John Brett

John is a professional engineer with 50 years experience.

John has designed and built many cars, trucks, and vehicle assembly facilities.

John has worked on design of roads, bridges, cranes, transmission towers, and buildings, and operation, maintenance and upgrade of hydro and gas turbine power stations.

John was a LVV Certifier for 13 years. John has long been a whistle-blower, expressing the view that the LVV system is dangerously deficient. John's authority was revoked in December 2012.

John rides a 1992 Yamaha FJ1200ABS, and is also a keen road and off road cyclist.


“The LVVTA has brought it to my attention that statements I have made in relation to it and its employees may have been perceived as defamatory.

I sincerely regret that and apologise for any harm caused. I have taken down the statements identified by the LVVTA of concern to it.

I have strong views about the low volume vehicle certification process and intend in the future to direct my energies into the public inquiry now being held in relation to it.”

John Brett 7th October 2015


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Classic Nissan

The rear wheel drive Nissans are absolute classics in their own right, and a gold-mine for anyone wanting to build a fast, reliable, good-handling car, either for road, track or drifting.

Nissan RB25DET

Nissan RB25DET

Nissan SR20DET

Nissan SR20DET

There are the six cylinder cars- Skyline, Laurel and Cefiro, and the four cylinder cars – Sylvia, 200SX, 180 SX, all available with and without turbo.
The sixes (the RB’s) come on 2 litre 2.5 litre, 2.6 litre (the Godzilla) and 3 litre (Aussie Nissans and Holdens) It is possible to build a RB30DET by taking an aussie 3 litre block and fitting an RB25DET head. It is common to fir bigger turbos, and some phenomenal power outputs can be achieved.
The fours (SR’s) are no slouches either- conversions of a DE to a DET by fitting a turbo are common, as is fitting bigger turbos.

The suspensions on all of these cars is basically sound from the get-go, and respond well to fitment of adjustable platform struts (coil-overs), adjustable camber arms, caster bars, etc.

The braking systems can generally be interchanged- the bigger brakes come with 5 stud hubs.

Front Intercoolers are commonly fitted, and often holes cut in the inner guards for Intercooler ducts.
There is a problem with later, “frontal impact” cars- no LVV Certifier can test the crash performance of a car, so cannot approve anything that affects frontal impact. We heard of a man who bought an intercooler kit from Japan, and followed the instructions to modify the front siderails to make it fit. He ended up having to have the whole front of his car re-built with new side-rails. If your car is fitted with airbags, or is later than about 1997, check FIRST with your LVV Certifier

John Brett Technology Ltd. Ph 0800 LOWVOLUME (0800 569865)

177 comments to Classic Nissan

  • johnbrett

    Hi Conor-
    Nice project- nice car. Adjustable arms- I am unable to advise you, as these now are apparently decided at the LVVTA not by the Certifier. Hole in Battery tray- I and other Certifiers allowed this, so long as it was no bigger than necessary, and finished off smoothly.

  • Mitch

    Hey, I have a 180sx witch came out with a ca18det in in, now has a sr20det conversion. Bigger turbo, front mount , 3 inch exhaust, all the basic mod. Have drive shaft hoops to fit. It is already vetted for adjustable suspension and rims. What do I need to do to get the engine certified? Cheers

  • johnbrett

    Hi Mitch- Unfortunately I cannot give you a straight answer, as the LVV system is currently under review by the NZTA, changes are happening, plus most of the LVV Certifiers I could have recommended have now pulled out.
    I have Certed many 180 SX cars modified to SR20DET, and had no problems.
    Sorry I can’t help you any further



  • Brook prentice

    Hey john, quick question I have a 96 Nissan laurel 2.8L diesel factory with a rd28 straight 6 and it’s now been changed to a Nissan td27 2.7L 4cyl Diesel engine, mounts are factory td27 with no modification, power difference between engines is 5-10hp, does this require a cert?

  • johnbrett

    Hi Brook
    Unfortunately it does need a LVV Cert. See VIRM
    Your new engine would not be regarded as from the”same family of block and cylinder head”.



  • Ethan Seagar

    Do you need cert for a 20e to a 20de conversion? i couldnt find anything in the lvvta guidelines

  • Clifford Wilson

    Where do you get your brakes from and who does the work for it considering that it is likely that there are no brake kits for your particular cars? I want to know for my own quirky car that I would like to upgrade the brakes for.

  • johnbrett

    Hi Clifford

    I don’t understand your query- I have never been a car modifier, just a Low Volume Vehicle Certifier up until a couple of years ago.
    Your best approach is to performance brake specialists to see what they have available
    Sorry I can’t help any further.

