RB25DET Help.

[JayJay777]

Hey everyone, I've recently been looking to move around a few things in my engine bay. I have a C34 Nissan Stagea with an RB25DET. I'm hoping to relocate my turbo to a more top mount as well as adding a front mount intercooler and a front facing intake. I was just wondering if I needed to get a different manifold for the turbo or can I re-use my old one?

I'm fairly new to the RB and the Turbo as I have been with an EJ for the past 4 or so years. Any help would be appreciated as I'm also trying to figure out what turbo I should get to put on my car as well, mainly looking for something that will allow me to cruise comfortably but also chop my mates haha. I know there's other threads about all this but I have trouble finding these exact forums and going through the hundreds of comments.

also does anyone know if the coil packs from Maxpeedingrods are any good or even just their parts in general? cause I've heard a lot of mixed reactions about them.

[TurboTapin]

You'll need a top mount manifold. Turbo choice will depend on what power you're chasing and stay far away from maxspeedingrods products. 

[robbo_rb180]

36 minutes ago, JayJay777 said:

Maxpeedingrods are any good or even just their parts in general? cause I've heard a lot of mixed reactions about them.

Proper junk stay away.

Turbo setup is always budget dependant.......

[joshuaho96]

42 minutes ago, JayJay777 said:

Hey everyone, I've recently been looking to move around a few things in my engine bay. I have a C34 Nissan Stagea with an RB25DET. I'm hoping to relocate my turbo to a more top mount as well as adding a front mount intercooler and a front facing intake. I was just wondering if I needed to get a different manifold for the turbo or can I re-use my old one?

I'm fairly new to the RB and the Turbo as I have been with an EJ for the past 4 or so years. Any help would be appreciated as I'm also trying to figure out what turbo I should get to put on my car as well, mainly looking for something that will allow me to cruise comfortably but also chop my mates haha. I know there's other threads about all this but I have trouble finding these exact forums and going through the hundreds of comments.

also does anyone know if the coil packs from Maxpeedingrods are any good or even just their parts in general? cause I've heard a lot of mixed reactions about them.

You need a different manifold for top mount. The factory setup is fine even if you want to bump up the power, it's not like an EJ where the intercooler is barely adequate even at stock power levels. Most front facing manifolds make less power at low RPMs compared to stock. Personally I would stay away from Maxpeedingrods considering I've heard their coilovers have failed in surprising ways. These engines are too expensive to gamble on garbage parts. Same goes for Private Label MFG, their parts are also garbage and they've started moving into the Skyline world after getting their start on Hondas. If you just want to bump up the power talk to Hypergear about high flowing your stock turbo if you still have it. The less stuff you change the more time you get to spend actually chopping your mates instead of just talking about it.

[JayJay777]

14 minutes ago, TurboTapin said:

You'll need a top mount manifold. Turbo choice will depend on what power you're chasing and stay far away from maxspeedingrods products. 

ah okay good to know, do you have any you recommend? and I was looking for around 350ish horsepower. and yeah from the replies so far Maxpeeding doesn't seem as good as I thought haha

[JayJay777]

4 minutes ago, joshuaho96 said:

You need a different manifold for top mount. The factory setup is fine even if you want to bump up the power, it's not like an EJ where the intercooler is barely adequate even at stock power levels. Most front facing manifolds make less power at low RPMs compared to stock. Personally I would stay away from Maxpeedingrods considering I've heard their coilovers have failed in surprising ways. These engines are too expensive to gamble on garbage parts. Same goes for Private Label MFG, their parts are also garbage and they've started moving into the Skyline world after getting their start on Hondas. If you just want to bump up the power talk to Hypergear about high flowing your stock turbo if you still have it. The less stuff you change the more time you get to spend actually chopping your mates instead of just talking about it.

love that last line haha. Had a quick look, and I have what could possibly be a stupid question.. but what does it mean when they say internal waste gate porting? 

[Duncan]

260ish kw might be possible on a standard location, high flow turbo, that would be a lot cheaper.

FYI, High mount turbo, front mount intercooler, forward facing plenum (ECU, injectors etc etc) is a $10-20k job

[joshuaho96]

2 minutes ago, JayJay777 said:

love that last line haha. Had a quick look, and I have what could possibly be a stupid question.. but what does it mean when they say internal waste gate porting? 

