Upgrading Twins need help (Long)

[Boostage]

Car details:

1996 S14
1jz-gte with 264 cams/springs and retainers.


I recently bought a Custom TT kit for my 1jz, that has stock skyline gt28r twins..

http://i188.photobucket.com/albums/z191/drewgoperformance/DSCI0294-1.jpg

http://i188.photobucket.com/albums/z191/drewgoperformance/DSCI0296.jpg

Now I understand that the stock RB twins have ceramic wheels and also not big enough to meet my power goals of around 525rwhp.

Here is a dyno of a very similar 1jz kit but with steel blade gt28r's..

http://i12.photobucket.com/albums/a249/Afrodziac/IM00024720Medium.jpg



Thats the poweband I want but with about 50rwhp more before it starts to fall off.
that 480rwhp was made on 21psi. but I dont know the specs on those particular gt28r's so What I am trying to find out is this:

if I upgrade stock to steel wheel, what would be the turbos' safe rwhp limit?

Or should I just get new turbos? if so what do I get? gt2530? gt2871?

I am willing to give up just a little response for a bit more top end power/RPMS. but I dont want a slug under 3k.. dare I say I would like a good compromise of response and all out power similar to the MINES Skyline

[jeeper_x]

Wow, Mine's Skyline...that thing is almost as fast as a GT car...why don't you try single turbo?

[[H.C.W.T]]

what is the advantage of having twins?

[Boostage]

Wow, Mine's Skyline...that thing is almost as fast as a GT car...why don't you try single turbo?

I said MINES skyline as a loose example, not as a true Benchmark. my point was that they put alot of focus on response. and still makes over 630bhp and I notice they ran gt2530 twins. but I do already have a single.

[steve shadows]

;1583534']what is the advantage of having twins?

more CFM with less lag.

but because of the newere GT garrett tech this is almost absolete.

You can get a single to spool up faster and make more cfms in most cases now.

If I were the I would consider trying a 2871R as one turbo and a gt28rs as the other or run on .86 2871R and one .64 with something in the 270 duration range for cams - You will have lag though.

That would be an interesting experiment.

Otherwise- for the sake of both spool and powerband switch to a gt3076R with a .82 turbine housing and run longer duration cams.

Im not that familiar with the 1jz, you might want to peruse the toyota forums.

I believe the mines car uses twin gt253os which is similar to a 2871R

Btw thats a great number for a DD even with the torque drop off!

[Boostage]

Steve your suggesting using two different turbo sizing, usually thats a problem usually the bigger turbos causes the smaller to surge, plus boost controlling becomes impossible.

[steve shadows]

not with externals + I should clarify, I was suggesting seqential, not paralell

but thats only if your trying to be cool

I would just go gt30r + 260 intake 270 exaust.

should be a rocket. Tune the car at 20 psi.

[Boostage]

not with externals + I should clarify, I was suggesting seqential, not paralell

but thats only if your trying to be cool

I would just go gt30r + 260 intake 270 exaust.

should be a rocket. Tune the car at 20 psi.


Not impressed with that turbo..here is a 1jz like mine with 264 cams like mine

http://supraforums.com/forum/attachment.php?attachmentid=56788&stc=1&d=1152931027


thats a 3037..
compare that to the twin gt28r in my original post. the twins make much better TQ. Btw, only the 2jz is sequential, and both twins are identical in size.

[steve shadows]

yeah Im saying go sequential

your not impressed with a gt3076r?

Thats one particular car, and I cant see the graph, it might have been tuned on a dynojet, in that case its worthless comparison.

DD cars always more more torque and spool up faster because of the off throttle tuned portions of the map you can fully build-every cell.

have you ever used one (gt30r)?

I dont have an account on supra forums anymore so I can't access your link.

Twin gt2871R would be my next reccomendation but it really depends on what the car is going to be used for?

[jeeper_x]

why don't you try T04Z?...i tried it in a 1jz cefiro in thailand and it gave a good response and high hp....

[steve shadows]

If hes complaining about torque at 4k with a g30r hes going to shit a brick with the to4z, because the illusion of surge on makes people believe they arent making as much power at x rpm.

[Boostage]

have you ever used one (gt30r)?


Not me but according to a few on Supramania the gt30r, is very weak, and doesnt start to get going untill 18psi. but then again thats a heavier chassis. anyway I have a 62-1 now with t3 .70 exhuast. quick spool but nt a long powerband, and doesnt put the tq where I want it. I have already bought the Twin kit, so please help me figure out where to go from here with them, not suggest selling it to do single again :bigok:

[Z33dori]

you would be amazed at how much a good tune can bring out more........

