67Straightsix and
'muller'.
Both of you and
thatblue_67stang and
fast64ranchero too.
And the others...I know your out there...
Props to you all.
pmuller9, you are right about the dynamic and static compression being too low, and the cold cranking compression probably being too high. It may bee that aligning the csm heads up without the 4 degree advance might help the idle to 1100 rpm area.
First up I'd go 3.73 gears. Normally, I like 3.20-3.36's for a 3.3, that is what normally works with short 2.95 firsts found in T5's from V8's.
Drag racers say for straight line power, go cubic inches.
My turbo mantra is if you "think" you've over cooked the cam timing for off boost transition, then add upstream air or fuel (anti lag) down or upstream to the turbo to stop it stalling. Downstram exahsut air speed is 10 times more important than raw CFM flow numbers.
The turbo size, cam verseses port area thing is more related to shapes than cfm figures, but an addition of more cfm to the turbo impellor will always help.
The info I got when I was a little boy late 1970's was to add an AIR pump. On Hugh Mcinnes's early copy of Turbocharging,
the early copy, not the later one edited. Man, I hate people editing books, because they remove really important info which they think is irrelevent or wrong.
In a picture, Hughe showed a tunner who used a 17 pound per hour NipponDenso Air Injection Reactor A.I.R pump to add 3.5 cfm of air flow to the turbo on a propane 18R powered SR5 Toyota pickup.
Pressure equals roh(air or exhaust density) times gravity times pressure head.
Adding to the psi from 800 rpm to before 1050 rpm helps idle.
For times when you need a bigger cam with proper off the lash reading that make performance, The low speed idle thing is easily taken car of by dumping the PCV valve before to turbo, and using an AIR pump.
Blow by at wide open throttle on a boosted 200 six is about 5 cfm.
A stock Ford six or 5.0-5.8 V8 air pump rated at 31lb/hr air pump yields 6.9 cfm.
If you combine the PCV and an AIR pump, you will add cfm to the base stall speed of the turbo, and help idle.
All the early Robert L Bosch injection systems used a fiddle valve (auxilary Vent Valve) to control the PCV and air into the Injection unit so the vane meter or MAP or MAF could be controlled properly.
The simple facts are this:-
On any two valve per cylinder 3.3 liter engine,
a 1973 Holden Torana GTR XU1
a turbo Mustang 200,
an air cooled production car 1978-1989 Porsche 930 Turbo.
a 3.3 liter Porsche 935 twin-turbocharged FIA Group 5 or IMSA racer...
The off the cam performance is modest, and can cause off idle transition/ progression problems.
The way to get around them isn't to go down on cam size, but to control the exhaust or Gas turbine part.
Stock iron headers on the 235-245 hp 1973 racing Torana was a perfect example of making sure the 5th stroke of the exhaust had enough flow velocity to drag more cfm out of the engine.
In fact, the 202 Holden engine is the key thing to observe. With the right cam, it can easily make 235 hp, but the exhaust defines how close to that you get. One year ealier, the engine got 216 hp net at the flywheel, and the next year, the engine with a slightly smaller cam than the other two race cars had better low end torque...but they all had the iron header system, and with just a divider welded in to it, it made an extra 10 hp, tripping the 240 to 245 hp mark with a nearly stock cast iron dual outlet factory header.
Porsche's 930 3.0 and 3.3's, like Ford in the emission era 5.0 fromn 1986 to 2002, kept the exhaust duration down for emissions but they had a vast array of special cams with more intake duration. The traditional engineerig response was right for emissions, but they had access to AIR pumps, and yet didn't use it as a smog mop up device with more stout cams.
You can go downwards and make a back step to a split pattern cam with reduced exhaust duration, and attempt to find the turbos sweet spot, or just augement the abdiatic cycle with more AIR pump or PCV air.
In 1988, David Vizard in the SOHC Pinto book,
showed just what a T-4 turbo needed, and his crash off the turbo boost avoidance was to look at a more efficent exhaust, but still try to keep the cam duration up.
Try a used LS1 Secondary AIR injection system, and one or two Rock Auto check valves with a 7/8 to 1 inch adaptor to an area before the turbo.
ACDelco 215-414 GM Original Equipment Secondary Air Injection Pump
The only thing I'd say is whatch the volts consumption for running the fans, the AIR pump, and the EDIS. If your running in a new engine, you'll suffer the same issue Jimbo65 had when he used a 130A alternator with a tight rope seal. It'll not want toi run below 950 rpm. Everyone was thinking the cam, big 2V head was hurting his idle. It wasn't... it was accessory and running in drag.
Be mind full of that, and add an electric AIR pump, and make sure your current drain doesn't hurt your igntion system or idle tracking speeds.