Starter problem

Removed the dB killer, topped up with coolant.

Went to start car. Didn't fire, noticed the LED on the MS showing cold engine wasn't lit. Assumed I had dislodged a spade connector from the temperature sensor. Carried on cranking.

Engine missfired. Stopped cranking.

Tried cranking again and starter just whirred. Damn, hit it with hammer, just whirred.

Turns out that the ECU thought the engine was warm, so supplied less fuel on startup. This cause missfire which resulted in the engine trying to go the wrong way which broke a gear on the back of the clutch (starter gear).

Had to take out the clutch (actually took out 3 clutches as needed to find a replacement gear), not difficult on a motorcycle engine with air-tools. You can even do it with the engine oil in place as long as you can tip the engine a few degrees.

Anyway, it is all back together now. Also removing the dB killer has sorted out the boost. Getting a nice 8psi from 6kRPM (better than the 7kRPMbefore), and this can be controlled nicely with the boost controller. Aim now is to get a steady 8.25psi (155kPa) from 6kRPM to the red line with sensible fueling. Then need to work on the ignition timing and on the acceleration enrichment (which is rubbish at the moment).

Of course its the dB killer

The boost was dropping off at high RPM. I asked around and it appeared that this was probably due to pressure from the gases acting on the newly ported wastegate.

So, I put in a stiffer spring, and messed with the boost solenoid control. Both of these things helped, but it seemed difficult to stop it dropping off. Really I want 8psi from 6kRPM to the red-line, maybe dropping slightly at peak RPM to avoid running the injectors at 100% duty cycle. At the moment I get 8psi at 7kRPM, but it trails off linearly with RPM ending around 5psi.

Anyway, I will remove the baffle (dB killer) tonight and see if that does the job. I am pretty confident that things will spin up even bit quicker and that the boost drop will go away as that was the characteristic before I put the baffle in.

Once it is all stable I might see if the engine (clutch really) can handle an atmosphere of boost, which is my personal target.

Turbo update

I spent ages trying to optimise the EAE algorithm values. This is a clever "wall wetting" algorithm. But I just couldn't get it to work properly, so I gave up and tuned using the normal MAPdot and TPdot parameters. It isn't perfect, but it seems to work.

I also installed a boost controller, and added a second spring to the present wastegate spring.

Here is a screenshot from tonights datalog. The acceleration enrichment isn't perfect but the car drives well enough, and it is nicely controlled under full throttle so it is safe. Presently I am running a cautious AFR of around 11.5, but all in all the tune is pretty decent and gradually improving.

Boost duty controls how much the pressure comes from the turbo pressure and how much comes from the atmosphere. Confusingly 100% means use the outlet turbo pressure. 0% will allow loads of the control pressure to leach out. This would allow the wastegate to stay closed longer and so build up more boost.

If you look at the log, for low RPM I try to keep the wastegate closed for as long as possible to get the turbo spinning up quickly. After about 7kRPM the boost controller goes to 100% so that the boost is controlled purely by the spring. The thing is that there are forces from the exhaust gases that push the wastegate open and so the boost drops off with RPM.

I should be able to maintain the boost after 7kRPM by playing with the Boost Duty Table.

Now the problems:

1) oil leak, but I know where it is and it should be easy to fix

2) water leak into oil. This is the big one, but I have a plan.

3) starting, is still a nightmare. I think this is related to low battery and sub-optimal values, but it is annoying.

Everything I ever needed to know about Volvo turbos

Really useful video. If only I had seen this earlier!



Basically explaining how the wastegate works on a volvo turbo charger and how the boost control system works. Yeah, I know a bit dull.

Water cooled turbo, now water cooled

I don't think I am going to win any prizes for my headline writing, but.

I've added water cooling to the turbo. My turbo bike buddies always talk about how they don't bother with water cooling. But in their installs the turbo sits right at the front in serious airflow. In my case the turbo is hidden from this airflow in the engine bay.

When I did the rebuild some of the oil was rather nasty. Sort of black and gloopy. I assume this is from heat damage. So adding a few water cooling pipes seems to make good sense. I had a few small leaks, but I think that I have now addressed them.

Pretty much time for an oil and filter change and then a test-drive.

Look at my fancy crankshaft (ooh eer)

Not sure whether I mentioned it, but the engine developed a water leak into the oil.

I ignored this for a while hoping it would go away, but once the oil-overflow bottle was actually full of "mayonaisse" I realised that it was time to act.

Turns out the top of the barrels had a nick on them. I did actually know about this when I put the engine together, but my local engine folk didn't have the tooling to sort it (aluminium with steel liners is to difficult for them) so I had hoped it would be fine (and it was for 200miles). Anyway, I found a new place (Paynes in Eynsham) who sorted out the barrels (quick service, very professional too and didn't treat me like an idiot, which is polite).

Here is a photo of the rather interesting crank and con-rods on my existing engine. There have been trimmed down a bit, with the counterweights seriously attacked, and the rods look like they have been shot peened or sintered or something (these are not the normal castings that I have on the other engines). Note also the residual anti-freeze from the water leak (oops).

I also discovered that I had forgotten to install a cam chain guide, so it was good to get the engine opened up.

When rebuilding the engine I reset the cams aiming for stock on inlet and 5deg advanced on the exhaust. This is supposed to give best power on turbo suzuki's, although I need to measure it more precisely to get it right.

Turbo porting, fast and furious

So, I had a problem with my turbo overboosting. Basically this means that even with the wastegate wide open the boost still builds so it is out of control.

This is not a good thing, because too much boost can result in engine damage.

I had temporarily addressed this by installing a exhaust dB killer (a device that reduces the noise a bit by constricting the exhaust at the outlet). This results in slightly higher pressure in the exhaust and it is the pressure difference between the two different sides of the exhaust turbine that provides the drive to the turbo.

Anyway, that was a short-term solution and did work, but it isn't ideal. The whole point of turbos is to get lots of boost and lots of boost when you want it. Decreasing the efficiency of the turbo would (in theory anyway) make boost come in later and generally make things more laggy.

So, I hit the internet and discovered that I needed to make the wastegate more efficient. This is done not by changing the wastegate, but buy making it easier for the gases to whip through the hole. As expected the casting was crude, so my die-grinder, a carbide bit and 20minutes was all that was needed to open up the flow paths so as to allow the gas flow to more easily get through the wastegate (when it is open).

Here are a couple of photos, post port (none before, sorry).

I opened the flow path, removed the sharp corners, and also increased the diameter of the wastegate hole (by maybe 1 or 2 mm).

It will be interesting to see whether this sorts out the problem.