OK so I spun a rod bearing in my L67......my fault :icon_cry: so now I'm sorting out my options. I have mild mods, right now running:
XPZ Cam
Home P&P Heads
Full LT Headers and Exhaust no Cats
130# Springs
Tune
3.5" CAI
3.1" Pulley
TR8IX Iridium Plugs w/ 8mm Wires

My goal is 450 rwhp. My original plan was to buy L32 connector rods, all clevite bearings, have the crank reground, and put it all back together. However I started thinking that the L67 bottom end is supposed to be plenty durable for the HP I want so I could just throw in a crank kit and line hone my rods and be good to go.......of course then I read about how buying a reman 3800 crank is a bad idea because no one grinds them correctly and they break, and I also don't want to go stock bottom end if its not gonna be durable enough, and lastly because everyone except GM ONLY SELLS FREAKIN REMANS!!!......I'm calm again. Anyways so I found an L67 core that had an engine bay fire for not too expensive and I thought wonder if the short block from there would be safe to use hell it only had 65,xxx miles on it and fire cant hurt metal right RIGHT? What do you guys think? ................O Yeah since I pulled everything out and took it all apart I'm pretty much gonna do a full on documented build thread from engine to wiring once I figure out what I'm gonna do.............and the wife lets go the credit card!

Skip the iridium plugs, stick with coppers. Autolite 104's and 103's have never let me down. As for the durability of the bottom end, it depends on several factors:
- Oiling, you can make some changes to the oiling system to make it more efficient. I'll look on my home forum and see if I can find the details posted on there for you.
- If using upgraded hardware with increased clamping force (ARP studs/bolts) on the connecting rods and mains, it's highly recommended that the bores of each are checked for concentricity after they are clamped. The metal will go slightly out of round when clamped at these higher pressures and you're more likely to spin a bearing if you don't get them modified by a machine shop.
- Tune! Seriously, knock is bad for not only your pistons and rods, but it will also beat up your bearings as well.

That's just a few items to keep in mind, there's plenty of others.

Thanks for the advice on the ARP studs I honestly didn't know that. I never planned to increase clamping force, I just was gonna torque-to-spec. As far as skipping the TR8IX's not possible they are already bought and actually worked quite well up until the spun bearing. Since the ones I have still have about 2000 miles left on them I'll keep em for now. ZZP site says they are the best for reducing knock they just have to be changed every few thousand miles as they foul fairly quickly.

If they work for you, I'm not going to try and dissuade you!

Here's a link with some info on oiling mods for the 3800 SII:
http://www.fullthrottlev6.c...owthread.php?t=36512

I'm sure if you troll flyingtp's posts over there, you will pick up quite a bit of extra information. Good luck!

First off, the only way you will ever see north of 400whp through a automatic trans, is with nitrous. A high compression XPZ build with a 2.6 pulley, and decent gas, will get you near 380, with comparatively good tuning, and CNC ported heads. Honestly I would be happy with an even 350 with your setup, and without aggressive pulley/tuning (aka a 3.1 pulley is not aggressive), 320 would be amazing.

Secondly, ANY series2/3 bottom end will handle your 450whp goal without issues, nitrous or no nitrous. Building an engine will most likely result in the crank bearing failure you already had, so hit up the local junkyard for a 100k+ L36/L26 block.... it shouldnt be much more than $300 out the door with a wiring harness you could sell for ~$150-200.

If you are really staying with a M90, you would be very silly to go with a L67 block, even if you plan to spray tons of nitrous. If you want to make your setup a BIG nitrous setup, ala direct port etc, spraying 200+, then I would consider getting that fire damage L67 block, as MOST of my motors have been fire victims, and you will note that most all of the engine fires does nearly nothing to the motor, as the fire actually burns on top of the motor, and all the crud just melts down onto the motor. The L67 typically sits 20-40whp short of L36 blocks in xpz setups, but a giant nitrous setup should help balance that out.

You know DH, and anyone else please feel free to input, I really thought about going with a NA block as yes they are cheaper and do handle boost more efficiently I just wondered what my limits would be with the NA block since the SC block was built to handle boost and the NA block wasn't. How do they hold up and at what levels? Could I just bolt it all up or should I do a few preventive measures to it first in regards to oiling, or pistons, etc?

