RB26 -7 upgrade suggestions for optimum performance

[RB335]

RB26 -7 upgrade suggestions for optimum performance

Hi Guys.

I have chosen to put a set of R31 N1's (-7's) into my RB26DETT on my R33 GTR.

My Goal is to make the most out of the turbos and intake, exhaust setup.
I would appreciate any suggestions ontop of what I am doing already to get it performing to it's best in terms
of response and power.

Here is the list of supporting upgrades and mods I am doing and the ones I am thinking about, fuel is taken care of
but more so in terms of airflow.  I'd appreciate if you guys can read through this and perhaps comment and make suggestions
if anything should be different or improved based on you guys experience.

1. HPI Dumps to Custom made 3" to 3.5" Front pipe, 5" Bodied cat 100 CPSI to Twin 2.25" Twin exhaust pipes.
Here I have chosen to give the turbos the maximum area right at the front part of the exhaust to fill up so they are not immediately choked,
so I went with the largest dumps and front pipe I could find.  

The front pipes will be unequal length, some people do talk that equal length allows both turbos exhaust to evenly meet up at the same time, however I think it shouldn't make a difference as it's constant continuous pressure, is that correct?

2. Apexi high flow panel filter in factory airbox, removing plate in side intake to fender off factory Airbox.
I calculated the factor snorkel has a 10% larger surface area than the inlet piping leading to turbos so it wont restrict it,
I am hoping the Apexi panel filter is much higher flowing than the OEM nissan one, or whether I should have gone for a K&N one.

3. This is the difficult decision.  Whether to port match the OEM Manifolds to the -7 Turbine inlets, or not.  My research showed opinions on this were divided.
It has been mentioned that port matching them will increase lag, while everybody else mentioned that it's something that should be done.  Two people who I have talked to, one a turbo rebuilder/tuner and other a tuner shop have mentioned this, so based on their experience I am chosing not to port them out.

It is odd that doing this can create lag, because the exhaust gas simply will come to a smaller area again if you peak down the -7's turbine inlets.  I'd appreciate any advice on this perhaps if anybody had experimented with similar sized turbos like GT-SS too.

I have been advised against TOMEI Expreme manifolds, most say it will create lag on smaller turbo setups, yet the Dyno graph by TOMEI shows gains at every power level.  I had also considered N1 Manifolds.

4. Apexi Power FC L-Jet, switching to Nismo AFM's.

6. Intercooler.  Even though the factory R33 GTR intercooler can make big power, my goal is cooling and I want to always give the engine the coldest air so the ECU puts in more timing especiall for the hot summer days.  Would switching to something like an ARC cooler or one of HKS's best cores give any improvement?  I've never looked at a Standard R33 Core to see how it's fins look like internally.

7. Boost Level.  I want to push the turbos to their limit even if they get unreliable.  This is my first time modding an RB26, coming from 1JZ's I always got more power even if I pushed the turbo beyond its efficiency range.  For -7's would there be a noticeable difference going from 20 PSI to 25 PSI?  I'd like to hear from people who've done it not simply to be told it will make zero power more.

8. Oil.  Everybody has their own choice.  Would running a thinner oil such as what the factory recommend compared to 10W40 which most appear to use.

I just thought I'd ask, I noticed my -7 turbos are not as free spinning as my original ones, could this be because they have less wear?  The original ones spin much longer, one of my -7's is more free spinning than the other.  Is it anything to be worried about?

Any other suggestions are welcome to get the most out of this setup.

Thanks.

[R.3.2.G.T.R]

don't run thinner oil, factory recommendation was for Japan not Australian climate

Also look at getting the heavy duty wastegates and syncing both to open at same time

[Dose Pipe Sutututu]

EFR7670 or GTX3576 in TS flavour..

... wait just read that the "chosen" has now turned into you actually have them.

My suggestion is to sell the PowerFC, sell the Nismo AFM get a real ECU + get a real FMIC like a Plazmaman Pro Series 76mm OR 100mm (which I can help you with).

 

[JGTC]

There are a few good points to start, there have been many great -7 builds over the years.

Just on the note of R33 N1 turbos and -7s, they are similar in they share a steel compressor wheel with similar efficiency and output, however the actual -7 is a more reliable turbo as it uses ball bearings, where the N1s use roller or thrust bearings i believe.  

