging out up there in the revs especially doing pulls on the highway


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astonmartian

Thanks! Yeah Martin (Martin of RS Enthalpy) said something Is up. Thinks either the wastegate isn’t prematurely opening OR most recently asked me to check for engine throwing code 34 which is knock sensor loop failure (could be break in wiring, ground, dead sensor). The latter would put the car into limp mode (retarded timing, increased fuel) in lower rpm range to protect against detonation. Said he’s seen it rob 50 HPC

Apparently the Ecu stops looking for detonation after 4500 (or thereabouts?) as there is too much engine noise to discern accurately so it just doesn’t.

This would absolutely explain the loss of power down low, crap spool. He’s under the impression from experience that this turbo should still be hitting hard beginning at 3800 rpm, despite it being known to be laggy.

I’ve chased and researched why/how this could be so laggy (summed it up to ROM tune+turbo design) and this is one of the last things that could seemingly create a condition for consistent lag/sluggishness down low yet still deliver a punch in upper rpms. I’ve learned to drive around it by rolling into throttle below 3/3500.

I will be checking for the code and any issues w the sensor this weekend. Would be cool if that was it and it spooled faster. I’d take even 500 rpm sooner .


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astonmartian

5k actually for full beans and it’s ‘78 trim’ with 54mm exit opening for the turbine (s15 is 42.4mm).


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Kingtal0n

S15 turbo is old. And weak.

It was still good in like 08'

Nowadays, you can get a 'larger' turbo that flows wayyy more.
for example a couple months ago


dynojet roller hit for a 500bhp turbo, with the usual 4400~rpm range of spool. The SR20 goes to around 7k and does 140mph in 1:1.
You can see the peak torque (max boost) is way before 5252rpm because the horsepower always crosses torque exactly 5252 (which is 33,000lbs/2*pi feet)

RalliartRsX

Spool is almost 100% dependent on turbine. Keep the turbine the same you are going to get the same (or very similar) spool no matter what sorts of billet compressor wheel you go to. Worse yet, an upgraded compressor wheel from tomei.

I agree with King; S15 turbo is junk and ass I mentioned before based off a 30 year old designed turbine wheel.

A 6758 will make 450 WHP easily and have spool characteristics which are MUCH improved on any GT2 series turbo of that era. And this doesn't even take into account boost recovery.........which almost nothing on the market (including the new GTX as the wheels are Inconel based and still almost twice as heavy than the equivalent Gamma ti EFR twheels) compares.

But yeah, it all cost money in the end lol so I feel your pain

However, it's either you do it right, or do it twice

RalliartRsX

Goodluck!!!!

Thursday7

I have a hard time boarding the train of thought that we enjoy ourselves more with 2010s turbo technology than they did in the golden era with "30 year old technology"

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astonmartian

UPDATE - UPDATE - UPDATE

Ok so doing my nut and bolt check before the last lock city drift event of the year, I had the thought (at 12:15am) to check the other nuts on the turbo to manifold. I was having an issue with the rear nut backing out. I'd cinched it down and car ran much better so figured that was it...

It wasn't.

I've now learned that 'locking tabs' are great at preventing the nuts from falling off the stud but DO NOT prevent them from loosening and just hanging out, with the appearance they're tight. Like the front two nuts were. SMH.

Tightened those up with a couple custom cut box wrenches and BAM! I HAVE TORQUE.

Yes, it was dumb cold on the drive down to the drift event (26 degrees when I left at 630am) however I was goosing it and hit 16 psi at 3800 rpm in 5th ...I was like hmmm... So i turned down the boost target on the controller and let fourth rip. And she RIPPED - full boost by 4100 or so. Unreal having literally driven this for 2 years with an exhaust leak that because it didn't get worse, i thought it was setup related. The biggest change is the immediate throttle response and torque. The car starts moving fast now, with the rpms slowly moving. Before, it was very linear (see dyno) where more rpm meant more shove. Now she just mooooves.