I think you have that backwards, the site says you can run iridium's for up to 50k miles, they are meant to be long lasting. Well atleast I hope they are. My equal length headers are such a pain on l32 swap that I have to pull the engine, to pull the headers to change the plugs, so I bought the iridiums hoping they would last a long time...


Chris

quote Originally posted by Khaos88GT:Could I just bolt it all up or should I do a few preventive measures to it first in regards to oiling, or pistons, etc?

I'd recommend forged pistons since they'll survive KR a bit longer, and since the L36 has higher static compression I'd consider it a "really good idea." However, with a good tune you'd be just fine.

HAHA yes apparently I did have it backwards, damn dyslexia! Well that sucks! LOL! Guess I am getting new plugs as I don't care about changing em its KR reduction I want. I also did a little looking on ZZPs site and answered one of my own questions and apparently they have run the L26s up to 500hp without failure.

Yes, it would. It's a tradeoff. If you think you can rebuild the bottom end properly, you have to decide if the additional piston reliability is worth the possible loss of bearing reliability.

quote Originally posted by GS Jon: Yes, it would. It's a tradeoff. If you think you can rebuild the bottom end properly, you have to decide if the additional piston reliability is worth the possible loss of bearing reliability.

How can you even say the forged pistons are more reliable, if you have never used them?

So you refuse the science that a forged slug which is installed with properly gapped rings will be more reliable than a stock piston?

Really?

Are you just being cheeky? Or are you just turning a blind eye to the reality that is the huge numbers of chipped stock pistons? How about this. Post some evidence that runs contrary to my statement and belief. I don't want your opinion. I want someone else's. Provide a source. Go on, do it. I'll wait.

No need to change your plugs, the iridium serves both purposes, keep what you got and hopefully keep them for a long time

Chris

Why build a 1400HP motor, when you are trying to build a 500hp motor?

It does nothing to try to accomplish the goal laid out in this thread, and in turn offers no positive advice. I would consider it trolling myself.... You speak from zero experience..... and I struggle to count the amount of 400+whp builds I have worked on.

This is pretty simple--Get a low mileage L-26(they are to damn cheap), swap all your parts over to the new block and call it a day. If you are set on using a L-67/32 engine then grab the 65K one that was fire damage and use it. I myself would grab the L-26 and build off it since it has been proven by many that it can handle the power. If you are depending on plugs to battle KR then you need to up the size of pulley you are running. Running a 3.1 on a non ICed motor down here with a mail order tune and no way to tune for changes in the weather is a bad thing IMO. Yes other say you can run XX.X pulley with XX.X MODs but those same people are not from the same area. If you want 450 HP for what ever reason then ditch the M90 and go turbo.....


And the important question is--What caused the spun bearing?

[This message has been edited by MstangsBware (edited 12-29-2009).]

Yeah I agree with you on the pulley issue Mstangs given our southern weather. Me and you may like it but I can see how PCMs might not. LOL! Funny thing is though I was getting no KR and thats scanning at WOT with a live scanner! Of course I knew I was gonna get called out on why I had a spun bearing........notice how all I wanted to say was it was my fault well I guess I will spill the beans. So when I initially did my swap..........which would never ever have been completed without the help of Mstangs, FieroFlyer, Lloyde, Darth Fiero, PR, and even the occasional help from DH, along with uncountable others.....I digress, but thanks guys..........I sent my heads to have the valve guides machined down so I could run the higher lift of the XPZ cam. After getting them back I port matched intake and exhaust myself. I cleaned them the very best I could short of having them revatted and assembled my engine knowing full well there was probably still a ton of metal powder stuff in them but I thought.....I'll just run some good ol cheap oil through the engine after I get it running and change it over to synthetic not long after. After getting my engine assembled and in the car and running I fought with a damn electrical misfire for months until lastly changing the ICM and it clearing up. In my troubles of trying to fix the misfire and the enthusiasm of how awesome I thought my car was after fixing the misfire I forgot about changing the oil to get all that crap out. Now keep in mind this is over a period of 8 months but even so its me putting only about 50 miles on the car. When I remember about the oil change I wasnt having any issues with the way the car was running it was a beast. I went out and bought some royal purple and a K&N Gold filter and change it. The next day I'm coming in from a drive up the street and it starts making a funny grinding noise at high RPM and it had lost power all of a sudden. So right then I knew. Of course I pull it apart and I discover two spun rod bearings. That powder from porting those heads was so fine that it all gummed together at the bottom of the oil pan after the engine would cool down and wasnt circulating oil that it didnt even matter that I had changed the oil most of it was still at the bottom of the pan when I pulled the pan off during disassembly.....well that and what was left of my no.6 rod bearing. So there you have it the story of my dumbass not thinking about something well enough before taking action.

