What can you tell me about the 74mm TB?

[The Radium King]

Originally Posted by Topless

This is what I would expect as well. I don't see the stock intake, TB, and plenum as a significant restriction with stock displacement. Unless you add 3.4L the result will just be a narrowing of the torque curve. Maybe a few Dyno ponies above 6k rpm but overall slower lap times on a race track. Less than ideal results.

I apologise in advance for the hijack, but I have to question this statement. looking at EDCs before and after dyno posts for his mods (and those posted by ipd which I typically try not to reference as they are biased) the tb/plenum change doesn't appear reduce torque at anyplace in the rpm range, so the statement about narrowing the torque curve is incorrect from my interpretation. I too wondered about the loss of low load intake tuning due to the opening of the intake path, but everything I've seen seems to indicate otherwise. *** edit to add that edc appears to have beat me to this ***

I know I've been involved in this dialog about intake modifications, but have never made any claims about hp increases on my car. I too think claims of 20 hp are optimistic when unsupported. a quick note about the ability of mods to affect hp, however (porsche hp figures, summary of changes upon review of porsche parts catalog):

2000 S: 250 hp.

2003 S: 258 hp - intake tube change, head and cam change (valves and lifters same size) ecu change to 7.8 (but no variocam+ until 2007 with the change to 3.4).

2004 Anniversary: 266 hp - airbox change.

2005 987 S: 280 HP - exhaust change, intake plenum change.

uncertain what role factory tuning played on these hp increases.

at this point Porsche retired the 3.2 and started using the 3.4 in the boxster. note that 280 is the same power:displacement ratio as the 911 3.4, so it is like Porsche gradually removed the restrictions from the boxster engine over 5 years.

I figure we should be able to find that same 30 hp using the same approach Porsche did (perhaps even using the same oem parts). we might even be able to get more if we are willing to do things Porsche wasn't (due to liability concerns?) -larger tb 5 hp proven (but causes a twitchier throttle) udp 5 hp proven (but reduces alternator output) tune 5 hp proven (but can affect engine longevity). of course these gains may not be additive, but it is fun to think that 45 hp might be boltonable (new word for the day).

hijack over!