intake swap Questions

[cruiser54]

good info there Cruiser. Did you really think that the manifold upgrade was worth it without the upgraded head?

I think it would be much more beneficial to just swap an HO head and the HO manifolds, you would pick up that extra flow and the better manifolds. Personally, if I was going to be swapping manifolds I'd take the head off anyway and go do it on my workbench. I've not had to deal with mine yet, but it looks like it would be a PITA to do all of that in the engine bay.

I didn't upgrade the manifold, and no I don't think manifold swapping is worth it. These are inline sixes for crying out loud. . I port matched a Renix intake to an HO head. I don't see where much performance comes from the head anyway. MAYBE some at the top end? The point I'm trying to make is that the HO head is getting way too much undeserved credit for the horsepower increase when there were other things done to the engine at the same time which actually contributed more if you add them up. Get rid of the "crush spot" in the exhaust which restricts the downpipe by almost 40%. Put a much better flowing exhaust manifold on. Increase throttle body size from 52mm to 58mm. Use a better injection system. That's where the power came from. I have upgraded my 90 Renix in steps, but still have the original exhaust manifold. Got rid of the "crush spot". Then installed the 60mm throttle body. Then used 19# injectors. Very nice incremental improvements each time a mod was done. On my 88, I installed an HO, used the 60mm throttle body and 19# injectors. I also used the HO exhaust manifold which automatically gets rid of the "crush spot". The vehicles run about equal with the 88 having a slight advantage even though it's got 31" tires compared to stock on the 90.

 

[87manche]

OK, I misread, I thought you put the HO intake on a renix head.

 

[cruiser54]

OK, I misread, I thought you put the HO intake on a renix head.

No big deal. You prompted me to vent and dispel a few myths. It's all good.:cheers:

 

[joe_peters]

After doing the HO Tb modification, would I be able to use a newer air intake kit say from K&N? Doing a custom snorkel so not too relevant for me, but would be nice to know if I ever need to remove the snorkel or do another Jeep... Thanks,

Paint

Yeah, once you have a HO throttle body on there you won't be able to use the old Renix tube.

 

[Paintballpsyco2369]

I didn't upgrade the manifold, and no I don't think manifold swapping is worth it. These are inline sixes for crying out loud. . I port matched a Renix intake to an HO head. I don't see where much performance comes from the head anyway. MAYBE some at the top end? The point I'm trying to make is that the HO head is getting way too much undeserved credit for the horsepower increase when there were other things done to the engine at the same time which actually contributed more if you add them up. Get rid of the "crush spot" in the exhaust which restricts the downpipe by almost 40%. Put a much better flowing exhaust manifold on. Increase throttle body size from 52mm to 58mm. Use a better injection system. That's where the power came from. I have upgraded my 90 Renix in steps, but still have the original exhaust manifold. Got rid of the "crush spot". Then installed the 60mm throttle body. Then used 19# injectors. Very nice incremental improvements each time a mod was done. On my 88, I installed an HO, used the 60mm throttle body and 19# injectors. I also used the HO exhaust manifold which automatically gets rid of the "crush spot". The vehicles run about equal with the 88 having a slight advantage even though it's got 31" tires compared to stock on the 90.

You mention using a different exhaust manifold, is that something I could just get from a newer model XJ and put on my '88? Or is there fitting of some sort required?

Yeah, once you have a HO throttle body on there you won't be able to use the old Renix tube.

Oh, so I would have to upgrade the air box as well anyways? Would be glad to do that, planning to use that box as part of my snorkel modification so I guess I would have to do it. After finding this thread now I think I am going to get a throttle body from a HO XJ, make the adapter plate for my '88 Renix and get or make a t-body spacer to use the the HO t-body. Then just put in the air box and do the snorkel mod the was I was going to. I am liking the idea of the exhaust manifold upgrade as well, if it's like a bolt on upgrade...

Paint

 

[cruiser54]

You mention using a different exhaust manifold, is that something I could just get from a newer model XJ and put on my '88? Or is there fitting of some sort required?

I used a 1992 HO exhaust manifold. You need a new headpipe made with an O2 sensor bung in it. $50. For eGR, you can have a bung welded to the manifold to adapt that.




Oh, so I would have to upgrade the air box as well anyways? Would be glad to do that, planning to use that box as part of my snorkel modification so I guess I would have to do it. After finding this thread now I think I am going to get a throttle body from a HO XJ, make the adapter plate for my '88 Renix and get or make a t-body spacer to use the the HO t-body. Then just put in the air box and do the snorkel mod the was I was going to. I am liking the idea of the exhaust manifold upgrade as well, if it's like a bolt on upgrade...
You don't have to adapt anything if you get the 60mm bored out throttle body. Bolt on with new gasket, adjust TPS, and go. Besides, it's 2mm bigger than the HO throttle body and only costs $90 from www.strokedjeep.com.
Paint

 

[cruiser54]

At least on the 95, 96, and 97 I've checked out, that crush was still there and at stock height, the front driveshaft will still "self-clearance" a pipe without it. Tested this personally... Not really relevant to the Renix-HO head discussion, but I wanted to point that out. Lifted and bump-stopped, it might not be an issue.

