anyone tried using a gasoline intake manifold?

[Master ACiD]

i got a spare one sitting here from an 84 rabbit with cis.  it shouldnt be too hard to fab up a 4 bolt intake tube adapter to replace the throttle body.  you all think there is any gains to be had by using a gasser intake manifold and routing a intake tube to a cone filter stuck behind a headlight?

or is the stock diesel intake manifold good enough?

[Dr. Diesel]

not much point on a Turbo engine, i'd say. you need to flip the exhaust manifold and turbo upside down to fit anyway, then you're into a new downpipe, oil supply and return lines, and air pipes. for whatever gain you might see, it'd probably be easily duplicated just by upping the boost a few pounds on your original setup .

[Master ACiD]

how about on a normally aspirated setup.

[veeman]

The gas intake should bolt up, no problem (of course)...

I believe Jake was considering this for his VNT project (turbo, of course).  There were concerns about manifold clearance and such with his TD setup.

I was thinking that maybe a gas intake would make slightly better power because it has somewhat longer intake runners, but Jake might have more to say about that.  Not sure about an NA setup...

[Dr. Diesel]

the na engines already have long runner manifolds.
long runners really only benefit low rpm.  I really think it's pointless on a turbo engine, when you compare benefit vs cost/effort.

[fspGTD]

There is technical discussion including anticipated effect for changing the intake manifold runner lengths, some calculations, etc for 1.6lTD intake manifold modification here: http://www.vwdiesel.net/phpBB/viewtopic.php?t=209

The 1.6lNA manifold does already have nice long runners, also very nicely contoured with "D" shaped cross-section, so should be pretty close to optimal for mid-range torque.  Perhaps you could gain a small bit of torque/power higher up on the RPM range by bolting on an A1 gasser manifold as their runners are slightly shorter, but it would likely be at the expense of some mid-range torque.  I have not seen a back to back test done before comparing the two manifolds.  It has been done before, but no one has tested the effect very well.  This thread discusses gasser intake manifold swap on a 1.6lNA (among other things): http://www.vwdiesel.net/phpBB/viewtopic.php?t=1106

IMO, the 1.6lTD intake manifold leaves lots to be desired as the runners are practically nonexistent, but like Dr. Diesel says it would be a lot of work to relocate the turbo lower and out of the way far enough to bolt a long-runner manifold on there.  This thread discusses more thoroughly what work would need to be done to convert one: http://www.vwdiesel.net/phpBB/viewtopic.php?t=614

veeman: Indeed at one point I was considering using the 1.6lVNTD project as a test bed for various intake manifolds on a 1.6l turbo-diesel, but since installing the external wastegate, (which sticks up from the EGR flange of the VNT exhaust manifold's EGR flange quite a bit,) it is no longer a viable option.  Pics of the intalled external wastegate here: http://www.vwdiesel.net/phpBB/viewtopic.php?t=1306&start=184