S14 and S15 T28s

[Silverbullet]

Does the S15 T28 really give more power over the S14 T28s?

I did some searching and i've read two different conclusions. Most of them i have read say: Yes, the S15 T28 does create more power. The only physical difference is the separation plate between the exhaust and wastegate exit correct? Then how does this create more power?

On the other hand, i've read that the reason the S15 Silvia creates more power over the S14 Silvia is because the S15 runs a higher stock boost (10psi) over the S14 boost (7psi) AND the S15 comes with injectors that flow 100CC faster and THAT is the reason for the power difference between factory S14 and S15 Silvias.

what do u all think.

[Edgar]

"The only physical difference is the separation plate between the exhaust and wastegate exit correct? Then how does this create more power?"

That is true. I know a guy that has a s15 powered S14 and it has more pickup then the S14(sr20det)reason ill have to say the turbine. :)

[Silverbullet]

err so he had an S14 turbo... then bolted on the S15 turbo and it had more pick up?

thats pretty interesting. I wish someone starts a real in-depth discussion about flow theories behind the S15 and the S14 T28s.

[Dweezil]

The reason for the divider is to help smooth the flow from both sides of the exhaust housing. If done correctly spliting the wastgate flow and the turbine flow will result in a higher velocity and ammount rather than dumping both together.

[Edgar]

err so he had an S14 turbo... then bolted on the S15 turbo and it had more pick up?

thats pretty interesting. I wish someone starts a real in-depth discussion about flow theories behind the S15 and the S14 T28s.
Sorry Kid had s15(sr20det) vs a s14(sr20det) the s15 for some reason had more pickup. I dont know on the mods they both were pretty similar im still trying to read on both turbines but I cant find any good articles ill post if I do.

[driftyour40]

i think this might help you out.

S15 SR20DET
2.0L DOHC VVT
Turbo Type: T-28, 60 trim 60 mm BCI-1 compressor in T-04B housing
Injector Size: 480cc
Power (hp): 250 @ 6400 rpm
Compression Ratio: 10.0:1
Top Speed: 180 Km / Hr ( with speed limiter installed )
Stock Boost: 8 psi

S14 SR20DET
2.0L DOHC Turbo
Turbo Type: T28
Compressor A/R: 0.64
Injector Size: 380cc
Power (hp): 220 @ 6000 rpm
Torque (ft/lbs): 203 @ 4000 rpm
Compression Ratio: 8.5:1
Top Speed: 112 mph ( with speed limiter installed )
Stock Boost: 8 psi



I also remember reading somewhere that the s15 had a more advanced vvt, than the s14. but as you notice this site had little turbo specs to make a good comparison. but i think you were woundering about the s15 has a higher comp not more psi, and that would be the reason for more gas ( bigger injectors ) i know I've read about this somewhere, I thought the s15 turbos exhause side was improved apon and that was the reason they worked better than the s14 turbo. i don't know it's been to long but i hope this helps a little

[Touring240]

there is no hard info about the s15 making more power. I've read many different posts about the s14 vs s15 turbos. On US boards people assume that the s15 turbo is better. In Japan I've read they don't see much of a difference.

The price difference will always be there for the same reason that an s13 black top is more expensive than the s13 red top. One is newer.

I'm running an s15 auto turbo on my s13 red top which has the same specs as the s14 turbo. I'm waiting on a greddy turbo outlet which has a divider that goes into the exhaust housing. If you have an s15 turbo you have to cut the piece off.

Until we get some hard dyno #'s from someone dynoing the same car back to back I doubt we will ever have the answer.

[Silverbullet]

i think this might help you out.

S15 SR20DET
2.0L DOHC VVT
Turbo Type: T-28, 60 trim 60 mm BCI-1 compressor in T-04B housing
Injector Size: 480cc
Power (hp): 250 @ 6400 rpm
Compression Ratio: 10.0:1
Top Speed: 180 Km / Hr ( with speed limiter installed )
Stock Boost: 8 psi

S14 SR20DET
2.0L DOHC Turbo
Turbo Type: T28
Compressor A/R: 0.64
Injector Size: 380cc
Power (hp): 220 @ 6000 rpm
Torque (ft/lbs): 203 @ 4000 rpm
Compression Ratio: 8.5:1
Top Speed: 112 mph ( with speed limiter installed )
Stock Boost: 8 psi


acutally that does not help out this discussion at all really lol.
where did you get this info from, because it is most certainly incorrect. The S15 runs 10psi, and the S14 runs 7psi. The S15 SR20DET also does not have 10:1 compression. Maybe on the SR20DE (N/A) but ALL of the factory turbo SR20DETs were 8.5:1.

if you ask me, the increased boost pressure and larger injectors really compensate for the 30HP difference between the S14 and S15.

[vsp3c]

silverbullet you are correct. all SR's run 8.5:1 cr and s15 run 10psi boost. you gotta keep in mind which s14 turbo you are refering to. some s14 turbos were non-ball bearing as some s14 t28's were ball bearing ( like the s15 t28's )

the extra 30hp most likely comes from higher boost, smoother flow of exhaust gases (exhaust divider), and the t28 being ball bearing. it's also possible that the s15 runs different afr compared to s14. it wont make much a difference but it could help a little bit.

[Edgar]

I cant find anything anywhere on this. Looked for info all night last night.

[element240]

i remember reading that the s15 turbo uses a different material for the turbine blades also?
iirc it is lighter and therefore spins faster.

do a search on FA, you'll come up with more info.

[s14srpilot]

iirc the s14 t28 has a single ball braring cartridge and the s15 t28 has a dual bb cartridge hence the s15 turbo spools up faster

[Muzzy]

element: u talkin about inconel?? like in the latest skysline turbos??

[rps13_fastback]

no no no people.
s14 and s15 turbos are both ball bearing, only the s13 t25s are journal bearings. yes the difference between the two motors is stock boost and injectors (simply able to support more air with fuel delivery). spool up is about the same on both turbos, however the s15 turbine wheel is made of inconel as far as facts show.

[Edgar]

Where did you get this info?

[Silverbullet]

incone: is this a type of material?

[RedSuns]

incone: is this a type of material?


yes..it is lighter than ceramic and steele

[driftyour40]

http://www.xatracing.com/nissanS15sr20det.html
thats where i found the info sorry it was wrong my bad.
i was just at total jdm.com and they said the s15 had 10.0:1 too so are you guys sure it wrong?

[Id-]

yes... we are positive :) 10:1 + 18psi of boost = detonation city on pumpgas

[SoCalS14]

I have an S15 turbo, and from what I was told, there is two different bearing configurations, a single and dual...I was told that the S15 turbo has dual ball bearings, exhaust gas seperator, and iconel turbine wheel...This all equals fast spool up. I must say, from experience...this turbo spools quick...I hit full boost around 3500 rpm's...and it comes on strong...

[driftyour40]

if you don't belive me then see for your self

http://www.xatracing.com/nissanS15sr20det.html

http://www.totaljdm.com/index.cfm/fuseaction/engines.displayengine/item_num/JDMNISSANSRS15/jdm_engines.htm

there you go. two sites and i'll find more if i need to.

[sr240mike]

Well they are misinformed. Never believe all you read on the internet.