89 2.5 converted to t2. Can I use t2 smec?

[neongary]

OK, I know this was asked before, but my combination is a little different. I am still going to use the automatic trans, but also have +20% injectors. Will this work properly with the '89 TII SMEC? Everything else is '89 T2 correct (intercooler, turbo, etc.)

[cordes]

No. The timing and fuel will be off for the 2.5. Just use the 2.5 SMEC.

[turbovanman²]

And don't use +20's on a stock 2.5L computer, it will be pig rich.

[neongary]

And don't use +20's on a stock 2.5L computer, it will be pig rich.

Damn, OK. I could have sworn somewhere I read that using a +20's on a 2.5 with a TII SMEC would be "just right" with regards to fuel requirements.

---------- Post added at 09:08 AM ---------- Previous post was at 09:01 AM ----------

Ah, it was from Gary Donovan's web site:
2.5 engine with 2.2 computer and 42 pph injectors.
Ahh the one special case! Mopar Performance sells a 42 pph injector- It flows exactly 20% more then a stock 33 pph injector used in the 2.5 engine. Now from what I understand the 2.5 is 11% larger in displacement then a 2.2 BUT it's fuel curve is 17% larger... so what does all this mean? If you install a Turbo II 2.2 computer on a 2.5 engine the calibration will be 17% lean... unless you install a the 20% larger 42 pph injectors at the same time! This is the setup I ran on my K-car and it works pretty well and the extra 3% of fuel will get you up to 16-17 psi. Some cars seem to need a little tweaking with the fuel pressure and others have no problem at all. This of course lets you swap a 2.5 into a car like a GLHS that never had a 2.5 computer available for the application from the factory... you get the idea..

[cordes]

Guys did stuff like that back when and got away with it for a while. Some even had good success with it. There's no reason to toast an engine over a cal these days though. You can make your own or have Shelgame do it for cheap.

[Orangetona]

Guys did stuff like that back when and got away with it for a while. Some even had good success with it. There's no reason to toast an engine over a cal these days though. You can make your own or have Shelgame do it for cheap.

Yeah, I agree. With the advances we've had theres no point in risking that. Not to mention, idk anyone whos actually ran a 2.2TII cal with a 2.5. I'd say just because Gary did it doesnt mean it would work on all accounts. Even still, injectors dont always flow the same amount. If ones a little funky, who knows, could go boom.

[cordes]

Yeah, I agree. With the advances we've had theres no point in risking that. Not to mention, idk anyone whos actually ran a 2.2TII cal with a 2.5. I'd say just because Gary did it doesnt mean it would work on all accounts. Even still, injectors dont always flow the same amount. If ones a little funky, who knows, could go boom.

The timing is the real problem IMO. Vastly different curves between the 2.2 TII and 2.5 TI cals. Add in the fueling differences and, wowza that could be an issue.

[neongary]

OK thanks guys. Guess I'll just go with a cal custom made for my application to be on the safe side.

[Juggy]

have ran 2.2 TII computers on 2.5 cars with the +20s and all worked well. you still wont get the complete benefit of a custom calibration tho. however it seems that all of these custom cals are EXTREMELY safe and always run rich.....

I think they do this for 2 reasons. 1: to keep the car from blowing up and being risked blame, and 2) to keep the customer coming back so that the programmer has to make frequent changes, which equates to money in hand. with so many setups that have been cloned and tuned, i dont see any reason why people are getting custom cals that only perform a little better then stock when they have already been taken to the extreme in some cases

---------- Post added at 01:09 PM ---------- Previous post was at 01:07 PM ----------

under stock type boost the timing curve is still safe for a 2.5 with a 2.2 curve

its just when you get into the higher boost that the 2.2 will be able to take more timing then the 2.5
when i ran my 2.2 and 2.5 setup with the same top end. the 2.5 timing curve was greater then the 2.2 curve, and they had finally equaled out around 18psi...this is when the 2.5 curve had kept diminishing where as the 2.2 curve didnt drop off as much from this point

[neongary]

have ran 2.2 TII computers on 2.5 cars with the +20s and all worked well. you still wont get the complete benefit of a custom calibration tho. however it seems that all of these custom cals are EXTREMELY safe and always run rich.....

I think they do this for 2 reasons. 1: to keep the car from blowing up and being risked blame, and 2) to keep the customer coming back so that the programmer has to make frequent changes, which equates to money in hand. with so many setups that have been cloned and tuned, i dont see any reason why people are getting custom cals that only perform a little better then stock when they have already been taken to the extreme in some cases

---------- Post added at 01:09 PM ---------- Previous post was at 01:07 PM ----------

under stock type boost the timing curve is still safe for a 2.5 with a 2.2 curve

its just when you get into the higher boost that the 2.2 will be able to take more timing then the 2.5
when i ran my 2.2 and 2.5 setup with the same top end. the 2.5 timing curve was greater then the 2.2 curve, and they had finally equaled out around 18psi...this is when the 2.5 curve had kept diminishing where as the 2.2 curve didnt drop off as much from this point

Thanks for that info. My plan was to keep near stock levels of boost...nothing radical at all. So you are saying that I should be OK with the 2.2 TII computer?

