Dogote Posted November 8, 2017 Share Posted November 8, 2017 My 1986 2.5, 5 speed Comanche is running pretty good now for a Renix 2.5. About all that wrong now is a quick cough or two when its cold, and I think I have that figured out now. But, the 2.5 is old and worn. It will only get worse. I am considering overhauling it, the parts kits seem cheap. But, then I have a overhauled pushrod 4 cylinder with one of the worst fuel injection systems I have ever dealt with. As I think about other engines I could swap into the Comanche, I keep thinking about the Ecotec's. They have a lot of after market support, they are getting used in everything, Off road racers, autocross cars, rock crawlers......... I would most likely just buy a wreck with the engine I need. Upon looking at eBay and Craigslist, there are several possibilities out there for cheap. Another idea. Find a wrecked JK, and put as much of it's drive train and electronics in the Comanche as possible. Link to comment Share on other sites More sharing options...
Pete M Posted November 8, 2017 Share Posted November 8, 2017 what size tires and what gears in your axles? Link to comment Share on other sites More sharing options...
Dogote Posted November 8, 2017 Author Share Posted November 8, 2017 Since it is an '86 four cylinder MJ, I gather from searching this, and other forums that it is probably 4.10:1, but I have not verified that. I just took off 265/70/15's on aftermarket wheels and put on stock wheels with stock sized 215/80R/15 studded snow tires. It it much nicer to drive with the small stock tires. Ideally, I would like to put it on 255/75/17 or similar height/width. What would my tire size and gear ratio have to do with doing a drive train swap? Link to comment Share on other sites More sharing options...
Pete M Posted November 8, 2017 Share Posted November 8, 2017 because in the world of Jeeps the most common reason for an engine feeling old and tired is owners that go with bigger tires without regearing. it is my go-to question each time. I've seen a stock 2.5Ls do burnouts with 38s. (I think that particular Jeep had 5.86s or some such thing) Link to comment Share on other sites More sharing options...
WyoCherokee Posted November 8, 2017 Share Posted November 8, 2017 It all comes down to how much work you want to do, and how much wiring you want to mess around with. The 2.5 is a punchy little engine, and very reliable. If you are going to rebuild it, look into a bore and stroke while you are at it. a couple folks on here have done it and love the results. Of course you can swap in an ecotec, but you are still sitting with a 4 cylinder and having to adapt the renix harness to the ecotec controls. your best bet if you are dead set on yanking the little 2.5 is to find a donor cherokee with a 4.0, and just swapping everything over. it will be cheaper and easier in the long run. Link to comment Share on other sites More sharing options...
Dogote Posted November 10, 2017 Author Share Posted November 10, 2017 Yeah, I have came to my senses. As far as the amount of work, I have done that much work, many times. I really don't want to much that much effort into a 30 year old pick up truck. But........... I would not keep much of the factory harness. I would use most of the donor vehicles harness. I wouldn't use any of the Renix system on a different engine. What would be the point? The engine feels old and tired, because it is. Too much leak down around the rings is the issue here. I think I was leaking nearly 15% at 80 PSI, cold engine. No valve loss, due to a recently installed new head, but the rings are shot. No oil leaks anymore though, fixed all of them. I think I'll stick to the "normal" plan, just pulling the engine and doing an overhaul. I'm sure it will be just fine with the 2.5. Who make bigger bore/stroked cranks? All I find online is 505 performance. Their stuff looks okay, but they have a horrible reputation on the internet, especially in the JK world. Link to comment Share on other sites More sharing options...
Pete M Posted November 10, 2017 Share Posted November 10, 2017 might want to start a new thread for that so more will notice it Link to comment Share on other sites More sharing options...
johnj92131 Posted November 10, 2017 Share Posted November 10, 2017 Rebuilding the stock engine makes the most sense to me. Both in terms of work required and reasonable expense/bang for the buck. Looking for more power out of the 2.5? I would look at a supercharger. But that would put your $$ cost right back to what you would spend for a EcoTech factory turbo engine. And with the factory EcoTech turbo, all the engineering has been done by the factory. Link to comment Share on other sites More sharing options...
