NA performance upgrades?

[racer_x]

Has anyone here put a GTI cam in thier diesel? I would be interested in doing it, if it would work, what would you clearance to clear the GTI cam?

You need to cut valve reliefs in the pistons.

The JH cam is the worst cam you can get for a gas engine. But it has a little more lift and more duration than the diesel cams, plus it has a few degrees less time with both valves closed at TDC between exhaust and intake strokes.

But if you put a JH cam in a diesel head, the valves hit the pistons. Some relief space is needed in the piston for the valves to fit in. But Diesels also have a very small volume above the pistons at TDC, and any valve relief you machine in the pistons will increase that volume and drastically reduce compression. That would make it harder to start the engine. Depending on how much the compression is reduced, it could also affect power in a bad way.

I've thought about trying it, but I don't have a spare diesel engine around to play with, and diesel pistons are a bit too expensive to be experimenting with, at least on my budgets.

[greggearhead]

Wow - so much info...

Seriously, GTI valves in a diesel head would not be a good thing.  The Land speed truck was a 1500 and we used a Diesel block with  a GTI head (carbed gas motor) - we had to notch the BLOCK BORES to make room for the valves.  This shrouds the valves  a  lot and decreases the effectiveness of the bigger valves.

Diesel heads respond greatly to porting - pocket porting near the seat and unshrouding the valves slightly.  

Running any gasoline-engined cam wouldn't work - I don't think, haven't tried it (someone that has, please post).  There was one person that used a late 1.8 solid lifter cam in a diesel back in Iowa and never got it started.  I would think Delta Cams or one of the regrinders could make a higher lift cam w/o affecting the duration much.  Can someone talk about the issues with  overlap on a Diesel - I have not read nearly as much about diesel engine dynamics as gasoline and would like to learn more.

I haven't used it, but propane injection is common with the full-size diesel crowd.  Might be an interesting option to explore.  

Anyone tried mechanical supercharging on a IDI VW?

[fspGTD]

The "original" 1.5 liter Diesel SAE paper has the most detailed info I am aware about the IDI VW Diesel's cam timing, why it was selected the way it was, etc that I am aware of.  Here is the link:
http://vwdiesel.net/phpBB/viewtopic.php?t=46&start=16