[turbovanman²]

Thanks for that info. My plan was to keep near stock levels of boost...nothing radical at all. So you are saying that I should be OK with the 2.2 TII computer?

I wouldn't and that's saying alot, lol. But its your engine so only you can decide,

[cordes]

I wouldn't and that's saying alot, lol. But its your engine so only you can decide,

That sure is saying a lot! IIRC you need to back the timing off in addition to running the larger injectors. I forget how much is necessary though. It's been a while since I've spoken of this with anyone who's actually done it.

[Juggy]

a buddy in town used to run a 89 TII MP cal, on a 2.5 swirl head engine setup. it was a FM big valve swirl head, ported 2 piece, 52mm, ported exhaust manny, 3" exhaust, first turbo was an MP + series, then went with a T04 with 60 trim compressor wheel and stock clipped turbine in stage 1 .48 housing (very wierd setup), also intercooled. He also had the +20 injectors in there as well, but they were dialed down a few psi as well....that just goes to show that there was still room to play with for fuel

the car pretty much performed the same with either turbo, not much of a difference....but yeah it ran mid 13s at 107 on 15-16 psi boost

[x.Gen]

don't do it! been there (with the +20's). fuel will be OK, but like Cordes wrote timing is (WAY) off. when I did it, I backed the base timing down and it still wasn't right. if you leave the base timing, the stock cal will have to pull timing to keep the knock down under 3000 rpm. finally rolled my own for the 2.5, and WHAT a difference - even out of boost, and especially down low. the mis-matched timing curves kill the torque advantage you get from the 2.5. don't waste your time if you have a choice. not worth the cracked ring lands you'll probably end up with if things go the wrong way for even a split second. read up on the stock 2.5 pistons some if you feel like you have to do it, that should change your mind.

[neongary]

don't do it! been there (with the +20's). fuel will be OK, but like Cordes wrote timing is (WAY) off. when I did it, I backed the base timing down and it still wasn't right. if you leave the base timing, the stock cal will have to pull timing to keep the knock down under 3000 rpm. finally rolled my own for the 2.5, and WHAT a difference - even out of boost, and especially down low. the mis-matched timing curves kill the torque advantage you get from the 2.5. don't waste your time if you have a choice. not worth the cracked ring lands you'll probably end up with if things go the wrong way for even a split second. read up on the stock 2.5 pistons some if you feel like you have to do it, that should change your mind.

Now I'm really confused with the conflicting advise. Anyway, I'm going to be using forged pistons (Wiseco) if that helps.

[tryingbe]

Easy decision. Get the correct calibration for the engine size.

You can do it yourself, pay for one, or just use your stock 2.5L cal with stock injectors.

Buy a wideband so you know what's gong on.

[cordes]

Now I'm really confused with the conflicting advise. Anyway, I'm going to be using forged pistons (Wiseco) if that helps.

I don't think there is any conflicting advice here. Some have said that it can be done, but I don't think anyone has stated it's a good idea.

[GLHS60]

I have used an 88 T-1 SMEC on my 89 2.5 T-1 Caravan and it was fine. I'm not saying you should or should not but I just had to know. Sounds like a doable deal to me. Just curious as to why??

Thanks
Randy

[x.Gen]

it is do-able.
it is NOT recommended (speaking for myself). do you know anyone who professionally tunes? ask them for an opinion independent of mine.

it is the timing curves, at the forefront of the discussion. 2.2 curves are much more aggressive down low; the longer stroke of the 2.5 does not lend itself well to incorrect timing. the WHOLE reason to run a 2.5 (other than the fact it is what you have), is the (low RPM) torque. there are plenty of other reasons, for the sake of driveability - like AIS settings. mixing cals/engines like that will give you small little stumbles here & there, nothing you'll care about if it is your only daily driver and you have no choice. the little mis-steps here & there drove me nuts. even before all the fine tuning I did on the 2.5 tune, the correct cal resulted in noticeably better driveability, and throttle response was night and day in comparison. boost went from being an on/off switch to usable power through the whole curve. can't say it enough - I STRONGLY recommend getting the right cal. I say it any time the subject comes up - I wish someone would have been vocal about this combination before I did it, I'd have never wasted my time.

forged pistons are better - but most will tell you it will only buy you some time in the wrong conditions. besides, going forged is a pretty significant investment. spend the extra $150, you won't regret it.

[turbovanman²]

^^^Well said.