Rice Rocket

iTrader: (23)

I have been reading that some people remove them when they change their Inlet manifold or paint there old one!

Could someone please explain what they do, why you remove them and what difference it makes?

Thanks for your help

S!

Butty

iTrader: (2)

The tumblers are valves that close during warm up and are found on newage JDM, EU and US WRXs and US & EU STis.
The valves close over a dividing wall, across 1/2 the diameter of the lower inlet bodies, to increase air velocity and help atomisation of fuel for reduced cold start emissions and driveability.
The tumbler assembly takes up IRO 10% of the cross section in the inlet bodies, so the assumption is that by removing them will delete an airflow restriction - but at the expense of a slightly rougher warm up phase.

Tumbler removal involves a lot of grinding to remove divider walls and valve assembly, plus pluggin of spindle holes.
The quick way is to buy and fit a Spec C inlet manifold as they have no tumbler assembly.
The throttle position sensors and valve actuators become redundant and need a CEL fix or remap to delete the CEL light that will come on as a result of the work.

I've never seen any prove of the gains to be had by removing the flow restricition.
Tumbler deletion has never caught on in the UK but is well known in the US (see NASIOC website).
I've fitted a Spec C manifold on my car out of curiosity on how to do the tumbler delete and do some basic porting on these manifolds to sell them in the US when I get my hands on them over here.

Nick

Rice Rocket

iTrader: (23)

Thanks alot Nick for the info, helps abit, abit thick me!!

S!

Butty

iTrader: (2)

Spookily enough, the MRT newsletter has a write up about the TGVs. It looks like the AUS STi doesn't have TGVs unlike the US & EU cars.

http://www.mrtrally.com.au/performan...letManTech.pdf

Nick

Rice Rocket

iTrader: (23)

Cheers nick

S!

swisstonihasher

I have APS tumber delete CEL warning units for sale - £50 if anyone interested, they come with oe subaru switches and motors, you used need to plug them in and no ECU fault.