Need Turbo Selection Help

[StealthX]

Hey all.

I've bin researching for the last 3-4 months and slowly piecing together my turbo kit for my X-trail

Im looking for no more than 6psi of boost, and i dont want to spend a thousand dollars on a turbo.

What would you guys suggest?

Since my engine is that same size (2488cc - less two cylinders tho) as an RB25, the logical suggestion is a stock RB25 turbo.

I've followed the same lines as that, and gone with the T3 turbo from a VG30DET (single turbo 300zx) with a .48 AR exhaust housing.

From what i understand, its sorta the same as a '25 turbo, but with a slightly bigger exhaust housing. The internal gate is set at 6.5 psi.

On paper this sounds like a perfect turbo for making around 240-260whp on 6 pound (10 psi yields 300whp on my engine no problem, proved by dozens in the US)

Its in great condition, no shaft play, ball bearing, genuine garrett airesearch product, just wanting some input from some of you guys on if it is the right selection or if i should sell it and look for something bigger/smaller.

Besides this, I'd be leaning towards a KKR, second hand garrett or the like.

Thanks

[Yeedogga]

Sounds like a good little project!

I think if the turbo is in good shape then you may as well use it. I know some people have had issues with boost creep on the KKR turbos. I say stick with the VG30 unit, put it all together, and if you find you need to upgrade to a larger unit (unlikely i would think on a stock motor) then you can do it at a later stage.

Is the X-Trail motor based around the KA24DE motor used in the US-240sx?? IE; could you source a KA turbo-conversion manifold from the states? How are you going to get on with the WRX injectors? Are they a straight fit in the std rail (?) or are u looking at custom rails etc?

Sounds like fun!

[WYTSKY]

sounds interesting,

whats the compression on the motor? at 6 psi i imagine u wouldn't need an intercooler... or a big one atleast...

edit...just checked ur sig... well its safer i guess and looks shiny

personally I have been pretty happy with my hypergear turbo, look them up... better then a kkr imo, but alot of these somewhat larger aftermarket turbos have a much higher efficency range... ie. at 15-16psi they really get some power and before that no where near as much.. whereas a stock 33-34 turbo came from factory running that sorta boost (about 7 from memory) so therefore would have more punch at that psi... so a vg30det turbo is probably a pretty good choice for now if u want a little head room for the future...

gl with it

[TRB-001]

hey sorry to take away from the turbo topic but i had this same thought (altho didnt get very far) and im really keen to see how u go with this...

i worked at nissan for many years and was the xtrail man back in the day.....im sure this thing isnt very stock any more but give me a yell if u unsure bout anything.....

keep it updates on the forums or send me some pics/info

its a shame ur in wa

[StealthX]

thanks fellas.

yeedogga,

ive heard many ppl having problems with boost spikes and shit too.

ive never seen one used for under 1 bar of boost, pretty sure its a def no go.

the x-trail motor is a QR25DE. it was made to be the replacement of the SR20 and KA24.

its engineered to be light and powerful like the SR and torquey and reliable like the KA.

but unfortunately the manifolds/fuel rails/intakes of both dont fit.

theres a car sold in the us called a Sentra, which has exactly the same engine as my x-trail.

several companies (turbonetics, treadstone and a few others) make full, high quality turbo kits for the cars, they give a 12month warranty on 9psi...

so im copying everything off that. the manifold and dumppipe is getting made professionally by my best mate whos a fabricator (oh joy!) at his work...

teh WRX injectors are perfect fit, same size, same o-rings, everything. they flow 440cc and max out at 10-12psi and are high impedance top feed

even the wiring clips are the same...

wytsky,

my motor has a 9.4:1 compression ratio, which is pretty low for a new, all alloy motor IMO.

im going with the intercooler just for a little added piece of mind.

everything about this kit is extra conservative (fuel pump doesnt really need to be upgraded, dont really need an IC, but im doing it anyway)

+ im getting it tuned professionally with a GReddy emanage ultimate.

thanks for ya help.

Cam.

[StealthX]

hey sorry to take away from the turbo topic but i had this same thought (altho didnt get very far) and im really keen to see how u go with this...

i worked at nissan for many years and was the xtrail man back in the day.....im sure this thing isnt very stock any more but give me a yell if u unsure bout anything.....

keep it updates on the forums or send me some pics/info

its a shame ur in wa

thanks mate!

how far did ya get with the kit before ya decided against it?

i saw a custom turbo'd HYANDAI EXCELL, flutter its guts past me one day and i thought, f**k it, if that thing can be blown, why cant mine?

