Good turbo compression numbers.

So I'm still planning on using Eagle 6.25 inch long, small journal Chevy rods part number CRS6250SLW, Pistons I was planning on using are Icon IC723 but after more research I found Icon IC731 which are for a 350 chevy with 6in rods.
I also tracked down the actual specs of a Fel-pro head gasket #1015-1.
It is .039 inch compressed and 4.100 inch bore. I found the specs on Jeg's website. So using the Engine Compression Calculator which takes into account the gasket thickness and bore........

 using the specs:   

bore 4.03

stroke 3.00

head gasket bore 4.10

head gasket thickness .039

combustion chamber 45.6

piston dome/dish cc -18.6

deck clearance 0.11

I got a compression ratio at approximately 7.55:1, and if I did any chamber work on the head that number will only go down. Of course I will have to cc the head and the block with pistons in it to be absolutely sure of my numbers.
                    

Still trying to make a descision.

I'm leaning more and more towards rebuilding the four cylinder engine, the twisted logic behind this is the money I would have to spend on a bigger turbo and time and materials to mount it on the 3400 should be nearly equal to the four connecting rods and four pistons I would need to make the four cyl work. The factory exhaust manifold for the 3400 might work, they are cast iron, but the crossover is regular pipe and has a flex piece in it and I don't think that would be good for the turbo, maybe I'm wrong, don't really want to be wrong and have something melt down or break. So I'm planning on using Eagle 6.25 inch long, small journal Chevy rods part number CRS6250SLW, they are H-beam con rods and they are rated up to 600hp in a v-8 so 300hp in a four cyl, and I'll be under 200hp, so should be good. Pistons I plan on using are Icon IC723 designed for a ford, but the numbers work for my application. Using the flash driven calculator on the Eagle home page, the rod and piston combo will give me a 8.4:1 compression ratio, assuming a .04" head gasket thickness, and 45.6cc head volume. I plan on working the combustion chambers and opening them up, if I can open them up to 47cc that will knock me down to 8.3:1 and if the head gasket is .05 that will drop me down to 8.12:1 and that is a good turbo compression. Since I don't plan on running over 7psi.

If anyone is interested, the specs I used are:
deck height    9.125
bore                4.03
stroke             3.00
rod length      6.25
chamber vol  45.6            47
gasket thick  .04             .05
piston dome  -28.5 ( don't for get the minus sign!)
pin height      1.365

Still Unsure Which Engine To Build....

So I'm back in the internal debate of which engine to use, the 4cyl that came in the car or a 3400 v6. I guess I'll try the old pro and con list.

                 2.5  4cyl                                                             3400 v6  
         pro                           con                                pro                             con
1)already have       lower performance     |   higher performance      need to buy 

And that's as far as I get, with either engine I will have to purchase a new ecm and re-wire the engine (less wiring with the four cyl then the 6 cyl) and buy a prom emulator and reprogram the ecm. I will need to buy a new and bigger fuel pump. On the four cyl I will need to custom build an intake manifold and fuel system, but only will need four injectors, with the 6 cyl I will need six injectors and custom fuel system. With the four cyl I will need to make a turbo header, with the 6 cyl I will need to do even more exhaust work. I have a T25 turbo for the four cyl that just needs a rebuild kit, I will need to buy a different turbo for the 6 cyl(so far I can't figure out which turbo). The four cyl will need new rods and pistons and hi-po cam, the 6 cyl can use the factory internals, hi-po stuff is even pricier than the four cyl stuff. With the 6 cyl I will need a new flywheel, and need to fabricate a front mount. The four cyl will be unique, very few four cyl have a turbo if any, they are out there, but very few. The 6 cyl is more common and has more support in the aftermarket, look up http://www.wot-tech.com/shop/ they do a lot of 6 cyl stuff.

The other thing I have been considering is the way I drive, or will drive. I think the four cyl will survive just fine with my driving, I'm not trying to build a race car (road race or drag). I know the four cyl can't be revved past 5000 if I expect it to live, so I want to design the turbo system to spool up early. My basic goal is to be able to merge into highway traffic easily. The Fiero already handles great, I just need a little power boost. I know the 6 cyl will be more reliable and faster.

So this didn't help me decide either.

Project on hold....

Business has died off something terrible, I'm barely making enough money to put gas in my car to get to work. So all project work has stopped until income goes back up.

Engine saga continues.....

So the junkyard demanded their engine back and all I was left with was a 3400 with a broken camshaft. Now most of the time when the cam breaks the engine runs so bad that the owner will stop driving the car, but on this engine the owner tried to diagnose the problem himself and kept running the engine. Now the number 2 cam journal is so worn out the block is junk. Clevite or some other company does make a .08" oversized cam bearing set for this problem, but unfortunately the block I have is only useful as a boat anchor. I now have a good crankshaft, good rods, upper and lower intake, oil pan and all the bolts. All I need is a good block, new camshaft and heads. The head department took the heads from my engine to rebuild for another head job so when the junkyard guy showed up to get his engine I didn't have enough parts to give him. I was going to give him the broken cam motor and keep the good motor but I got screwed. So I don't know what I'm going to do about the motor, get a 3400 block and heads (another junkyard motor will cost me around $200 to $400) or rebuild the 2.5 tech IV.

Does anyone read this????

So....as I have said in previous posts, I work in a garage that does a lot of engine overhauls, and occasionally a junkyard install for customers with less money. After the tech in the next bay swapped a junkyard engine for the 3rd time, we now have an assortment of parts with which I could build a complete engine. I was planning on rebuilding the 2.5 liter four cyilinder that came in the Fiero. (My original plan was to build a small displacement V-8, but that project became way too expensive.) So I settled on rebuilding the 2.5 as a cost savings (because I didn't have to buy an engine to rebuild) and strapping on a turbo.
But now I have a complete 3.4 V-6 from oil pan to intake and most of the brackets. The 3.4 actually costs less to rebuild than the 2.5 and I can still use my turbo (I think). I might have to reroute the belt and move the alternator down to the side of the block to clear the hood. I have already figured out a idler pulley replacement for the power steering (Fiero's don't have power steering). The new to me engine didn't come with the A/C compressor, but hopefully my original one will bolt up. Biggest problem will be the computer, I believe that I could use the ECM from the four cylinder. I'm basing this on several things, first, I know that the ignition module will run the engine without the ECM connected (I've started these engines with the plug disconnected and was trying to figure out why the engine ran so sluggish). Second, if I connect all of the injectors to fire at the same time the OE ECM should be able to control the fuel. I also know that the TPS and the IAC are the same as the OE parts so the computer should have no problem with them. I was planning on running a prom emulator anyway, so I can reprogram the ECM to overcome any problems I may have. Granted I will loose the "sequential injection" that GM spent so much money developing, but so what? I'll have a 3.4 liter V6 that will spin to 6000 and live. Now I hope I actually can have the engine, the junkyard might want some of the stuff back and then I might not have enough parts left to build it.