crank decision

[wowzer]

the rod journals (forged crank) in my 88 2.2 daytona t2 block need to be turned. i believe they have already been machined .020 based on the info i have from the previous owner. they are in tough shape - looks like it was run without any oil pressure. ALL the bearings were a pretty bronze color! couple questions.

1) how much more can the journals be reasonably machined? is there a downside of undersized journals?
2) is the forged crank that much better, or should i look for a new cast one? ultimate hp goal is 450ish.
3) what are the best sources for either a new forged or cast if i need a new one?

[wowzer]

ok - since no replies to all 3 questions how about just an answer to question number 2? i need to get off of dead center and get going on this project again.

[GLHS60]

1: There is no problem with undersized journals as long as you can get bearings.

2: Forged is preferred but not essential.

3: Very hard to find a new crank but good used are available.

Thanks
Randy

[iTurbo]

I for one, wouldn't worry at all about an undersize journal. I don't know everything there is to know, but if you think about it, the smaller journal will have less rotational speed at the bearing because of the smaller diameter for a given RPM. Built by somebody who cares about longevity (you), and using proper sized bearings ,methods, and tools, you should be good to go.

I built a TI shortblock at work today. It was interesting because I decided to take my vacation time by working on car stuff in the shop. Massive turbo Mopar productivity! But no beach:(

EDIT: to answer your questions in post #1 (like I said, I don't know everything...)

#1: I've seen bearings available for a max 'cut' of .020" After that, if it needs work you're likely lookng at having to replace the crankshaft. On the upside, the lessened rotational speed of an undersized journal might actually help. Naysayers blast away....I can take it if I'm wrong here.

#2. Forged vs Cast. You have to ask yourself how often do you hear about people breaking crankshafts? At the 450 HP level I would most definitely go with a forged unit since they aren't that hard to find. But a cast crank might just live quite a while just fine. Best to ask those that have been there and done that, and have been building these motors for a while. I bet if you PM a few different people on this forum that they could give you a better answer than I could.

#3. Best place to find a decent crankshaft might just be the junkyard unfortunately. You can always try FWDP of course; they are bound to have something in stock. If I had a spare I'd sell it to you, but unfortunately I don't at this time.

[supercrackerbox]

If it comes down to it, I've got an '88 2.2 crank/shortblock I can check. I have no idea if it's cast or forged. Shipping would be a bit of a pain, but doable.

[Johnny]

If you used a common block, the forged is not as needed. They went to forged because of block flex.

[Pat]

If you used a common block, the forged is not as needed. They went to forged because of block flex.

This should be put in perspective though...I've been at the 350 whp mark with a non common block cast crank motor for nearing 4 years and have not had any issues. Will it last forever? Likely not. Will it last a long time? Likely yes. Will it last longer if it's a street motor that is not seeing the same hp level on a regular basis? Definitely yes.

Common block and/or forged crank would be better, but that's not to say that a cast crank non common block isn't good enough.

[Johnny]

Besides, a non-forged crank is lighter. I run that because it is, the engine rev's quicker. (autocross car)

[2.216VTurbo]

Rick D was using a CB Masi Head motor a few years ago with a cast crank. He was at the 450 WHP level and LOVED the way it reved up quick with the CAST crank he was using. Couldn't say enough good things about that motor:eyebrows: He loved it for less than a couple thousand miles tho before the crank walked/block flexed whatever you wanna call it.:( The bearings were down to color but I don't think any spun. He went forged on the next motor but I don't think that one is running yet, he's going for much bigger numbers this time:thumb:he keeps some projects pretty close to the chest;)

[Reaper1]

I'm pretty sure both Shadow and Larry B. both are using or have used cast cranks over 450hp with no issues. Even Rick agrees that cast crank isn't as weak a part as people seem to think. I can't remember why Rick had issues, though.

[Johnny]

Many issues with rod bearings can be pre-detonation.