GT-ER

I keep thinking about the days when I had my Pontiac Grand Prix ( I had two of them with the 3.8L Series II V6, I turbocharged both of them ) and I am thinking " why is the M113 Kompressor so weak when compared to the lousy GM 3.8L V6"? The bone stock bottom end of an L67 ( the GM 3.8 V6 ) can handle over 700whp....yes 700!! and the engine has CAST pistons and rods. They aren't even hypereutectic as far as I can remember.

Comparatively speaking, an M113 should be able to handle 1000whp at it's upper limit, yet we get blown engine at 500whp.

Exotic metal posted on another forum the ring gaps for the M113 engine and it hit me...the gaps are too small for serious power. They are apparently within 11-14 thousands of an inch when the L67 has gaps from 18ish on the top rings to over 30ish on the 2nd ring. This is a big issue as tight ring clearances can cause the ring lands to collapse due to excess pressure being forced upon them from the rings due to heat. A LOT ( almost all ) of the piston failures I've seen on this forum are caused by ring land failure so I put 2 and 2 together.

I'm almost positive that by just opening the gaps on the ring our engines can become unstoppable!!

Who here is with me?

pearlpower

IMO most that have 'blown' a motor just did not get a proper tune or allowed for even fuel distribution. Brooke has blown 2 or 3 motors, however his motors are far from stock including his block. Though it may be more sensitive, many here are pushing 500rwhp without issue because they properly thought out their goals instead of just slapping in parts. I truly believe these engines can put down substantially more with a stock block once other supercharger options are readily available. Right now we are still stuck with the old inefficient blower and promises from vendors on top mount intercoolers, blowers,etc .

Sir-Boost-a-Lot

iTrader: (1)

The ring gaps closing up and cracking the ring lands off the tops of the pistons would be a result of high combustion temperatures, not a failure due to power output.

Inadequate Tuning, fueling, and intercooler could be responsible for this.

adianaty

These things but lets face it, it's still detonation that causes the pressure spikes. Stock motors have blown the lands even. I agree with GT-ER though that increasing them will help but there are trade offs. Blow by being the biggest. It's likely they kept them tight to keep blow by down.

splinter

Hot Rod got 1200+ horsepower to survive in a stock 5.3 Chevy short-block by opening the ring gaps a bit.
Damned American cars. :D

http://www.hotrod.com/techarticles/h...#ixzz1po60IMUW

Quadcammer

as noted, if the gaps were too tight, they would butt together and pop the top of the pistons up.

The failures I've seen have been melted pistons as the result of a poor tune or mechanical issue.

Too many people like to risk their motors with 100%DC injectors, inadequate fuel rails, etc.

Btw, do you have any proof of these 700whp GM 3.8s? Its rare for any engine to sustain 3.5x its original rated hp.

Forrest Gump 9

+1

The tuning option is the biggest handicap in this flatform.

e55amgrocket

Detonation is what kills these engines plain and simple. I've been a witness to .5 degrees of timing killing an engine and made a mitake like that years ago myself. My engine builder just had engine that was happy at 42lbs of boost for over a season on C16 and they added .3 degrees of timing this year and the first pass melted 7 of 8 pistons. A lot of that does come from the tunes and like I've always said in the past. When we put 10 gallons of 93 octane(east coast) who knows how much 93 we actually got. If a car is tuned for that then that could be a problem. My engine looked perfect when we tire it down and since my last tune it has run on Q16 only and I've always mixed race gas with my pump gas. The piston are the weakest link and the tight ring gap kills us for the chance of making RELIABLE high horsepower. I know for my new engine build it will be built to live happy above 800hp.

GT-ER

I agree with this.

Btw- ZZP had a stock bottom end when their grand prix ran 8's.

GT-ER

X78478

Firechaser

Easy now The Series II V-6's were based on the Stage 2 Block they ran in Nascar...they are very stout.

