Im bout to do my hughes plenum kit next weekend. I read on one write up, and he said on a 5.9, you can cut the runners all the way down. Meaning, make it flush with the inside of the intake or what? Anyone have pics of how much they cut off on the 5.9?? Im considering doing this mod, but dont want to mess up a good intake, since I dont have an extra one...

Thanks guys!

 

From all my research on the topic, that's what I would do if I had the 5.9. I've talked with guys who did dyno's on various intake cuts, and that's what always worked best on the 5.9. I'll see if I can scrounge up some pictures for you.

 

That's correct. The 5.2 can only be cut down a little bit, but the 5.9 can be made flush with the inner wall of the manifold.

 

Here's one, runners cut all the way flat. 5.9 engine.

 

Here'e my DIY on doing this mod in case you hadn't seen it already. I have a 5.2, so I didn't cut the runners all the way down. In fact, I also cut the runners different then most guys do on the 5.2's. I did an angled cut rather then a cut parallel with the original edge.

https://dodgeforum.com/forum/2nd-gen...e-mod-diy.html

 

i have it done to my 5.9 and i love the way it runs now. i have the hughes as well, but i got a spare manifold and had it cleaned at a machine shop to make it look brand new.

 

Ya, I used a spare manifold too incase I didn't like it - or worse in case I messed it up.

 

I am getting all my parts together for when I put my heads, new cam, and kegger mod on what is the best way to cut the runners for a 5.2 I am also going to epoxy it too.

 

I don't think anyone really knows for sure what the best way is. The only way to definitively say for sure is to get an intake, cut the runners one way, install it and run it on the dyno. Then do another a different way and test it the same way. No one has ever really done this because it is labor intensive, and the results probably wouldn't vary much. So you have to just do what feels right to you.

Most people cut theirs to match the orignal factory edge. I cut mine at an angle to the factory edge because I wanted to open the runners up to the center of the intake a little more while still keeping the runner length the same on the back side of the runner. I felt like this might improve airflow into the runner. Who knows though. I don't have the time to do it all over again with a different cut to see which is better.

 

I think I am going to cut them just like you did yours