What BHP Should I Expect?

[Rich]

Hi, brief spec of the car as follows:-

- Tomei manifold and elbow
- FMIC
- Walbro 255
- Superspark coil packs
- Gizzmo boost controller running 1-1.2 BAR
- Nistune mapped by Greg @ Protuner
- Full 3" exhaust system with decat
- Blitz induction kit

Stock MAF, fuel pressure regulator and injectors.

What kind of power would you expect the car to be and would it be worthwhile me fitting a Z32 MAF and 740cc injectors and having it mapped again? At the moment it feels phenomenally quick as-is.

Cheers - Rich

 

[hugh janus]

Around the 285-310bhp mark, the limiting factor is the AFM and the squirters, the turbo will also be on its limit assuming its a journal bearing unit, a roller bearing may give a few more ponies but not much, at one point mine had a GT2560r (same as an S15 unit), 480cc injectors and a std AFM and gave 301bhp and 294lbs but that was right starting to push hot air.

Going for bigger injectors and a Z32 on the standard/BB turbo won't give you any more power it'll just be safer, the next step up would be :

Older tech GT2860r and that yields 330bhp
slightly newer is a GT2871r circa 340-370bhp
the latest crop of turbo's are the GTX series but to be honest I know they perform well but i couldn't give a power range.

For future proofing i would have the 740 and Z32 fitted whilst you are getting car ready to be mapped the first time (bearing in mind once the Z32 and 740's are fitted you won't be able to drive the car at all until its mapped), as time passes and you want a bigger turbo, its just a case of slinging it on and remapping.

 

[dave_t]

Rich, that is near identical spec to my S15 & Greg tuned it to 307bhp. You should expect around that figure.

 

[Rich]

Around the 285-310bhp mark, the limiting factor is the AFM and the squirters, the turbo will also be on its limit assuming its a journal bearing unit, a roller bearing may give a few more ponies but not much, at one point mine had a GT2560r (same as an S15 unit), 480cc injectors and a std AFM and gave 301bhp and 294lbs but that was right starting to push hot air.

Going for bigger injectors and a Z32 on the standard/BB turbo won't give you any more power it'll just be safer, the next step up would be :

Older tech GT2860r and that yields 330bhp
slightly newer is a GT2871r circa 340-370bhp
the latest crop of turbo's are the GTX series but to be honest I know they perform well but i couldn't give a power range.

For future proofing i would have the 740 and Z32 fitted whilst you are getting car ready to be mapped the first time (bearing in mind once the Z32 and 740's are fitted you won't be able to drive the car at all until its mapped), as time passes and you want a bigger turbo, its just a case of slinging it on and remapping.

I don't know what turbo is fitted other than to assume it is the standard item for a 2002 Spec R JDM S15. Thanks for the advice though, it looks like if I want to upgrade I should look at the GTX series then to go alongside larger injectors and the Z32 MAF.

Rich, that is near identical spec to my S15 & Greg tuned it to 307bhp. You should expect around that figure.

Hi Dave, thanks for the heads up. It feels quick and drives very well - much better than my S14a ever drove. I would definitely go back to Greg for any work in the future.

 

[dave_t]

Yeah the 310bhp mark is great, I've enjoyed it - Ive recently been contemplating upping the power and I sent Greg an email about options. Might give you an idea of future options rich

Hey Greg,

If you remember you tuned my S15 back in 2013 before my Nurburgring trip, and then again when i returned once you hard wired my fuel pump.

We ended up @ 307bhp on the stock T28 with this spec list:

-Stock S15 SR20DET
-OEM T28 with Braided Lines
-Tomei Manifold
-Tomei Elbow
-Blitz Downpipe
-De-Cat
-Tanabe Hyper Medallion Cat Back Exhaust
-Apexi Intake Filter with Apexi Air Box
-APEX intake pipe
-HDI GT2 Front Mount Intercooler
-Splitfire CoilPacks
-NGK ngkbkr7eix Plugs
-Walbro 255lph Fuel Pump
-MOCAL Oil Cooler
-Apexi AVC-R Black Edition
-Apexi Power FC with Hand Controller

Been a great trouble free 3 years, but this year I'd like to upgrade the T28 and get some more power out of the stock SR20DET, something realistic like 370-380bhp??, so i would like to ask your advice on upgrades & re-tune Greg.

I believe the quiet Tanabe Exhaust, Stock S15 AFM, Stock S15 Injectors, and stock S15 T28 were the main limiting factors.

