Turbo and TBI Common Blocks

[Koreth]

I know that past 89, everything used the same block, thus the name common block. My question is though, how different are the TBI and Turbo blocks, and how much work would it take to turn the TBI block into a Turbo one? At the junkyard near my place, turbo dodges are somewhat rare, but there is always at least one TBI car.

Looking to build a new engine for my 87 Shelby Z, I figured rather than trying to recondition the T-2 block, I might as well build up now for the power level I know I am eventually going to want, considering the Daytona's weight.

So, I figure take a 2.2 TBI, keep the cast crank since it is plenty strong and lighter than forged, T-II rods, forged pistons, drill and tap somwehere on the block for the turbo oil line and I'm good, right? Minus machine work, reconditioning of the block, crank or rods or anything like that.

Is there anything I am overlooking, or have incorrect?

[89acclaim]

The late 1990-1995 TBI blocks are cross-drilled according to thedodgegarage. As apposed to the 89 TBI common blocks not being cross-drilled.

Daniel Merrill

[beefalobilly]

Quote:

So, I figure take a 2.2 TBI, keep the cast crank since it is plenty strong and lighter than forged, T-II rods, forged pistons, drill and tap somwehere on the block for the turbo oil line and I'm good, right? Minus machine work, reconditioning of the block, crank or rods or anything like that.

That's exactly what I'm doing, the only difference between a turbo and tbi commonblock is that the TBI has no oil return tube, so I'm drilling and tapping a hole and then running a stainless AN line to it from the turbo.

[Putter]

I used a carb/tbi block and drilled the hole and tapped it out for 3/8" NPT, threaded a cut off pipe into it, it lines up perfect with the turbo and looks just like the factory drain tube, although very strong heh.

[87OmniT2]

You cant use the pistons and rods from a TBI motor though right?

[slasky]

Quote:

Originally Posted by 87OmniT2 You cant use the pistons and rods from a TBI motor though right?

Right. The turbo ones have a lower compession ratio

Quote:

Originally Posted by putter I used a carb/tbi block and drilled the hole and tapped it out for 3/8" NPT, threaded a cut off pipe into it, it lines up perfect with the turbo and looks just like the factory drain tube, although very strong heh

The return tube is still available from chrysler but I think your solution would be easier to do yourself.

[Dave Sigman]

Quote:

Originally Posted by 87OmniT2 You cant use the pistons and rods from a TBI motor though right?

you can but you never know when its going to blow

I tossed a turbo top end on a 94 tbi block the pistons are holding up ok but I did have to rering it.(that could have been the mileage too 150k) I just put a return fitting in the pan becuase I didn't want to drill the block for the return fitting. seems to hold up ok so far

hth

[87OmniT2]

Quote:

Originally Posted by Dave Sigman you can but you never know when its going to blow I tossed a turbo top end on a 94 tbi block the pistons are holding up ok but I did have to rering it.(that could have been the mileage too 150k) I just put a return fitting in the pan becuase I didn't want to drill the block for the return fitting. seems to hold up ok so far hth

hmmm...whats the difference in compression ratio? Anyone know? That could be kind of a wild ride with a bunch of boost and some 110 octane race fuel....

[Timmay2]

Quote:

Originally Posted by 87OmniT2 hmmm...whats the difference in compression ratio? Anyone know? That could be kind of a wild ride with a bunch of boost and some 110 octane race fuel....

You dont even need high octane fuel. Put in the good ol 91 octane, and then just a good intercooler and watch the boost level and air-fuel ratio. Also pull the plugs after upping the boost to make sure its doin ok'.

Now im sayin i wouldnt trust anything above 16psi.

N/A engines were usually around a full point higher, about 9:1. You can narrow the chances of detonation by getting a g head, or using copper shims on the head.

No need to be afraid of 9:1 compression as long as you dont crank it up without be cautious.

[Putter]

Well, i have some good TBI engine info for you becuase i run one in my turbo1 car

Started rippin things down for t2 conversion and piston swap tonight, took the head off and at 14psi it looks like there was some detonation that went unnoticed, i had minor bits of carbon missing on tops of my pistons (i'll take pics tomorrow) that show that it was detonating, it was unintercooled. The compression ratio is 9.5:1 with the carb motor i am running and i think the tbi's were the same. That 9.5:1 is with the bathtub head and flat top pistos.

It also had the stock rods in it, which will probably get changed out, i'm still debating that idea though.

[87OmniT2]

I have a 93 2.2 TBI motor. Are the rods forged on this one? I dont think they are, but I figure I would ask.

[glhsken]

They s/b the lw rods.

[Koreth]

New question: Will I still be able to use my '87 T-II rods or will they be incompatible becuase crankshafts were different between the T-II and common block? Will I have to go find 89+ T-II rods?

[slasky]

Quote:

Originally Posted by Koreth New question: Will I still be able to use my '87 T-II rods or will they be incompatible becuase crankshafts were different between the T-II and common block? Will I have to go find 89+ T-II rods?

you can use everything but the crank from the 87

[marcoze]

How about this brain teaser?

Can i install Turbo pistons in my 2.5 and still run a n/a top end? Crazy question, but worth asking.

Also what do you think the stock 2.5 n/a common block rods are good to?