Variable nozzle turbos were first launched in the industry by Garrett in the mid 90’s and are now found on most diesel engines. It was the introduction of variable nozzle (also known as variable geometry) technology in turbos at the same time as common rail fuel injection systems, which led to the huge increase in popularity of small displacement diesel engines in passenger cars.
As the decades moved on, emission levels have continued to reduce as vehicles have been designed to meet the Euro 4, 5 then 6 regulations. As a result of these changes, engine technology and turbo technology increased in complexity, and the settings and control of the variable nozzles in the turbocharger have become more critical to the correct operation of the turbo. This is now presenting new challenges to turbo repairers as the correct setting of the turbo on later models now requires further specialist equipment in the form of an air flow rig.
VNT Air Flow Rigs - A Changing Market
There has been an ongoing debate for many years between the original turbocharger manufacturers and the turbocharger repair industry, over whether a turbo can be repaired.
Over the last decade, vehicle technology has continued to improve to reduce emission levels in order to meet the Euro 4, 5 then 6 regulations. As a result of these changes, engine and turbo technology has increased in complexity, and the settings and control of advancements, such as the Variable Nozzles, have become more critical to the correct operation of the turbo. This is now presenting new challenges to turbo repairers as the correct setting of the turbo on later models, now requires further specialist equipment in the form of an air flow rig.
What is a Variable Nozzle Turbo?
When a turbocharger is matched to an engine, the Engineers have to balance the low speed response with high speed efficiency. The variable nozzle (also referred to as a variable geometry), is designed to change the exhaust gas inlet area with the engine speed to closely match the desired boost requirements of the engine. For low speed response, the nozzle vanes move to the ‘closed vane’ position to reduce the nozzle area – this increases gas speed through the turbo giving improved response at low engine speeds – similar to squeezing the end of a hose pipe to make the jet of water more powerful. As the engine speed increases, the actuator moves the nozzle vanes to the fully open position to maximize the exhaust gas flow.
Vane Setting Accuracy
During the manufacture of a new complete variable nozzle turbo, vane positions are set using accurate air flow equipment, which ensures that the ‘minimum vane opening’ position is set to allow a specific mass of air flow through the vanes. If the vanes are too closed, this can cause choking of the engine and overspeeding of the turbine. If it is set too large, the turbo will have too much ‘lag’ and not respond as well as it should.
Traditional methods of setting the vanes when repairing a turbo can produce quite large inaccuracies in the air flow. The actuator arm measurement is often set against a cast finish on the bearing housing, the position of which is not accurately controlled during manufacture. However, as the older engines would accept quite a large tolerance of air flow, the repaired turbo still performed well compared to the broken turbo which it replaced, so the vehicle owner was still happy with the results. On older turbo repairs, the variable nozzle position had to be a long way out before the performance was unacceptably affected or for the ECU to flag a problem. From an OEM perspective, this is not acceptable and is the reason for their lack of support of repairing.
Today’s Turbos
In more recent years, as engines have improved to meet tighter Euro emission regulations, the control over the whole air / fuel system has improved dramatically. Many premium brand vehicles have moved to electronic actuation which gives positional feedback to the ECU. Some more advanced turbo controllers now sit within the CANbus talking directly to the injection system and air mass sensors, to respond more quickly to engine demands. For these turbos, the settings are both correct and accepted by the ECU – or not, which results in warning lights, limp home mode or refusal to start.
As more of the Euro 5 compliant vehicles enter the aftermarket, problems will continue to arise and for some turbo models, flowing the turbo will be a necessity and only possible by workshops who have the correct equipment. This will naturally mean that older turbos also become more widely repaired using air flow equipment, which will bring further improvements to the turbo repair market.
Availability of the Air Flow Rig
Just as the market demand led to there being several high speed VSR machines on the market, so too has the demand for air flow rigs. Over the last 10 years, the need to set the accurate air flow of a turbo has been well understood by reputable repairers, who recognised it was not acceptable to guess at the vane setting position. As a result, in the absence of machines on the market, many quality repairers developed their own air flow equipment to accurately set their turbos – giving them a competitive edge and a marked reduction in warranties, whilst also building on their reputation as a quality repairer. In more recent years there have been a number of different air flow rigs released to the mass market. This is good news for the repair industry and for customers looking for a quality repair option, as the bar for quality has been lifted further.
Melett UK will close for the Jubilee bank holiday at 17:00 on Wednesday 01 June and reopen at 08:00 on Monday 06 June. Any orders that are not picked or dispatched before we close will resume preparation when we reopen. If you would like any more information or guidance on the above, please contact our customer care team on +44 (0)1226 320939.
Memorial Day 2022
Melett North America will be closed for Memorial Day on Monday May 30th and will reopen at 8.00 am on Tuesday May 31st.
Melett Poland
Melett Polska will be closed for a public holiday on Thursday 16th June and will reopen on Friday 17th June. Any orders that are not picked or dispatched before we close will resume preparation when we reopen. If you would like any more information or guidance on the above, please contact our customer care team on +44 (0)1226 320939.
