[oldman]

Originally Posted by wnta1ss

With .015 ring gaps, yes you were somewhat fortunate in that aspect. You say that your car made 724hp, but what was the dyno correction factor applied (like 1.15 or 1.20 or ???)? With you being in Colorado, my guess is that your actual horsepower was much lower than 724, and the observed/uncorrected figure is what we need to know to properly evaluate your experience with that car. High altitude means thinner air which means less horsepower.

I do have a tendency to agree when we are talking HP related failure OR how much fuel per HP, an uncorrected dyno is important. The whole CF is broken, it is made for NA cars under very LIMITED changes like single digit. After that, we are talking unicorn HP, and yes a unicorn is a horse.

Nutshell especially with STP / STD HP, we are getting far removed from the concept of having a wheel HP number that we can compare with other dynos or with the SAE engine HP using a drivetrain loss factor. The vast majority of magazines apply STD HP to a FI engine in Denver Co. say Supra and then apply a 15% drivetrain loss and wonder why it does not equal SAE. For sure not all engines are certified SAE (even though they report SAE HP), that said, you are 100% certaint that if the engine is SAE certified it is producing within a very tight tolerance the HP and torque listed.
https://www.sae.org/certifiedpower/data/

That is what happens when people start racing dyno numbers..

I have no dyno numbers but my LT1 stock pistons and rods were run with heads, cam, header, E85 4.0 pulley D1X and the pistons look mint.

[wnta1ss]

Originally Posted by 95 imp

All that high altitude stuff goes out the door with supercharging....
You might have to run a smaller pulley to make the same HP at altitude though...

Besides, it isn't the rings. The failure in the pics doesn't support that theory.

If it were the rings butting, there would be seize marks all over the cylinder walls since the rings ends came together and bound up on the walls causing the lands to crack.

It's a detonation failure. Oil in the cylinder, going lean at WOT, bad tune, low octane, etc, is what everyone should be more worried about.

Obviously you don't understand what a dyno correction factor is. Dyno tests on supercharged cars done at high altitude can inflate the numbers pretty noticeably when the CF ends up being 1.15 or worse.

Also the guy that I quoted did not break his engine. When he said that he was fortunate that his ring gaps were .015", it's pretty obvious to me that he meant he was fortunate not to get one of the cars that come with .007" gaps. And I agreed with him.

[oldman]

I think with such small sample sizes and such wide variance in HP and usage prevents us to state what exactly leads to engine failure. IMO, I think there is minimal failure with base setups, and extensive failure on the most aggressive setups on stock engines ( or even built engines). I think road racing (or long street events), next would be year on year aggressive street driving, followed by 1/4 usage. Note I'm only addressing engine stock engine failure on FI. For mods, 7 PSI would be a minimal failure, 14 PSI up better start that forged short block project. These two separate things probably can be multiplied out.

ie minimum boost x not crazy DD = low failure

14 PSI boost and the Silver State Challenge= explosion somewhere, sometime soon. I hope you are not going 180 MPH.

[95 imp]

Originally Posted by wnta1ss

Obviously you don't understand what a dyno correction factor is. Dyno tests on supercharged cars done at high altitude can inflate the numbers pretty noticeably when the CF ends up being 1.15 or worse.

Also the guy that I quoted did not break his engine. When he said that he was fortunate that his ring gaps were .015", it's pretty obvious to me that he meant he was fortunate not to get one of the cars that come with .007" gaps. And I agreed with him.

I guess it would depend on the dyno, how it's set up, and the inputs available. But, I see your point.

As far as the ring gap.... Still not buying the whole ring butt thing. I can see your point on that also though.

[JANNETTYRACING]

I said it many times Ring Gaps are not the problem.

One of the 7 deadliest sins Greed.

Ted.

[Hyper SS]

Originally Posted by Dysan911

Really? I dont' think I would say it's common. Think of the masses that aren't represented here on this forum who are under 600 rwhp with a good tune and no issues. Many of us here are boosted and there honestly hasn't been many that were 600 or less that lost a motor that I can think of. Granted nothing is ever guaranteed though. Chit happens!.

Most of the failures I read about are heavily tracked LT1's making 650+.

Most piston ring gap failures occur when you push the stock LT1 past 8 psi. Go for as much NA power as possible and keep boost at 8psi. Long tubes, cam, ported LT1 heads and intake will get close to 700rwhp. With LT4 fueling components and low side help from Dsx you can increase the piston life. The fuel has to be there

[DWR]

Originally Posted by JANNETTYRACING

I said it many times Ring Gaps are not the problem.