Dogote Posted November 11, 2017 Author Share Posted November 11, 2017 18 hours ago, johnj92131 said: Rebuilding the stock engine makes the most sense to me. Both in terms of work required and reasonable expense/bang for the buck. Looking for more power out of the 2.5? I would look at a supercharger. But that would put your $$ cost right back to what you would spend for a EcoTech factory turbo engine. And with the factory EcoTech turbo, all the engineering has been done by the factory. I don't really care about bang for the buck/effort involved that much. It is more about doing a project like this. I have never added a turbo to anything. I have also never put an engine into a car it didn't belong in. It is all about the project to me. What I have done that makes me think I can do something interesting to the Comanche: rebuilt/modified 100's of new or nearly new Ducati motorcycle engines for customers. fully disassembled, inspected, and modified several turbine helicopters. (and put them back together and flew them) restored, maintained, inspected, and modified 100's of airplanes restored several cars restored dozens of motorcycles. I have tools, a shop, and an old Comanche. If not the Comanche, I'll do a homemade turbo set up in something else. I am kind of back to turboing the 2.5. I've been looking at Megasquirt injection to help with fueling. I don't care if it is fast, has as much power as a small block chevy, or is that reliable. Link to comment Share on other sites More sharing options...
Pete M Posted November 11, 2017 Share Posted November 11, 2017 I like where this is going Mnkyboy put a supercharger on his 2.5L. should be way at the back, like page 22 or so. Link to comment Share on other sites More sharing options...
johnj92131 Posted November 11, 2017 Share Posted November 11, 2017 A turbo 2.5 should be very interesting!! Any number of recent VNT turbos out there that will support a great low end response and nice top end. For the he street, a smaller turbo is a better choice. Link to comment Share on other sites More sharing options...
carnuck Posted November 12, 2017 Share Posted November 12, 2017 Going later MPFI will help powerwise too and especially if you go HO throttlebody off a 4.0L (if you can stand the noise) with the performance injectors people run in stroker 6 cyls. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Jeep Driver Posted November 12, 2017 Share Posted November 12, 2017 The ecotech is a transverse engine, the engine mounts would be the easiest part of the swap. What did you plan for a transmission? 2x or 4x? Where's the starter? What did you plan for the adapters? can you make your own? If you plan a turbo on the 2.5, are you going to make your own exhaust manifold? Where are you going to place the turbo? How do you plan on plumbing exhaust? Intercooler? How are you going to evacuate heat? How will you control timing? Are you starting with a new 2.5? (My opinion)- 2.5 clap-out by 100K miles, look to rebuild first. I've yet to see, I won't do it, but your best bet would be a centrifugal supercharger. I know it's not a matter of -bang for buck- with you, however, there is nothing worse than putting a ton of effort into something and then realize it's for not. If you can control fuel and spark............centrifugal, expensive. Anything else with the 2.5/4.0 is a waste of time, IMO. Link to comment Share on other sites More sharing options...
Dogote Posted November 12, 2017 Author Share Posted November 12, 2017 8 hours ago, carnuck said: Going later MPFI will help powerwise too and especially if you go HO throttlebody off a 4.0L (if you can stand the noise) with the performance injectors people run in stroker 6 cyls. Sent from my iPhone using Tapatalk I think going to MPFI is the next step with this engine. I have been reading as many threads as I can find to see what others have done. Not a lot out there, at least no any renix to mpfi threads that go anywhere. Link to comment Share on other sites More sharing options...
Jeep Driver Posted November 12, 2017 Share Posted November 12, 2017 2 minutes ago, Dogote said: I think going to MPFI is the next step with this engine. I have been reading as many threads as I can find to see what others have done. Not a lot out there, at least no any renix to mpfi threads that go anywhere. http://www.naxja.org/forum/showthread.php?t=1144729 Go here...........MPI............nothing but complaints there too. Link to comment Share on other sites More sharing options...
Pete M Posted November 12, 2017 Share Posted November 12, 2017 renix to mpi is straightforward enough. you need an 91+ 2.5L XJ and then swap it all over. Link to comment Share on other sites More sharing options...
