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The mkiv Supra Owners Club

trying to decide


Guest Z-Kev
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Hi

After owning a 300zx for a while I have decided its time to move on, I have always loved the supra and it used to be a 1 horse race untill the price of bmw e39 M5's has dropped , just looking for honest feedback on the supra because it seems uk spec ones are hard to come by and the lower engine spec of the J spec would make it more expensive to tune, can these run reliably 450bhp all day every day on standard internals?

 

thx for your time people

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My brother has a 2001 M5 and they are a close match for a bpu supra. But they do have all the lovely extras, very comfy etc.

But the supra is totally different car. You will find it hard running 450bhp on standard turbos but the engine is a very strong and over engineered thing of beauty. Jamie p is running 700 something bhp on a totally stock lump and thats held out well.

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Hi there buddy,

 

You wana have a look at Jamie P's car to see what he is doing on a standard engine, gives you an idea of how good they are.

 

A healthy 2jz that has been looked after and serviced, should be certainly capable of a reliable 450bhp.

 

I'd be more worried at the amount of fuel you might have to put in it.

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and the lower engine spec of the J spec would make it more expensive to tune

 

FAIL.

 

Yes they'll happily run reliably as daily drivers putting out 450bhp on standard internals although that power figure is realistically a little beyond what the standard larger J spec turbos can provide.

 

Welcome to the club Kev.

 

Cheers,

 

Brian.

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FAIL.

 

Yes they'll happily run reliably as daily drivers putting out 450bhp on standard internals although that power figure is realistically a little beyond what the standard larger J spec turbos can provide.

 

Welcome to the club Kev.

 

Cheers,

 

Brian.

 

thx for the welcome

 

dont the j specs have smaller injectors and ceramic tubs?

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I think the general consensus is BPU twin tubby is the way to go. Some people like N/A but I don't personally see the point of having a Supra if it's not turbo'd - and single's as I went for are just 'AG ! TT's are blinding when set up correctly and looked after and more impressive and a BPU is a happy medium between TT and single. Anyone dissagree ?

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thx for the welcome

 

dont the j specs have smaller injectors and ceramic tubs?

 

They have smaller injectors yes (440cc vs 550cc) but this is no inhibition given these cars overfuel at BPU and you need some form of aftermarket control to correct that and ideally adjust ignition timing (turbo transition point yields detonation). If you wanna go single turbo conversion then you'll really need aftermarket injectors bigger than either OEM size - for JDM cars, these are readily available as 'drop-ins'.

 

They don't have smaller turbos though, they have larger ceramic turbos that spool quicker and beause of their size as compared with steel 'UK spec' will see more power at a given boost level. Running either set of turbos at more than 1.2bar is into the land of diminishing returns because they're out of their efficiency island and as such should not be recommended.

 

Check out the drag times thread and rolling road results thread for an idea of what the respective cars are capable of along with what mods net what gains.

 

Cheers,

 

Brian.

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TDR

thanks for taking the time to explain that, hope you dont mind me being cheeky but could you explain how people have overcome the det problem at transition? ( apexi afc?)plus how they have gone about ignition mapping for the transition

 

thx again for your time

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I think its a risk when bpu but failure due to det is vary rare. Most cars are bpu and dont suffer.

I dont think there is an aftermarket ecu that deals with the twins in a sequential setup (maybe wrong?) so an after market ecu can control the two in parallel mode. You can also run in parallel mode on a stock ecu but some advise against it.

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TDR

thanks for taking the time to explain that, hope you dont mind me being cheeky but could you explain how people have overcome the det problem at transition? ( apexi afc?)plus how they have gone about ignition mapping for the transition

 

thx again for your time

 

You need either a piggyback ECU (I used a MAP2 but most popular has been the Emanage Ultimate, gaining popularity is the new AEM piggyback) with both fuelling and timing adjustment. The timing adjustment is the important bit to retard the ignition timing at the boost levels where det happens for the cells that cover that point in the RPM range.

 

How many turbos a car has is really transparent to the ECU - it measures airflow so single or twins is neither here nor there, in simple terms you map boost vs. fuelling (a voltage signal) and boost vs. ignition timing (plus or minus however many degrees over stock ECU timing with a piggyback); both across the RPM range.

 

A full standalone ECU could be deemed overkill for BPU and it's correct that nobody has really done one and stayed in sequential mode (turbo1 on it's own then turbo1&2 together). However, that's more about being willing to spend the mapping time to get it to work as it's just a voltage signal that needs triggered at the right time (according to load conditions) to operate the solenoids involved with the VSV's in charge of sequential operation.

 

As to what most people do about the det that comes with BPU - they put their fingers in their ears and sing 'lalala it's all OK!' :D and to be fair most BPU cars are fine. I chose to optimise my setup however so accounted for that at the same time.

 

Cheers,

 

Brian.

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TDR

thanks for taking the time to explain that, hope you dont mind me being cheeky but could you explain how people have overcome the det problem at transition? ( apexi afc?)plus how they have gone about ignition mapping for the transition

 

thx again for your time

 

At BPU levels it simply isn't needed provided the fueling system is in normal serviceable condition. I've never heard of an engine letting go because of lean transition point, it's always due to 'other' issues, even so that is extremely rare indeed. My old car did 30k miles at BPU over 4 years, run HARD and at 1.2bar. Never had an issue apart from leaving the plugs in too long (7k miles on coppers is too much ;) )

 

If you want peace of mind then a mappable ECU is the way to go. As tDR says the MAP2 or EMU are good piggyback options, though EMU has fallen out of favour lately due to a high failure rate. Though they can be made to work I certainly wouldn't recommend a baisc unit like the Apexi AFC as their resolution is far too low to capture the transition point in all gears in the first place.

 

All depends on your goals (and budget) though!

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