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Discussion Starter #1
Hi guys,

Wanted to introduce my self, I'm new as u can prob guess with 1 post. Currently looking into the prospect of buying the ne GTR (R35).

Just wondered, it comes with 480 bhp stock. With Full BPU (i.e. double
decat, FMIC, Boost controller (if its not already got one but I suspect it'll have one). What kind of performace figures can we expect!

I've currently got a Supra MKIV, I know you guys prob will knock me for putting a pic up. But its probably the one of the best looking Supra in the country.



Moving on, how do you go about placing an order for one?

:)
 

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Plenty of info just a search away too :D
 

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im sure i recognise that car, are you on mkivsupra.net ?

Mods are still questionable at the moment as i dont think anyone is sure what security nissan is putting onto the car to stop people from modding it unfortunatley. Im sure Smokey Nagata will have something to say about that though :)

Nice soop mate, whats the spec?
 

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that *is* a beautiful Supra. I'd love to have a car like that, but I really wanted Skyline handling. In retrospect though, as a city car it'd be more fun to do burnouts and donuts with a Supra (very hard to pull off in an R32). Wagging rear ends at 100mph are scary though, don't think I'll ever have a go in a big-power Supra.

No word on tunability with the R35, but at this stage in the game (early, mind you), it's not looking good. Nissan is trying to make the ECU hack-proof, so you're left with exhaust mod gains, maybe 25hp at the most? Intake mods maybe, but it'll take some computer wizardry to raise the boost (unless someone got in there and welded the wastegates at a certain opening!).

Damn, I really fancy your rear wing especially. Makes my plain R32 look like pants.
 

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Welcome, I thought you was a supra owner while reading through your post. All supra owners call stage 1 'BPU' :)

I was also from mkiv forums.
 

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what the hell does "BPU" stand for??
 

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Name:
BPU

Also known as:
Basic Performance Upgrade
Full decat

What is it?
BPU stands for “Basic Performance Upgrade”, a term coined by US firm Suprastore for a basic upgrade package for the TT Supra. BPU is essentially what other marques refer to as "Stage 1” engine modification.

The BPU upgrades allow the engine to produce more power by raising the boost pressure the turbos produce.

In stock form, the TT produces 0.76bar (11psi), however this can be raised; it's generally accepted that the stock ceramic Jspec turbos will handle 1.2bar (17.4psi). The Export spec (UK/Euro/US) has steel blades so will, in general, survive at higher boost pressures. 1.4bar (20.3psi) is not unheard of.

1.2bar is the "accepted" safe limit with regards to a) detonation, b) actually getting more power, and c) some level of longevity. It is also accepted that you are spinning the cylinder and pulling the trigger each time you use them, but 1.2bar you have one loaded chamber, 1.4bar you've got three
There are limitations with pressures above 1.2bar, the turbos are already outside of their efficiency range and the additional heat generated will raise the intake air temperature considerably – thus negating the effect of increased boost pressure.

In both Jspec and export spec, BPU will raise engine power to around 400bhp. Not only will it release more power but it allows much quicker turbo spool-up, which vastly increases drivability.

How it works
In stock form, the boost pressure the turbos produce is controlled by back pressure in the exhaust system (I.e. highly restrictive catalytic converters and exhaust system). There are two approaches to BPU dependant on the model of car; as such the next section is split between Jspec and Export spec:


Fundamentals of BPU

Jspec:
To raise boost beyond the stock level the restrictive catalytic converters are removed, thus allowing the turbos to spin faster and produce more boost pressure.

There is a down side to this. With both cats removed the turbos will in fact over speed far past their safe limit and reach over 1.6bar (23.2psi). This is due to the small size of the jspec wastegate which cannot cope with the increase in exhaust gasses.
At these pressures the ceramic blades in the turbo can become detached from the shaft and therefore cause catastrophic failure of the turbo.

In order to add some restriction back in to the exhaust a restrictor ring is added to the exhaust system. A restrictor ring is simply a metal plate that fits normally between either between the 1st and 2nd decat pipes, or the 2nd decat and cat-back. The centre of the restrictor is drilled out to a smaller diameter than the exhaust itself (normally around 2inches). A properly sized restrictor should bring the maximum boost pressure down to 1.2 bar or less.

UK/Euro/US (Export) spec:
To raise boost beyond the stock level the restrictive catalytic converters are removed, thus allowing the turbos to spin faster and produce more boost pressure. Different to the jspec, the export spec has a larger wastegate which can handle the increase in exhaust gasses.
Therefore boost pressure will be maintained at only slightly above stock levels, typically 0.85bar (12.3psi). In order to raise this further it is necessary to install a Boost controller to change the way in which the wastegate opens.
A restrictor ring is not required on the export spec

Note: On both models it’s possible to raise the boost with simply adding a Boost controller or Bleed valve; however this is not recommended since the huge resistance of the cats is still in place. This will result in significant extra heat being generated in the manifold and could cause serious engine damage due to raised exhaust gas temperatures.


Parts required:

Obviously all that’s needed to raise the boost pressure is a double decat & restrictor ring (Jspec) or double decat & boost controller (export spec). However, it will not work without further modifications. The following will be required in both models:

1) Aftermarket cat-back exhaust
The stock cat back (the pipe after the 2nd decat pipe) is extremely restrictive. In order to allow a good free flowing system this needs to be replaced with an aftermarket system. There are a huge amount of systems available, but any good quality aftermarket system will be suitable for a BPU level of modification.

2) Fuel cut defender
The stock ecu will initiate fuel cut when boost pressure reaches 1 bar for a 3 second period. In order to stop this, a device is needed in order to trick the ecu into thinking the boost pressure is lower.
(See quick link for further details)

3) Updated fuel pump
The stock fuel pump in the jspecs is not considered suitable for BPU level power, the one in the export spec is higher specification and will be suitable. However as many of these cars are approaching 13 years old it should be standard practice to replace the fuel pump.
The Walbro pump is commonly used, however the standard pump that comes with the export spec is a better specification and has quieter operation (though considerably more costly).

4) Colder grade spark plug
With an increase in boost, a ‘colder’ grade plug is required with a closer gap. There are two basic options:
- Iridium IK22 plugs
- NGK BCPR7ES
The iridium’s will last longer (most people get >10k miles) but typically cost £60 a set
The NGK’s need replacing around 3k miles, but cost £14 a set
 

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Discussion Starter #18 (Edited)
ya bpu brings a supra to around 460-500bhp.

I know its crazy with the Jap Spec Supra they came with 280 bhp stock. Full BPU on 1.2 bar you can get it up to 410 bhp.

The UK spec Supra (320 bhp stock) had steel blades, hence run higher boost, at 1.4 bar they can hit 450 bhp.

With it remapped and new fuelling, bigger 650 injectors, cam etc you can get it up to 500 bhp reliable.

The new GTR looks like a beast with 480 bhp stock, just immagine full BPU you can prob expect figures around the 550 bhp mark. It'll quickly take the smug smile of 911 997 turbo, Gallardo, 430 owners faces :)

All for under £60k estimated, how do the Japs do it. It makes the Germans and Italians look over priced boys toys!!
 
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