H.O. Intake swap on Renix
 

I have a 88 Renix XJ and was trying to install a Header for a H.O. engine I bought only to find the Renix manifold will not bolt on. What problems would I face if I changed the Renix intake manifoldb for a H.O. ?

It's not the intake manifold's fault. It's the exhaust manifold's fault. See below:

So all I would need to do is file my Renix intake manifold and the header for the H.O. should bolt up? I thought I would have to use a H.O. intake manifold, which would of led to a lot more problems.

https://cimg6.ibsrv.net/gimg/www.che...e0ddfd4b9f.jpg
This is the header I'm trying to use vs my old manifold

As long as the only interference spot is between the FLANGES of the intake and exhaust, yes.

After going back and checking two of the intake runners are hitting on the header pipe not allowing it to "sit low enough" to bolt up it seems. The H.O. looks like the runners would have more clearance.https://cimg0.ibsrv.net/gimg/www.che...644bdd4391.jpg
https://cimg5.ibsrv.net/gimg/www.che...03733d7cb5.png

What year is the exhaust for?

91 to 99, I've already lengthened the oxygen sensor wire, got a later model downpipe and have done the EGR delete for my intake.

Shouldn't have to lengthen the O2 sensor wires. I never did on the slew of them I did.

Once I saw the the intake wouldn't fit I put it back together with my old exhaust manifold and downpipe so I haven't actually tried the oxygen sensor. I guess that's what I get for assuming I had to lengthen it, oh well. I just don't want to have to use an H.O. intake manifold if I don't have to because of throttle body mounting issues, power steering, and fuel rail.

Correct.

This dude on YouTube is super smart with the Renix

Watch this video for his Renix to H.O. swap

Update?
 

I know it's probably a long shot since this thread is a bit old but, were you able to successfully compete the swap and were there any other issues along the way? Getting ready to do the same swap using the same type of aftermarket header on my 90 XJ because of a cracked exhaust manifold..I've already got the 91 to 96 down pipe. I'll do the grinding that Cruiser54 mentioned along with any other modifications that's needed, just not going to do the full HO swap..I like the old Renix systems, over 310k miles and running strong! Also thinking about using a flex joint in the down pipe between the exhaust flange and the catalytic converter to try and keep it from cracking the new header..I have aftermarket poly motor and transmission mounts so the motor, transmission and transfer case has very little movement..also have the block off plate and plug for the EGR. Just trying to get it done and back on road/trails on a budget..Thanks in advance!

The intake swap isn't worth the aggravation and results.

Exhaust header swap..
 

It looks like the the exhaust header swap is pretty straightforward..thanks for sharing your wisdom on the Renix systems, it's helped me a lot since I got my 1990 XJ..