*Note* please see question at end! I need advice!
While at the junkyard, I had a crazy thought.
I've heard a few people say the lower intake for the f- Body flows really well, but the upper stinks. I've also seen the gains made by having a larger plenum and short runners especially with boost (hv3). So why can't we have the best of both worlds?
The gasket for the f- Body is flat and covers everything but the ports, essentially mimicking the hv3. I also noticed the bolt pattern kind of looks similar...
So I picked up a full f- Body intake, and courtesy of Selliot's car being torn apart, I test fitted the intake.
If the two alignment pins are removed on the f- body and drilled and tapped like the rest of the bolt holes, every main bolt for the L26 lines up EXACTLY!
Obviously, the pcv needs work. for the f- Body, both the front and rear head pcv passages are now left open to vacuum so they'll need to be plugged and pcv routed externally. (I won't detail that here since I have a thread about pcv detailing what's involved).
The other thing that needs plugged is the egr stove pipe hole since this now is completely open. JB weld works nicely!
You'll actually cap/ remove the upper pipe for pcv intake on the L26 upper, plug the evap hole or tap for vacuum, and relocate the map sensor (see pcv thread). You can also jb weld the vacuum hole for evap and egr to smooth the airflow. Also, you'll have to plug the vacuum for the old pcv valve.
The only cutting involved would be the corner where the old pcv valve and map sensor were located on the L26. Since this is blocked now anyhow, you could actually remove this whole fixture if desired.
The f- body thermostat is located in the upper intake, so you'll have to drill out the hole in the lower intake and drill and tap holes for the thermostat housing, but the clearances are already there, and there's plenty of material to work with. You'd use the stock housing from the L26 lower.
You would have to plug the camaro throttle body heater passage, much like the ones commonly plugged on the L26 lower.
The lower and upper physically fit in the car, though you will probably need the camaro tensioner and alternator (we'll see if my Cs144 will fit, but it should; see alternator upgrade thread).
Side note, if you use labarge's throttle body adapter, you'll need to plug the pcv intake elbow he machines in, since it won't be hooked up. Either way, you'll have to draw fresh air after the maf sensor but before the throttle body (see pcv thread).
Strange note is on L26,L36,L32, and L67, the rear coolant passages are used and the front are plugged on the lim, but the f- body does the opposite. Not sure if one is better than the other or why both aren't used. I'm assuming the flow is good enough with front or rear.
Obviously, on a stock n/a car, the gains would probably only be in the top end, if at all, but I'm curious what the gains for turbo are.
The only thing that keeps me from being able to do this is that the thermostat housing is now on the wrong side of the engine . I've seen several turbo cars with this intake, but no one talks about what hose they use to reach.
Originally Posted by SgtMarshal