Exhaust: I have a Tomei Expreme Titanium Cat-Back to replace the restrictive Tanabe.
AFM: Would you still recommend a Z32 AFM as an upgrade?
Injectors: What injectors would you specifically recommend to get???
Turbo: I would want to get something compatible with my current Tomei Manifold setup etc. Is the GT2871R still a good choice or is one of the newer Garett GTX range be the one to go for?

Upgrading the Cams: A side thought, would the bigger turbo benefit from upgrading to I.E. Tomei Pon Cams, to have more top end power

Much Appreciated Greg, Thanks

-Kind Regards
-David Turville

His reply:

Hi David
Nice to hear from you.
The 2871r is still a great turbo. If you want more response a gtx 2863 is the way to go or alternatively for more power a gtx 2867 (this with a set of pon cams will make more than a standard bottom end is really good for).
Yes I'd recommend a set of pon cams they will help to make the power easier and will enable more peak power for any given turbo or boost level.
We can supply some great injectors that we have made for us for £350 alternatively you can use nismo 740cc do go for cheap ebay injectors we see allot of failures.

Best regards
Greg gush

 

[hugh janus]

Speaking from experience the 2871 is a superb turbo, kinda feels like how the 200 (I know this is a 15 forum) should have been from the factory.

a can of worms that does seem to come up when Roller bearing turbos are mentioned is the restrictor, a lot of people will tell you either of the following I spent longer pondering over this than searching for the best price I could get;

1) they come built in.
2) they don't need one.

both cases are incorrect, if you properly read up about it, the oil pressure (above 40psi from memory) at WOT is too much for a BB turbo, in fact I believe now some of the major suppliers indicate it's needed on an SR in the product description, just be careful.

 

[TomK]

Then you get into the issue of is my s15 one of the ones that left the factory with a ball bearing turbo or journal bearing?

And if it came with a BB does it already have the restrictor present with in the engine and oil lines?

 

[hugh janus]

I really don't know if Nissan made any provisions between the different turbos, you'd think they did..

but it if you are fitting a new turbo it's unlikely you'd use the standard hard lines!?

it was a major headache when I started looking in to it as nobody seemed to have any idea and decided it use an additional restriction...been ok up until I removed the engine covering some 14k

and now suppliers are stating on some engines an additional restriction is required.

 

[TomK]

I agree you'd rarely use the original lines, could Nissan have put a restricor in the block where the oil line connects for the ball bearing turbos?

So are you saying adding an additional restrictor would do no damage (working under the pretense we don't know if one is or isn't present on factory ball bearing turbo s15's, so adding a restrictor will give you either 1 or 2) but if you fail to have one at all damage is almost certain?

 

[hugh janus]

I really cannot say if there are any further restrictions in the engine, it's highly unlikely though.

the purpose of a restrictor in the turbo is to make the oil passing through "foam up" this foam it's just enough to lubricate the bearings and shaft, a restriction in the engine would see the "foam" returning to a full or partial fluid state by the time it's arrived at the CHRA, my restrictor was connected directly to the CHRA and the braided line connects to the back of it. the size of a standard restriction is something like 1.1-1.2mm from memory my restriction is 0.8mm so considerably smaller.

my thought processes basically went along the lines of;


I replaced my journal T28 for a GT2560 (same as an S15 BB) it lasted approx 18 months WITHOUT an additional restrictor.
all the intercooler pipes always had oil residue inside.

then I bought a 2871, I ummed and ahhed about what to do then found an article in Garretts website that stated cars with 40psi of oil pressure at WOT was recommended to fit an additional restrictor, then found info on SXOC about oil pressures and decided to fit the restrictor.

the intercooler pipe work now is as clean as a whistle

 

[TomK]

Can you fit a restrictor with the turbo and manifold still on the car?

I've just fitted a gt2871r, and it's getting mapped as we speak, for obvious reason i would rather not have to take the car to bits AGAIN to fit a restrictor, but it sounds like something worth doing for peace of mind.

I probably wouldn't do 14k in 4 years, as this isnt my only car, but that's no excuse if what you say is true, i want it to be done properly and be faultless.

 

[hugh janus]

Yeah although fiddly, but the restrictor screws into the CHRA and then the oil line screws to back fairly easy...but fiddly

the restrictor is just a male to make connectir

 

[immy21]

My 99 S15r banjo bolt on the block had a tiny hole in it, smaller hole than the restricter bolt I bought from Driftworks, so ended up reusing stock bolt with 2871r.

It's easy to access so pop it out and have a look, I missed the small hole at first as the end of the bolt has a large opening, but narrows right down so check properly.