Porting refers to improving the flow through the wastegate, if your wastegate doesn't flow enough you'll get boost creep.

[JayJay777]

4 minutes ago, joshuaho96 said:

Porting refers to improving the flow through the wastegate, if your wastegate doesn't flow enough you'll get boost creep.

ah okay cool. their services ain't bad, for around 950 I can get it high flow, may just have to do that.

[GTSBoy]

54 minutes ago, JayJay777 said:

I was looking for around 350ish horsepower

Measured where? At engine, at wheels, or at hubs? In what country? All these things have a bearing on the actual power level we're talking about.

I'm making ~350 engine HP on a standard turbo on a 25Neo. OK, maybe 340. The point being, that if you're talking about engine HP then you're not talking about a very big turbo, and there is no way that you need to high mount it, or any of the other stuff.

But even 350HP at the wheels, is.....

50 minutes ago, Duncan said:

260ish kw might be possible on a standard location, high flow turbo, that would be a lot cheaper.

This. That is dead easy to do with a highflow in standard location. Or a new Hypergear turbo, which would be slightly better than a highflow.

 

And....you really do not need or want a front facing plenum. They are purely decorative and do not assist with making power. They almost invariably reduce low end torque and subjectively (and objectively) make the car worse.

[JayJay777]

5 minutes ago, GTSBoy said:

Measured where? At engine, at wheels, or at hubs? In what country? All these things have a bearing on the actual power level we're talking about.

I'm making ~350 engine HP on a standard turbo on a 25Neo. OK, maybe 340. The point being, that if you're talking about engine HP then you're not talking about a very big turbo, and there is no way that you need to high mount it, or any of the other stuff.

But even 350HP at the wheels, is.....

This. That is dead easy to do with a highflow in standard location. Or a new Hypergear turbo, which would be slightly better than a highflow.

 

And....you really do not need or want a front facing plenum. They are purely decorative and do not assist with making power. They almost invariably reduce low end torque and subjectively (and objectively) make the car worse.

im looking to make it at the wheels if at all possible.

for the top mount turbo and front facing its for 2 reasons, i wanna mount a front mount intercooler and replace the tiny stock one, and because I want this to be something I can open the bonnet on at shows and have people wanna look at it haha, and i just find that the rocker covers look so much better without an intake wrapping over the top of them.

[JayJay777]

1 hour ago, Duncan said:

260ish kw might be possible on a standard location, high flow turbo, that would be a lot cheaper.

FYI, High mount turbo, front mount intercooler, forward facing plenum (ECU, injectors etc etc) is a $10-20k job

ive started making a list, so far to get my stock turbo to highflow its about $950

intercooler ive found is around $300 (Aeroflow)

i found a front facing intake with throttle body, fuel rail, all the lines and fittings second hand for $500

plus i wont have to pay for labour or anything as im a mechanic by trade.

[Duncan]

Great to hear, particularly for the labour, but just to think of a few other things so you don't get half way and run out of money

-Fabricate intake piping from air filter to turbo to intercooler to plenum. Air filter (and potentially box to suit)

-Silicone joiners and hose clamps for intake

-Highflow turbo *may* need new oil and water lines.

-External gate, manifold to suit if not internal gated turbo

-Boost control solenoid

-Dump pipe, front pipe and exhaust to suit the larger turbo without choking

-Injectors to suit the higher power (standard will run out)

-Oil breather setup to suit new intake (atmo or plumbed back)

-Tuneable ECU for the larger injectors and extra airflow, boost control. Might need to swap to ECU MAP or otherwise a new AFM eg Z32

-Tuning the ECU

Also keep in mind that most of this has to happen together, so the car will be undriveable from when you start until that tune is done, and if you run out of budget it will be off the road until it is all done

[JayJay777]

4 minutes ago, Duncan said:

Great to hear, particularly for the labour, but just to think of a few other things so you don't get half way and run out of money

-Fabricate intake piping from air filter to turbo to intercooler to plenum. Air filter (and potentially box to suit)

-Silicone joiners and hose clamps for intake

-Highflow turbo *may* need new oil and water lines.

