Description
Product Description
Adjustable Actuator for Seat/Audi VAG K04 Transverse 1.8T Engines
Forge Motorsport were one of the first company’s in the world to design and manufacture the billet two-piece replacement aluminium turbo actuator. Originally for the Cosworth, Renault 5 GT turbo, and Lancia Integral turbos, we soon developed the largest and most diverse range of actuator replacements.
- Choice of spring pressures to suit your car
- Manufactured from 6026 grade aluminium
- Vehicle specific
- Turbo specific
- Built to order
- Machined and hand polished in the UK
- Choice of piston or diaphragm operation on most actuators
- Nomex reinforced flurosilicone diaphragms
- Laser cut stainless steel brackets (where applicable)
- Tuning and service kits available
- Made in England
- Lifetime warranty*

Please Note:
The pressure figures listed in the drop-down menu above are minimum regulated pressure figures. If you are unsure, please don't hesitate to call us on 01452 380999.
When you fit a Forge turbo actuator you will be able to fine tune and manage your specific boost requirements, this will allow for improved response and better control. This product is built with a predetermined actuator spring suitable for, or slightly above factory boost levels. The actuator can be assembled with a stronger spring upon request for tuned vehicles, and where a higher boost level is required. Please contact us directly concerning this process. It is designed and built with the intention of increasing the boost output of a turbocharged system. We cannot guarantee compatibility with all applications, nor the ability to increase the boost output beyond a level that is within the parameters set by the engine-management-system of the given vehicle at the time of installation, whether that system is factory or aftermarket
Diaphragm sealed internals are the default selection for this actuator product but customers now have the option of piston sealed internals. Unique to Forge Motorsport, this innovation offers equal performance to the diaphragm type and low maintenance due to the hard wearing nature of piston sealed valve internals.
Forge Motorsport nor any of its authorised distributors can assume any responsibility for any adverse effects resulting from the installation and tuning of this product onto a vehicle whose engine-management-system, whether factory or aftermarket, is not capable of allowing for the desired level of adjustment. While Forge Motorsport is happy to supply you with an actuator capable of holding boost beyond that of your factory unit we are in no way capable of knowing nor suggesting that your vehicle's engine or related systems are capable of supporting or surviving the stresses of such elevated boost pressure.

In The Box:
1 x FMACVAG01 Actuator
1 x Forge Sticker
This actuator is built with a green coded spring as standard. If you require the FMPACTUN spring tuning kit seen in the associated products below, you will need to select the Diaphragm Type 2, 049 option.

All actuator rods are manufactured from 303 grade stainless steel.
Please note that the quoted spring pressure against the various colour codes relates to the mechanical aspect only, applicable to earlier turbocharged engines that are not ECU/solenoid regulated.
However, modern ECU/solenoid engines do not require the target boost pressure to be matched pound for pound by the quoted mechanical specification of the springs we offer. Please take advice from an appropriately qualified tuner if you are unsure of the correct spring application for your model and the planned level of tuning.
For our T2 spring range (FMAS049):

Check your vehicle compatibility: Click here
Please Note: In line with our policy to constantly review, revise, and improve our product range, the appearance of the product you receive may differ from the one advertised.
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Compatible Vehicles
Instructions
Audi VAG K04 Transverse 1.8T Adjustable Actuator
Warranty
10 Year Warranty Information
The majority of Forge Motorsport products come with a limited 10 Year Warranty (brakes pads excluded). All warranty claims must be accompanied by the original proof of purchase to enable us to help you. Failure to supply this proof will result in your claim or enquiry being denied.
For further information, please call our customer service team on +49(0)3222/1097-308 or email info@forgemotorsport.eu.
Do not use aggressive (acidic) car cleaning products, particularly traffic film remover solutions or shampoos to clean your intercooler, radiator, or oil cooler. The use of these products can damage Forge Motorsport cooling systems and invalidate your warranty. These are often found at car washes. A light, warm, soapy solution (free of harsh acidic cleaning compounds) should be used to clean you cooler and thoroughly rinsed away. We recommend that you should inspect your product on a regular basis for bent and/or crushed fins. Any bent fins should be carefully straightened to allow ambient air to pass through the core face. At the time of installing your Forge radiator, an approved coolant must be used and added to the coolant system. Be sure you never mix coolant and always use distilled water.
This warranty does not apply to any defect in the goods arising from fair wear and tear, wilful damage, accident, negligence by you or any third party, use otherwise than as recommended by the supplier, failure to follow the supplier’s instructions, or any alteration or repair carried out without the supplier’s approval.
Shipping
European Shipping
We ship to selected EU countries as displayed during the checkout process.
Delivery service charges will vary depending on the quantity of product ordered, the related parcel size, and your destination.
Our shipping methods ensure safe and timely delivery of your new Forge products. For further information on cost and delivery times, please contact us if you require any more information via our contact page.
We reserve the right to change the delivery service and our shipping providers at any time.
Once a product has left our warehouse and is in the possession of the shipping company, any claims must be made directly with that shipper, however we may be able to assist in some cases.
FAQ's and other info can be found here.
Manufacturer & EU Contact Details
Manufacturer
Company Name: Forge Motorsport
Address: Unit 1A, Ashville Trading Estate, Gloucester, GL2 5EU, United Kingdom
E-Mail: info@forgemotorsport.co.uk
Phone: +44 1452 380999
EU Responsible Person
Company Name: Milltek Sport GmbH
Address: Gottlieb-Daimler-Str. 1-3, 53520 Meuspath
E-Mail: info@millteksport.de
Phone: +49 (0) 3222 1097308
Expert Answers
Got a TT Mk1 BAM, threw me when it asks piston or diaphragm
Its a matter of personal choice and I have included the explainer below to help you decide.
Piston type actuator vs diaphragm type actuator (explainer).
- Wear and tear/reliability
Roughly 95% of UK/EU actuator sales are for the diaphragm type, but the USA Forge Motorsport branch supply the piston type only to the markets they serve. We have been supplying the piston type to the USA for 20 years and related service kits are significantly low in comparison to the diaphragm type, testament to the wear and tear quality of the piston type.
- Performance
From a performance perspective It is difficult for us to recommend one type over the other as their performance is very much the same. There is a school of thought that suggests the diaphragm type is quicker to respond, but from our perspective the difference is negligible.
We do have reports of the piston type sticking in sub-zero temperatures and this seems to only occur on start-up but is apparently quickly overcome by rising vacuum pressure/turbo heat. We have little information on this “problem” as the reports are few, suggesting it is not a common occurrence.
Both types are serviceable, the same price, and service kits are available to order off the Forge Motorsport website for both types.
Hello, im running at 1.4 bar, sometimes it gets to 1.5. Will the red spring be strong enough. And a second question. How do I know if i need a piston or a diaphragm.
I would recommend using the standard spring equivalent (green) if you are not going to have the vehicle rolling road tuned after installing as boost is controlled via your ecu and a solenoid, purple would be the maximum stiffness of spring if you are going to have a new rolling road tune after actuator installation.
diaphragm and piston are down to customer choice , for longevity and ease of direct installation without a tune I would recommend the piston version with green spring.
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