quote Originally posted by darkhorizon:I would consider it trolling myself.... You speak from zero experience.....

From your reputation on this forum I could agree that you are the subject matter expert on trolling. Many could agree with me on that point. As for my experience with the L67, you assume far too much. In addition, if you read my ENTIRE comment regarding the pistons that I said with a good tune he'd be fine with the stockers. Both of my statements are true, and you are grasping at straws talking about a 1400 HP build.

Let me break down my reasoning so that you many benefit from my perspective.

Higher compression exacerbates any KR-inducing problems. Incorrectly tuned fuel or spark timing with the additional compression will cause KR much easier than you'd see on an L67. As such, small mistakes will cause KR. KR can cause damage either instantly (catastrophic failure) or over a prolonged period of time (usually showing up as chipped ring lands.) So, small amounts of KR left unchecked for a long period of time will eventually weaken a stock piston enough to chip off the land. This is what I've normally seen. Heck, most of the time the owner says "Oh gee, there was some noise but it's gone now" and go about their way. Of course, this is assuming the broken piston chunk doesn't get pushed into an open valve and either bend or snap it and exits with the exhaust uneventfully.

A forged piston, at least when it's made of 2618 alloy, will be able to shrug off the effects of detonation moreso than a stock piston can especially over a prolonged period. Of course, a detonation event that's severe enough can break even a forged piston. The great thing about a 2618 alloy piston is that a small crack that would typically travel through a normal piston will stop at a low-stress area of the 2618 piston. So, even if you do have some KR that causes a small stress fracture, the 2618 has a much higher survivability. Let's see your stock piston do that.

So, WHY do I recommend a forged piston for a 400WHP build, especially a high CR one? Because I don't know how savvy the OP is when it comes to tuning and making smart choices in supporting mods regarding pulley selection. Because there's less wiggle-room for mistakes in a build like this. You can make all the assumptions you want, DH. Seems to be what you're good at! I would rather give someone advice that leans towards caution, rather than trying to convince everyone that you can build an L67 as cheap as possible and HOPE your luck holds out. Two words for that method of building and modifying:

Screw that.

Question, what is the MOST commonly failed part on HIGH horsepower 3800 setups?

I will tell you right now it is not the pistons. In every case that I have experienced when the "**** hit the fan" it was a rod that went (most commonly L32 style rods, but that seems to be just because most high power builds use them).

Again, you are not getting my point.. I was not asking why a forged piston is awesome, I was asking what busniess you have telling me/the world that a forged piston is the best way to make a 3800 a better motor.

Also, one of my favorite advantages to a stock piston, is its ability to shrug off events that cause knock through the form of compression ring blowby. It helps knock events significantly more so than a forged piston with fancy "total seal" rings

[This message has been edited by darkhorizon (edited 12-29-2009).]

quote Originally posted by darkhorizon: Building an engine will most likely result in the crank bearing failure you already had.

Please explain that because I plan to install main studs in my 3900 build up requiring align boring afterwards.

Just a small fyi. I'm running a completely stock high mileage junkyard L67 bottom end over 500hp. It made 518 on the dyno and trapped about 129 in the 1/4 mi. The stock bottom end can handle the power. Also, I'm doing this with an XP cam.

