Bigger turbo/setup questions

[Coltron]

so i've got some decent mods already done to the car.. s13(sr20)

gt2560r turbo, koyo rad, 3" exhaust, fmic,bov,isis mani, but i just recent got a head shipped to me...

-greddy valvesprings
crower ti retainers
-supertech blue viton valve seals
-oversized ferrea ss valves
-bronze magnesium valveguides
-full bowl work/p&p/valve job
264 cams (apparently they are stock, he got a shop to mic them? but thats the size i was thinking of getting...)
freshly decked

ive also got a tomi hg that will be getting put in aswell.. So my question is what would be a good setup for something like this? bigger turbo? will this reduce a lot of turbo lag? baiscially just wondering what it can handle.. and what id be looking at...

[sr20s14zenki]

Double post...whoops.

[sr20s14zenki]

The more power you make the more turbo lag you are going to have pretty much. At a certain point, something has to give. On a stock bottom end, you can safely make around 350-400 whp MAX for reliability sakes, and even at that level, you need to realize you are sacrificing reliability. The 2871 is a popular turbo for a reason, its a good balance of quick spool and great peak power, somewhere around the 370whp mark. The 2876R is also a great turbo, i am running one, and am very pleased with it, the nay sayers say the ratio between the compressor and turbine is too much, but bah, whatever, i have good dyno numbers and performance to prove it works.

The bottom line? That 2560 is only going to get you around 260 whp..thats IT. You want more horsepower, you need to flow more, simple as that.

[Coltron]

flow more as in getting a bigger turbo, i was thinking the 2871 would be a smart choice to go upgrade to.. what would be a safe boost range for this turbo if i get some 550 injectors..

[sr20s14zenki]

Originally posted by Coltron
flow more as in getting a bigger turbo, i was thinking the 2871 would be a smart choice to go upgrade to.. what would be a safe boost range for this turbo if i get some 550 injectors..

You need to decide your power goal. If you want over 300 hp, 550s wont do. I would get 750cc or 850cc. If you want to stop at 300 whp and go no further, you will be running your 550s at around 80% duty, which is ok, but i dont like to cut it that close personally.


You basically need to come up with a goal and size accordingly. For you personally, i would do 750cc injectors, powerFC or whatever you have, 2871R.

A turbo can ultimately only make as much power as its meant to make. Your turbo can make a maximum of around 250 whp, thats it. Turning up the boost wont do shit, it CAN NOT flow any more than that. After you get to a certain point, you are passing your choke lines, and you are basically superheating the air going in, thusly making no more power, just more detonation :D

[Coltron]

Hmmm what about *650cc Nismo Injectors with fuel rail/ nismo FPR and fuel pressure gauge - $450*

are 650's and that turbo enough for a lot more room of hp? Sorry i just got a power fc (the guy had it tuned on 550's, gt2871r .84,z34 maf) Could i piggy back off his tune and tweak it or is that a no no...

i also found this turbo i dunno much about the t3/t4 ones...

Garrett 60 trim turbo..

[sr20s14zenki]

like i said man, you arent hearing me. What is your horsepower goal? without that, i cant give you direction.

[Coltron]

ah.... okay easy 300 say....i have no idea.. like i dont even know what im sitting at now but it would be nice to have more... hmmm

i would like to keep the bottom end safe like i dont want to have to rebuild that to lol..

[sr20s14zenki]

Well, if you want 300 horsepower even, then 550cc will do, its cutting it close, but i would say safetly close. a 2860RS will do you for a turbo too, less lag than the 2871. I would get the 2871 anyways, you wont notice the lag difference, hell, i dont even notice the 2876 making a difference.

[Coltron]

and would this new head make a big difference in reducing turbo lag? im just thinking with it being ported and ill probably put in bigger cams, But i guess bigger turbo=more lag...

if its cutting it close then 650cc would probably be a smarter way to go then if i want more i have more room to grow to right..

[sr20s14zenki]

Originally posted by Coltron
and would this new head make a big difference in reducing turbo lag? im just thinking with it being ported and ill probably put in bigger cams, But i guess bigger turbo=more lag...

if its cutting it close then 650cc would probably be a smarter way to go then if i want more i have more room to grow to right..

Yep, room to grow is good. The head will most likely not make too much difference on lag, when you port, you notice alot more power up top, and loss down low. The reason is that when you open your ports up, you gain room for flow, but you lose velocity.

experts correct me if im wrong, porting is not a huge area of expertise for me.

[Coltron]

hmmm intersting.... what is the benefit of going top mount then? or is that just for the turbos that arent internally gated?