Real nice -7 builds

https://www.facebook.com/Tarmac-Solutions-Pty-Ltd-189006661230825/photos/?tab=album&album_id=418233531641469

http://www.sau.com.au/forums/topic/429930-1994-r32-gtr-stock-to-~320kw/

http://www.sau.com.au/forums/topic/414162-bnr32-once-in-a-lifetime-build-all-gt-r-owners-must-see/#comment-6634595

 

Also a good way to see dyno results with different turbos/setups

http://www.sau.com.au/forums/topic/93880-rb26-turbo-upgrade-all-dyno-results/

 

[Dose Pipe Sutututu]

However I highly suggest you sell the twins and drop in a single, with a divided rear housing and a proper twin scroll manifold.

Single = more low down, better response, better transient, better top end, less plumbing, better heat management.

[sneakey pete]

1 Equal length is more about the sound. It does sound sex. Can be changed later easily. Sounds like you've got the exhaust well covered.

2 No idea, see how it goes, when its on the dyno take the filter out to see, can always swap that and modify intake if required easily.

3 Tomei dyno charts will show whatever tomei wasn'ts them to show, not the truth. So yeah, don't get their manifolds.

4 ECU wise get a haltech or a link plugin, or if you are going to have a flex tune get the link. (Second hand haltechs are easy to come by... like mine that i'm still trying to get rid of)

5 Where is number 5?????

6 tough one. Intercoolers have a few distinct factors. Fin design means they will cool the air passing through better, but as they get hotter that matters less and less. The size of it increases the size of it as a heat-sink so this dictates how hot it gets. In other words for a low flow situation having a super efficient inter-cooler the same size won't make much of a difference as it will not get that hot.

Now there's more to it than that, pressure drop and the like. Plazamaman is the only thing i'd go brand new unless you find a second hand ARC core, all the rest I wouldn't trust as they'd be the same price and probably an inferior design, however if you even need to upgrade the cooler is still debatable. there will be a difference but i'm not sure it'd be worth the 9xxbucks price.

7 Mate of mine has -7's on a rebuilt 9.2:1 rb26 and E85. made 365kw at 25psi. So yes there are still gains to be had at high boost if everything else is running right. Tis a nice setup

[DJBarnstar]

That combo will be very underwhelming, unless it is on E85. it will make about 290KW on 98 and 360KW on E85.

It is a waaay better drive with e85 as it wont be so laggy.

I got my car with -7's from the previous owner. If I had a choice I would 100% go a big single.

Don't bother with an intercooler... mine has the stock one as is fine.

[MrStabby]

Hi - i'm running -7s, currently 305kw @ ~17psi. I've ordered Nismo MAFs to try to push the boost at bit further to see what happens. I will instruct the tuner to keep going until he hits the sweet spot. Each setup is a bit different, so whether that's at 20 or 22 or whatever PSI is best left to tuner to decide IMO.

You will also need injectors if you dont have them already.

EDIT: Also get adjustable cam gears

Re #1 - any expansion causes turbulence, which is restrictive, but losses inside a tighter pipe will be higher than those in larger diameter pipe so its complicated...

Re #2 - I reckon the best way to know if your air filter setup is restrictive would be to measure the pressure in the air box immediately down stream of the filter. Would require some instrumentation which i dont know how to do, but will look into what's available with a electronic vac/boost gauge that logs.

Re #3 - there is a lip right at the turbo flange, on the right had side if you were looking at the manifold with turbo flange facing upward with the head flanges facing away from you. I would measure this dimension on the turbo flange and remove enough of the lip to make it the same. To really make it perfect you would also measure the openings from the bolt holes to determine if the lip side is the right bit to remove, but IIRC it was on mine. There's also a little imperfect machining on the opposite side to the lip that can be smoothed off a bit.

Re #6 - Dunno. Might be worth washing your current one out. If its full of greasy blowby shit that probably wont help heat transfer. My guess is it would negligible different tho. At -7 level changing it is probably very low bang for buck.

Re #7 - as above, let the tuner find it.

Re #8 - may ppl are neanderthals WRT oil. I run Mobil 1 0w-40 but i havent tested it yet. If you are going to run thinner than that, I would get a used oil test at say 3000 or 4000kms to see how its going. Full synth only of course, and overfill to the dipstick bump if you are doing any track days.

-7s are R34 N1s - is that what you mean? They should spin freely as they're ball bearing. I'd take them to a turbo specialist for a quick look. Replacing the turbos is big painful job...

Other than that, maybe think about getting the twin pipe divider mod. Might be worth a few kws. There's threads on here about it.

[Darmanin10]

1 - twin 2.25 pipes will be restrictive in the exhaust

2 - stock airbox is usually good for -7 power, however that bloke with the z tune rep R34 claimed to have made some decent gains going to pods.