I strongly recommend the ARP head studs and cometic MLS gaskets. I don't know what the general consensus on the head gaskets but I daily drive my car and it has been trouble free since day 1 and has seen 27psi peaks and 24 psi regularly, with no leaks or readjustment.

quote Originally posted by Khaos88GT: Yeah I agree with you on the pulley issue Mstangs given our southern weather. Me and you may like it but I can see how PCMs might not. LOL! Funny thing is though I was getting no KR and thats scanning at WOT with a live scanner! Of course I knew I was gonna get called out on why I had a spun bearing........notice how all I wanted to say was it was my fault well I guess I will spill the beans. So when I initially did my swap..........which would never ever have been completed without the help of Mstangs, FieroFlyer, Lloyde, Darth Fiero, PR, and even the occasional help from DH, along with uncountable others.....I digress, but thanks guys..........I sent my heads to have the valve guides machined down so I could run the higher lift of the XPZ cam. After getting them back I port matched intake and exhaust myself. I cleaned them the very best I could short of having them revatted and assembled my engine knowing full well there was probably still a ton of metal powder stuff in them but I thought.....I'll just run some good ol cheap oil through the engine after I get it running and change it over to synthetic not long after. After getting my engine assembled and in the car and running I fought with a damn electrical misfire for months until lastly changing the ICM and it clearing up. In my troubles of trying to fix the misfire and the enthusiasm of how awesome I thought my car was after fixing the misfire I forgot about changing the oil to get all that crap out. Now keep in mind this is over a period of 8 months but even so its me putting only about 50 miles on the car. When I remember about the oil change I wasnt having any issues with the way the car was running it was a beast. I went out and bought some royal purple and a K&N Gold filter and change it. The next day I'm coming in from a drive up the street and it starts making a funny grinding noise at high RPM and it had lost power all of a sudden. So right then I knew. Of course I pull it apart and I discover two spun rod bearings. That powder from porting those heads was so fine that it all gummed together at the bottom of the oil pan after the engine would cool down and wasnt circulating oil that it didnt even matter that I had changed the oil most of it was still at the bottom of the pan when I pulled the pan off during disassembly.....well that and what was left of my no.6 rod bearing. So there you have it the story of my dumbass not thinking about something well enough before taking action.

As long as you learn from your mistakes then it is all good. Even though some mistakes just plain suck and are $$$$. Good luck with getting the swap back together and glad I could be of help when doing it.

quote Originally posted by Joseph Upson: Please explain that because I plan to install main studs in my 3900 build up requiring align boring afterwards.

It seems that all "reman" cranks are just not straight enough and bearings never get installed with the correct tolerances. IDK if the book is wrong, or the shops just do it wrong, or there are oiling bits that are different, I do not know.

Nearly EVERY single dang rebuilt 3800 I have seen that was not done by zzp or tishler, ends up blowing up in the form of crank bearings.

quote Originally posted by darkhorizon: ...I was asking what busniess you have telling me/the world that a forged piston is the best way to make a 3800 a better motor. ...

the SC3800II god hath spoken

In my experience, the most common cause of a spun rod bearing other than an oiling system failure has been overly aggressive timing. The excessive load placed on a piston during pre-ignition forces the thin film of oil between the rod bearing and journal to dissipate for an instant. This creates a temporary dry contact between the surfaces.

quote Originally posted by topcat: the SC3800II god hath spoken

DH seems to be pretty antisocial. Is he always like this with other 3800 people? I mean I can't help that I've got an opinion that runs contrary to his own.

It's funny that he says that he's seen a lot of rod failures. I do have to admit that I have not. Of course, people who post about their cars on the internet are not exactly a reliable source. What do I mean by this? Well, can he vouch for these people's ability to build an engine properly? I wouldn't unless I know them personally and doublechecked their work myself.

But hey, when he can use random failures to avoid conceding a point or having a rational and levelheaded discussion to "protect" his self-declared status, it's all good right? While I will still take DH's advice into consideration, I will not respect how he does so.

quote Originally posted by GS Jon: DH seems to be pretty antisocial. Is he always like this with other 3800 people? I mean I can't help that I've got an opinion that runs contrary to his own.

