: When to Start Thinking About Forged Internals



hlantin
06-27-11, 02:13 PM
glad to see that there are vendors offering forged alternatives specific to our cars. thanks guys!

those that are starting to think about or have mods, at what point does one have to consider forged internals? at what rwhp? i've read all the seasoned guys preaching about having forged internals on anything over 600+ rwhp and others saying it depends on the tune? is this any different on the LSA motor? would 590+ rwhp considered borderline?

vendors (lpe/hennessey) are offering 700+ bhp packages w/o bottom-end enhancements and with warranties, what are you thoughts on these?

i accept that the majority of it is in the tune, but up to what point? obviously, if you mod, you take a risk! but for most people, like myself, i want a calculated risk.

thoughts/opinions are welcomed...

kirbyCTSV
06-27-11, 02:35 PM
i guess it depends not just on your rwhp but how hard u are running the car and often. I think GM didnt forge the internals like the ZR1 bc of the smaller boost the 1.9 is pushing (and i'm sure cost). So if you pushing it around the 600whp+ i would think its something to consider.

Ross L
06-27-11, 04:24 PM
IMO we havent seen the limits to the stock short block. But with the larger blowers hitting the market, who knows. ALso, our short block IS mostly *forged*. The crank is forged and the rods are forged powdered metal(and very durable from the reading I've done). The pistons are, of course, not forged. Who really needs titanium rods, and mystery gas filled valves. people have been making big power with stainless valves for thousands of years. ;)

PremierJosh
06-27-11, 06:34 PM
There is no reason to forge the lsa until you upgrade the blower. With a proper tune the stock motor can handle anything the 1.9 blower can throw its way. Now with a marginal tune up a forged motor gives you more room for error.

DrumStix
06-27-11, 07:16 PM
Agreed. I'm going to push past 660 and keep the tune dialed in. No worries here as the crank, block and rods can handle it. Keep the timing right and the AF in check and the pistons can handle it too.

PhxTriode
06-27-11, 08:06 PM
There is no reason to forge the lsa until you upgrade the blower. With a proper tune the stock motor can handle anything the 1.9 blower can throw its way. Now with a marginal tune up a forged motor gives you more room for error.

Agreed

assuming no bah bah

hlantin
06-27-11, 08:47 PM
thanks fellas..this is helpful to me, and hopefully to some others as well. as ross mentioned, things are going to get really interesting when more blowers become available in the market. i know the camaro mkt have different types available to them, what are you thoughts about offering the same thing for LSA application? kd sent you guys a pm..

Junkie414
06-28-11, 01:13 AM
what about 700ish through an auto on nitrous? Car makes right at 620ish right now and I'm debating throwing a kit I've got laying around on. Would NOT be spraying very often. 1-2 bottles a month and tune will be nailed and safe

cbloveday
06-28-11, 01:30 AM
I sprayed the stock internals a small 35 nitrous pill to 725 rwhp repeatedly. After maybe 20 runs, my pistons were egged.

Junkie414
06-28-11, 01:32 AM
I sprayed the stock internals a small 35 nitrous pill to 725 rwhp repeatedly. After maybe 20 runs, my pistons were egged.

what went wrong with the pistons? Detonation?

M5eater
06-28-11, 08:01 AM
IMO we haven’t seen the limits to the stock short block. But with the larger blowers hitting the market, who knows. Also, our short block IS mostly *forged*. The crank is forged and the rods are forged powdered metal(and very durable from the reading I've done). The pistons are, of course, not forged. Who really needs titanium rods, and mystery gas filled valves. people have been making big power with stainless valves for thousands of years. ;)

The block is also heavily strengthened, and the crank is connected via 8bolts instead of 6 in the LS3. Considering what the LS3 guys manage with just rods and pistons, It wouldn't surprise me if the short block could handle 1000 easily.



i've read all the seasoned guys preaching about having forged internals on anything over 600+ rwhp and others saying it depends on the tune?
Engine longevity depends on the tune more than anything. You could probally kill an LSA(or any engine) with as little as 10-15% increase on a very bad tune. 600whp as a limit is a joke however; stock manual's dyno 510ish iirc.

haterinc
06-28-11, 10:56 AM
I'd be more concerned with the auto trans at 700 than the motor...

Prof
06-30-11, 12:58 PM
Mother-in-law research says that cast pistons simply will not withstand temperatures, stress and pressure beyond 700 hp...that is the Viper mantra, and I bet that there is an engineer that can correlate 700 hp as the upper limit of non-forged pistons...or maybe a metallurgist...

If the engine comes out...it should always go back in with forged rods and pistons...just a rule of thumb in my book.

Luna.
06-30-11, 01:09 PM
In my opinion, it depends on what your goals are in terms of engine longevity. I refuse to believe that you'll see 100k+ miles on a, say, 620+ rwhp LSA motor, regardless of tune. It just isn't in the cards with the stock bottom end.

And, don't forget, the pistons aren't the only weak-link in the motor...the rings aren't stellar either. Don't ask me how I know...

I believe Prof NAILED it with, "If the engine comes out...it should always go back in with forged rods and pistons...just a rule of thumb in my book."

AMEN...

Mike TexaSS
06-30-11, 03:37 PM
99% of the failures are tune related.

Heres a LS3 that we have been pushing kinda hard. Dyno's 760 rwhp on 13 psi with meth. Customer roll races the shit out of it every weekend.

http://www.youtube.com/watch?v=y5lLELFZz0M&feature=player_embedded

Here is another LS3 vette that is beat on daily stock shortblock. Even ran 192mph at the Texas Mile over and over!

http://www.youtube.com/watch?v=HejYdoK_QYc&feature=player_embedded

PhxTriode
06-30-11, 04:05 PM
In my opinion, it depends on what your goals are in terms of engine longevity. I refuse to believe that you'll see 100k+ miles on a, say, 620+ rwhp LSA motor, regardless of tune. It just isn't in the cards with the stock bottom end.

And, don't forget, the pistons aren't the only weak-link in the motor...the rings aren't stellar either. Don't ask me how I know...

I believe Prof NAILED it with, "If the engine comes out...it should always go back in with forged rods and pistons...just a rule of thumb in my book."

AMEN...

+1 and rod bolts are also a concern when we get into high HP #'s

hlantin
06-30-11, 07:32 PM
If the engine comes out...it should always go back in with forged rods and pistons...just a rule of thumb in my book.


I believe Prof NAILED it with, "If the engine comes out...it should always go back in with forged rods and pistons...just a rule of thumb in my book."
AMEN...

god forbid this happens to me, but if ever, i would follow this and build a motor with forged rods and pistons along with the other parts to compliments these parts.

shade
06-30-11, 10:02 PM
The rods are already forged. Only thing IMO would be pistons...??

PhxTriode
07-01-11, 10:22 AM
Rods are forged powdered metal I beams. Aftermarket would be stonger and depending on selection lighter too.