Any cast iron intakes made for this engine?

This is not really your question but I would stay away from 4.1s if possible. They had so many weak spots that they are just too much of a problem waiting to happen. 4.5s and 4.9s aer much better engines.

I've never heard of a cast iron intake for these engines.

Yeah, no cast irons that I've ever seen.

Bottom of the page are links to the rebuilder article. It will list every change from 4.1-4.9.

http://www.fieroaddiction.com/caddy49b.html

Thxs Guys .I didnt think there was.
But I had to asked.

4.1s were also rated at 135bhp, and 4.5s were only 155bhp. The allante was 170 and 200 respectively but that is a harder to find motor. The 4.9L is the only motor worth your time in my opinion.

1990 4.5's were about the same as the 4.9's, PFI engines. They were not TBI. I have read that they had better torque off the line than the 4.9's did. But I have never seen data sheets on the 90 4.5 I would not be afraid of a 1990 4.5

4.9s had the benefit of better oil pump, oil pan (with windage tray), pistons to reduce cold start noise and better counter wieghting on the crank. Overall a better engine........but I have noticed something.

Drive a 1990 caddy.
Drive a 1991 caddy.

The 1990 caddy will rev easier.

4.5's have 84mm stroke, 4.9's have 92mm stroke. I think that's what they are anyway.

I have a 4.5 in my Formula and have noticed it revs higher, quicker than 4.9's do.

Better engine than a 4.9, no, more fun, yes. Escpecially with a 5spd tranny.