[WYTSKY]

thanks mate!

how far did ya get with the kit before ya decided against it?

i saw a custom turbo'd HYANDAI EXCELL, flutter its guts past me one day and i thought, f**k it, if that thing can be blown, why cant mine?

lol, could have just been the passenger with a megaphone making sounds

[Yeedogga]

That's great about the WRX injectors. Who'd of thought it!

Yeah, me and my mate just finished doing a turbo-motor conversion on a 1990 Golf Mk2 GTi and I used to own a Volvo 240 with a turbo motor swap.

Sleeper projects are fking great fun!!

[kwickr33]

If its similar to a KA or a SR engine the best go is HyperGear's ATR28 turbos. They are T28 size turbos made to produce any thing from 230 to 300rwkws. Power curves on them are solid. have a look at:

http://www.digi-hardware.com/atr28.html

They are a sponsor on this forum.

Edited June 10, 2009 by kwickr33

[StealthX]

If its similar to a KA or a SR engine the best go is HyperGear's ATR28 turbos. They are T28 size turbos made to produce any thing from 230 to 300rwkws. Power curves on them are solid. have a look at:

http://www.digi-hardware.com/atr28.html

They are a sponsor on this forum.

thanks for your help but i think thats gonna be a little too small.

after all my engines got 500cc more than an SR20 and 700 more than a CA18

also due to my engine having a huge stroke (100m vs 89mm bore), it will be kinda restrictive.

im thinking along the lines of keeping this turbo for a while, trying it a little, see how it goes , then upgrading to a Garrett T-series (about 600-700 bucks)

which would get me a solid quality product, and i can sleep easy at night...

[femno]

Well considering you engine is .1:1 off from a RB25 (9.5:1) id say that turbo is ok, but you should run more boost to make the most of it.

You could also say you have an SR20 thats been stroked to 2.5...in that sense id maybe use a Garrett 2871r with a .86 rear housing or even a .64 for insane midrange, that would be the ultimate in my opinion. That would give awesome response being BB with great power overall. Once again alot of potential for big power with more boost.

How are pistons, rods and headgaskets strength-wise in the xtrail?? Being a turbo-level comp ratio id run more boost. Say 10psi - not far from factory standard of RBs and SRs. Considering standard nissan RBs and SRs can run 20 comfortably, halving it for your non-turbo factory engine seems very safe.

Have faith in Nissan engines!!

[StealthX]

Well considering you engine is .1:1 off from a RB25 (9.5:1) id say that turbo is ok, but you should run more boost to make the most of it.

You could also say you have an SR20 thats been stroked to 2.5...in that sense id maybe use a Garrett 2871r with a .86 rear housing or even a .64 for insane midrange, that would be the ultimate in my opinion. That would give awesome response being BB with great power overall. Once again alot of potential for big power with more boost.

How are pistons, rods and headgaskets strength-wise in the xtrail?? Being a turbo-level comp ratio id run more boost. Say 10psi - not far from factory standard of RBs and SRs. Considering standard nissan RBs and SRs can run 20 comfortably, halving it for your non-turbo factory engine seems very safe.

Have faith in Nissan engines!!

from what the sentra guys have experienced over in the US, 8psi is the safe limit without meth or alky on a stock motor.

the pistons, crank, bearnings are good for 350-400hp.

its the rods that are the problem, they are pencil thin. (the rods on QR25s from 2007 and up are BEEFY as, so along with some forged, low comp. pistons, theres a great option for a build right there, cheap as chips too)

having said that, 90% of those guys only use SAFCII or NEO to tune with, leaving no control over ignition timing, or FULL control over new injectors.

since im using a full piggyback as opposed to just an air flow converter, id suggest theres more potential on a stock motor but to be on the safe side, im gonna start off at 6pound, then if i feel confident, ill up it from there with a boost controller.

a few guys have suggested using the 2871, but how much would that set me back, and wheres the best place to look?

[urtwhistle]

if you are running low boost why not go a stock RB25 turbo?

[StealthX]

if you are running low boost why not go a stock RB25 turbo?

yeh would be a logical choice, but its too small i think.

even tho the engines are the same size, my engine has a huge stroke.

and as a general rule of thumb, the larger the stroke, the larger the turbo.

the VG30DET turbo is essentially a ball bearing version of the '25 turbo, with a slightly bigger turbine housing...