Jeep Driver Posted November 12, 2017 Share Posted November 12, 2017 10 minutes ago, Dogote said: I think going to MPFI is the next step with this engine. I have been reading as many threads as I can find to see what others have done. Not a lot out there, at least no any renix to mpfi threads that go anywhere. I'll leave you with this thought- I married Chryco with Renix, I'm the only one to do it as far as I know with the 2.5. Again, -IMO-, the MPI intake is perfect for the 2.5, great flow, uniform runners, longer runners. You'll want air/fuel to mix at the plenum, not at the intake port. If you are going to turbo/supercharge look to mega-squirt and use the MPI intake. You'll have to plug the injector holes. Link to comment Share on other sites More sharing options...
mnkyboy Posted November 12, 2017 Share Posted November 12, 2017 My MJ is MPFI converted and supercharged, Pete posted a link to my build. The MPFI conversion is pretty straight forward and pretty similar to a 4.0l HO swap. Link to comment Share on other sites More sharing options...
carnuck Posted November 13, 2017 Share Posted November 13, 2017 I won’t be supercharging, but I will be getting a 2.5 from a ‘99 TJ and the MPFI manifold comes with it along with the tone ring flywheel (it came from an LS swap). If I could easily do the harmonic balancer Renix tone ring set up then I could go HO later on but I need 4x4 ASAP as a storm is breaking and hopefully everything is fine with gusts of wind from 50 steady to 70mph like the storm that crushed my neighbor’s place with a 5’ diameter tree. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Dogote Posted November 13, 2017 Author Share Posted November 13, 2017 9 hours ago, carnuck said: I won’t be supercharging, but I will be getting a 2.5 from a ‘99 TJ and the MPFI manifold comes with it along with the tone ring flywheel (it came from an LS swap). If I could easily do the harmonic balancer Renix tone ring set up then I could go HO later on but I need 4x4 ASAP as a storm is breaking and hopefully everything is fine with gusts of wind from 50 steady to 70mph like the storm that crushed my neighbor’s place with a 5’ diameter tree. Sent from my iPhone using Tapatalk There is a storm breaking? Looks like you must be near Monroe/Sultan area. I am all too familiar with the area. I drive Stevens Pass at least once a month, usually at night, and often in a storm. Link to comment Share on other sites More sharing options...
Dogote Posted November 13, 2017 Author Share Posted November 13, 2017 On 11/12/2017 at 7:35 AM, Pete M said: renix to mpi is straightforward enough. you need an 91+ 2.5L XJ and then swap it all over. I know a local guy who may have "blown up" his 2.5 YJ. I think he has a '93. I also think he just blew the head gasket. I heard he was pulling the 2.5 and dropping in a small block Chevy. I find out what he is doing with the '93 YJ stuff. I wonder if there is anything he will need to his SBC install, that I would also need to use from his MPFI? Link to comment Share on other sites More sharing options...
mnkyboy Posted November 13, 2017 Share Posted November 13, 2017 The YJ stuff will work, but you will probably want a different wiring harness, you will also need a 91/92 MJ fuel pump and sending unit. You could make the YJ harness run stand alone but it will be much easier if you can find a 91 up 2.5l MJ or XJ harness. I ran 95 YJ stuff on my 89 MJ long block with a 91 MJ harness. Link to comment Share on other sites More sharing options...
Crash Posted November 14, 2017 Share Posted November 14, 2017 SBC.. Or even better LS swap. Otherwise, a potentially less expensive simpler swap, 4.0. Link to comment Share on other sites More sharing options...
Dogote Posted November 14, 2017 Author Share Posted November 14, 2017 9 hours ago, Crash said: SBC.. Or even better LS swap. Otherwise, a potentially less expensive simpler swap, 4.0. I really want to keep a 4 cylinder in it. Link to comment Share on other sites More sharing options...
mnkyboy Posted November 15, 2017 Share Posted November 15, 2017 2.5l turning 37s at only 3psi. Link to comment Share on other sites More sharing options...
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