I had a new headpipe made with an O2 sensor bung so I guess I missed that the "crush spot" was in the 91. Yu can still have the "crush spot" eliminated by having a muffler shop make a different downpipe with better routing. I did that on the 90.

 

[Paintballpsyco2369]

cruiser54

I used a 1992 HO exhaust manifold. You need a new headpipe made with an O2 sensor bung in it. $50. For eGR, you can have a bung welded to the manifold to adapt that.
||
You don't have to adapt anything if you get the 60mm bored out throttle body. Bolt on with new gasket, adjust TPS, and go. Besides, it's 2mm bigger than the HO throttle body and only costs $90 from www.strokedjeep.com.

I am not too familiar with engine modifications yet, but working on it. I thought the exhaust manifold was all one piece? is the headpipe like the first "exhaust hole" from the engine? What exactly is a eGR?

I would rather adapt to a newer body honestly, I emailed the guy there earlier today and it is just too much for me with shipping and the core charge and such. I can make an adapter plate myself, and do the rest of the modifications to the t-body myself. I can also then bore out the new body bigger, and buy a standard (or make one) t-body spacer. I have yet to see a t-body spacer for anything older than a '91 so by upgrading I get the standardized t-body, and a bigger bore and a lot more options and better flow.

Paint

 

[cruiser54]

How are you gonna modify the TPS? The downpipe is the first pipe that is bolted to the outlet of the exhaust manifold.

 

[87manche]

How are you gonna modify the TPS? The downpipe is the first pipe that is bolted to the outlet of the exhaust manifold.

there;s a how to in the old XJ files, and you can find that info elsewher eon the net. It takes a dremel and some spacers but you can rig the renix TPS to the HO intake. Hesco makes a spacer kit to to adapt them, but it's $150.

 

[Paintballpsyco2369]

How are you gonna modify the TPS? The downpipe is the first pipe that is bolted to the outlet of the exhaust manifold.

Going to make the spacer plate that this guy did:

You can make a spacer plate to put the HO throttle body on the Renix intake: http://www.rockmodified.com/Tech/TB/tb_perf.htm

He has info on how to adapt the tps in there as well so I am planning on doing that.

Oh ok. I will have to see if the muffler place can just do that when they do my exhaust. I still may end up doing my own, but if the price isn't too bad I will just take it somewhere. Easier except it will need to be trailored...

there;s a how to in the old XJ files, and you can find that info elsewher eon the net. It takes a dremel and some spacers but you can rig the renix TPS to the HO intake. Hesco makes a spacer kit to to adapt them, but it's $150.

You say "old XJ files", where might this location be to search that? For $150, I will pass lol. Doing this on the cheap, and I can just as easily make that spacer plate out of aluminum. Is also just so happens that I have a perfect size plate in my garage scrap pile and it would be pretty easy to make. The hardest part will be all the little odds and ends in the rest of that link. I can do it no problem, will just take some time. Then also, I will be able to just buy a regular t-body spacer.

Paint

 

[truck7575]

Ok, here is the other end, I have an exhaust header that I bought used from someone. I realize the intake ports changed over the years but what about the exhaust ports? My head is to an 88 with the renix system but I am not sure about the header as far as which head it is made for, or does it matter?

 

[75SV1]

Is this a stock header or an aftermarket header? With a stock header, I have heard there may be problems with 91+ factory headers. I think the dowel pin location holes are higher or lower. With an aftermarket header, the header tubes are a bit larger, so the cover the exhaust port on both types of heads. I'd take your intake/exhaust gasket and fit it to the header you have. If the ports fit the header, with the dowel pin holes loctated, then your good to go.

Tom

 

[joe_peters]

The locating dowels are for the intake.

Exhaust headers for the 4.0 will fit on all years with only ONE issue--87-90 4.0s have the EGR system and the o2 sensor located in the header. This issue can be overcome by welding in two bungs to the 91+ headers.

Good luck.

 

[Paintballpsyco2369]

I have been wondering about this for some time, the exhaust headers I mean. Would be one other nice upgrade I can do for my 88 lol. Were there any other modifications other than the bungs that need to be done to get the header to fit?

 

[truck7575]

yeah, the header has two bungs welded into it already. Could anyone tell he how to add a picture to a post. like I am responding to this with a post and I want to put a picture of the header. I am sure its really easy just for some reason I don't know how.

 

[truck7575]

Here is a picture of the header, anybody know what brand or who made this header? Is it stock or aftermarket?

http://sphotos.ak.fbcdn.net/hphotos...453746556683_1623891907_1068103_5975327_n.jpg

 

[joe_peters]

If that isn't OEM I will come to your house and eat prime rib and drink beer.

Looks just like mine on the 90.

 

[cruiser54]

I've got a cracked one just like that, using it as a wheel chock for my donor Jeep. Joe, what's your favorite beer, and is medium rare okay?

 

[joe_peters]

I've got a cracked one just like that, using it as a wheel chock for my donor Jeep. Joe, what's your favorite beer, and is medium rare okay?

Stuck on Dos Equis for awhile and anything with "rare" in it's name is fine.