[CA18-S13]

The real benefit of going top mount is accessibility. Since you seem to be shooting for a T2 style flange, a bottom mount mani will be your most likely choice as not many top mount mani's are T2 flanged, at least for the SR. If you really wanted to go top mount on the 2871 then a custom mani would be needed.

Lager turbo's also need top mount as the compressor housing has no room on a bottom mount between the block and strut tower.

[Coltron]

Garrett 60 trim turbo.. he was mounting in on bottom mount.. in an s13, what is that turbo comparable to?

[sr20s14zenki]

Originally posted by Coltron
Garrett 60 trim turbo.. he was mounting in on bottom mount.. in an s13, what is that turbo comparable to?

He must have done some mods he didnt talk about, a 60 trim is a t3/t04e, which is a t3 flange....


like he said, top mount is just for clearance. For me to run my 2876, its compressor housing was so big i had to notch my motor mount to fit it. The housing sits about a quarter inch or less from the block.

[Coltron]

hmmm interesting.. thats all good info to take into consideration.. ha, clearance would be a big thing then...

[CA18-S13]

Not only clearance, the most important things are accessibility to water/oil lines and manifold removal.

[Coltron]

hmmm thats true yeah... dang eh..

[stevo 27]

Originally posted by sr20s14zenki


Yep, room to grow is good. The head will most likely not make too much difference on lag, when you port, you notice alot more power up top, and loss down low. The reason is that when you open your ports up, you gain room for flow, but you lose velocity.

experts correct me if im wrong, porting is not a huge area of expertise for me.

not necessarily increasing port size doesnt reduce velocity

port shape has more of an affect on velocity AND flow

[Coltron]

soo it would increase a turbo's effeciency to spool faster?

[Nissan_Fanboy]

Originally posted by sr20s14zenki
The more power you make the more turbo lag you are going to have pretty much. At a certain point, something has to give. On a stock bottom end, you can safely make around 350-400 whp MAX for reliability sakes, and even at that level, you need to realize you are sacrificing reliability. The 2871 is a popular turbo for a reason, its a good balance of quick spool and great peak power, somewhere around the 370whp mark. The 2876R is also a great turbo, i am running one, and am very pleased with it, the nay sayers say the ratio between the compressor and turbine is too much, but bah, whatever, i have good dyno numbers and performance to prove it works.

The bottom line? That 2560 is only going to get you around 260 whp..thats IT. You want more horsepower, you need to flow more, simple as that.

HEY!
KEIOFFICE built a S15 with a HKS GT2540 turbo making 320whp.

http://www.youtube.com/watch?v=ZnwoNxtdJpI

[Cooked Rice]

Originally posted by Nissan_Fanboy


HEY!
KEIOFFICE built a S15 with a HKS GT2540 turbo making 320whp.

http://www.youtube.com/watch?v=ZnwoNxtdJpI

A HKS 2540 vs a Garrett 2560 is not quite the same here myles. It's comparing apples to oranges.

[sr20s14zenki]

Originally posted by Cooked Rice


A HKS 2540 vs a Garrett 2560 is not quite the same here myles. It's comparing apples to oranges. \

Exactly. From what garrett tells me, the 2560 is a stock s14/15 turbo.....and you aint gonna get much more than 260 outta that haha. The hks has a bigger turbine wheel and compressor wheel, and is also a t3 housing.

[Toma]

Originally posted by Coltron
soo it would increase a turbo's effeciency to spool faster?

Not really... the most critical area for turbo cars i the exhaust throat area, and there isn't much to be done there that will improve spool.

Keeping a constant cross section there to trubine will maintain energy, and keeping it as short as possible will as well.... Most guys go in there and start cranking open the port area (cross section), and that will hurt you... think smoothe, and constant crossection and well shaped bowl and short turn.

Camshafts in general will hurt your spool...

But really... we are talking a 7000 rpm motor, so if you are out of the powerband, just downshift.

My 2860RS on a roll side by side with a new GT500 Shelby will CREAM it, and we are talking a positive displacement blower. versus my turbo lol.

[Revhard]

Anything you can do to make the engine more efficient will help power delivery on a turbo car. The only exception is cams. Turbo cams just need less overlap so you don't blow the boost out the exhaust ports.
Porter heads are a step in the right direction, hopefully somebody knew what they were doing. It's easier to wreck import heads then to improve them if you are not a pro.
The 2871 makes power all over the map for sure. The SR20 can't take the compression of the newer motors, but it's something to look into. If you want good spool and have a power number in mind, running max compression for that number will give you better spool and slightly better power.

[Nissan_Fanboy]

Originally posted by sr20s14zenki
\

Exactly. From what garrett tells me, the 2560 is a stock s14/15 turbo.....and you aint gonna get much more than 260 outta that haha. The hks has a bigger turbine wheel and compressor wheel, and is also a t3 housing.