    There is no charge for this free advice, but could I ask that you make a small donation to my ‘Give-a Little’ campaign? This is to cover legal costs for defending myself from Defamation charges made by Mr Johnson of the LVVTA.
    If you did want to, just click though to the Give-a Little page.

  • bryden

    i have a 1988 nissan laurel c33 it was factory RB20E automatic it now has and RB20det and manual gearbox , it has a front mounted intercooler and the bumper support has not been cut but the intercooler piping has tidy holes through body no rough edges , it has brand KW bucket seats on KW brand rails and the seat belt stalks bolt to same bolt as seat mounts too ,it also has 17″x 9.75″ wheels and the 5 stud and bigger 4 pot 2 pot brakes added and adjustable suspension branded BC gold it has 2 driveshaft hoops , do you see any issues with certification ? also do i need a catalytic converter , Thankyou very much

  • johnbrett

    Hi Brydon

    This is a great, classic Nissan conversion, and I have Certified a few! I see no problem with any of the mechanical changes- the front intercooler only has to meet the WOF ‘General safety’ requirements- that is- no sharp bits pointing forward. The Piping holes, you have probably cut a hole in the inner guard panel- that won’t look like structural weakness. BC Gold is good stuff, just make sure it is adjusted well, and not too low, keep the wheel alignment reasonable, not excessive negative camber. Wheels and tyres seem fine, again, don’t do ‘stretched’ tyres, keep them within makers recommendations. As to a Catalytic converter- the LVV standard says:
    A modified production low volume vehicle that has undergone an engine conversion, other than one to which 2.5(3) to 2.5(6) applies, is required to have its exhaust gases directed through one or more catalytic converters, if:
    (a) the vehicle was manufactured after 1 January 1990; and
    (b) the vehicle was first registered in New Zealand after 1 May 2010; and
    (c) the retro-fitted engine was originally manufactured in either:
    (i) the United States of America on or after 1 January 1975; or
    (ii) Europe or the United Kingdom on or after 1990; or
    (iii) Japan on or after 1 January 1985; or
    (iv) Australia on or after 1 January 1986.
    NOTE 1: The intention of 2.5(1)(c) is to say that if the engine being used in the engine-swapped low volume vehicle originally had catalytic converters, then ‘cats’ must be fitted to the vehicle being engine-swapped. Engines manufactured before the years specified in 2.5(1)(c) were generally not designed to meet any kind of emission standards, or to be operated with ‘cats’, particularly those engines fitted with carburettors.

    So you WILL need one!

    Seat belt mounting- this has long been a contentious issue, see my article here-
    At present I think you will need to have a seat-belt anchor point fitted to the tunnel. Go to a seat-belt shop to get this done the approved way.

    Best of luck with getting it Certified, you shouldn’t have any real issues.

    There is no charge for this free advice, but could I ask that you make a small donation to my ‘Give-a Little’ campaign? This is to cover legal costs for defending myself from Defamation charges made by Mr Johnson of the LVVTA.
    If you did want to, just click though to the Give-a Little page.

  • Hayden

    Hi john I have a 94 c34 laurel with a 20det engine and a 20det box in it what drive shaft will i need or do I need to get one modified

  • johnbrett

    Hi Hayden
    There should be no need to custom make or modify a driveshaft.
    You should be able to source a stock driveshaft to fit, ideally one from the same or higher output vehicle. You should have a good read of the LVV Standard for Engine changes, it has been extensively revised. You may not need driveshaft loops if you fit a driveshaft which matches the engine you are fitting.

    Hope this information helps
    Best of luck with getting it Certified, you shouldn’t have any real issues.

    There is no charge for this free advice, but could I ask that you make a small donation to my ‘Give-a Little’ campaign? This is to cover legal costs for defending myself from Defamation charges made by Mr Johnson of the LVVTA.
    If you did want to, just click though to the Give-a Little page.

  • Joshua Percy

    Hi there, I have a 94 R33 coupe which came with a factory RB25DE Manual, but I swapped the 25DE with a 20DET because I blew it up, with no mods other than some silicone piping and a standard 25DET intercooler mounted under the bonnet with a air scoop attatched above it, is a cert needed for this? no other mods done to the car.

  • johnbrett

    Hi Joshua

    Yes, you will need a Cert for this modification



  • Matt

    Hi John,

    I’m thinking about doing the following mods to a 1994 PFL S14 (SR20DET). Which (if any) of the following mods would need a cert?

