on the snoots (jlm) , air horns (others), I.E. supercharger output duct and intercooler output duct where they connect at the rubber boots to the intercooler.
I recently removed my intercooler to clean and do the VGS Mod.
I observed that the the above parts have a substantial lip exposed to the air flow path.
Who has radius-ed or blended this lip to reduce turbulence?
Does anyone have any input or measure of results on doing this?
Anyone with pictures of these parts that have been worked on.
Please share......... :smile:

 

Hi Norm, I have no such experience, at least not yet. I didn't see you chime-in here, so I'm not sure if you saw this thread started by jlm recently:

https://www.northamericanmotoring.co...6&page=1&pp=25

Plenty of photos in his provided link...

 

Here’s more than you asked for, but why stop with just the runners? The upper lip of the intercooler output duct does indeed put a square edge into the flow path. This is accentuated by the offset created by the support mounts under the intercooler. At the exit of the output duct there is a nub providing some backing to one of the bypass valve’s boltholes. The intake manifold will have some mismatch in the interface with the IC output duct providing a ridge in the flow path also. There is a slight mismatch at intake port entrance. There may be one or more exhaust primaries welded off center giving a less than optimum exhaust exit path. Down at the supercharger intake duct there are square shoulders that jut into the flow path and there may be some plastic weld squished out between the jointing of the end pieces. On the supercharger, there is an edge sticking up at the intake side and the output triangle and sound ports have squared off edges at the lobe interface. The intercooler intake and output ducts may have casting ridges large enough to cause a minor disruption to laminar flow.

Here are some things you can do that will mostly only cost time. In all cases the parts need to be removed before working on. You will need half round and round files, different grades of sandpaper and a blade. The exit of the IC input duct should only be deburred, the flow path should see smaller exits than the following entries. For the intercooler output duct, file and sand the entrance concentrating on the upper lip. I wouldn’t go as far as a knife-edge shape. The small nub on the exit can be filed a few millimeters shorter and smoothed. There are small edges to be deburred everywhere facing has been done. Put your hand into the duct and feel the internal short side radius. There can be a ridge (some parts have a channel) from the joining of the two casting halves that can be sanded down. Look at the fitment of the gasket and make sure that the IC output duct exit is smaller. You can relieve the gasket with some rough sandpaper if it is sticking up over the edge. Place the gasket over the intake manifold entrance and mark the edges showing. These edges can be filed and sanded until they are slightly larger than the gasket’s interior perimeter. The mismatch at the head requires an explanation that is beyond the scope of this thread, which is already becoming a book in length. The exhaust header’s primary placement can be smoothed with a file to match the flange port contours. The bottom and top edge of the supercharger entrance can be filed to match the end piece of the supercharger intake duct. Extreme care should be taken to prevent shavings from entering the supercharger. The exit openings of the SC should be left to the professional. As for the supercharger intake duct here is a thread to explain that procedure http://www.webbmotorsports.com/forum...+intake+runner.

While the IC output duct is off, adjust the bypass valve butterfly to close completely. There is a great deal to be gained from the BPV adjustment.

I have done all of these and done together they have made a difference; be sure to include all new gaskets when modifying and torque to spec afterwards.

 

You two covered all my request's!
Tony I've been following jlm's build up @ too's but I had not seen those pictures..
k-huevo your write up was great, I have it printed out and the book is started :smile:
I think chasing down the details and cleaning things up will add a nice cumulative effect. If anything it will keep me out of trouble for awhile.
This will become my punch list to refine what's already there
I just finnished cleaning up and blending the flange ports on my OBX header. It is a nice piece of work except for that area on mine.
The OEM metal gasket now needs to be port matched to the ports or it will hang in the exhaust path .

 

As for the header gasket, if your exhaust ports on the head have not been opened up larger than the gasket opening, the gasket will not be in the flow path.