4500rpm
 

Tell me, why is there such a marked increase in performance after 4500rpm? What changes at this point - can't imagine it's cam profile/timing or gas flow as it seems too well defined.
Oh, and by the way I read elsewhere on the site that there are no more windscreens available. Is that right?

Re: 4500rpm
 

That's where the peak of the torque curve is.

Re: 4500rpm
 

It has been reported that only bronze glass is still available in the USA. However, Subaruparts.com still offers bronze, blue and green. Glass from Japan may still be in supply.
Gene

Re: 4500rpm
 

Search for threads on the IRIS valve or read about it in the road and track guide - this will explain the power increase around 4500rpm

This one is a good read - http://www.subaru-svx.net/forum/show...highlight=IRIS

Re: 4500rpm
 

Firstly, thank you for the screen info. Much appreciated. This IRIS valve seems to me to be a way of increasing gas speed and fuel/air mixing at lower revs, then allowing high flow at higher revs? Works like an intake version of a Yamaha exhaust EXUP valve. I wonder if anyone has tried combining the two? Or is VVT a more cost effective solution?
Does IRIS stand for intake resonance induction system? Or the name of the marketing managers girlfriend.....?

Re: 4500rpm
 

Inertia resonance induction (or maybe intake?) system

Re: 4500rpm
 

Thanks for the acronym definition - my horizons now broadened. Anyone know what's amiss when the fault codes tell me both speed sensors are kippered (32&33)? Is that likely - I've checked the connectors and wiring, all seems fine. If I take the transducer bit off SS2 and can twist the shaft freely presumably that points to a broken plastic gear? Haven't tried it yet btw.
All I did was leave it stood a while, and the only clue is that it 'only just' started (has an alarm fitted which kills the battery over time). There were some odd electrical malfunctions for a few miles but everything but the speedo is normal now. I didn't 'jump' or 'boost' it.
Drives fine but after about 5 miles the check engine light comes on. And no speedo at all.
Help...

Re: 4500rpm
 

Giday Steve, when the Inertia system is on at low engine speeds it increases the inlet tract air pressure; they are using the low 7mm lift to increase the velocity at that time.

The Yamaha exhaust EXUP valve, and the Inertia system are both based on the Helmholtz chamber principle, of bouncing a air pressure back and forth, producing high and low pressure pulses. The EXUP uses the chamber formed by the 4 engine pipes and the junction, to form the pressure chamber, when the valve is closed at low engine speeds.
Here, it is powered by the exhaust pulses, and uses the low-pressure pulse, to drop the pressure in the cylinder, at valve overlap.

The Inertia system uses the, ‘sucking’ of the three inductions to power the Helmholtz chamber, formed by the inlet manifold, to use the high-pressure pulse, to push the air into the cylinder.

Same principle, just using the different pressure pulse, to suit their purpose.

The bikes use this exhaust trick because they don’t have the space to use the long pipes to utilise the inertia of the gas flow to produce a low pressure, and pipes long enough to form the resonate length, that the lower torque speeds of the car needs, there are no space problems with the car.

The Variable Valve Timing has more to do with being able to use longer cam duration, but still be able to shorten it back for low speed running, and of course Emissions.

Always enjoy talking to bike blokes.:)
Harvey.

Re: 4500rpm
 

Harvey - thanks for the info. If you haven't already ridden one have a go on the latest R1 with it's 'long bang' motor. Not only does it ride well it sounds, at differing rpm, like a twin,triple,four then a 'don't know what', top end!
Now come on all you IT wizards, log in to my SVX with Bluetooth, diagnose and fix my speedo. And while you're at it, hack into the DVLA computer, remove my licence points and tax the car for 12 months.
Thanks in advance,
Steve

Re: 4500rpm
 

Just to let you all know that speed sensor 2 was at the root of my problems, very kindly sorted by the Irish and International SVX Guru - Joe. No signal generated apparently. And it doesn't come apart without destroying the bugger so not fixable. WTF would something that has no mechanism as such, no touching parts, therefore no reason to croak stop working? 'Kin electricity...

On a lighter note I managed to get a pair of glass headlamps off fleabay so may be able to see the road as well as my speedo now. Have 2 sets of RHD plastic lensed ones if anyone is desperate.