1 June 2013

The engine is back in and the car’s running again, finally! It’s very promising; no grinding going into reverse, though the car needs to be driven more to better let it heat-soak. The icing on the cake is that Competition Clutch also changed the diaphragm springs to lighten the clutch pressure, and it’s much nicer.  No longer is it a constant reminder of driving a “race car”, now it’s not like a regular OEM clutch. Very impressive for a clutch that’s rated at “only” 500 ft-lbs!

Regarding the higher-pressure wastegate springs, either Tial makes inaccurate springs, I design awesome headers, or the MAP sensor is reading a bit low. The new 0.6 bar springs produced an indicated 0.54 Bar, which is okay, but that’s not the main curiosity. It’s that there doesn’t appear to be any boost-creep – except that’s just not possible. Think of boost as a water pressure gauge attached halfway along a length of garden hose. With the hose pressurized but the spray valve closed, the pressure gauge will read the pressure fed to the hose. However, open the spray valve and the pressure reading will drop to read the back-pressure caused by the open spray valve, plus the fluid drag along the walls of the hose. No matter how high-flowing the spray valve is, there will always be some back-pressure, and the higher the flow, the more there’ll be. And yet, a third-gear pull showed boost maintaining 0.53 Bar within a few counts from 3000-7000 rpm.

For those wondering why I’m using Bar units for boost measurement and not PSI, it’s due to how the flat dash handles data. The Honda ECU measures MAP in Bar, so initially – being American – I  converted it to psi. That worked fine – but only for positive boost. The dash is apparently unable to digest negative MAP values, wrapping negative values around to 65XXX – a sure sign that their software can only handle unsigned (non-negative) inputs. Not a big deal, and after using it for a while it’s become quite natural but took a bit of getting used to. 1.0 Bar = 14.5 psi (atmospheric pressure at sea level.) Most of the time the dash displays about 0.4-0.6 Bar, meaning that the intake manifold is pulling a vacuum (anything below 1.0 Bar.) If it reads 1.0 Bar it means boost is balanced against manifold vacuum, and 1.6 Bar means it’s 0.6 Bar above ambient pressure, or 8.7 lbs, though my setup isn’t quite reaching that for some reason.

There’ll be more driving tomorrow but I can’t go too far from home; I’m on-call this weekend. Would have been tempting to do a run up Palomar Mountain… but oh well. Probably just as well since things need to be checked out several time since it was so heavily torn apart.