[discopotato03]

Hi , I haven't been to them for ages but you could have a sniff around in the American Sentra SE/R and SE/R Net sites - if they still exist !

From memory in the US Nissan smallish front wheel drive platforms were B series rather than N series like ADM Pulsars but they had sort of parallel mechanicals like engines and gearboxes etc .

For example our N15 Pulsars had GA16DEs and SR20DEs and I believe their B15's were similar deal .

However unlike their B16s I don't think we got the QR25DE in the N16 like they did in their B16SE/R - I think SE/R is sort of like SSS in Pulsars .

Also from memory QR25DEs are reasonably long in the stroke and may have a pair of balance shafts to smooth things out .

In the states they were playing with turbocharged versions and JWT (Jim Wolf Technology) was possibly doing parts for them .

Cheers A .

Ah also it may not be relevant to compare an inline 6 with an inline four because for the same capacity the 4 has larger capacity cylinders and a flat plane 180 degree crankshaft , its a bit like comparing an SR20 to an RB20 with their different relative characteristics .

[femno]

Wasnt comparing was just looking at it from 2 different perspectives, between RB and SR. The SR is a better comparison for the reason you stated.

The 2871 will blow your budget, as it is usually had for around the 1300 mark. You may be VERY lucky and find one for a grand or less.

Its worth spending the money on it as it is the heart of your conversion and is the part that will yield results, or not.

[StealthX]

Hi , I haven't been to them for ages but you could have a sniff around in the American Sentra SE/R and SE/R Net sites - if they still exist !

From memory in the US Nissan smallish front wheel drive platforms were B series rather than N series like ADM Pulsars but they had sort of parallel mechanicals like engines and gearboxes etc .

For example our N15 Pulsars had GA16DEs and SR20DEs and I believe their B15's were similar deal .

However unlike their B16s I don't think we got the QR25DE in the N16 like they did in their B16SE/R - I think SE/R is sort of like SSS in Pulsars .

Also from memory QR25DEs are reasonably long in the stroke and may have a pair of balance shafts to smooth things out .

In the states they were playing with turbocharged versions and JWT (Jim Wolf Technology) was possibly doing parts for them .

Cheers A .

Ah also it may not be relevant to compare an inline 6 with an inline four because for the same capacity the 4 has larger capacity cylinders and a flat plane 180 degree crankshaft , its a bit like comparing an SR20 to an RB20 with their different relative characteristics .

hey mate yeh ive been doing all my research on that forum!

its called MSV (my spec-v)

myspecv.com have a look if youve got a spare 2 mins.

the B platform is americas version of the N platform over here.

and yeh the sentras come with QG18DE, SR20DE, and the upper spec SE-R and SE-R spec V came with the QR25DE, tuned for 130 and 135KW respectively, taking the car from 0-100 in 6.3 seconds - not bad for a FWD four banger.

my x-trail is based off the the FF-S platform, essentially, the 4WD variant of the B platform. in 2007, the FF-S platform was super seeded by the C platform, making the new X-trail shape, shared with the murano, rouge and dualis and of course the 2007 and up (B16 model) sentra.

JWT make heaps of parts tfor the QR engine.

some of these include, balancer shaft removal kits, clutches, flywheels, cams and multi layer head gaskets specifically for turbo applications.

back on the turbo...

i think im gonna stick with this turbo for the moment.

if the poweband turns out like shit, then i can always sell it and look for something different, but it should be ok.

[discopotato03]

Your call but to my way of thinking you need to take into consideration that a factory NA engine will have a higher compression ratio and cams speced around that and the engines breathing characteristics .

OEMs almost always drop the static CR and use shorter cams in factory turbo engines .

It becomes very important (IMO anyway) NOT to restrict the exhaust path from the ports any more than is absolutely necessary or chronic detonation often sets in .

OE turbos are intended for OE turbo engines not OE NA ones , I'd be wanting to go a bit larger on the hot side for your sort of app .

A factory NA engine should have higher cylinder pressure than a factory turbo engine off boost , if you then raise the cylinder pressure with forced induction the extra pressure and heat is what drives it into detonation - especially with factory NA ignition timing control .

If its good response and a torque boost needed you could do worse than to try a GT2860RS or one of the small or medium trim GT2871R's - in the larger of the two available (0.86 A/R) turbine housing .

