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.

Back to the research......

That's enough venting, I decided to go back to the research. I had been trying to figure out exactly how the ECM told the ICM to advance or retard the timing, I know it's a 5v PWM signal, but I haven't had the chance to test a running car yet to see exactly what the wave form looks like. I figured once I knew what the wave form looked like and how it changed I might be able to build a box that would modify the signal under boost. Then David A. told me about the Ostrich 2 prom emulator. This thing replaces the prom in the ECM and convinces the ECM that it is a prom. It allows you to adjust the prom program while you are driving! And can be left in place as long as you would like. I'll have to use a program like Tuner Pro RT or others, and I'll have to get a laptop or some other form of computer in the car, and that's where the really neet geek stuff comes in.  Mini Computers as small as the radio in a car, with a 160gb hard drive. I could load all my music onto the hard drive and use a media player and toss my radio all together. I found an in dash monitor with touch screen and it retracts into a radio sized box in the dash. I also found a website that sells LCD screens with and without touchscreen capabilities, these LCD screens are not mounted in a case for more of a custom install. Only problem I was running in to was making sure that the monitor had a compatible signal connection with the pc, most car video monitors just use the old simple RCA cables, the pc has VGA, or DVI and some even have HDMI (hard the find a small monitor with HDMI). Now I'm still back to my original problem, coming up with the money for all the neat stuff I've found.

The great engine debate....

So I'm getting the typical internet crap for doing this project. What crap you might ask? The typical "non fact based", "I heard it from someone once" and don't forget people giving advise for a car/engine combo I don't even own because they are too lazy (giving them the benefit of the doubt) to actually read what I've posted. Let's start with one that I've already covered in my previous posts.

I was told to use a "2.8/3.1 TBI throttle body (requires an S-10 computer)"

            First off the 3.1 only came with a TBI unit on the first generation of those slant nose minivans I think. And why would I choke the engine like that when I already have port injection plans in motion? AND the 2.8 and 3.1 engines are both v-6 engines, my 2.5 is a 4cyl engine, am I supposed to use a the 4cyl s-10 computer? Because a v-6 s-10 computer wouldn't be happy trying to run a 4 cylinder engine with a dis unit when it was built for a v-6 with a distributor. And all of the research I have done so far shows that the s-10 4 cyl only came with a distributor, I have a dis unit and I want to keep it. Could I probably reprogram a ecm? I don't know. But why add even more work to the project"

Then I get jewels like these....

1)"Use an S-10 crank" 

           ---- I've seen pictures of both cranks and the differences are minimal. Both use the same bearings, so the journal sizes are the same. Later years did have counter weights where mine does not, this probably was done to try and smooth out the engine since they do not have balance shafts. But since I know someone that rebuilds and balances cranks and rotating assemblies for a living I asked him, and he said that on a four cylinder engine the crankthrows offset each other so adding crankthrow counter weights to a four cylinder does not add strength just weight. The extra weight would be good if I wanted to balance the engine to spin over 6000, but i don't plan to go over 5500. So the best way to balance my engine would be to weight match the pistons and weight match the rods, then balance the crank with the flywheel and balancer installed. Yes some s-10 blocks are stronger (vin "a") I believe, but that's because that engine was designed to carry more of a load (it's a truck) and the timing curve is too aggressive. So the block had to be able to handle the detonation and stress. And I can't find proof that I can swap blocks, again my vir "r" is a dis type block and the vin "a" uses a distributor, and I don't know if the crank sensor hole is in the side of the vin "a" block or not.

2)"build a long tube equal length header"

       ---- Duh, I'm building a turbo motor, where should I put the turbo? under the engine?

3)"You would be better off (and gain as much power) by strengthening the engines weak points and remaining normally aspirated"

         ----Really, "gain as much power"???? best setup I can put together and stay under 5500 rpm puts me at 120hp at the crank, now if I wanted to spin it to say 7000 then yeah I could build a 180hp motor. But I will agree that at 7000 rpm I'm looking at a very very very short lived motor. And the fact the the timing curve in the ECM is so aggressive that it always runs on the edge of detonation is o.k. if I did it their way?

4)"Go for the Murcury Marine version of the 2.5 which is a 3.0. Port the heads and stay at 7psi or below"

       ----Port the heads? I only have one. Why stay below 7psi, I thought these cranks are the answer to all of our prayers. But as you will read a little farther down the rest of this idea will be laid to rest.

5)"The stock crank will fly apart at 150hp, its trash. A marine 3.0 crank(with some machining, although I dont think it will work in a FWD) will hold up to 200+hp pretty well and be reliable and cheap. Dont bother with the stock rotating assembly on the duke, the turbo will destroy it pretty quick."

      ----My engine is basically a front wheel drive setup but also listed as rwd so will it work?, and I am not going to use the "stock rotating assembly" I am going to use forged rods and low compression forged pistons to give me a base compression of 7.5 to 8:1

Then I found this on a S-10 forum.......

