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The mkiv Supra Owners Club

What does BPU mean?


Aerotop Dave
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*Needs checking - non-technically minded author writing this*

 

BPU stands for Basic Performance Upgrade. This is the first level of performance upgrade for the Supra and consists of...

 

1) Removing both catalytic convertors from the exhaust system

This frees up the whole exhaust system to breathe more easily. You will need to put at least one cat back in (meow) when it comes to MOT time, so don't chuck them away. You may also want to keep them for when you come to sell the car.

 

2) Replacing the standard exhaust with an aftermarket one

There are lots to choose from. A search on the forum should throw up (barf) lots of opinions and views on the different ones. Generally they all give about the same performance gain, it's just the looks, noise level and exhaust tone/note that you need to decide upon.

 

3) Fitting a boost gauge to keep an eye on boost levels

Again there are lots about, and several places to fit them too. The most common practice is to replace the clock, or you can replace the air vent next to it. Alternatively you can replace the air vent on the other side (where the ignition switch is), or go for a pillar pod which puts it into a little pod jutting out from the A pillar. Again a search on the forum should provide opinions and even some pics, or look at some of the traders sites for what's possible.

 

4) Fitting a fuel cut defender

Toyota prevented overboosting on the Supra by setting a 1.0 bar fuel cut. Once the boost level reaches this point the ECU cuts fuel to the engine to prevent boost reaching any higher - a simple safety/reliability idea. Once you take the cats out of the exhaust the boost levels will go easily over 1.0 bar, so you need to fool the ECU into thinking that this level hasn't been reached yet and that it needs to keep supplying fuel. This little electronic gizmo does just that.

 

5) Fitting a restrictor ring

As I said, boost levels will easily go over 1.0 bar once the cats are removed, so in order to prevent them going to hand-grenade levels you need to fit a restrictor ring to keep boost levels around the 1.1 - 1.2 bar level. This ring is exactly what it sounds like - it's like a washer that fits inside the exhaust and restricts the flow to keep the boost levels reasonable. Yep, stunningly simple and a little crude, but hey... it works.

 

6) Fitting colder spark plugs

You may have to play about with different plugs in order to achieve smooth running and idling.

 

7) Checking the fuel pump

This will really depend on how old your car is. With some Supras now 12 years old some of those early fuel pumps might be getting a bit crusty - even the youngest UK car is now 9 years old. If it's pumping ability has dropped to 90 or 80% you're risking running the engine on the lean side. If you're splashing out on all the other BPU stuff you might has well fit a new fuel pump to be on the safe side. Most people fit the Walbro aftermarket one.

 

 

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  • 8 months later...
:sos: hi all, this is my very first post since joining site, i have a basic 3.0 litre supra non-turbo version with auto gears(1993), and my local garage said it will be very hard to remove the front cat and the rear cat is no problem to remove, but my main worry is that "will i pass my emissions test on the m.o.t.???", please can anyone give me some knowledge on this matter, many many thanks Dom..:sos:
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