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The mkiv Supra Owners Club

Derestricting Jspec TT?


Sparky

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Um I tried to search for this but couldnt find anything usefull!

 

Uk spec TT is 320bhp right, and the Jspec is 270? Is 270 restricted from 320 or is that the actual power put out?

 

Its only i know some Jspec cars can be delimited back to the original bhp!

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Urban myth, UK is 326 stock iirc and J-Spec is 300-326.

 

It is bollocks that the J-spec only has 270bhp, it was a gentlemans aggreement between all the big Jap car makers to limit power to 270ish bhp but none actually stuck to it if it was over they still put the power to 270 ish, I think thats how the story goes.

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The UK car's ARE more powerful then the J-spec car's, they have slightly bigger BETTER steel turbos not ceramic one's like the J-spec's also the injectors are bigger 550's instead of 440's plus the cam's are a sportier profile on UK cars. This mean's if they go BPU a UK car can make more power for the same mod's and the standard turbo's on UK car''s are much stronger so can take more boost equalling more power.

 

Having said this I don't think there's much in ON ROAD performance between the 2 car's but the UK car's have the edge.

 

I'm not bias because I run a J-spec there just the fact's:(

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The UK car's ARE more powerful then the J-spec car's, they have slightly bigger BETTER steel turbos not ceramic one's like the J-spec's also the injectors are bigger 550's instead of 440's plus the cam's are a sportier profile on UK cars. This mean's if they go BPU a UK car can make more power for the same mod's and the standard turbo's on UK car''s are much stronger so can take more boost equalling more power.

 

Having said this I don't think there's much in ON ROAD performance between the 2 car's but the UK car's have the edge.

 

I'm not bias because I run a J-spec there just the fact's:(

 

Garbage. The J-Spec has the bigger turbos of the two. They are also ceramic so spool quicker making them the more responsive car. Power wise there's bugger all in it between the two models as standard. Going BPU is cheaper on a J-Spec because you don't need a boost controller to raise the boost.

 

I don't have a problem with performance from my J-Spec car and don't know of any BPU UK Spec cars that are quicker :D

 

Cheers,

 

Brian.

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The UK car's ARE more powerful then the J-spec car's, they have slightly bigger BETTER steel turbos not ceramic one's like the J-spec's also the injectors are bigger 550's instead of 440's plus the cam's are a sportier profile on UK cars. This mean's if they go BPU a UK car can make more power for the same mod's and the standard turbo's on UK car''s are much stronger so can take more boost equalling more power.

 

Having said this I don't think there's much in ON ROAD performance between the 2 car's but the UK car's have the edge.

 

I'm not bias because I run a J-spec there just the fact's:(

Your 'facts' suck mate.
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Turbo Spec's ;)

J-Spec

 

CT20A (Ceramic)

Turbine Size: 60mm/48mm (inducer/exducer)

Compressor Size: 62mm/39mm (inducer/exducer)

Turbine material: Ceramic

Scroll area (mm^2): 600

A/R ratio: 0.42

 

UK Spec

CT12B (Steel)

Turbine Size: 52mm/44mm (inducer/exducer)

Compressor Size: 58mm/39mm (inducer/exducer)

Turbine material: Steel

Scroll area (mm^2): 740

A/R ratio: 0.53

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So apart from the turbo size issue which I got wrong, the rest of what I said was correct and ultimately the UK turbos are still the stronger and can take more boost pressure which means more power or am I still wrong. I don't think my comment are garbage as I said I drive a J-spec TT

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So apart from the turbo size issue which I got wrong, the rest of what I said was correct and ultimately the UK turbos are still the stronger and can take more boost pressure which means more power or am I still wrong. I don't think my comment are garbage as I said I drive a J-spec TT

 

Not completely wrong. The UK turbo's are steel, yes. But anything over 1.2 bar on Either J-spec or Uk spec turbos is out of their efficiancy range. Ie, 1.4 bar on j-spec turbos will make them shit themselves. However 1.4 bar on Uk turbos wont destroy the blades, but will be out of the effiancy range of the turbo, so will just be blowing hot air into your intake.

The only way I can explain the difference in UK power and J-spec power: J-specs are quick, UK specs are fast. I know what i mean in my own head. :D

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So apart from the turbo size issue which I got wrong, the rest of what I said was correct and ultimately the UK turbos are still the stronger and can take more boost pressure which means more power or am I still wrong. I don't think my comment are garbage as I said I drive a J-spec TT

You were right about the spec (steel turbine blades, 550cc injectors, different cam profile). Those things are facts.

Stating the turbos are bigger, that they are stronger, that the UKs make more power for the same mods, that they can take more boost, isn't fact - it's just an opinion.

 

Chris Wilson knows a bit about Supras ;) See his comments about those super UK turbos in this thread.

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It's differently spec'd, no question.

Whether that spec is "better" is a matter of opinion.

 

I was'nt specifically talking about just under the hood, there are many differences, bigger brakes fuel tank, heated seats different colour leather glass headlights etc etc etc, like i said no question

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Plenty of question IMO.

 

Bigger brakes - depends on the J Spec.

Bigger fuel tank - not sure on that one but big deal regardless.

Heated seats - big deal.

Different colour leather - again depends on the J Spec.

Glass headlights - true but I prefer my facelift J Spec lights.

 

Now consider the flipsides, J Spec carries less weight = quicker on road performance. UK Spec cars tend to have done moon mileage and are very long in the tooth as a result.

 

We've had these pointless UK vs. J Spec arguments on the forum literally thousands of times now. Neither can be named the outright better car 'FACT' - choose the one that tickles your fancy and get on with it.

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Plenty of question IMO.

 

Bigger brakes - depends on the J Spec.

Bigger fuel tank - not sure on that one but big deal regardless.

Heated seats - big deal.

Different colour leather - again depends on the J Spec.

Glass headlights - true but I prefer my facelift J Spec lights.

 

Now consider the flipsides, J Spec carries less weight = quicker on road performance. UK Spec cars tend to have done moon mileage and are very long in the tooth as a result.

 

We've had these pointless UK vs. J Spec arguments on the forum literally thousands of times now. Neither can be named the outright better car 'FACT' - choose the one that tickles your fancy and get on with it.

 

Now from your point of view owning a vvti facelift in a IMO top colour now things blur together again IMO, YES the average UK spec is'nt in great nic & is rather high on mileage, any debate where there is debate is usually still open to debate. Confused no well i am good night.

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I was'nt specifically talking about just under the hood, there are many differences, bigger brakes fuel tank, heated seats different colour leather glass headlights etc etc etc, like i said no question
Here we go again with the "no question" rubbish. Your "no questions"s and "FACT"s are highly subjective.

 

Who wants heated seats in a sports car?

Who wants a massive fuel tank?

Who wants beige leather?

Who wants soft suspension and a heavy kerbside weight?

 

Which of things things makes a UK spec desirable to you? None of them do to me.

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The only thing I like about the UK spec is the brakes and the bonnet, as Jake said the rest is a bit erm ....................."peppery"

 

The larger size (I hate the term UK spec as it is not accurate) brakes were fitted as standard on many J-spec Supras.

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