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Discussion Starter · #1 ·
I recently popped a freeze plug in my 88 horizon. I don't think there's any block damage, but its obviously possible. Now I was thinking, if I have to swap in a new short/long block, would a 2.5 be possible to swap in? I would just put it back together like stock, would it run right or is there something I'd have to do to it? Would my 2.2 head work on a 2.5 or would I have to get the 2.5's head and swap on my tbi stuff?
 

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i am running a 90 horizon with a 2.5 dakota engine everyday. i am also running the 2.2 throttle body and computer without problems so far. the only things i have noticed are increased vibration at idle(dakota engine has no balance shafts) and if you hold it down for a little while it seems to lean out some in the upper end. as far as the head it should be the same.
 

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you will need a larger injector in the TB? also consider an 88 computer for a 2.5 car - you will need to be specific on auto vs. 5spd also!
 

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Only differences between the 2.2 TBI and the 2.5 TBI were the computer and the engine stroke. They shared the same everything else. Same throttle body, head, injector, etc etc etc. Everything is the same.

In the common block years, everything was exactly the same between the two other than the pistons and the stroke of the crankshaft. That's it. That's why they called it the 'common block'. In the pre-common block years, the 2.5 did have it's own tall deck block, it's own crankshaft, rods and pistons, as well as it's own timing belt. Other than that, the shortblock itself, every other item was exactly the same between the two.

The computer is the only real difference you should be aware of - be it a logic module, smec or sbec. 2.5's got a different timing curve at part throttle and full throttle. The 2.5 also had a higher fuel curve for obvious reasons. However during part-throttle driving, the o2 sensor can cover the difference, however at WOT a 2.5 with a 2.2's computer would probably run on the lean side. However the TBI engines are so slow there's never a point in going full throttle anyway(this from a tbi owner).
 

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i put a 2.5 inplace of a 2.2 on a 1986 lancer. everthing worked fine and the car ran well for many years, until blazer creamed the front end
 

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Discussion Starter · #6 ·
Thanks for the info guys, I'm considering grabbing a 2.5 CB short block at least, computer, and converting to 5 speed, its an auto now, but I'm not set in stone on this. I think it could be a good durable setup with some added torque. Is the computer just a plug in play set up or is there any rewiring?
 

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Thanks for the info guys, I'm considering grabbing a 2.5 CB short block at least, computer, and converting to 5 speed, its an auto now, but I'm not set in stone on this. I think it could be a good durable setup with some added torque. Is the computer just a plug in play set up or is there any rewiring?
as you were told by someone in this post, the parts between a 2.2 and 2.5 are all the same so just use all the 2.2 electrical parts with the 2.5 short block and everything will plug in... if you want to use the 2.5 computer, it will plug right in. and if you want to be sure, get a service manual and study the wiring schematics between the 2.2 and the 2.5 and verify every wire is in the same locations
 

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Physically and functionally the computers are exactly the same between the 2.2 and 2.5 TBI's. They're just calibrated a little different to optimize the engine they're used on.
 

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Discussion Starter · #9 ·
Okay, that makes sense. Is there any way to recalibrate my stocker or would it make more sense to just get a 2.5? I like this idea, NO WIRING. Maybe I'll have the head decked, port some bits, and open up the exhaust a tad. Maybe even a cam. This sounds fun but kind of cost un-effective at the same time.
 

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easier to get the correct computer than pull yours apart and tap the chip to download a new program.....not worth it on a tbi car and the turbo cars already have support from aftermarket vendors.

just get the correct year/engine/trans tbi computer:
85 dual power/logic module,
86-87 dual power/logic module setup (not compatable with 85)
88-89 smec
90-91 sbec I
92-95 sbec II
 

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Too much info there cape. All he needs to know is he needs a computer (SMEC) from a 88-89 2.5L TBI car with either an auto or a 5sp trans, depending on what you have in your horizon.

That way it's plug and play. However, no other years of computer are compatible, just 88-89.

Your stocker cannot be recalibrated. There is no support for the TBI cars as far as recalibrations go. Also, a 2.5 SMEC can be had for $20 at the local you-pull yard. Having your comp recalibrated(even IF it was doable) would cost close to 10x that.