Big shout out to Martin who kept pushing me that something was wrong w the setup. I'd turned just about every last bolt or diagnostic and it was right in front of me the whole time. I think having the car like that when i got it, gave me the false impression that was just the setup.

Made the drift day a whole lot more fun. You can watch the recap on my shit youtube channel here: http://bit.ly/JSlcd2019

@Thursday7 - I'm tending to agree. I had a 2016 340i and the silvia at the same time for two years and while the bmw was lighting quick to boost, like so much so it was just a single indistinguishable powerband, it missed the drama of the silvia, even in all her laggy glory. The b58 is soo smooth but my god the silvia is eventful when you mash it, by comparison.

Having the same debate right now with my dad who has a 98 c4s with a circa 2001 protosport twin turbo kit where they literally bolted the turbos where the muffles are (were) with some airResearch turbos (garretts). The car fucking mobs with all the on/off power delivery of a low comp 993 turbo pushing 400+awhp. Spoke w the protosport guys and they said they could upgrade for a more linear power delivery at earlier rpms but not sure if that would detract from the period correct hot rodness of the current setup.

TheRealSy90

I just wish the newer turbo options that are on the market (EFRs and G25's) still had the option for the 5-bolt exhaust flange. I like bolt-on setups and the PBM cobra downpipe is really the best thing on the market.

All the newer technology turbos have no bolt-on downpipe availalbe and require custom fabrication. Phooey.

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RalliartRsX

There is a reason the market has moved away from such an ill designed flange option.....just as the market has moved away from 30 year designed turbine wheels.

You mean to tell me you cannot buy a $30 v-band flange and have someone weld up a quick downpipe from a set of 90 and straight stainless pipe?? Also, those 5 bolt flanges are prone to warping and leaking and just adds another area of failure. I am glad the market has moved away from another archaic design. It's worth the extra $1-$200 investment to not deal with that headache and lose another $3-$500 on a track day as all the bolts backed and fell the hell out (which has happened before). They are only m6 (??) studs/bolts mind you and don't take to heat cycle well and also limit proper internal wastegate design (see EFR and new garrett turbo)

I mean shoot sell your prized cobra downpipe and you may even end up on top!

PoorMans180SX

I agree with most of your statements and sentiments here, but I must correct you on your statement on spool being 100% based on the turbine. If you take a turbine wheel, let's say an old T-series like a P-trim, and you take off the shitty 60-1 compressor wheel and add a new, much higher efficiency compressor wheel to it, you actually reduce the work the turbine has to do to get the compressor to generate airflow. This means improved time-to-boost over the old junk, which translates to most people as "it spools faster". While you're not changing the rotating inertia or outright flow of the turbine, you are in fact increasing the efficiency of the entire unit.
This is how Garrett has gotten away with using the GT turbines for so long, adding more and more efficient compressor designs has made the turbo more efficient. Even Gen II Garrett GTX stuff uses GT turbine wheels. This is also why they released the GTW line, which are GTX compressors paired with old T-series turbine wheels.

Even Borgwarner has done this on their S300SXE line, using the cupped tip 76/68 S300SX turbine wheel (which is the higher flowing/slower spooling version vs the flat tipped one), which results in the 61.3mm S300SXE, which flows 78lb/min, to spool identically to the old 60lb/min S360 with the flat tipped turbine wheel. That is 30% more airflow with identical spool!

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RalliartRsX

Ok fair statement as I wasn't being nuanced enough but wanted to bring my point across. However that doesn't negate the fact that spool is still HEAVILY dependent on turbine wheel for the fact of it being directly coupled to the driving force. However as have been shown time and time again, increasing efficiency of the compressor doesn't always directly correlate to spool. However, it directly correlates to volume of working fluid at the same pressure ratio. See Garrett turbos moving from a GT to a GTX series turbo.

It's so odd manufacturers tend to be tepid about releasing turbine maps to the general public (one for the fact that people would just fuck up the readings anywho lol). but also because that is where all the keys to the castle lay. Matchbot comes the closest by already inputting the (turbine) maps into the tool.