What, Why and Where...

[speedstar]

Kind of new to the Skoda world, but not new to the modifying world.

There seem to be a lot of terms being passed around the forums and I'm struggling to fully understand what they mean, why you do them, and where to get the parts for them.

For instance:

Dog Bone?

TT Bushes?

TT Arch Mod?

R32 ARBs? (Am assuming this is a set (front and rear) of anti roll bars from a Golf R32?)

Any other terms you think are useful to as the mods are easy and make a difference to the car?

[chicken_eyebrow]

Dog Bone - the engine mount between the back of the bottom of the engine/gearbox and the chassis. You can replace the rubber bushes on it with uprated polybushes and it prevents wheel hop when pulling away and makes gearchanges a bit smoother. Parts are available here: http://www.awesome-gti.co.uk/product.php?xProd=14276&xSec=294

TT Bushes - usually refers to the rubber bushes in the wishbone, the standard Skoda ones are rubbish and will deteriorate after a few years so better to replace them with the tougher TT versions. You can buy the whole cast alloy wishbones with the bushes fitted from Audi themselves or from online parts suppliers like Eurocarparts:

http://www.eurocarparts.com/ecp/c/Audi_TT+Coupe_1.8_2002/p/car-parts/suspension-and-steering/suspension/suspension-arm-and-suspension-joints/?616440670&1&6237c0742a1f1c28e9becbc9d25bffbd4c40f191&000320

TT Arch Mod - cutting a hole in your drivers side front arch behind the intercooler and riveting (or gluing) in a section of the equivalent Audi TT arch which has a slatted vent in it, this allows air to flow more freely through the intercooler. The genuine arch can be bought from Audi or just drill your own one.

R32 ARB - is just the front anti roll bar on its own. Standard VRS item is 19mm, R32 one is 22mm so it stiffens up the front end. Not usually fitted unless you have an large diameter uprated rear anti-roll bar (25 or 28mm) fitted to balance it out otherwise it makes the car understeer even more. R32 ARBs can be bought new from VW or 2nd hand from Golf Mk4 forums.

Other terms:

CAI - Cold air intake

TIP - Turbo intake pipe - the standard ones are prone to collapsing under high boost. Uprated ones can be bought from Awesome:

(silicon section) http://www.awesome-gti.co.uk/product.php?xProd=6976&xSec=294

(wider metal part of it) http://www.awesome-gti.co.uk/product.php?xProd=3705&xSec=294

FMIC & SMIC - Front mount intercooler / side mount intercooler (standard one is SMIC)

Cage mod - Applying silicon electrical contact grease to the pins in the MAF plug, protects them against corrosion and dodgy MAF readings

CG-lock - Seatbelt lock that keeps the belt tight around your waist, useful if you do the occasional trackday as the VRS seats are slippery so you don't have to brace yourself in tight turns: http://www.cg-lock.com/

Definned Airbox - removing the plastic ridges in the standard airbox with a dremmel to help air flow

Quickrack - the steering rack from a TT/S3/R32, 2.5 turns lock to lock instead of 3+ on the standard VRS

[skoda auto]

Yep absolutelly agree wiv chicken eyebrown

[speedstar]

Where would I get a RARB from?

Also, I'm a mechanical engineer and deal a lot with fluid flows and the like. Why would you "defin" your airbox? Volkswagen know what they're doing when it comes to designing an airbox. Surely the fins are there for a reason?

[missingmyvrs]

Where would I get a RARB from?

Also, I'm a mechanical engineer and deal a lot with fluid flows and the like. Why would you "defin" your airbox? Volkswagen know what they're doing when it comes to designing an airbox. Surely the fins are there for a reason?

Very true and there in there to cause turbulence ;-)

Leave them in do not remove ;-)

[group1rs]

RARB from awesome gti. If you are fitting a front golf R32 FARB then you will need a Neuspeed 28 mm RARB. This seems to be the best combination and will transform handling. However if you are keeping the standard VRS FARB then go for a smaller diameter on the rear otherwise you will promote understeer.

[already_1uk]

someone wanna explain the purpose of n249 and n75 valves etc so I can know which is which and Wat they do

[speedstar]

SAI? (Secondary Air Injection... but what is this?)

N249?

N112?

n75?

etc?

[GeeVRSman]

all other answers available here.. :p

[chicken_eyebrow]

Apologies to Rob for nicking his diagram

Secondary Air Injection:

System which runs on cold starts to warm up the exhaust and catalytic convertor and improves emissions. How it works:

1. Coolant temp sensor tells the ECU the coolant is cold (i.e. it's a cold start)

2. ECU engages the variable valve controller, and sends a signal to the N112 valve to open.

3. N112 valve opens and lets vacuum through from the vacuum reservoir and/or manifold which opens the secondary air combi valve on the side of the exhaust manifold

4. ECU starts the secondary air pump. This pumps fresh filtered air from the airbox through the open combi valve and into the exhaust manifold.

5. Because the exhaust valves are opening for longer, and fresh air is being injected into the manifold, combustion occurs in the manifold which warms the exhaust and cat up quickly.

6. After 90 seconds the whole system stops as the exhaust is considered to be up to temperature.

N249 Valve:

Part of a failsafe system, connected to the inlet manifold, vac reservoir and the diverter valve. Normally the diverter valve is only opened by vacuum from the inlet manifold when the throttle is closed, but if for some reason the turbo overspeeds (e.g. if the wastegate won’t open properly) then the ECU can use the N249 valve to send vacuum from the vacuum reservoir to the DV to pull it open so the boost is vented back to the inlet before any damage to the engine occurs.

N75 Valve:

Wastegate control valve. This provides air pressure to the wastegate actuator to open the wastegate when the turbo has reached maximum boost and needs to be stopped from spinning any faster. When it needs to provide pressure this comes via a feed from the boost pipework. The ECU has electronic control of the N75 valve so it decides at which point maximum boost has been reached and the N75 should open the wastegate.

N112 Valve:

This is part of the SAI system between the vacuum system (including the N249 valve) and the combi valve. When it is open it creates a vacuum in the pipe to the combi valve which pulls the combi valve open so the air pump can inject fresh air into the exhaust manifold.

So if you remove the N249 system you still need to retain the N112 and a vacuum feed to open the SAI combi valve… otherwise you could remove the whole SAI system and N249 system (pipes in yellow, dark blue and red in the diagram) at the same time.