May Bank Holiday opening hours
Melett UK
Will close 5.00 pm Friday 29th April and reopen 8.00 am Tuesday 3rd May
Melett Poland
Will close 4.30 pm Friday 29th April and reopen 8.00 am Wednesday 4th May
PLEASE NOTE -THE ABILITY TO SUBMIT YOUR ORDERS THROUGH THE MELETT WEBSITE HAS BEEN RESTORED
We are delighted to advise full website functionality has now been restored, meaning you can view stock and pricing, add parts to your basket and submit your order via the website. In addition, all turbo/part number searches are fully working.
Until further notice please place your orders by 2.30 pm and we will endeavour to dispatch the same day dispatch.
We will keep you updated as we navigate through the remaining internal connectivity issues, we have dedicated teams working round the clock to resolve any remaining issues as quickly as possible.
We, at Melett, would like to stress our gratitude for your continued patience and support throughout this difficult time.
Please note you can now view your pricing on the Melett website.
We appreciate this is not a complete solution at this stage, however, please be assured our internal website and IT teams remain focused on reinstating the stock availability function.
We cannot stress enough that we are doing everything we can to reconnect our internal system, and we will restore full website functionality as soon as possible.
If you experience any problems whilst ordering online, please do not hesitate to contact:
W związku z awarią sieci telefonicznej prosimy o kontakt na telefon komórkowy: Damian 512 372 612; Kasia 511 372 612
Melett UK will be closed on Monday 29th August and will reopen at 8.00am on Tuesday 30th August.
Any orders that are not picked or dispatched before we close on Friday 26th August will resume preparation when we reopen. If you would like any more information or guidance on the above, please contact our customer care team on +44 (0)1226 320939.
Melett Polska will be closed for a public holiday on Friday 11th November and will reopen on Monday 14th November.
Any orders that are not picked or dispatched before we close on Thursday 10th November will resume preparation when we reopen. If you would like any more information or guidance on the above, please contact our customer care team on +44 (0)1226 320939.
Queen Elizabeth II state funeral - Monday 19th September
Melett UK will be closed on Monday 19th September for the state funeral of Queen Elizabeth II . Melett will be joining people and businesses across the country in reflecting on Her Majesty's incredible contribution and enduring legacy.
Melett North America and Melett Polska will remain open as normal.
Easter opening hours
Melett UK - will close 17:00 Thursday 14 April and reopen 08:00 Tuesday 19 April Melett Polska - will close 16:30 Thursday 14 April and reopen 08:00 Tuesday 19 April Due to essential maintenance, the Melett website will be temporarily unavailable on Thursday 14 April from 17:30 to 19:30. We apologise for any inconvenience caused.
Essential Maintenance
Due to essential maintenance, the Melett website will be temporarily unavailable on Friday 25 February from 18:00 to 20:00 (GMT). We apologise for any inconvenience caused.
Planned maintenance – Thursday 24 March 2022
We will be undertaking planned maintenance on our internal systems this evening between 17:00 and 20:00 GMT, which will affect some website functionality.
We aim to keep disruption to a minimum and the website will remain online. However, we will need to temporarily disable online ordering during this time.
Thank you for your understanding.
Essential Maintenance
We are undertaking essential maintenance this weekend (February 19-20) and some of our website services may be unavailable at times. We apologise for any inconvenience this may cause.
Essential Maintenance
- Due to essential maintenance, the Melett website will be temporarily unavailable on Friday 28 January from 18:00 to 20:00 (CET). We apologise for any inconvenience caused.
Festive opening hours
- Melett UK Will close 5:00pm Thursday 23rd December and reopen 8:00am Tuesday 4th January
- Melett Polska Will close 4:30pm Thursday 23rd December and reopen 8:00am Monday 3rd January
- Melett North America Will close 5:00pm Thursday 23rd December and reopen 8:00am Monday 3rd January
Please note: Due to essential maintenance the Melett website will be temporarily unavailable on Friday 10 December from 5:00PM (CET) to 11:00PM (CET). Apologies for any inconvenience caused.
Please note; Unfortunately, we are experiencing processing delays for all orders which may result in delays in shipping. If possible, please confirm orders at your earliest opportunity to help minimise disruption to our normal high standards. Please accept our apologies and rest assured that we are working hard to resolve the issue.
Melett Poland will be closed for a Public Holiday on Thursday 11th November. Any orders that are not picked or despatched on Wednesday 10th November will resume preparation when we return on Friday 12th November.
Melett Poland will be closed for a Public Holiday on Thursday 6th November. Any orders that are not picked or despatched on Wednesday 5th November will resume preparation when we return on Friday 7th November.
Melett will be closed for a Public Holiday on Thursday 11th November. Any orders that are not picked or despatched on Wednesday 10th November will resume preparation when we return on Friday 12th November.
Melett will be closed from 5 pm on Wednesday 24th November until 8 am on Monday 29th November for the Thanksgiving holiday
Online ordering now available
Para além de visualizar os níveis de inventário e os preços, pode agora fazer encomendas diretamente a partir do nosso sítio Web. Descarregue o nosso guia do utilizador abaixo para o ajudar a começar.