Something else to think about is the torque capacity of your transmission , if its full time 4WD (AWD) you need to be real careful of how much torque you feed through it - particularly if it has a low range (two spd transfer case) .

I find lots of late model cars , some with reasonable capacity , lack torque down low and I have to wonder if it allows factories to use lighter weight and less expensive drive lines to cut production costs .

I'd hate to see you trash a late model and likely expensive gearbox doing your own "R and D" .

Like a lot of things I reckon if you approach it conservatively and have realistic expectations it could work quite well .

One last , you may give it more stick but don't forget that type of cars original intended use which is not really to be a sports car . Brakes and handling are very important - I'll leave it at that .

Cheers A .

[krizza_ca18det]

This is something I have thought about as I bought the missus the same model x-trail about a year ago and love how torquey the motors are down low(at least compared to my ca18det with cams anyway ).

It will be interesting to hear how the QR reacts to forced induction especially over 5k rpm, as even after replacing the factory headers and cat on our exxy with extractors and a hi flow setup the cams seem to really be matched to low rpm torque production. The power really feels to nose over after 5k, and because of this I have thought that an RB25 turbo with its light weight internals (ceramic exhaust wheel etc) would be perfectly suited to a stock QR25DE+T setup ie. no lag and the right amount of compressor flow. I think the aim with these engines would be to improve low down torque rather than aim for high rpm HP. Also look forward to hearing how the driveline copes with the increased torque loading too.

Discopotato03, the brakes are actually pretty good on the xtrails as they put reasonable sized rotors all round, but the handling leaves a fair bit to be desired as you would expect.

Keep us informed.

Edited June 12, 2009 by krizza_ca18det

[StealthX]

Something else to think about is the torque capacity of your transmission , if its full time 4WD (AWD) you need to be real careful of how much torque you feed through it

the x-trail has a 3 mode 4WD system, 2wd, auto mode (uses sensors to distribute torque between front and rear wheels) and 4WD mode.

it is front wheel biased, and the rear wheels are activated by a wet clutch system just before the rear diff. 4WD mode locks this clutch and drive is set @ 50:50

ive already upgraded the clutch and flywheel, plus i dont think this will be an issue too much. consider how much torque gets put through the drivetrain (post gearbox) in 1st gear. theres a shit load

now consider that no boost level is gonna match that amount of torque in any other gear. plus with what ive dont already, i can break traction to ALL FOUR WHEELS (in AWD mode) in 1st gear, so any more torque is just gonna induce more wheel spin, because im already reached the maximum tractive effort that the tyres can handle - if i had 10-inch wide tyres all round, it would be a different story, and MUCH more stress would be introduced to the drivetrain.

i know for a fact my gearbox is tough as. the sentra guys in the US use a similar gearbox, and theres a few guys in the 600whp club, all using stock gearboxes.

especially with factory NA ignition timing control

the GReddy e-manage ultimate has full ignition timing maps.

as for the breathing rate of the two engines, the VG30ET that my turbo comes off, flows this:

.00005305 (approx density of air @ 6psi) X 183cui x 6800rpm / 1.8

= 36.675 lbs/min @redline

and my QR flows only 30.662 lbs/min @ redline

so if that turbo was designed to flow 36 p/min at 6psi, then my engine that only flows 30 p/min should give me a little bit of headroom in terms of restriction.

in laymans terms, that turbo was built to flow 3000cc through its hotside @ 6psi, and my engine only has 2500cc worth of flow, so as long as i keep the boost pressure @ 6psi, it should be fine.

in this equation, compression ratio has little impact on flow rates, because air goes in, it is compressed at a the comp. ratio, then it expands to roughly the same density when it leaves the cylinders - disregarding the effects of heat on density + the addded mas of the burnt fuel

BUT if the comp ratio of an RB25 (as someone already pointed out) is 9.5, and guys can slap on '25 turbochargers on, then my 9.4 comp. ratio should do fine.

having said all that, im still looking for a cheap way to obtain a slightly bigger turbo.

can replacement exhaust housings be swapped onto factory nissan turbos?

that would be the ultimate solution IMO

krizza_ca18det,

check out myspecv.com

thats a car in the US with the same QR engine.

DOZENS of guys have turbocharged those engines.

a few guys have even used a GT2871r turbo, which is infact smaller than the VG30ET turbo i have sitting infront of me.

Edited June 12, 2009 by turbo x-trail