One of the 7 deadliest sins Greed.

Ted.

I apologize for the thread revival, but I must ask… since (from what I read) you believe the weakness stems from lack of fueling, not the ring gaps. What do you think would be the weak point in a stock block with full bolt ons, cam, and FI be if someone were to go nuts and use a Katech Xtreme-DI Fuel System belt driven fuel pump or add port injection be? Also what do you think would be the hp limit?

In other words, what would you feel safe tuning to on stock pistons/rods if there were no fueling limit. On 93 and e85


Not arguing, simply asking out of curiosity.

[JANNETTYRACING]

Originally Posted by DWR

I apologize for the thread revival, but I must ask… since (from what I read) you believe the weakness stems from lack of fueling, not the ring gaps. What do you think would be the weak point in a stock block with full bolt ons, cam, and FI be if someone were to go nuts and use a Katech Xtreme-DI Fuel System belt driven fuel pump or add port injection be? Also what do you think would be the hp limit?

In other words, what would you feel safe tuning to on stock pistons/rods if there were no fueling limit. On 93 and e85


Not arguing, simply asking out of curiosity.

When everything is right you can confidently double factory HP

We made 800+ RWHP on the LS3 back in 2010 and it's still running perfectly today, Proper fueling and octane and Tuning is the magic potion.

LOL we just added 430 RWHP to a 53000 mile L99 that is double plus 15%

The LTs are stronger than the LS.

Ted.

[95 imp]

You're boosting a motor with an 11.5/1 compression ratio. It isn't so much fueling that is the issue in piston failures, it's the octane. You're knocking the thing to death.

E85 has (more) octane, but the LT4 fuel system can't push enough.

If you go with an additional fuel system and more PSI, it goes back to octane vs boost vs detonation until you find the weak link. Whether that be head gaskets, or pistons, who knows.

I don't know of anyone who has tried taking it that far. Usually when the first motor blows up, a buttload of money is spent upgrading everything and false theories abound as to the cause. (IMO)

Every picture of failure I have seen on the board, there is no evidence of seizing. If the piston/rings are expanding due to heat and the rings are butting, there would be scoring of the bore. All the pics show nice bores and cracked pistons.


"A hypereutectic piston is an internal combustion engine piston cast using a hypereutectic aluminum alloy with silicon content greater than the eutectic point of 12 weight percent silicon. Most aluminum-silicon casting alloys are hypoeutectic (Si content lower than the eutectic point) and contain relatively fine elemental silicon crystals formed through the eutectic reaction during solidification. In addition to fine silicon crystals, hypereutectic alloys also contain large primary silicon crystals that form before the eutectic reaction, and as a result contain a much higher phase fraction of silicon. Consequently hypereutectic aluminum has a lower coefficient of thermal expansion, which allows engine designers to specify much tighter clearances."

https://en.wikipedia.org/wiki/Hypereutectic_piston

"The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation as well as when power adders are installed."

http://www.strokerkits.com/cast-hype...orged-pistons/

[DWR]

Originally Posted by JANNETTYRACING

When everything is right you can confidently double factory HP

We made 800+ RWHP on the LS3 back in 2010 and it's still running perfectly today, Proper fueling and octane and Tuning is the magic potion.

LOL we just added 430 RWHP to a 53000 mile L99 that is double plus 15%

The LTs are stronger than the LS.

Ted.

Since our cars seem to dyno around 397whp you’re saying around 790-800whp?

[KingLT1]

Originally Posted by DWR

Since our cars seem to dyno around 397whp you’re saying around 790-800whp?

Not Jenetty but imho that is the top end of where I would take one. And I would probably keep it down around 700whp on E if you want some longevity out of it.

SBE LT1's are not going to live long @ 800whp. 600whp on pump 93 or 700whp with fuel system upgrades on E is doable. Meth and E @ 800whp can be done but it's getting dicey. Re-gap the rings then I could see sustainable power above 800 being made.

The LT1 has tight ring gaps so it's not as boost friendly as a LS3... Being stronger or not is a Moot point. LS3's have routinely made 900+ whp on boost. It was GM's most boost tolerant Aluminum block NA engine to date imo. They have enough ring gap to allow it. GM went to even tighter ring gaps on the NA DI engines to help control oil consumption and blow by from the high pressure fuel system.

You can install a cam to bleed off some dynamic compression and that will help raise the HP and Octane wall about 50whp, but imho it's not worth tearing into a LT1 for a cam swap and not doing drop in rod/pistons with it. The engine has to be torn down to the short block anyway.