You're not the only one...

Concerning the pistons, I think the forged pistons for these engines got a bad rap long ago because idiots were installing them. Yes, I said idiots. People were literally taking them out of the box and putting them into their engines -- WITHOUT taking measurements to ensure proper clearances were present, such as piston to wall and piston ring end gap. And they wondered why they failed or failed to do a good job or last long.

On the other side of the coin, some people tried to take these engines to a machine shop to have them rebuilt when the shop they took it to only had experience building Chevy V8's. You can't set up a Buick V6 like a Chevy V8 (concerning clearances); different animal. You need to find a shop that knows how to correctly build and set up these engines.

I've learned a lot of lessons from the Turbo Buick (GN) community over the years. They've been building up the Buick V6 since the early 80's. Which is why I was surprised to see that the Buick V6 community (and the lessons they learned) were largely ignored by the Grand Prix / 3800 SC community once it got going. I kept hearing (and still do hear) people say the 3800 Series 2 and 3 engines are nothing like the Buick V6's of old. Well, I'm sorry but they are of the same basic design. Yes, many things have changed and have been made better. But in the end, it is essentially the same engine. So why not use the experience of people who have been down this road before instead of discovering (and paying for) the mistakes yourself?

The forged pistons available for our engines do what they are supposed to do. They buy you additional margin for error. But they are not indestructible, as I have seen with my own eyes. A friend of mine tore down a highly modified Series 2 SC motor he had previously built (and built correctly) using Diamond Forged Pistons. It got torn down because the head gasket blew on a cylinder (I think it was #3, IIRC). Well, when the heads were pulled he also found the piston in that cylinder was slightly melted in the area where the piston ring land usually breaks off of a stock piston. He was pissed about it and commented to me 'why should money be spent on forged pistons?' I told him that piston did exactly what it was designed to do when there was a problem in that cylinder. It did not fail. Yes it suffered some minor deformation from melting, but it held together. I'm sure a stock piston would have been in pieces due to what we saw happen to the head gasket (and how badly it was in pieces). And the thing is this "damage" happened when the AFR's looked good and there was no knock detected. Well something caused that head gasket to blow and it wasn't the piston.

The fact of the matter is I don't care how good you think your tuning is or how many things you monitor while driving down the road. If you build a 400+ HP engine, you need to realize how much power each of our 6 cylinders is producing and how little it would take to upset the balance of a proper combustion event. Apparently in this engine something was not right during the combustion process on this one cylinder, and it was not enough to either upset the wideband O2 monitor or the knock sensor. A hot spot formed probably due to irregular combustion, and as a result the head gasket failed and the piston melted. But imagine the damage that would have been done to this block if he was running stock pistons and there was a catastrophic failure. As it stands now all he needs is a new piston, some honing, perhaps some decking, and some new gaskets. It could have been a lot worse. But that's the insurance forged pistons buy you.

By all means if you want to take the "cheap and easy" road and try to use stock parts, that is your choice. I run stock pistons in my turbo motor (but they are L67 parts). But I do know their limits and I don't push them because I don't feel like flushing a perfectly running engine down the toilet. It is just not worth it to me. If you don't mind rolling the dice and taking the chance that a stock part won't hold up at your power level, be my guest and use them. Just don't cry if and when your engine fails and your car is sitting on jackstands while the car show season is in full swing. I've read enough about other people's mistakes to know I don't want to be part of that statistic.

-ryan

------------------
6+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

Speaking of ryan glad you dropped. Pretty interesting topic it seems I have started I mean I definately got multiple opinions which is what I wanted so no complaints...but anyways did you ever find out the programmable specs of the XPZ cam? O yeah and I decided to save my money and get the ZZP performance short block for the peace of mind of having a knowledgeable person do bottom end work on top of bored 20 over, improved oiling and a 10:1 compression ratio, you cant beat it........well I can't. And it'll come with forged pistons so no biggy there. I'm not doing anything this time up to chance I just dont have the time or money to do it more than once......again........so twice............well you get it. LOL

[This message has been edited by Khaos88GT (edited 12-30-2009).]

quote I'm sure a stock piston would have been in pieces due to what we saw happen to the head gasket (and how badly it was in pieces). And the thing is this "damage" happened when the AFR's looked good and there was no knock detected. Well something caused that head gasket to blow and it wasn't the piston.

