2.2 to 2.5 tbi

[srt-rex]

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?

[estilljoe]

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.

[capev86]

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!

[DaytonaTurbo87]

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).

[22dodge]

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

[srt-rex]

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?

[22dodge]

Quote:

Originally Posted by srt-rex 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

[DaytonaTurbo87]

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.

[srt-rex]

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.

[capev86]

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

[DaytonaTurbo87]

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.

[srt-rex]

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.

[srt-rex]

hopefully

[Lone Eagle]

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.

[william]

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.