Ohh, i never really found any specs on either of them for that.
Just thought their sizes could mean somethinkg.
Thanks, taught me something.

What do you think would adapt better to the SR20,
HKS GT2540 or Garrett GT2871 ?

[Coltron]

i think both would hook up with minimal effort, pretty common turbo in most builds these days :/

[sr20s14zenki]

2871 is pretty much your generic ticket, thats why its so common. Combine it with a port matched and smoothed stock manifold and off you go, unless you can afford the expreme (=

[Nissan_Fanboy]

Originally posted by Coltron
i think both would hook up with minimal effort, pretty common turbo in most builds these days :/

I don't mean would hook up, i mean adapts to the SR20 power curve and everything.

Yeah, the 2871 is the more popular one,
but i havent seen many 2540's, which is still a decent turbo.

Like the keioffice one, 320 wheel isn't bad.
Whats max on a 2871? they go around 350+ can't they?

[sr20s14zenki]

Originally posted by Nissan_Fanboy


I don't mean would hook up, i mean adapts to the SR20 power curve and everything.

Yeah, the 2871 is the more popular one,
but i havent seen many 2540's, which is still a decent turbo.

Like the keioffice one, 320 wheel isn't bad.
Whats max on a 2871? they go around 350+ can't they?

for a 2871 garrett lists them at around 460 horsepower, keep in mind thats CRANK horsepower. 400 would be a good goal for that one. Kei office may have been making that power on that engine, but they didnt mention if it was stroked, or the cams, or the tune, or the gas they were using, or any other supporting mods....mind you i didnt watch the whole video lol

[Nissan_Fanboy]

Originally posted by sr20s14zenki


for a 2871 garrett lists them at around 460 horsepower, keep in mind thats CRANK horsepower. 400 would be a good goal for that one. Kei office may have been making that power on that engine, but they didnt mention if it was stroked, or the cams, or the tune, or the gas they were using, or any other supporting mods....mind you i didnt watch the whole video lol

yeah thats true, but it did say the engine was "NORMAL".
Not sure, but yeah the GT2871 is a popular choice.

I would go GT30 if i could, had the chance to do so and money haha

[sr20s14zenki]

Originally posted by Nissan_Fanboy


yeah thats true, but it did say the engine was "NORMAL".
Not sure, but yeah the GT2871 is a popular choice.

I would go GT30 if i could, had the chance to do so and money haha

The only thing standing between the two is money for a manifold. 3071 or 3076 is a nice choice.

[RZRSHARP_SVX]

I am running the 2871 .86 and it produces a great power band. I am currently doing 340ish whp will be closer to 400whp next year once I finish the improvments. From what i have seen most people who run the 2871 use the .64 which may have faster spool but lack where the .86 makes that little bit more.

[Coltron]

hmmm hard decisions really..

[sr20s14zenki]

Originally posted by Coltron
hmmm hard decisions really..

Its actually not hard at all. Why do you think there are so many people selling used parts all around the world. Part of the fun of this game, is the excitement of getting a new setup and seeing how it performs. The great thing is, if you dont like it, you can sell it and try something else. I would pop the 2871 on there with some big injectors, and give er a go, im almost positive you will not be disappointed.

[Coltron]

yeah if im going to do it i might aswell just go for it eh...

[Coltron]

that garret 60 trim t3 turbo he wants 450 shipped for the lot, turbo,down pipe,and manifold.. only 2k miles on it. only thing is its not a dual ball bearing turbo.. what are the draw backs to this turbo compared to just getting a 2871 for 800.

[Nissan_Fanboy]

Originally posted by Coltron
that garret 60 trim t3 turbo he wants 450 shipped for the lot, turbo,down pipe,and manifold.. only 2k miles on it. only thing is its not a dual ball bearing turbo.. what are the draw backs to this turbo compared to just getting a 2871 for 800.

for turbo downpipe and manifold thats not a bad price dude.

The only difference is the power curve that i can think of, just how it reacts to power.
The gt28 will most likely spool faster and have a greater wideband, but the 60trim might make more power.
Someone correct me if im wrong.

[Coltron]

gt2871r with 2k miles on it.. 700 bucks should i just get that and injectors and call it a day lol

[Nissan_Fanboy]

Originally posted by Coltron
gt2871r with 2k miles on it.. 700 bucks should i just get that and injectors and call it a day lol
offer 600 and call it a day ;)

[TRD_jordan]

Yes honestly just get the 2871. I have the gt2860 and I wish I just got the 2871. Only a bit more in price when new but it's seems to be a way better balance from what I have read. I got sucked into the 2860 for the quick spool and my goal of 300-320whp. But now I want 400 lol.