Hi Guys, it seems a long time since we proved our induction kit is best and why. As you know we conducted live 'on the road' testing to check the pressure drop of various filter setups .
We also flow bench tested the (practically identical) R5 version many years ago which also proved all the theorys on ram pipe design and positioning are as correct today as 40 years ago.
This brings me onto power/ restrictions and RR testing .
ROLLING ROAD TESTING.. The GTT kit (and also Alta and a few others) are designed to reap the benefits of the natural small (but worthwhile) positive pressure (like a free very low turbo if you like) that occurs under real world driving conditions. That is the area beneath the base of the windsceen pressurizes forcing air into the filter. This 'positive pressure' will never be replicated on a RR unless bonnet is closed and car moving full frontal into the air at the true speed it would achieve at peak revs in 4th (ie 100mph or so). A RR in a wind tunnel is the only way to replicate that.
INLET RESTRICTIONS
Ok the way restrictions work within each area is simple and I offer this simple example. If you have a length of tube of say 30mm diameter and you weld TWO washers inside it ,part way along ; one with a 20mm diameter hole and the second washer with a 10mm diameter hole . Ok now connect to a flow bench which is in effect a powerful hoover with adjustable 'suck
' combined with a very accurate vacuum guage (nanometer). If we now check the maximum flow of this setup compared to removing the 20mm 'stock' washer and replacing it with a 22mm 'race'
washer and you will see no gains.
WHY Simply is this experiment although the 20mm washer is a restriction to the ultimate flow of the tube, there is a greater restriction.....the 10mm washer!
Now if we remove the 10mm washer completly and repeat the test, this time you will reap the benefits of using the 22mm race washer (GTT Cold Ram) in place of the 20mm washer (stock filter).
Of course the test above still relies on reaching the point where the air is starting to stretch (ie go below atmos pressure) and in an engine this is more likely to occur when a highly modded car which is sucking alot harder. If you were to stick your mouth over the 30mm tube and suck or blow down it you wouldnt notice any difference as your lungs (the engine) cant consume enough CFM to benefit from losing even all of the washers!
Going back to our cars , if you have a restiction greater than the stock filter then you may not gain anything . What you should do is find that restiction and deal with that then repeat the experiment. of changing filters What could that restriction be? In the case of the
MCS the favourite is the 'plastic SC inlet plenum' .We have proved in tests long ago this varies alot in its moulded form , at worst it can restict to about half its ideal cross sectional area. Another is the TB ...check the throttle plate opening angle, a part open throttle is usually going to be a bigger restriction than any filter.
So there you have 3 issues
1) unsuitability of RR testing for this type of product
2) ensuring no other restiction is greater than the stock filter in that zone (the zone being all the way from the atmosphere to the SC inlet )
3) Bearing in mind that your current state of tune may not 'demand' the increased flow......so
mod more !!!
Finally the flow bench is the only way to prove that you have optimised that component (individually) to its best. If you do it this way with everything eg head, manifold, TB, inklet manifold, cat back......you have a MUCH greater chance of ending up with a powerful car than RR testing which is dubious in its accuracy, ability to replicate true conditions and its inability to test components individually due to the distorted conclusions that may be arrived at about a product due because of a problem elsewhere.
A proven ,balanced conversion is the only way to achieve a near guaranteed optimum result on the road.
Best Regrds Roland GTT
