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The mkiv Supra Owners Club

NSX review on 5th Gear tonight


Homer

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It'll be the one that gets them most cash from the company concerned due to a phone-in competition where you can win some petrol or something equally gay.

 

They will probably vote red diesel best.

 

aye. I was disappointed to see that they still want you to pay £1 to enter the competition via the website!.

 

On another note, Lots Of Trouble, Usually Serious, isn't it? :)

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On another note, Lots Of Trouble, Usually Serious, isn't it? :)

 

Yeah it is, but don't forget that they tried to do things on the cheap...and that V8 and Renault 25 gearbox is not going to like it...

 

AFAIK Lotus detuned the V8 to make the gearbox live longer.

 

And FWIW, the gearbox was/is the only mass produced gearbox of it's type in the world - so Lotus was pretty stuck unless they thought the punters would pay an extra 10k for a hewland/quaife (and that's not going to happen).

 

So yeah 5th gear started with the wrong car and then went forward without a clue after that...the turbo's for 1 - the person that designed the original packaging for the motor said that you can't fit bigger turbo's in the space...

 

15-18k would buy a supra and have it top 200mph - if you did the work/mapping yourself. 8k TT. T71 (might as well go that big as on a top speed run it isn't going to hurt). AEM. FMIC. few bits and bobs. ELF Turbo Race fuel.

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Yeah it is, but don't forget that they tried to do things on the cheap...and that V8 and Renault 25 gearbox is not going to like it...

 

AFAIK Lotus detuned the V8 to make the gearbox live longer.

 

And FWIW, the gearbox was/is the only mass produced gearbox of it's type in the world - so Lotus was pretty stuck unless they thought the punters would pay an extra 10k for a hewland/quaife (and that's not going to happen).

 

So yeah 5th gear started with the wrong car and then went forward without a clue after that...the turbo's for 1 - the person that designed the original packaging for the motor said that you can't fit bigger turbo's in the space...

 

15-18k would buy a supra and have it top 200mph - if you did the work/mapping yourself. 8k TT. T71 (might as well go that big as on a top speed run it isn't going to hurt). AEM. FMIC. few bits and bobs. ELF Turbo Race fuel.

 

Very interesting stuff Alex. What 'type' is the gearbox that makes it unique? Is it due to the location of the engine and it being a V8 or something?

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Very interesting stuff Alex. What 'type' is the gearbox that makes it unique? Is it due to the location of the engine and it being a V8 or something?

 

The only one that would fit with a V8 was a Transverse Transaxle Gearbox I believe...and only the Renault 25 had one of them.

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The Gearbox is the Renault UN1 (or UN1027 in Lotus trim) and it is a transaxle layout. The gearbox was developed by Renault and Lotus to keep pace with the Esprit since it was introduced (to replace a Citroen unit, I think).

 

The gearbox is widely used in the kit car fraternity because it allows relatively high output inline engines to be mounted in a mid-engined location, without pushing the axles too far rearwards. Also, the gearbox has a separate bell housing casting which makes it ideal for mating to different engines' transmission flange bot patterns.

 

The transaxle layout is by far not unique. Getrag make a box for Porsche and Audi have a huge range. There are also some old-skool designs from ZF being marketed. Unfortunately, most of these do not have the power and torque handling capability of the UN1027. On the other end of the scale, as Alex pointed out, you have your Quaifes and Hewlands, both of which have been mated to the Esprit V8 in the past for race applications and demo cars, but are not viable for production because of their unit cost. The same goes for the units manufacutred for Ferrari.

 

Renault officially stopped making the gear UN1027 box a couple of years ago after they had been supplying it solely to Lotus for several years. By that time the demise of the Esprit model was well and truly on the cards anyway. Shortly before the last Esprit rolled off the production line, Renault started up an in-house refurbishing programme that could have provided more gearboxes into the future so there may still be units out there, but futher development to increase its capacity was a no-go. The next component in line to fail would have been the inboard joints and changing these would mean carving up the gearbox anyway.

 

I'd like to see what 5th Gear did to the turbos because there is precious little space to fit in anything physically larger than a T25. The turbo package is a nightmare and quite heavily driven by the package space between the chassis rails. The routing for the feed up the back of the engine to the twin throttle bodies is very tight, too - also for packaging into the vehicle. I'd recommend having a look at the Lotus V8 up close to see just how compact a package it is. It really is tiny for a 350hp twin turbo lump.

 

Af far as reliability as high outputs goes, don't forget that the in-house race version with its big single turbo (freed of packaging restrictions) made north of 500bhp pretty much out of the box on largely stock internals in it protoytpe phase. It was of course properly re-engineered for the fully-blown race engine.

 

It's not a fragile engine, but tuning it does require a bit of knowledge and repect. You can't just turn up the wick like you can on the 2JZ.

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