Then how do you explain Matt m blowing a headgasket, and MELTING an aluminum head with stock pistons, to just put another set of heads and head gaskets on and ran the next weekend? The failure was due to a incorrect tune, and 100shot of DRY nitrous causing a extreme lean condition.

The melting forged pistons have happened many times over, in "idiot built" and non idiot built forged motors.

quote but anyways did you ever find out the programmable specs of the XPZ cam?

There is no such thing... If anything, there is some guy that had some tune on some car somewhere that worked with an xpz cam.... and that does not mean it would work for you. Spend the time and get it tuned, save your money and time dealing with mail order crap. I imagine that even loyde would be able to get it closer than most anyone over the mail, assuming you ask loyde to contact someone who has tuned a big cam before.

Well I think these pictures are relevant to this discussion. Unfortunately! I'm still not 100% sure what caused this. The engine had been together for a while and up to this point was coming along rather well. The engine was 98 l67, gen V , 3.25, s1x, n* w/Lq4 maf, 42lb inj, ported heads 105 springs, lim gasket matched, headers, full gasket kit, full bearing kit, rings, lifters, and push rods. Everything except pistons. I think its anyones guess whether they would've helped or not. The tune was on the safe side(DH's), no kr to speak of, afr seemed to hang around 10.5 to 11(although 1 time at wot it went to about 13 for a glance), timing was safe at 15.5 to 17 at wot. Well as stated before everything was going fine except I couldn't get 3rd gear to shift at 6200 instead 5600. On the pass that it blew on The only thing changed was timing. Done by me of course with very little understanding of what it was suppose to be. I know I should've went to 3.0 pulley before adjusting timing but I'm only human. AFR fine, running roughly 19 to 20 degrees through 2nd, but at the top of second it advanced to 24 degrees and then poof. Again no sign of kr before the blow out. It blew out a huge chunk of block from #3 cyl, broke #3 n #4 rods clean from their respective pistons and off the crank. Both pistons were still half way up in the cylinders with the rest of the shrapnel in the pan. I was never easy on this engine. Oil pressure was never really great @ around 25psi. I felt it would be doomed cuz of that but I had guys say theirs ran at that pressure without issue. I would've liked to had 50 psi but. Take your best guess or give your opinion on why this happened so I dont make that mistake again. DH told me the same thing he said in this thread being a rod bearing failure as a result of the engine builder. I could buy the way ryanfrommichigan explains it. Like I said this thing had no prior odd noises, rod knocks, or anything so I dont think I had a spun bearing going into that run. Would a rod know show up as kr but more of a false knock? Chris

quote Originally posted by darkhorizon: Then how do you explain Matt m blowing a headgasket, and MELTING an aluminum head with stock pistons, to just put another set of heads and head gaskets on and ran the next weekend? The failure was due to a incorrect tune, and 100shot of DRY nitrous causing a extreme lean condition. The melting forged pistons have happened many times over, in "idiot built" and non idiot built forged motors.

Can't explain something that happened on someone's car I have never seen based on YOUR words alone. In all of the engines I've torn down or seen torn down after failures, I can tell you there are a billion different things that can cause a failure and as many different results you can end up with. Sometimes the head gasket fails. Sometimes the head suffers damage. Sometimes the piston suffers damage. Sometimes a combination of these parts suffers damage and others don't. Without being able to analyze the failure myself, I can't explain why one part failed and another did not. I can only speculate that the aluminum head casting in the area where it melted was made of an inferior material or construction vs. the stock piston. But that doesn't mean stock pistons are superior to forged slugs. It just means in the case you cite, the head and gasket failed before the piston did. That doesn't mean the piston would not have failed eventually.

