Common Block

[bdub840]

I've been trying to do some research on the CB. I have a few questions though. I know the 2.2 is good for top end power and the 2.5 is good for low end. My question is they started making these blocks in 89 so I can swap any 2.2/2.5 cb in my 86 omni? I'd rather buy a turbo block opposed to the N/A. Is it a direct bolt in? I was wondering what is the big difference b/w balanced and unbalanced crank? Which one is better? I know this has probaly been asked before but I can't find any good threads on it. Also did the daytona/lebaron only have the 2.2 cb? I want to get a good platform for hp. Any help would be greatly appreciated.


Thanks

[Koreth]

The common block was used in 89 and on up for both 2.2 and 2.5 enignes. The only main difference I know of between an N/A common block and the turbo version of the common block is they have the holes drilled and tapped for the oil feed and oil and coolant drainback lines for the turbo. The coolant feed for the turbo is fed off the waterbox on the head.

Yes a common block will bolt up to your omni, you will simply need to use the correct mounts (which were the same from 82-89, than different for 90-95 I believe, somebody correct me if I am wrong)

I haven't heard anything about an unblanced crank, do you mean the difference between one balanced by a machine shop or using a stock crank? From what I have read on here, crankshafts come pretty well balanced from the factory.

Go to www.turbododge.com and read the turbo database. Lots and lots of good informatino on that website.

[bdub840]

Quote:

Originally Posted by Koreth I haven't heard anything about an unblanced crank, do you mean the difference between one balanced by a machine shop or using a stock crank? From what I have read on here, crankshafts come pretty well balanced from the factory. Go to www.turbododge.com and read the turbo database. Lots and lots of good informatino on that website.

Well I was talking to someone about this swap and they acted like their was a difference b/c the 89+ had balanceshafts. What exactly does that mean? I figured since that was stated their was a difference.

[bdub840]

Quote:

Originally Posted by Koreth Go to www.turbododge.com and read the turbo database. Lots and lots of good informatino on that website.

Do you mean www.thedodgegarage.com ?

I've read it a few times (turbo database)

[cawcislo]

I've done a common block swap into my 87 shelby daytona. The block was an 90 N/A block. There is already the coolant return tapped in the block, it's just plugged with a bolt. You would have to drill an oil return hole in the block and the only other difference between turbo and non turbo blocks is turbo blocks were cross drilled. I drilled these 3 holes myself. You can take a headgasket to get your started where the holes go, then drill on a 45 degree angle but be careful to go straight inbetween each cylinder, or get a machine shop to do it for you. Other than that all common blocks are the same.

[Koreth]

starting in '89 (first year of the common block) the Turbo 1 was a 2.5L engine instead of the 2.2's used previously. the 2.5's did have balance shafts, these are a pair of rotating weighted shafts powerd by a chain run off the crank. These were to cancel the vibraions put out by the 2.5L engine, which does tend to vibrate a little more at idle than the 2.2L. Most people remove these shafts for the horsepower freed up by not running the shafts (about 10hp).

They do not have anything to do with the balance of the crankshaft.

[bdub840]

oh ok I was really confused. So what you are saying is I can take off the balance shafts and get 10 more hp out of the 2.5? Opposed to the 2.2 that doesn't have these. Is this hard to do? Or would I be better off getting a 2.2?

[Koreth]

Do a search on this board for "removing balance shafts" or "balance shaft removal" or something of the sort, you'll find a few really good threads regarding it. One thing that is very important to remember is that if you remove the balance shafts, you MUST plug or block the oil feed hole for the shaft assembly somehow, otherwise you will have oil pressure loss and you will fry your bearing in short order.

As for which engine is better, that is really a matter of preferene. The 2.5 will produce lots of torque at lower RPM, but tend to run out of breath sooner on the high end. The 2.2 can spin a little faster and still make power, but does not have as much torque on the low end as the 2.5, although it is a plenty torqey motor in itself. There have been many threads on this topic, a seach should reveal them. There is also a thread at the top of this particular section which has links to some of them.

[Daytona5spd]

I thoughs all the common blocks were cross drilled. Like all the heads on the common block are cross drilled. Correct me if I a wrong.

Steve

[bdub840]

Quote:

Originally Posted by Koreth As for which engine is better, that is really a matter of preferene. The 2.5 will produce lots of torque at lower RPM, but tend to run out of breath sooner on the high end. The 2.2 can spin a little faster and still make power, but does not have as much torque on the low end as the 2.5, although it is a plenty torqey motor in itself. There have been many threads on this topic, a seach should reveal them. There is also a thread at the top of this particular section which has links to some of them.

I know this I just wanted to know if it was a direct swap & the balanced shafts difference.