[Boostage]

Steve, here is the MINES skyline with twin 2530 vs the Amuse supra with a single gt30xx

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

[steve shadows]

Not me but according to a few on Supramania the gt30r, is very weak, and doesnt start to get going untill 18psi. but then again thats a heavier chassis. anyway I have a 62-1 now with t3 .70 exhuast. quick spool but nt a long powerband, and doesnt put the tq where I want it. I have already bought the Twin kit, so please help me figure out where to go from here with them, not suggest selling it to do single again :bigok:

everyone on there is a moron then

Ive used a 62-1 on both SR and drive RB with simlar (60-1)

the GT30R trumps it by a huge margin, both transient response, output at same boost and torque as well as use of power band

Supra guys are funny.

well go dual 2871R .64 (your still going to have some torque drop off because of the displacement it's not a 3.0)

Thats my vote (especially with your cam sizing).

[steve shadows]

Steve, here is the MINES skylike with twin 2530 vs the Amuse supra with a single gt30xx

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

ive seen that video a thousand times. Its not a good comparison.

its all in the "tuning" boro sun.

those engines are completely differnt, the heads are completely differnt, I mean there is almost nothing similar about those two cars except the fact they are both 6 cylinder.

If I had a supra (3.0 liter) I would run twin 3071Rs with a staggered camshaft.


1 jz is 2.5 right? So I would run twin 2871R, similar to 2530R but only a slightly larger compressor wheel.

[jeeper_x]

i vote T88....;)

[Boostage]

1 jz is 2.5 right? So I would run twin 2871R, similar to 2530R but only a slightly larger compressor wheel.

yes its 2.5, so, in your opinion the 2871r would not be too laggy for a daily right??

[CylonFrakker]

who made that kit? I am very much interested in that kit?

Also consider doing a 3.0 liter bottom end. it bolts right up. I know you can get a GE bottom bottom end for less than 500 bucks and slap that on there with a 3mm SP head gasket and head studs and you would be able to make a lot more power across a wider power band. Just something to consider. The 1.5JZ is a great setup. One of the best hybrid motors out there.

[Boostage]

Its custom. you cant buy it.

[GSXRJJordan]

The 2871R .64's will only be a little bit bigger than those GT28RS's... You could definitely do that.

My suggestion, if you don't want to go single, is nitrous. For under $1000, you can do a basic kit (start with a 50 shot, single jet into the intake mani) that'll spool your turbos a little faster and give you the extra 50hp you're looking for on top. If you want to go a little crazier with a progressive controller, you can go for a 30 or 40 shot to spool em and a 100 or so up top for some real fun. You'll improve your powerband and hit your peak number goal. Make sure that headgasket's good though.

If you're scared of nitrous, go single. Steve doesn't lie, that GT3076 can hit 500hp with cams (might have to go bigger, but you'll get close with your 264s assuming they have some big lift), and the 1JZ will spool it quick enough to have some serious fun.

[Prok0]

Pics of 1JZ S14 or fail.

Oh and why not go with an appropriately sized single..Boost Logic offered a kit for the 2J with a PTE67 turbo that spooled almost identical to stock twins but made 600-700whp.. So I would imagine you could get the same turbo with a smaller backhalf and spool about the same, or find a turbo better suited to the 1J

[Boostage]

Again I have never seen a 3076 on a 1jz with the powerband I want, and I have seen many. all 3076's make 100 foot lbs less at 3k than twin gt28r's

[Prok0]

Pics of 1JZ S14 or fail.


msglngth11111

[steve shadows]

yes its 2.5, so, in your opinion the 2871r would not be too laggy for a daily right??

Hold on here

What the fuck do you want from this car?

You want a 2.5 liter engine to give you a massive V8 power band of torque, be great for daily driving and not have power drop off in higher rpm ranges?

You need to figure out what you want to do.

2871R .64 on (two of them) will be slightly laggier than the twin gt28r, but grow some balls if you want the top end power you will have to make some trade off even if it is as small as 500 rpms of spool.

GT30 is better for 1jz than 2jz. 2jz is a big motor, and a gt35r would yield more torque because the gt30r turbine is probably actually stifling flow (because flow out of the head is not split between two turbos and is forced onto one small turbine wheel).

Pics of 1JZ S14 or fail.