Instead of presenting us with examples in an attempt to prove your argument (which I could counter with as many or more examples that counter your argument), why not provide us with some factual information to back up your claims? PROVE to us why you say stock pistons are "better" than forged pistons. Provide the scientific facts, tests, and other data that back up your claims. Otherwise, all you are doing is presenting an opinion with examples. And anyone can do that. But that does not make them right.

quote There is no such thing... If anything, there is some guy that had some tune on some car somewhere that worked with an xpz cam.... and that does not mean it would work for you. Spend the time and get it tuned, save your money and time dealing with mail order crap. I imagine that even loyde would be able to get it closer than most anyone over the mail, assuming you ask loyde to contact someone who has tuned a big cam before.

I will be the first one to tell you that a mail order tune is inferior to a live, in-person tune that can be done on your car (but only if it is done correctly, however). I will also say I set up ALL of my mail order tunes with a degree of safeguards built in because I know I won't have the opportunity to tune that car, in-person. Does this mean a mail order tune won't get you maximum HP? Probably. But I'm also not in the habit of tuning people's cars to within an inch of their life either, even if I do an in-person tune on it. There are too many tuners out there that do that, and there are plenty of failures that prove it. You can never know every operating condition that car is going to encounter after it leaves your shop. I prefer to lean towards the side of caution when it comes to tuning. But I guess you could say that's the reason why my personal build has lasted 6+ years with no failures. I just don't feel like getting that last 2 or 3 hp squeezed out of an engine is worth the risk of potential failure.

Handing the customer a grenade with the pin pulled in the form of a "max-effort" tune is just not worth the risk to my reputation. I would much rather give the customer something that is safe and works. And I've never had a customer request I do otherwise (just had other tuners tell me I should...???).

Just to say in relation to demtentia's failure.

I have ran 24 degrees of timing, on the same gas, on the same pulley, running leaner AFRs without issues before... and I didnt have the cam. So I was a bit confused at to the failure being directly from the extra timing. The knock sensors on that car were actually turned up a bit in sensitivity, and adjusted for the cam properly, so he always saw KR when tuned wrong... yet it poped without even a hint of KR before it went.

Could it have lean spiked from the fuel pump? Probably, and thats still to this day what I account the failure to, but I also think it could have been crank related, due to the rod blowing out, then taking the piston with it. If you look close at the piston pictures, you can see where the piston rotated in the bore, causing the ringland failure. It is most likely, unless prior damage was done, that that piston was perfectly clean, until the rod snapped and twisted it in the bore.

quote PROVE to us why you say stock pistons are "better" than forged

I cant, and you know it. On paper, the metalurgy of forged makes 100% more sense, and yes, they most likely wont chip like a L67 piston does. Does that make the motor stronger? No, because I have already shown that the pistons can take enormous loads, in comparison to what the headgasket (stock or cometic), or the rods can take. I have never personally seen a chipped piston from a properly setup L67. Yes Justins turbo car while supercharged 2+ years ago chipped nearly every piston in the block (due to him not letting me tune it), It was from large amounts of unchecked knock (he had no knock sensors). Would that have saved the motor? who knows, but who cares, because if you knock you make less power... so why do you need knock resistant pistons? So you can make less power, and risk breaking rods/headgaskets?

quote Originally posted by darkhorizon: ... , because I have already shown that the pistons can take enormous loads, in comparison to what the headgasket (stock or cometic), or the rods can take. ...

Shown where? I read of all your claims about all the high HP motors you've tuned and built, but where are they? Are you published somewhere with all the data to support what you've "shown" All I ever read is what you claim, but nothing to back your data up. Do you have dyno slips of all the motors you've built?

Support your claims with hard data, and not heresay. Hard data lends itself to more credibility.

quote Originally posted by darkhorizon: I cant, and you know it......

Just checking....

quote ......so why do you need knock resistant pistons? So you can make less power, and risk breaking rods/headgaskets?

Forged pistons are just not "knock resistant". They also tolerate the heat better which means they can withstand lean AFR's better than stock cast pistons. Furthermore, the piston ring arrangement on the aftermarket forged pistons also protects the rings from the heat of combustion better than the stock piston design. So it is just not the material the forged pistons are made of but their design that lends them to being stronger and better suited for these types of applications.

What good is making more power if the engine doesn't stay together?

