The mechanical vvt looks like it has a special cam - with a spiral gear on the end. Can good racing or high-performance cams be ground on this core, or are they otherwise available?
Seems like a good way to use a high-lift, high overlap cam set with some cam retard to get a decent idle. Anybody (besides Murray and his electronic wonder dual vvt) try this?
Here are some conversations I had with my engine builder about the Montronic VVT. Don't konw how it differs from a L-Jetronic's
I had to buy a used VVT for the exhaust side and found that it's advance was different then the one I had.
Here is what Steve said about it:
"The intake cam advances 14.5 degrees when the oil valve is closed. This is more than indicated by the service manual so I was skeptical of the numbers. I then took apart the cam that I purchased to use as your exhaust cam and found that it did match the 11.65 degrees that the manual indicated. So Alfa evidently made a change in the VVT timing somewhere along the way. It will be easy to make spacers that will reduce the advance for the race engine."
Spacers were made to change the advance:
The spacers for the VVT cams are made so we can cut the stock advance of 22 degrees down to anywhere between 3 and 10 degrees.
Results at 1st dyno with 4 degree advance:
Bob tried the VVT cams and found that he gained 4 hp at high rpm with the advance turned on. There was no change in the power at lower rpm. On the exhaust side, with the advance "on" he gained 3 hp across the full rpm range, indicating that the initial setting should probably be set with more advance.
On the final dyno with a different exhaust system we pick up considerable HP but with the advance turned on the VVT had zero increase in HP across the rpm range...................Don't know why and by this time I just wanted the car back and we ended the testing.
100.7 KB Views: 1,835