I didn't recall seeing M113 motors fail from rods, spun bearings, crank failures...it all seems fuel related w/ piston failures. I wonder what nice independent, dual-feed rails and maybe even a shot of Meth (nice progressive system) would contribute to this...the Meth would definitely cool cylinder temps and the dual rails should keep each bank fed. I know you guys probably hate when I keep making statements towards my GN, I do this because the problems I see here are the problems we had 10+ years ago and we SOLVED it.

pearlpower

Have yet to see a single blown motor once larger injectors and fuel rail mod are in place. Coincidence?

zneB-sedecreM

That's what I'm talking about .
I have the complete Eurocharged Stage 3 plus TCU tune, K&N filters with no resonators or secondary cats (left the primary cats on there, which Eurocharged said they really haven't heard of) but am really debating on cutting them off too. It runs great now, but deep down would like just a little bit more power. Don't have a fuel rail, that probably would be a safe idea. I want Kleeman cams, port/polish my heads. Then what? I don't want to run any NOS, I gonna avoid that. How do you get to that 800 HP level with the 55K's?

GT-ER

There was someone on this forum that blew their engine with injectors I believe...can't remember who though.

pearlpower

Someone did however they installed the rail/injectors after they had already damaged the motor if I recall.

GT-ER

BTW- here is some info on the ZZP/Stattama drag car. 753whp on the stock bottom end and 8.65@158mph.

http://stattama.com/index.cfm?id=159...owse&pageid=53

adianaty

There was a CLS on here that had it happen. You can still nuke it with timing, bad cooling, bad tank of gas, etc. Post 393 of the mess below. It was a rumor that it blew before the mods. The piston itself is posted the page before and clearly demonstrates GT-ER's point.

https://mbworld.org/forums/w211-amg/...my-e55-16.html

benz_addict

Very easy to blow these motors. Don't **** with the timing. Just saying
Stock pistons suck none the less.

DorethaRockl

Though it may be more sensitive, many here are pushing 500rwhp without issue because they properly thought out their goals instead of just slapping in parts.

GT-ER

Here it is guys:



This is precisely my point...this is a ring land failure NOT caused by detonation ( or not fully anyways ). This is the kind of damage that happens when a ring's ends butt with each other.

splinter

Too much carnage has been reported on these pages.
No guarantees, although sufficient mixture strength and sensible spark advance can help give our relatively weak pistons a fighting chance by minimizing expansion.




photos credit kjlindgr

https://mbworld.org/forums/w211-amg/...boom-boom.html
https://mbworld.org/forums/w211-amg/...oooooommm.html

Agreed.

GT-ER

Is that .020 the top ring or the 2nd? .020 isn't horrible but it's still small considering what some high hp cars are running ( .025+ )

adianaty

Don't get me wrong, the ring gap is certainly not right and needs to be increased. But this damage is not initiated by ring gap alone. Ring gap in itself will not melt the piston or cause the land to break off. You have to have excessive cylinder pressure and heat i.e. detonation. Here is Mahle's own description of the failure. See page 20.

http://www.scribd.com/doc/47784054/M...ushings-Manual

These hypereutectic pistons are like glass when they are loaded up under detonation and are unforgiving. e55amgrockets car made 619whp so let's assume that is over 700hp's but he did it with some excellent race gas that takes some work to get to detonate. If it was gaps alone, he would have had piston failure pushing that much through his motor. I've seen plenty of the hypereutectics go in other platforms and truth be told, they always blow up pretty fantastically and never have light wear like a forged piston. My only point to anyone is, if you are going to go so far as open her up to increase the gap, spend the extra $1500 for the forged pistons since I wouldn't reuse the rings anyway. Mahle's run $1950 for pistons, rings, and pins. Call me ridiculous but I wouldn't tear my engine apart and put the stockers in considering for $1500, I would NEVER have to worry about it and have a fully forged bottom end. The original purpose of the thread is spot on. Going into the motor before damage on these cars makes a tremendous amount of sense to fix both the ring gap and in my opinion, replace pistons with forged units early if you are really going to push it.

layzie12g

Does anyone know the stock piston to wall clearance of these motors? I run my forged 2 liter set ups with a 2618 piston at .021 top ring, .024 bottom ring, and .0045-.0055.

Good thread by the way. Has anyone blown their engines up stock from beating on them too much?

Evolved8

My Evo Makes over 600AWHP which is close to 700 Crank HP out of a 2.0L 4 cylinder stock BLOCK. It really helps when a standalone Fuel management system can be used, To really dial in all parameters the ECU. The car wouldn't do half those numbers safely without that kind of "Open ECU" option. Tuning is everything.