as of this past friday night, the rings are gone on my iroc, so i'm slowly starting the process of putting together a new engine for it.

I've been doing my homework, and i'm definitely going with forged pistons and good rings this time around, but at what point are forged rods and a forged crank necessary? It's gonna cost me at least an extra grand to go with the forged rods/crank vs. reusing the originals, and i want to know if it's justified. That money could be spent on better heads and/or tpi upgrades.

The engine i'm building is going to be a ballpark 375hp at the crank 355, depending on what heads, etc. i decide to go with. It's gonna have my paxton SN93 blower on it too, so i should be looking at maybe 475 or 500 crank horseys.

 

What rpm are you planning to max at? The forces that stress the rotating assembly are squared with rpm, so a 500 hp engine at 5k might be fine, while a 400 hp engine at 6k might not. I think about 450 is borderline for stock rods/crank. If you've got to replace the parts now anyway (as opposed to waiting till you break them later), spend the few hundred extra for the cheap forged stuff like Eagle or Scat. It's still much better than stock, IMHO.



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Andris Skulte
Skulte Performance Designs
Z28tt-89 IROC T56 DFI Twin Turbo
http://www.skulte.com

 

the paxton i'm running maxes out around 4900, so i'm gonna build a low end tpi beast that isn't gonna ever get revved out past 5000.

if my original crank and rods come out of the engine looking good, i'd like to reuse them. however if i wind up buying rods or a crank, they will be forged parts.

 

I'd spend the $500 for the cheapie forged parts. Inevitably, you'll make your power, and will want more, so you'll pulley up, add race gas and timing, or something else, and will have wished you did it when it was easy. Just the way my mind works at least

A.

 

If you stick with the stock stuff I would think about going to the pm rods like they use in lt4 engines they suposebly can handel 450 horses out of the box and you can get them from SDPC for 159 a set and use a good set of arp rod and main bolts and you should be ok.I have a 355 in my car and this is the set up I used i did polish the rods and have every thing balanced I used the arp bolt I also used a summit fluid dampner Im looking in to puting a paxton on my car now and I don't think I will have a problem I not going to be on the track every day with the car so it should be alrite if you look at some of the other msg bords you will see more engines have faled do to busted rod bolt then their crankes breaking and these are usaly at high rpms i think I read somwhere once befor that the stock parts start having truble after 6000 rpms.Any way I think if you change the bolts and upgrade to the pm rod you will be ok but if you are planning on running slicks at the drag strip I would worry about your rear end holding up Ive herd alot of bad things about the axles in are cars busting at the track when they have 400 hp at the rear wheels.But then again you never can tell Iv seen engines using stock every thing but pistons hold up for ever and then seen the same guys they were beating with all the high doller stuff blow there engines up.just so know one freaks out im not saying this is the best route to go but if you have to stick to a buget then this is a good efective cheap alternitve that in most of are cases will work depending on driving habets and how often your at the track but most of us use are cars as dally drivers except for the redlight to red light racing we do every now and then.

 

GMI FAST used a cast steel stroker crank with stock rods (shotpeened though) and his 383 lasted many many times to 6500rpm blasts with like 14lbs of boost

he has the engine for sale. throw him an email. might be what you are looking for