Originally Posted by
Kitch
Spark map smoothed and loaded, I'll data log tomorrow.
One thing that we picked up on the dyno was how restrictive the stock air cleaner assembly appeared be.
As shown at the start of this post I had locked the hot air intake flap inside the factory air cleaner open so that only cool intake air would get to the air filter.
I had dropped my van off at the workshop in the morning and hung around to help them if they had any issues connecting to the APU1 and they did, it wasn't the sort of vehicle they were used to working on and they gave up on the APU1 and connected up there own Ostrich.
I asked the dyno operator to give me a call when it was ready to make a few runs and I'd come back and have a look.
I had a phone call from the dyno operator asking me how much HP I thought the van would make, I said anything above 170 would be okay he said it was only making 165 but something was strange going on because the motor would just falling on it's face above 3500 RPM.
I headed over to see what was going on, he showed me on the computer screen the initial runs he had made and you could see the HP curve just keel over after 3500.
While I was there he decided to take the lid off the air cleaner assembly and try another run, we were both surprised to see the HP jump up by 13 to 178.
After that run he then put the lid back on and sure enough back down to 163HP. I suggested we disconnect the factory duct supplying fresh air from the front of the van to the air cleaner to see if there was a restriction caused by that but another run revealed not much difference, still around the 167 mark.
So at that point I suggested the old air cleaner lid flip trick to see if the air filter was the problem and the HP came up near 176 HP, one more run with the lid back on correctly to confirm the air cleaner was the problem and sure enough the HP dropped back down again.
At that point it appeared clear that the factory air cleaner assembly was costing 13 HP, with no other changes you could watch the AFR drop to 10:1@ 4500 RPM with the air cleaner lid on and jump to 12.3:1 with the lid off.
Not wanting to give up on the cool air provided by the duct running from the front of the van but having to conceded that something needed to change, I took the air cleaner assembly home and within ten minutes with a holesaw and an air nibbler modified it to let some more air in but still have a little cool air flowing towards the filter.
I dropped it off the next morning with the dyno operator and he reported when he later made a run with it on the HP levels were back up to levels with no lid on.
The improvements made from 176HP to 196HP were then made from basic chip tuning.