-External gate, manifold to suit if not internal gated turbo

-Boost control solenoid

-Dump pipe, front pipe and exhaust to suit the larger turbo without choking

-Injectors to suit the higher power (standard will run out)

-Oil breather setup to suit new intake (atmo or plumbed back)

-Tuneable ECU for the larger injectors and extra airflow, boost control. Might need to swap to ECU MAP or otherwise a new AFM eg Z32

-Tuning the ECU

Also keep in mind that most of this has to happen together, so the car will be undriveable from when you start until that tune is done, and if you run out of budget it will be off the road until it is all done

damn, i knew i needed some of that stuff bit there is a lot there i didnt even think of, thank you.

i probably need to start finding stuff to work towards as i didnt intend on starting until i could finish and was hoping to do it all whilst my car was getting its doors and boot rust fixed. 

is there an ecu, boost controller and injectors you would recommend? 

[robbo_rb180]

i have 300+KW at the wheels stock exhaust manifold with external gate mod.

gt3076 .86 rear housing
45mm turbosmart gate
1000cc injectors top feed onversion
link ecu
walbro/TI 460lph pump
Fuel turbosmart reg
3 inch exhaust
fmic

307kw on 16psi on E85

super simple and easy to replicate
You don't need an inlet manifold or throttle body. If anything 98% of inlets cause drivability and torque loss.

Pretty sure @Dose Pipe Sutututu made over 400kw on stock inlet

Edited May 10, 2023 by robbo_rb180

[GTSBoy]

This is a minimum $10k exercise, if you do not buy all the things that you don't actually need (the top mount manifold, the FFP).

I have no patience with the "looks better at shows" reason for modification. Performance mods are for performance.

I have a front mount intercooler with stock turbo in stock location and stock return pipe to stock plenum. Just need careful design of cooler and return pipework. It is not good for as much power as a straight through front mount, but then.....you're not asking for anywhere near that level of power anyway.

Duncan's list is good. You also need a fuel pump. You'd be mad to upgrade to a Z32 AFM though, given that you're going to have to use an ECU that will do it via MAP.

[JayJay777]

9 minutes ago, GTSBoy said:

This is a minimum $10k exercise, if you do not buy all the things that you don't actually need (the top mount manifold, the FFP).

I have no patience with the "looks better at shows" reason for modification. Performance mods are for performance.

I have a front mount intercooler with stock turbo in stock location and stock return pipe to stock plenum. Just need careful design of cooler and return pipework. It is not good for as much power as a straight through front mount, but then.....you're not asking for anywhere near that level of power anyway.

Duncan's list is good. You also need a fuel pump. You'd be mad to upgrade to a Z32 AFM though, given that you're going to have to use an ECU that will do it via MAP.

now im confused, youve said in the first part that a top mount and ffp isnt necessary however in your second youre saying theyre for performance? which one is it? cause in my mind i want them for both looks and performance. cleans it up and allows for easier routing of a front mount and less careful design of both intercooler and pipe work. plus even if im not asking for the power a straight through front mount will provide, it will mean if i want to add more power later that i dont have to redo it all. ill do it once and do it right so i dont have to do it again, even if it does cost me an extra few grand. you might not have the patience for people who want it to look better at shows, but if im going to have a show car which will hopefully put out more power then i want it to look nice. at the end of the day 350hp is what i was aiming for as a realistic number, but if i can get more i will.

[JayJay777]

24 minutes ago, robbo_rb180 said:

i have 300+KW at the wheels stock exhaust manifold with external gate mod.

gt3076 .86 rear housing
45mm turbosmart gate
1000cc injectors top feed onversion
link ecu
walbro/TI 460lph pump
Fuel turbosmart reg
3 inch exhaust
fmic

307kw on 16psi on E85

super simple and easy to replicate
You don't need an inlet manifold or throttle body. If anything 98% of inlets cause drivability and torque loss.

Pretty sure @Dose Pipe Sutututu made over 400kw on stock inlet

ah okay, thats really good to know thank you! someone in this thread has already expressed his disliking over what im about to say, but the main reason i wanted a top mount and front facing was because this is a show and id like to be able to have its bonnet up and have it look more presentable. 

[Dose Pipe Sutututu]

I used a stock intake manifold on various iterations of the build. First time made 372kW, then 407kW (with a leaking FMIC).

[JayJay777]

1 minute ago, Dose Pipe Sutututu said:

I used a stock intake manifold on various iterations of the build. First time made 372kW, then 407kW (with a leaking FMIC).

damn that insane