AMC-MJ Posted January 18, 2011 Share Posted January 18, 2011 What is available for rebuilding/building up such an engine ? . . ? Can the compression be increased ? With out affecting the TBI system ? Mike Link to comment Share on other sites More sharing options...
Incommando Posted January 19, 2011 Share Posted January 19, 2011 You can get them to make several hundred horsepower; all it take's is cubic dollars. that engine is pouplar in some NHRA classes. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 I know its the quickest 4 banger truck I have owned but I never thought of it as racing mill, but giving its 20-30hp jump on the big 3s big 4s I guess it all make sense. I was wondering about rebuilding it and keeping it around just in case I wanted to use it again. Mike Link to comment Share on other sites More sharing options...
jimoshel Posted January 19, 2011 Share Posted January 19, 2011 Just because a motors a 4 cylinder doesn't mean it's a dud. The old Offenhausers did a pretty impressive job making horsepower and speed on the bricks. Indy 500. Link to comment Share on other sites More sharing options...
Automan2164 Posted January 19, 2011 Share Posted January 19, 2011 IIRC, someone here found an RV cam and is running it in his, but I think the cam is discontinued. Rob L. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 I love my 2.5er once I repower my Manche, I would like to keep the 2.5 around maybe I'll get or build another MJ or I could repower another brand with my AMC big 4 popper ! ! ! Mike Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 19, 2011 Share Posted January 19, 2011 There are a few companies that make headers, and Clifford performance makes an intake manifold that a 4 bbl carb can be attached to, or a custom fuel injection system, which they also sell. Cams have been the stopping point at least for me. I have been so far unable to find ANYONE listing performance cams for them anymore. Someone here recently said that he had one reground at a local shop, so that might be your best bet... call around to the speed shops and see who in your area does that kind of work. Add all that to a port and polish, and maybe a maximum overbore and pistons, youd be good to go. Link to comment Share on other sites More sharing options...
Incommando Posted January 19, 2011 Share Posted January 19, 2011 A web search turned up a ton of links in a few seconds. Here is a good one: http://www.4x4wire.com/tech/clutch/inertiaring/ The old 225 odd-fire V6 was impessive in part due to its unusually heavy flywheel. It made the tq more usable and the engine harder to stall due to the greater inertia. This may be a solid upgrade. A 4.0 throttle body swap is also said to be good for a few real world HP. The ultimate on a streetable jeep may be the supercharger if it is still available. As always, the best boost in performance is probably optimizing gear ratios for a balanced package in relation to rpm band/tranny/x-fer/gear ratio/tire size. Playing with those numbers through one of the many online calculators can give you the info to build the best combo. Here is a good one: http://www.grimmjeeper.com/gears.html Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 19, 2011 Share Posted January 19, 2011 A web search turned up a ton of links in a few seconds. Here is a good one: http://www.4x4wire.com/tech/clutch/inertiaring/ The old 225 odd-fire V6 was impessive in part due to its unusually heavy flywheel. It made the tq more usable and the engine harder to stall due to the greater inertia. This may be a solid upgrade. A 4.0 throttle body swap is also said to be good for a few real world HP. The ultimate on a streetable jeep may be the supercharger if it is still available. As always, the best boost in performance is probably optimizing gear ratios for a balanced package in relation to rpm band/tranny/x-fer/gear ratio/tire size. Playing with those numbers through one of the many online calculators can give you the info to build the best combo. Here is a good one: http://www.grimmjeeper.com/gears.html The 4.0 throttle body will only work on the port injected models, I think the same goes for a throttle body spacer too. Though a homemade throttle body spacer might work. But as I saw it in my truck, there is only about a 1/2"- 3/4" of clearance between the throttle body topper and the hood, so that might be a problem too. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 What I was thinking how "primitive" this EFI is pre OBD-1 as I'm told cause nobody can libk to it aka plug in to it. Could it be bored .030 over and the compression increased from 9.2:1 to 10.0:1, then port n polish the head put it back together and have it run on the OEM injection system ? Mike Link to comment Share on other sites More sharing options...
streetjeep2.5 Posted January 19, 2011 Share Posted January 19, 2011 Delta Camshaft Co. in Tacoma, WA makes a regrind with more lift and duration for the 2.5, but not a real hi-performance one. When I rebuilt my 87 2.5 in 2007, I added a Delta cam and a header from Clifford (they quit making the header). I had a single in dual out Flowmaster also. Nothing more done, but just that really livened up the 2.5. After about 30 to 40 thousand miles on the engine, in my short box 4x2 4speed with no ps or ac, without power shifting and burning out I was doing 0-60 in under 10 seconds. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 My truck is Configured 2.5/AX-4/D35 with 3.73s, it hasn't had any power issues til recently but its got 197K miles and counting, This truck is a shortbed 2wd :-) Like I said this MJ is getting repowered still doing the AMC-290 V8/AX-15 5spd/D44 with 4.27s combo . . . So for now once the 2.5 comes out it'll get moth balled. Til I find a chassie to put it in :) ! I am thinking an AX-5 / 4.10 combo will be used behind the 2.5er in its next life. I figured being that I will have to rebuild it any way why not "tweak" it a bit while its apart ? So bore it 30 over, bump up the compression, and open up the head some ect. I would like to know how these mods will effect TBI system ? I'm assuming the EFI can be separated from the truck harness ? Mike Link to comment Share on other sites More sharing options...
Incommando Posted January 19, 2011 Share Posted January 19, 2011 Need D44 4.27's? :brows: Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 Well I wanted the AMC-20 with 4.10s, but I figured with the D44 then I could go with 4.27s. I could use an MJ 44 and 4.27s ;-) ! Unless you got an MJ AMC-20 with 4.10s that may get a set of AMC 4.44s ;-) ! But I got more to do before I get a rear end Mike Link to comment Share on other sites More sharing options...
dasbulliwagen Posted January 19, 2011 Share Posted January 19, 2011 To raise compression, all youd have to do is have the head shaved, but then youd need to make sure you have valve clearance, and to do that, youd need to have your finish build camshaft in it. As for the injection, I have no idea, I doubt anyone has any idea about that. That system works off throttle position, and O2 signal for mixture, so I would guess that it would, but I really don't know for sure. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 19, 2011 Author Share Posted January 19, 2011 Ok, because I had a friend rebuild a fuel injected 350 for his truck and he increased his compression from 9.3:1 to 10.1:1. It set off his "knock sensor" which retarded his timing as it thought it was pinging . . . So I wasn't sure if this EFI system was as sensitive ? Mike Link to comment Share on other sites More sharing options...
wallisek Posted January 20, 2011 Share Posted January 20, 2011 I had my cam reground but don't know the lift or duration. I just told the shop I didn't want anything crazy that was going to throw off my idle or require special machining and parts for the head. As for mods, I've heard putting a 4.0 intake on the MPFI models can give you a boost. The 4cyl isn't a bad little engine but the fact of the matter is this. It is 4 cylinders moving a 4000+ lb vehicle. As others said, gearing I think would be the best investment. Clifford header would be nice if you have the extra cash. Link to comment Share on other sites More sharing options...
AMC-MJ Posted January 20, 2011 Author Share Posted January 20, 2011 4,000LBs ! ? ! Some how I don't my short bed 2WD Comanche weighing no 4K-lbs . . . The GVWR is 4,550lbs the pay load is 1,475lbs . . . Your talking a 3,100lb truck ;) ! Now like I said this truck is not the unit in which the 2.5er will be used its just currently pushing it around for now ;-) ! I just like this 4 banger enough to rebuild it and reuse it in another Rig. Mike Link to comment Share on other sites More sharing options...
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