        """"THIS IS THE KEY TO THE 181 CRANKSHAFT CONVERSION IN THE IRON DUKE, you must use at least a 6.200" rod or the engine will self destruct! The reason you need at least 6.200" (6.25" preferably) rod is this: When GM cast the Iron Duke block it shaved weight everywhere it could. One of the places was in the height of the cylinder walls. The 151 only has a 3.00" stroke therefore it only needed a cylinder wall tall enough to accommodate the 3" stroke. When you install the marine 3.6" stroke crank (and rods) in the Iron Duke block you will literally pull the wrist pin to the very bottom of the cylinder wall at the bottom of its stroke. The piston will then "cock" itself in the bore breaking the piston and then probably send the rod through the side of the block. The stock marine 181 rod is only 5.7" (same length as a Small Block Chevy). ...... The cost of having custom rods also played a part in my S10 decision. The later (one piece seal) marine crank will also work but requires extensive machining of the seal and flywheel area (not to mention the filling if the original flywheel bolt holes). I do have another 2.5 that at some time I will do the 181 conversion for a Street Rod or something. I also have a Super Duty engine and parts so I am very familiar with both engines. None of this info is second hand as I have actually "done this myself", along with the hand machining of the custom flywheel.""""

So I don't want to go through that.

And Thank you! to people like David Allen who not only took the time to actually read what I posted, but offered constructive ideas, and not being one of those people that ends a non fact filled post with 

"Being able to say "I told you so" makes my day!""

Electronic Upgrades?

The 2.5 Fiero originally came with one fuel injector in
the throttle body, and only used 9 to 15 psi of fuel
pressure. I had always wanted to convert the fuel
system over to multiport or multipoint injection. I had seen in an Edelbrock catalog a multiport conversion for throttle body injected truck where they just hooked up four injectors to the original wiring for each tbi injector. The resistance of the tbi injector in the truck was high enough than four injectors hooked up in parallel would still be within specification. The Fiero 2.5 tbi used a much lower resistance so I couldn't just hook up four injectors, time to modify the circuit. My thought was to build a circuit like the first picture. Then I started to wonder what if the circuit failed? So I redesigned the circuit as in the second picture, I figured that if one part failed the engine will still run on three cylinders and I could still get home. Obviously not being an electronic whiz I am not sure if these circuits are correct, or will actually function as intended, but they should be cheap enough to build that I could test them fairly easily, if I have the time. Then I started to wonder if I could apply these circuits
to the ignition system. I had been reading about the individual coils the GM has been using on their trucks that put out around 60,000v and wanted to use them on my car, but they are triggered differently, the LS series coils use a +5v signal and my current system uses a 12v grounding circuit. So I drew up this circuit in the third picture. I believe that this will work, I am unsure as to length of operation or heat build up in the components, in fact I am not even sure which components to use, too many variables. Guess I just created more work for myself.

Revised throttle and revised intake plans....

I had sold the TBI unit earlier in the cars life because I had always planned on doing something bigger than the stock TBI could handle. I aquired a throttle body off of a 5.7 litre chevy truck (it looks almost identical to a LS throttle body). Picture to the right shows size difference from stock opening to new throttle size. WOW that's huge. So now I have to modify the stock intake to get the new TB to fit. This is going to take a  lot of work. First I started by cutting off the coolant  passage that ran under and around the intake, GM put it there for driveability with the TBI, but I am going to convert to port injection so i don't need a hot manifold. As I cut more and more of the coolant passage away I realized that the intake was very small inside. Notice in the second picture how small the opening is from the plenum to the runners. This can not be good for flow and HP. After some consideration I decided to remove the plenum and the  adjacent restrictions and start over to correct GM's poor design. See Third picture.After having gotten the intake down to short runners and a plate I started to mock up the shape of the intake using cardboard to see how big it needed to be to allow me to use the throttle body, and to see if it would fit in the car. The plenum was looking quite huge to accommodate the size of the TB and spacers needed for throttle linkage clearance. The setup was looking like a low budget version of one of Ron's Flying Toilets. At the same time I was researching intake design theories on the web trying to get some idea of what I sizes I needed to accomplish my goals.I found a few discussion boards where the guys were saying that to decease turbo lag the intake needs to be smaller and have no large size transitions. I had designed an intake tract that went from 2" to 3.5" to a large plenum, lots of lag in my plans. Back the the old drawing board. So I started my search for a new throttle body (smaller but still good sized). Working in a shop that does lots of engine work, we have a somewhat decent selection of used parts and after some digging I found the throttle body off of a 3100 v6. This allowed me to still use the OE IAC motor and TPS sensor, so my ECM will be somewhat happy. Next step is to install a piece of aluminum pipe to eliminate the bellmouth shape, and allow me to keep all piping under 2.25 inches, that should allow the turbo to spool up really fast.