FWIW, the 2.5 is just as much of a dog as the 2.2 in TBI form. The 2.5's got a little better bottom end, and therefore is better suited to an auto than the 2.2 is. IMO your best bet is to just install a new freeze plug in your 2.2 and spend the rest of the budget converting to 5sp. A 5sp will make 100x more difference than changing from a 2.2 to a 2.5 will.
 

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Discussion Starter · #12 ·
Yeah, I'm just fixing the freeze plug at this point. The current 2.2 is getting tired though at 150k, so I was gathering info for a potential overhaul/replacement and I'm a little intimidated by the turbo swaps. Specifically the wiring. I still have time to make up my mind though, the engine should have a bit left in it.
 

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I've had 2 CB cars now, one 2.2L, one 2.5L. I was able to do a little digging thru the dealer in Tacoma, and you'll need the puter specific for your motor. The 2.2/2.5 have different fuel curves, injector firing rates, spark advance curves, AIS control, ect. in the software. Same goes for an auto/manual puter. You can use an auto puter on a manual, but it will keep looking for certain things, like the lockup solenoid. One BIG difference I noticed after the 5-spd swap(both cars) was with the auto puter, if you pressed the clutch at high RPM(over 2800), the engine would try to hold the RPM at that point for a few seconds. With the manual puter, it was clutch, RPM dropped immediately. Your car being an '88, I'd find an '89 puter. Better diagnostic and drivability software, better fuel curves, ect. This was the only difference between 88 and 89 SMECs. Otherwise, it's plug-n-play. The motor sensors, TBI, wiring harness, ect are the same on both motors.

Oh, and if your car is a Cali car, it will need to be a Cali-specific SMEC. They had the EGR control solenoid, and Federal/Canadian models didn't.
 

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I have run my 92 TBI shadow 2.2 on both 2.2 and 2.5 computers with no difference in performance or economy. The computer has more than enough latitude to adapt the fuel based on O2 readings. That isn't to say that they are the same, only that I noticed no difference in my case.
 

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I have run my 92 TBI shadow 2.2 on both 2.2 and 2.5 computers with no difference in performance or economy. The computer has more than enough latitude to adapt the fuel based on O2 readings. That isn't to say that they are the same, only that I noticed no difference in my case.
IIRC, the '91-up cars software would adapt. Us pre-90 jocks are stuck with this issue....lol
 

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I'm throwing this in here just for grins, giggles, and a "What were you thinking....???" award...

I have a 1988 Dakota that came with a 2.2 Carb engine and a 5 speed. I got the truck for a good deal. It ran like crap. I had the carb rebuilt, performed a major tuneup and other yada, including much research on timing and replacing the timing belt. I got it to run good in the driveway, but not worth a plug nickel on the street. It then developed a knock, so I yanked the engine out and replaced it with... Get this... a 2.2 TBI common block engine out of a 1989 Shadow that had an automatic tranny. I grabbed everything, and I do mean everything. Wiring, computer, the whole kit and kaboodle. I had to get an oil pan, steering pump bracket, exhaust manifold, breather box, gas tank, fuel lines, and other odds and ends, which all came form a 1992 Dakota that had a seized 2.5 TBI with a (missing) 5 speed. After about 50 hours of tedious wiring, I got the original wiring from the bulkhead connector married to the computer. I have been told by many MoPar guys that because of the age, and since the A/T was the original tranny, and yada, yada, ya I should be okay. I have verified that the engine is getting electricity and that the lights, wipers, and all of the other stuff works as it should. As a side note, I had to use the waterpump assembly (not just the replaceable impellor part) from the 88 2.2 along with the 88 alternator bracketry and setup. The trickiest part of all on this swap was drilling and tapping three holes for the motor mounts. A warning to anyone doing the reverse of waht I did. If you get an engine from a truck, you will have three extra mounting holes. Keep the original bolts form the truck application and puth them back in the three holes you do not use. That is, seal up the holes with silicone and torque the bolts down as per the manual. I do know one of the holes on the driver's side (in the truck) goes all the way through the block.

Well, now you know how to build what I have, an 892 Dodge Shakota. If it does not pan out, I will find a bellhousing for a v6 or v8 and put my old Polyhead 318 in the truck!

By the way, I have parts for an 89 Shadow if anyone needs anything. I am also selling the almost complete 2.2 I yanked.

Blessings,
Sasky
BareFoot Soul - A Christian Rock Band
 
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