wyattroa

From what I have read around these forums it seems the Gen 3 rods are only good up to around 700hp. After that I keep seeing the suggestion for gen 4 rods and pistons.

But then I see SuperChevy being able to bring a gen 3 up to 1,400HP. It seems those guys are always able to get the most out of their gen three builds. They got the 4.8 over 1,200hp too.

ChopperDoc

I know the gen IV's use powdered metal as opposed to forged, and in doing so, (from my own research in the past) make the piston the thing to be worried about over 1000 hp on a gen IV. The powdered metal rods hold up fine, it's the pistons that start breaking at the wrist pins. I think that's pretty awesome to say a stock motor can take up to 1000hp in the first place. Where you at Ford? Lol

On the older ones I hear a lot about guys bending them and throwing rods above 800. If you are looking to go into the 1200-1400 hp range, why not just invest a few bucks to make it survivable for the long term? I don't know how long super chevy runs them at that power level, but why take the chance?

A lot of it has to do with tuning, too. If you keep pushing advance, you will build more and more pressure in the cylinder (and risk detonation), which is something the rod has to handle. Pulling timing on an engine that could potentially produce more hp on an aggressive tune seems like a waste of time to me. Why not just build it to maximize the potential in the first place? You're already going to be spending 6-7k on your power adder, why not throw another 2-3k at the motor to make it worth the effort?

That's just my .02

kingtal0n

iTrader: (1)

they dont make 1000 horsepower
http://www.yellowbullet.com/forum/sh...2&postcount=33


your best bet is compare MPH to weight. And always keep the application in mind.

ChopperDoc

Gen IV's can take up to about 1000 *crank hp. Not trying to say that's at the wheels. Watched a vid where they threw some boost at a bone stock LS3 they were about to rebuild, took it right up there on the engine dyno and it cracked a piston right around 1070 iirc. This is why aftermarket pistons have thicker material in the wrist pin area. It's practically the only difference in design if you sit them next to stock ones. The rest looks very much the same dimensions wise.

I'm not trying to start a lengthy argument on it, but word on the street is the gen IV's are at least 200 hp stronger than gen III's.

I completely agree with application being the best thing to consider. If he's not going for 800 or 1000 hp, then I don't see why it matters.

ChopperDoc

I actually found that video where it's talked about. It's in the first 5 minutes of this video.

ChopperDoc

So I know the actual test wasn't in the video, but still going to take his word for it. It's been a few years since I watched this.

wyattroa

My plan isn't to go above 1,000hp. I would strictly be putting this into a street car and be looking for around 600-650whp. I am finding mostly 00-02 engine in my area. anything newer people are wanting a premium on.

ChopperDoc

You also have to factor in drivetrain losses, so your goal may be pushing the gen III internals pretty hard. If you have 650 horse, then crank hp may be close or over 800 depending on the transmission. If you use 20% as parasitic loss through the drivetrain (could be less) it's coming out to 640 whp at 800 crank hp. Just a thought.

ChopperDoc

I'm sure there are some folks out there that have done it though, on really good tunes. That is probably the most important factor there, and the cam you choose can also have a HUGE effect on the strength internally. Dynamic compression is what matters. Static is just something you use to help calculate the dynamic compression. Anything is possible with enough planning... personally I'd just upgrade the rotating assembly and not worry about IF it can take it or not.

LLLosingit

iTrader: (4)

They do and it's been done quite a few time times but it takes serious tuning skills to get it right so it lasts over a 100 passes like they did.
I don't know the weight of this Fox body but it takes at least 1,000hp to get that ET at 2600lbs. I don't think the Fox on a diet is less than that with a legal cage. Personally I would go aftermarket pistons/rods for anything above 800 for peace of mind.
http://www.lsxmag.com/news/fastest-s...rld-goes-7-81/

kingtal0n

iTrader: (1)

In my eyes it doesn't count no matter how much power you make if the engine becomes a question mark. Personally I think anything over 600bhp (dynojet) is asking for fate to kick you in the nuts with a stock cast piston in most run-of-the-mill engines. I've seen a couple vids of 5.3's spit the wrist pin at 850rwhp dynojet.

its different when ur tryin to break records. they didn't break any record with the first SBE they tried probably. whereas in a street app i dont want to have to keep swapping engines in and out, trying to keep up with some on-line record they finally set after X engines.

LLLosingit

iTrader: (4)

LOL I figured you'd come back with something like that ..... Deflect deflect deflect To quote you AGAIN "they dont make 1000 horsepower"
Obviously they did and do... They made 1000hp or more and made over a 100 passes... That pretty damn repeatable in my book no matter what your eyes think end of story!

kingtal0n

iTrader: (1)

its not like I am somehow hurt by the fact that the engine in my car has godly capability. I am not sure why you think it somehow counts against me to use this engine. What exactly am I deflecting from? The only thing I am doing is being conservative and giving myself a safety factor boost. This is how engineers add to the reliability of their structures, this is what you are taught in school to do. taking you to school each time brother.

G Atsma

Talon, you made the statement, "They don't make 1000 HP" NO qualifiers, NO conditions.
When in fact they do. MANY do. Can't you ever admit being wrong? But above you just sidestep the whole premise, as usual.

LLLosingit

iTrader: (4)

Well you started out saying Then I gave you an honest example
Then of course you make it about you and how your eyes see it rather give the reply that most people would give and say oh I guess it has been done.
If you took two minutes to do a search you would see it's been done multiple times ( I still wouldn't try it myself but that doesn't change the fact that it's been done by multiple people over the years and lasted more than a pass or two)



Then more about you? Where did I or anyone else say anything in this thread about you using your engine??? ( I didn't in any other thread either)
Oh and by deflecting, I'm talking about how you always try to change the subject being discussed to something about your opinion rather than facts or like the quote below you just plain throw something out there that either wasn't said or has nothing to do with the topic. "like your engine"


What does "Taking you to school each time brother mean?

You being boost conservative is still over what the factory engineers designed the engine for.... So who says someone can't make a 1,000hp and still consider that being conservative in their own eyes?

LilJayV10

iTrader: (39)

do yourself a favor and ignore anything he posts.

ChopperDoc

The title on this thread fits perfectly. Except the pardon part... lol.

epfatboy

iTrader: (3)

So back to the OP, if you go gen4 rods does getting there and staying there mean Just some decent pistons w/rings gapped appropriately.

I assume main/rod/head bolts, proper cam, fueling, and a good tune,

Is that literally it? As for longevity what goes next? Crank, block, back to rods??

Assume FI build, I plan to retire my Nitrous stuff soon.

ChopperDoc

As far as I know and from what I've seen on multiple LS7's and others, the block holds up fine so long as it doesn't overheat. I don't know how much the stock GEN IV rods will take, but I'm assuming more than 1000 bhp since that's where the pistons break, not the rods.

Personally, if your already in there changing pistons out, might as well throw in some good h-beams. Cost wise, it's a sound investment. I just saw a post this morning talking about the stock crank. Seems like those hold up pretty damn good overall. Not sure how much it will take though, but aside from oil starvation, you just don't see a lot of spun or busted crankshafts.

And this is coming from a few local guys running over 1100 at the wheels with thier vettes. I don't know thier build lists though, but they are both aluminum blocks.

Maybe someone else can chime in on the hp rating for a stock crank?

ChopperDoc

Here's a thread talking about the crank

https://ls1tech.com/forums/forced-in...ast-crank.html

Seems like a lot of guys have gotten a lot out of the stock stuff.