Any way, for those of you who have not seen these video links over on the other board yet...
What always amazes me about any of the Alfa engines that I have had on the dyno, is how nice and flat the torque curves typically are (and how wide the usable torque spread is) - even on the higher horsepower builds!
From below 2K rpm this one is already over 210 lb-ft of torque (and we have not even touched timing yet!) The fueling in the middle isn't that great yet either - we're still chasing a stumble at 2,900-3,400 rpm.
At any rate, above 2,800 rpm you're already over 200 lb-ft and at 3,200 we have 250 lb of torque! There's lots more there once I get the fuel right! The curve stays pretty flat from there on up. It climbs to about 270 lb-ft at 5K rpm and falls back down to 250 through 6,500 and then about 230 lb-ft by 6,800 again - where Alex gets out of the throttle a bit. It's a nice flat usable curve and at about 5K the horsepower really comes in again!
I think all of this moves up when I get the fuel right and start doing some power work. We've only spent a couple of hours in real tuning so far and most of it has been spent trying to get it smooth down low! Still, I'm pretty lean right now from 2,700 to 3,800 - where we were chasing the bump and then rich again up to 4,600 and then lean to about 6,400 and then a bit rich again up to 6,800...)
I typically get my curves pretty flat, but I haven't worked on this yet - still messing with the stumble down low! Dawie's work is truly amazing though - to end up with a torque curve that flat with cams this hot and high compression - blows me away!
Like I said though, we haven't even started to map this thing for peak power yet. You can see the early stumble in the video (soon after Alex goes to full-throttle.) It's almost like a lean-stumble, but the fueling was good there at the time (before and after trying richer and leaner mixtures), so I don't get it!
We're thinking spark-scatter maybe? I'm going to get rid of the Double Platinum's and go with an 8 or a 9 NGK. I'm also going to run a smaller sparkplug-gaps and see how she does! We'll find it. (They were around 1.25mm and Dawie was suggesting .5mm.
The horsepower curve is also amazing - it just goes straight up and there was no sign of it tapering off yet! She hits 300 at the wheels around 6,300 rpm and around 310-315 at 6,800 where we lift for now - mainly we kept going back to that 3K rpm point where the stumble was... Besides, we're only running 28 degrees of timing there (and we can likely go to 32-33 degrees or so given the efficiency of the motor, the good gas and with accurate fueling!)
Enjoy!
http://www.youtube.com/watch?v=PJdBXviy7Yg
http://www.youtube.com/watch?v=7KHU9W8pe4k