Oh and why not go with an appropriately sized single..Boost Logic offered a kit for the 2J with a PTE67 turbo that spooled almost identical to stock twins but made 600-700whp.. So I would imagine you could get the same turbo with a smaller backhalf and spool about the same, or find a turbo better suited to the 1J

again the PT67 and GT3567 or T67 wheel with 35 turbine, so logically for a smaller motor a gt35R single would be most efficent, use a smaller comp housing and use a .63 turbine. but then again it might not have a v8 monster torque power band the OP wants.

The GT30R is not reccomened for motors over 2.5 liters by garrett (at least last time I talked to a tech).

I dont really know or care what the 2JZ likes. Most supra guys dont know what the hell they are trying to do and end up building dyno queens.

For a 1JZ if you want to keep it breathing up top you will have to allow for a turbo with a higher surge point and more cfm yielding compressor wheel. (if were talking strickly turbos).

The best compromise I can see for you is twin .64 gt2871R, and yes lag will be slighly more but it will be very marginal if the car is tuned right.

Even with this in mind, I would suggest running a 272 cam on the exaust with your current turbo setup (gt28R) and see if that helps.

Also get a standalone (Like a Haltech best for money most features ) and have it tuned by a good tuning on load bearing brake-eddy dyno.

For sr20det the GT30R is King. For the 2JZ its the T88. I can't really comment any more than that

1JZ response? or 1JZ top end power band?

Pick one.


please post some dynos of 1jz's with gt30r and shitty low end torque thanks

the origional graph looks like shotty Wastegate control. You need to post dynos with boost sysinc with the power.

Even on larger engines boost bleeds off, I bet if that car that made 480 had twin 38mm wg on each T28 feed on mani, that it would carry torque flat out because the wastgate flap would not be collapsing on itself due to the inherit garbage that is diaphram based internal gates. Either that or the EBC he was using is garbage. Most DD have record boost with power pull and you can graph it over torque or any two values try to source that.

even if the twins make more torque and low end, the gt30 wil make more power on a 2.5 500 rpm later and will plateu and carry off into the higher ranges of the rpm band.

I have yet too see a gt30r on any engine smaller than 2.6 liters with anything less than a semi to completley flat torque plateu for 3k rpms after bull boost comes on. Otherwise the tuning sucks asshole

[S14DB]

GT28RS is going to be the closest you're going to get to a HKS GT2530. GT2871R will give you a little more head room if you are upgrading the Intake Manifold or playing with cams.

[steve shadows]

If I were him I would stick with the t28s (although I hate the ceramic wheels)
and use a 272 on the exaust with a stiffer diaphram HKS actuator on both turbos cranked down all the way to start base at 12 psi to prevent boost drop off (which is what is probably displayed in the dyno graph he posted) and then get a good tuner and a good EMS.

[Boostage]

Hold on here

What the fuck do you want from this car?

You want a 2.5 liter engine to give you a massive V8 power band of torque, be great for daily driving and not have power drop off in higher rpm ranges?



Yes.. like this.. http://www.gtr.co.uk/forum/upload/513333-post3.html

It seems Gt2860r-5 is what I am looking for thanks for all the info

[steve shadows]

the Skyline head is better than the 1j and 2j in cfm rates iirc and overall efficency for racing iirc and that is a 2.6 litre

not 100%

600 BHP is like 500 whp MAX on most RWD cars, due to drivetrain loss.


try what I mentioned above im pretty sure it will work exactly as I theorized.

[Boostage]

the Skyline head is better than the 1j and 2j in cfm rates iirc and overall efficency for racing iirc and that is a 2.6 litre

not 100%

600 BHP is like 500 whp MAX on most RWD cars, due to drivetrain loss.


try what I mentioned above im pretty sure it will work exactly as I theorized.

Actually Someone in SAU flow tested the rb26 head and 1jz and 2jz head, the intake on the intake was a LITTLE better than the 2jz, but the exhuast on both the 1jz and 2jz outflowed the rb26 head. no question a JZ head will outspool an rb head.. my head is ported btw..

However I just might take your advice on the combination you recomended. My only fear was losing too much low end. thats why I started this thread. but I think yoru right on those two turbos..

[steve shadows]

should be a rocket, just keep that internal gate trap door from opening up too soon ;)

[slideways2004]

+1. i would also love to see the pics of your car. ijz s14. post some detailed pics of the engine bay

[Prok0]

For the 2JZ its the T88.

In 1999. yes. haha
For peak power t88 is never used anymore.. its all GT42 and bigger..

[kouki_s14]

i have twin Nismo LeMan GTR turbos that is good for about 670ps. Bolts up stock to a RB, so it should fit your kit with ease. I will have it up for sale soon if you're interested.

Part number is
14411-RR581
466089-7

Garrett turbos