    -Aftermarket ECU
    -Aftermarket seats – Read your article on seat belt problem. When you talk about the bracket option, Do you mean an L shaped bracket that connects to anchorage above the seat bracket?
    -Aftermarket Front Mounted Intercooler – Neat hole cut in battery tray for piping
    -3″ Exhaust – What are the rules on having a decat?

    Sorry if these have been answered, just want to make sure what I’ve read is correct as there’s a lot of conflicting info. Thanks.

  • johnbrett

    Hi Matt-
    What a great project- only wish there had been S14’s and Skylines when I was younger!
    Yes- you will need a Cert
    The CPU will presumably produce more power
    Installing the Intercooler, the hole by the battery tray will be fine, no structure is affected by that. Just keep it neat.
    Seats- The LVVTA decided that you need to install a new seatbelt anchorage in the floor. You will need to get this done by a seat-belt installer- it’s not really hard but has to be done just so.
    Rules on Cats- The vehicle DOES need to have a Cat, as it would have originally be fitted with one. See the Exhaust Gas Emissions standard under the ‘Documents’ tab on the LVVTA site

    Best of luck

    There is no charge for this free advice, but could I ask that you make a small donation to my ‘Give-a Little’ campaign? This is to cover legal costs for defending myself from Defamation charges made by Mr Johnson of the LVVTA.
    If you did want to, just click though to the Give-a Little page.

  • Matt

    Righto, so a cert WILL be needed for all the above mods?

  • johnbrett

    Hi Matt
    Yes a Cert will be needed.
    Hopefully you will find a certifier who is knowledgeable and helpful, and maybe get some good advice thrown in
    Good luck


  • clint

    hey john i have a c33 laurel with a 20det in it spmeone has cut holes for intercooler piping will i still get a cert and also have d2 adjustable suspension an truhart suspension parts where is a good certifier to take it to thanks in advance

  • johnbrett

    Hi Clint-
    Intercooler pipes- usually holes are cut underneath the battery tray, either on one side or both, on these Nissans, the Skyline already has the left hand hole. These should be OK for a Cert. Holes in the Radiator support panel are not good, I hope you have not got holes there. The Cert will also include the suspension, and include the ride height. Camber will have to be within 1/2 degree of spec. You may need to produce evidence about the Truhart suspension components, I don’t know this brand or what parts.
    What area are you in? I can’t recommend any Certifiers in Auckland, they have all left! Best you ask NZTA now!

    There is no charge for this free advice, but could I ask that you make a small donation to my ‘Give-a Little’ campaign? This is to cover legal costs for defending myself from Defamation charges made by Mr Johnson of the LVVTA.
    If you did want to, just click though to the Give-a Little page.

    Hope this helps


  • Adrian

    Hey john
    In the process of finishing my project, just a quick question regarding the requirements for footbrake to handbrake conversion, more or less wondering if it’s ok to drill holes and fix through the tunnel or do I have to weld a mount to the body instead

  • johnbrett

    Hi Adrian
    I guess you have a Laurel or a Cefiro, and have converted it to manual, so need to lose the foot park brake. There is no rule about welding anything, just do a decent job of bolting the lever to the tunnel. I can’t remember if other people have used a reinforcing patch, but not a bad idea anyway.
    Good luck


  • Daniel

    Hi John

    I have a r32 gtr that was imported into the country in 2015, came through compliance fine. Now im being stopped on WOF for braided brake lines, do i need a cert? I was told there was a issue with them being bolt on or something aswell, im not exactly sure.

  • johnbrett

    Hi Daniel

    There has been some too-ing and fro-ing on brake pipes, which is why you may hear different stories.
    Now they are just a WOF item, and the WOF inspector has to fail it if:
    g) has an end fitting which is not attached to the hose by means of swaging, machine crimping or a similar process (Note 3).
    See the WOF guide:



  • Jordan

    So I have a Nissan Pulsar Gti that has had an SR20VE engine put in, since the engine is very similar tro the original and is still a Nissan, could that pass a WOF?

  • johnbrett

    Hi Jordan

    I have just checked the VIRM (The WOF guide) and it says about engine modifications which DO NOT require Certification-

    when compared with the OE engine, the replacement engine:
    – is of the same or less cubic capacity, and

    – has equal or less weight, and

    – has the same or less power output, and

    – uses the same fuel (petrol, diesel, LPG, CNG), and

    – uses the same unmodified attachment points and system (ie bolts-in), and

    – uses the same family of block and cylinder head from the same vehicle manufacturer, and

    – is of the same configuration.

    So- if the WOF inspector thinks it is producing more power, he could call for a LVV Cert.

    Hope that helps-



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