Jakx13":18babews said:
My issue is it's making too much power for the turbo with less the 10lbs of boost.
You are correct that the compressor map gets narrow at low pressure ratios and there would be concern about running the turbo into the choke zone.
However the stock 300 head combined with a cam profile for low rpm torque will not flow enough past 4500 rpm to let that happen.
Concerning cam profile.
When using a log style exhaust manifold there is a lot of exhaust back pressure.
When the engine is operating at low rpm the intake port velocity is low and the pressure in the cylinder at the end of the exhaust stroke causes intake port reversion when the intake valve opens resulting in a delay in the start of the intake cycle.
In this case it is better if the time that the intake and exhaust valves are open at the same time is reduced.
This is less of a problem with a turbo engine being used to make boost and power at high rpm where the port velocities are higher.
I had a set of intake port injectors with the plastic tips melted due to intake port reversion on a big cam turbo engine.
If you are looking for early turbo spooling and low rpm boost may I suggest using a cam with less overlap between the exhaust valve closing and the intake valve opening.
The Howard cam you are looking at (#280026-08) has a tight 108 degree LSA which is good for low end torque in a N/A engine where there is exhaust system scavenging that can take advantage of the overlap period.
Here is the Howard turbo cam for low rpm boost. It has a 114 degree LSA and 18 degrees less overlap than the first cam.
What RPM power range are you looking for?
[image]https://www.dropbox.com/s/m7muan0xurh5cbq/Howard%20turbo%20cam.jpg?raw=1[/image]