Quote:
Originally Posted by poweredx2
A decent intake, ecutune stage1v5 and some minor exhaust work,underdrive pulley,thats a easy 20hp.Add some custom made intake manifold spacers.I'm just indicating how 20 hp is available.Thats just engine mods,you have tranny mods such as upgraded TCUs,valve bodies for quicker shifts,QC shift kit.
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Quote:
Originally Posted by TomsSVX
Im sorry to say this, I am a huge fan of power gains. But since when did 12whp become a noticeable increase?? Your HP and TQ will vary that much dependent upon air quality and density and I bet you have never noticed.
Tom
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My point exactly. It's simply the laws of diminishing returns. The SVX engine is at it's pinicle of development for it's era. 11:1 compression, 4 valve per cylinder, variable volume inlet system, sequential ignition and injection, knock and O2 adapting ECU......... it's a peach of an engine !!
The areas where performance improvement *could* be gained are from increased cam timing as from memory the cams have plenty of lift and fast ramps but the timing is pretty "soft", a porting job on the heads, some tuned length exhaust manifolds matched to both compression and cam timing, a carefully designed free-flow exhaust system and a remap to take advantage of these changes. None of these are, in reality, particularly cheap, nor "DIY-able".
Yes you can build your own exhaust, but some who have tried have found that simply removing or replacing a silencer/resonator doesn't yield the results they expected, in fact in some (most ??) cases the results have been negative in every sense.
You could grind your own heads but without a flow-bench how do you know if you've improved anything ?? Bigger isn't necessarily better !!
You could (and some have) specify your own cams, but they won't be cheap as there simply isn't the market to take advantage of the enconomies of scale of a decent production run, unlike for an Imprezza. And it's not all more pie, you might find that chasing that extra 20hp at the top end completely ruines the torque curve low down.
Subaru themselves have made some improvements to the performance of their H6 family by introducing variable cam timing and further improvements to electronic control, but that's simply changing the way you slice the pie, not necessarily increasing the amount of pie !!
As Tom says even a 20 "at the wheel" hp increase on an engine which subjectively puts 170 out as standard is only a little over 10%, and will not be that noticable.
You spends your money and takes your choice of course, and little mods here and there will, if correctly designed and applied, make little improvements which do all add up, but this whole idea that a free-flow air filter, a remap and some magnaflow silencers make an "easy 20hp" on an 1990's engine is laughable. Sorry to be so pointed, believe me it's nothing personal against you, just a general comment on the so-called "bolt-on tuning" world.
Phil.