Road Weazel
Registered
I'm putting my engine back together and will be using Wossner Pistons with the .080" spacer plate. I have the adjustable cam sprockets from APE and have done some research/spoke with a few knowledgeable blokes, but just wanted to bounce a few ideas around.
John from Wossner suggested an intake lobe center of 106 and said that the exhaust would land in about the right place without changing the sprocket. Gary Evans (local guy, has tuned a few bikes) recommended 105 intake and 108 exhaust, which he states is where the exhaust will land with the spacer plate and no adjustment.
After searching this forum I found only one thread on lobe centers for turbos, from 2005 where Mountainmotor suggested 105-105 or 106-106. I know that 1 degree won't make that much of a difference but 3 degrees might.
It seems that we're all in agreement on the intake side but the exhaust side is where the confusing part comes in for me...
I was just going to leave the exhaust alone but after a last minute decision to change the cam bearings, well, now I have to degree the exhaust anyway. Stock lobe center for exhaust is 99.5 degrees. Moving the LC to 105 or 108 would decrease the overlap (which makes sense) but will open the exhaust valve earlier, which doesn't make sense (unless the exhaust is already opening too late). I remember reading in Corky Bell's book that part of how turbos make more power is by pushing the piston longer and that opening the exhaust valve while there's still usable pressure in the cylinder would be wasting power.
Maybe I'm splitting hairs here but since I need to degree the exhaust anyway I'd like to set it at the optimal lobe center. Suggestions?
The bike is a Stage 1 (10 pounds of boost) with water injection and will be a street bike primarily with at least one trip to the Mojave Mile. I'm using APE valve springs and I'm probably going to raise the redline to 11,500 if it's safe (different question, different day). I'm looking for a goal of 250 horsepower or a little better.
Thanx for your time,
Weazel
John from Wossner suggested an intake lobe center of 106 and said that the exhaust would land in about the right place without changing the sprocket. Gary Evans (local guy, has tuned a few bikes) recommended 105 intake and 108 exhaust, which he states is where the exhaust will land with the spacer plate and no adjustment.
After searching this forum I found only one thread on lobe centers for turbos, from 2005 where Mountainmotor suggested 105-105 or 106-106. I know that 1 degree won't make that much of a difference but 3 degrees might.
It seems that we're all in agreement on the intake side but the exhaust side is where the confusing part comes in for me...
I was just going to leave the exhaust alone but after a last minute decision to change the cam bearings, well, now I have to degree the exhaust anyway. Stock lobe center for exhaust is 99.5 degrees. Moving the LC to 105 or 108 would decrease the overlap (which makes sense) but will open the exhaust valve earlier, which doesn't make sense (unless the exhaust is already opening too late). I remember reading in Corky Bell's book that part of how turbos make more power is by pushing the piston longer and that opening the exhaust valve while there's still usable pressure in the cylinder would be wasting power.
Maybe I'm splitting hairs here but since I need to degree the exhaust anyway I'd like to set it at the optimal lobe center. Suggestions?
The bike is a Stage 1 (10 pounds of boost) with water injection and will be a street bike primarily with at least one trip to the Mojave Mile. I'm using APE valve springs and I'm probably going to raise the redline to 11,500 if it's safe (different question, different day). I'm looking for a goal of 250 horsepower or a little better.
Thanx for your time,
Weazel