Gt3040 On A Standard Rb25? Yes Or No

[johnabs]

HI GUYS,

i have found a good n cheap GT3040 for $1300 and was wondering how well this will go on a standard RB25 engine. I got stock internals, stock cams, stock plenum however got a powerfc, fmic, big injectors n pump, intake etc. I am aiming at 260rkw which i know ill get but will my internals hold and will i get lag from this turbo?

Is it tooo big for standard RB25, will i stress it, or will i just get lag?

thanks

john

[johnabs]

btw heres some more info on GT3040:

compressor housing is an a/r 70

exhaust housiung is .63

external gate

rated at 550hp

[paulr33]

compressor is larger the exhaust? what the? are u sure ?

[johnabs]

this is the link http://www.nissansilvia.com/forums/index.p...howtopic=231857

compressor is larger the exhaust? what the? are u sure ?

[Al]

compressor is larger the exhaust? what the? are u sure ?

Very common Paul

The engine should be right, if the tune is kept SAFE and a little on the conservative side. This should be half decent on a rb25. The smaller ext housing will provide a faster spool up, but will limit peak power. At a later stage, if you thirst more power, you can always upgrade to a .83 ext housing, which is a better match for this turbo.

All the best. Make sure the flange is suited to a rb25 manifold.

[johnabs]

Very common Paul

The engine should be right, if the tune is kept SAFE and a little on the conservative side. This should be half decent on a rb25. The smaller ext housing will provide a faster spool up, but will limit peak power. At a later stage, if you thirst more power, you can always upgrade to a .83 ext housing, which is a better match for this turbo.

All the best. Make sure the flange is suited to a rb25 manifold.

thanks mate but what u mean the right flange. its a t3 flange however this turbo came off an sr setup. doesnt any t3 exhuast falnge bolt up to the rb25 t3 manifold.

thanks

john

[STR8E180]

Very common Paul

The engine should be right, if the tune is kept SAFE and a little on the conservative side. This should be half decent on a rb25. The smaller ext housing will provide a faster spool up, but will limit peak power. At a later stage, if you thirst more power, you can always upgrade to a .83 ext housing, which is a better match for this turbo.

All the best. Make sure the flange is suited to a rb25 manifold.

^ wat he said!

the only time u will see the exhaust housing bigger then the compressor housing will be on a rotor or a bigger engine eg. V8, truck even ur standard turbo has a smaller compressor housing then ur exhaust housing

being a .63 rear exhaust housing it will provide very fast spool on a 2.5L engine BUT will limit power up high in the rev range but if ur only looking for 260rwkw this turbo wont have a problem giving it to u, this turbo will make alot more power then that i made 276.6rwkw with a standard bottom end with a SR20

the rear exhaust housing has a .86 option so u can always change it at a later date if u want more topend power but the price u pay for more power will be lag

oh im the one selling the turbo by the way

Edited May 4, 2007 by STR8E180

[johnabs]

lol the pic gave it away lololol ill make my decision based on wat else i need to install but should be a problem

^ wat he said!

the only time u will see the exhaust housing bigger then the compressor housing will be on a rotor or a bigger engine eg. V8, truck even ur standard turbo has a smaller compressor housing then ur exhaust housing

being a .63 rear exhaust housing it will provide very fast spool on a 2.5L engine BUT will limit power up high in the rev range but if ur only looking for 260rwkw this turbo wont have a problem giving it to u, this turbo will make alot more power then that i made 276.6rwkw with a standard bottom end with a SR20

the rear exhaust housing has a .86 option so u can always change it at a later date if u want more topend power but the price u pay for more power will be lag

oh im the one selling the turbo by the way

[STR8E180]

well i can give u a list of wat ur going to need

because the turbo is external gated ur going to need an external gate

and because u need an external gate to control boost ur only to need a manifold with an outlet to fit an external gate onto

and ur going to need ur intercooler pipe moded to suit the compressor housing outlet, ur also going to need a new intake pipe because the compressor housing inlet is 4inch so ur going to need a new 4inch air filter (K&N fits perfect)

ur also going to need new oil and water lines made up and a new dump pipe

if are u are in sydney i will be able to make up all the new intercooler pipe + intake pipe + dump pipe for u

im a fabricator by the way

[sinistaGTR]

hey mate, i have a gt3040 with a .63 ex on my rb25, starts boosting 3200 full boost by 3800 its a sweet turbo on a rb25 and makes good power. i recommend it

[croat]

i have a gt3540 on my rb25 internally standard. no probs.

[discopotato03]

A couple of things I'd be concerned about .

1) Personally I'm not a fan of the big 82mm OD compressors on the 60mm turbine .

2) Advertised as a "4 bolt" turbine housing . Make sure its got the conical stand off on the back of it or its not a propper

GT30 turbine housing . Only available in T3 flange .63/.82/1.06 from Garrett , both integral and external wastegate .

No offense but I think its brave to compare turbine and compressor housing A/R ratios because they live in totally different environments . The difference in temperature of the gasses let alone pulsed exhaust gasses make their requirements very different .

Its entirely possible to run quite large divided turbine housings because the whole expansion of the hot exhaust gasses across a pulse divided system means venting into an area of lower pressure and ultimately volume on the way from the exhaust valves to the turbine blades . The single scroll turbine housing forces you to size its A/R ratio to work a bit like a venturi or nozzle to accelerate the gasses into the turbines inducer blades . If you have to do it this way the roads to rapid transients and acceptable boost threshold is to use conservative compressor wheels that need the least turbine energy to get them cracking .

This may make you laugh but Garrett would have been better off doing the GT3082R the other way round compared to a GT3582R ie the GT35's turbine with the GT3076R's compressor making it a GT3576R . That way you get the larger turbine shaft torque to drive the 76mm GT compressors power needs . THEN if you have to pull back on turbine housing A/R at least you get sufficient power from the 68mm vs 60mm turbine .

Funnily enough Garrett do make the GT3576 and GT3576R but its in the larger centre section (the ball bearing version) and I believe its the diesel spec HP turbine rather than the petrol performance spec UHP turbine . A "GT3576R" would be like an upsized real GT3071R ie turbine diametre closer to compressor diametre . The real GT3071R is 60/71mm diametres whe a "GT3576R" would be 68/76mm . One who worked for Garrett Aftermarket US did tell me this combination would be good but there is also going to be a slight turbine innertia issue . I think you could get around this easily enough with well thought out manifolds/turbine housings and as always tuning .

Off the topic , IMO the GT3082R is the wrong way round and tries to drive a 680 Hp capable compressor with a 500 Hp capable turbine . I think people find the things laggy because the turbine can't develop enough shaft power at low engine speed/exhaust gas velocity to supply the power an ~ 62lb/min (air) capable compressor . The real GT3076R's compressor is good for ~ 53-54lb/min and the real GT3071R's ~ 50lbs/min .

I reckon using the .63 A/R turbine housing on a GT3082R merely forces higher exhaust gas velocity into the turbine which my get it going but prematurely chokes up the exhaust side - its the engine that suffers .

Cheers A .

[Cubes]

I reckon using the .63 A/R turbine housing on a GT3082R merely forces higher exhaust gas velocity into the turbine which my get it going but prematurely chokes up the exhaust side - its the engine that suffers .

Cheers A .

Which is generally why the GT3082's make bugger all if any more power over the GT3076's UNLESS they are pumped full of 100+ron fuel and or water meth injection.