4 - Nothing wrong with the good old power fc. There are better ecu's around these days though. Have to factor in costs of afms too.

6 - stock intercooler fine

8 - 10w60 castrol edge seems to be a popular choice

 

can make 350+kw on e85 with flowing exhausts

[Dose Pipe Sutututu]

10W60 Castrol Edge?

I would use 15W50 Penrite Racing 

[Darmanin10]

I was recommended edge 10w60

Was also most popular choice on the R32 GTR fb page

[R_34]

I could measure the pressure in the airbox with a paper filter and an apex'i one.

They both have the exact same restriction (38mbars at 260whp). The only difference I could measure was during the boost recovery after a gear change, the pressure wasn't going as low when equipped with the apex'i but I couldn't feel any difference, didn't made any log though.

[KiwiRS4T]

Why so tight on the exhaust? Get two 3in and be done with it. No to Castrol Edge 10 60 - too thick. I like Motul but any full synthetic 5 - 40 would be my pick (or 15W 50 if you think your engine is well worn).

Also now fan of modern single turbos.

[MrStabby]

15 hours ago, KiwiRS4T said:

Why so tight on the exhaust? Get two 3in and be done with it. No to Castrol Edge 10 60 - too thick. I like Motul but any full synthetic 5 - 40 would be my pick (or 15W 50 if you think your engine is well worn).

Oh - good point about oil pressure. If you don't produce good oil pressure on thin oil, dump it straight away and keep stepping up in visc until you do.

[milanr34]

Mods so far are: -7s on 19psi, oil cooler, pod filters, full exhaust, 1550 injectors (went big now in case i wanted more power with a single), oil cooler, cams, walbro 460 fuel pump and a Haltech 2500, tuned and it made 304kw on 98RON.

I can push them to 25psi but tuner said best to replace the OEM cooler as there will be some temp surges rest is all stock

[Sinista32]

E85 is the answer.

Upping boost wont help.

[RBN1]

On 10/19/2016 at 4:11 PM, Darmanin10 said:

1 - twin 2.25 pipes will be restrictive in the exhaust

2 - stock airbox is usually good for -7 power, however that bloke with the z tune rep R34 claimed to have made some decent gains going to pods.

4 - Nothing wrong with the good old power fc. There are better ecu's around these days though. Have to factor in costs of afms too.

6 - stock intercooler fine

8 - 10w60 castrol edge seems to be a popular choice

can make 350+kw on e85 with flowing exhausts

My 32R runs -9's @20psi, stock airbox (good for mid to high 300's), RPM adj cam gears, stock cooler , powerFC, Tomei Expreme Dumps>Racepace 3.5 full exhaust, nismo afms and 600cc injectors on 98 @336rwkw. (all Racepace built & tuned - they run Castrol edge 10w60 in it). Everythings well within limits with the current setup on track days, motorkhanas and hillclimbs. No need to get a aftermarket intercooler or pods. ECU choice, depends on who is going to tune your car. 

I've owned the car for 11 years now and when Racepace sorted it out a few years ago, it's interesting how much they changed back to OEM (as apposed to how much was swapped out for aftermarket)

[Anfanee]

Anything more than 22-23 PSI those turbos run out of puff. 

I'm currently running 340KW on E85 and honestly i can't see you getting much/if any more than that, anyone that says they are running more that 350kw at the wheels either have a larger motor (2.8L or something), the dyno is out, or they are flat out lying IMO.

In saying that:

1. Equal length is all about sound, Fk all in gains if any. Yet to convince me anyway. 

2. Id pull the stock airbox off and put something else. Personally i run an ARC box because bling and power. 

3. i didnt port mine.

4. Apexi Power FC L-Jet, switching to Nismo AFM's. - should be fine. I f**ked off my PFC and AFMs because i got sick of the AFMs, and wanted a flex tune with the Haltech. 

6. Interwarmer will be fine. If i was doing long hard tracks i would replace it with an ARC item. But for the street driven/occasional track its fine. 

7. Any more than 22PSI and you will literally get nothing from them. I found a sweet spot around there. Pushing them harder is a stupid thing to do and you are asking for trouble, whilst getting no gains. They will NOT run 25psi. 

[DJBarnstar]

Wat?? My -7 run 25psi all day no worries. Stock cooler, stock airbox, and plenty of track days.

 

[r32-25t]

Running 24psi out of mine and they're loving it in fact going from 22 to 24 gave me an extra 20kw 

@DJBarnstar what else have you done to your car to get it up near 370?