Concerning head gaskets, if I am going to build a fuse into the engine, I want my head gaskets to be that fuse. I would rather those blow first then anything else if something goes wrong. But that's just my personal preference.

[This message has been edited by Darth Fiero (edited 12-30-2009).]

quote Originally posted by topcat: Shown where? I read of all your claims about all the high HP motors you've tuned and built, but where are they? Are you published somewhere with all the data to support what you've "shown" All I ever read is what you claim, but nothing to back your data up. Do you have dyno slips of all the motors you've built? Support your claims with hard data, and not heresay. Hard data lends itself to more credibility.

My real world experiences of rods breaking and pistons not breaking in high power situations, aka 400whp plus, which is a situation that NOBODY in this thread has ever been in. While I have not owned a ton of these, I speak for many that have.

quote What good is making more power if the engine doesn't stay together?

Been there done this... I (and others) already said that the stock block has been proven reliable, so it stays together just fine at whatever ANYBODY on this forum can throw at it.

One person in my crew runs a 150k+ L36, at 12:1 on the street with pump gas, and a XPZ with 20+ timing and a 2.8 pulley on a gen5. It is about as extreme as a street M90 car gets, and the motor has been in it for 2 years, and had the 2.8+xpz on the ENTIRE time, and been down the track god only knows how many times, and beat up on the street DAILY, YEAR ROUND. If that does not stress reliability, then what would? This is with the L36 pistons that you claim wont handle even a 3.8 pulley on a m90.

[This message has been edited by darkhorizon (edited 12-30-2009).]

quote Originally posted by darkhorizon:This is with the L36 pistons that you claim wont handle even a 3.8 pulley on a m90.

Who the hell ever said this?

Stop making things up to try to strengthen your position. It's counterproductive to your credibility.

quote Originally posted by GS Jon: Who the hell ever said this? Stop making things up to try to strengthen your position. It's counterproductive to your credibility.

I am not making things up... It is a WELL known fact that Ryan has paraded around saying that the L36 can not handle boost in any form. Multiple threads on this, but I have been playing call of duty too much today to have time to find them.

quote Originally posted by darkhorizon: I am not making things up... It is a WELL known fact that Ryan has paraded around saying that the L36 can not handle boost in any form. Multiple threads on this, but I have been playing call of duty too much today to have time to find them.

I don't think I've ever said that. I probably said something along the lines that it wouldn't be something I would do myself or encourage others to do because the L36 parts are not designed for boost duty, and I don't feel that they would be as durable as L67 parts in the same situations. But I don't think I've ever said L36 parts couldn't hold up to boost duty (at least in the short term), I've just said you will have very little margin for error in your tune if you push them hard.

What's the real deal here, DH? Every time someone voices an opinion contrary to yours, your feathers get ruffled. What gives? Why is it such a big deal to you that you always have to be right or come off knowing everything on this forum? And about the parading comment, I think you have me mixed up with what you do yourself. I would hardly call my 3000 posts in 7 years parading as much as your 8000 posts in 3 years, wouldn't you say?

Geez, it's just the internet.

[This message has been edited by Darth Fiero (edited 12-31-2009).]

As much as I hate agreeing with darkhorizon on stuff, if you have a halfway reasonable tune you won't break stock 3800 pistons, no matter if they are l36/l67/l32/l26, they won't break. I can understand people wanting to make their engines strong and thus going with the forged pistons, but there is no reason to do it, and you can save yourself a lot of money running the stock pistons. The added "safety" you arguably get from running forged pistons, you can more than makeup for with a better intercooler or other changes to the setup so you don't have to run it so far on the edge that you need said forged pistons. If you don't detonate, stock 3800 pistons don't fail at any power level you guys are running.

Matt M runs mid 8's and traps over 160mph with a stock junkyard l67 shortblock, 28psi boost, nitrous, 7500rpm, it gets beat pretty hard, makes over 750whp (without nitrous), thats north of 900 crank hp. Did i mention this was a stock shortblock? Not balanced, didn't get new rings or bearings or pistons, it was a used stock junkyard motor with a cam shoved in it and some good heads bolted up to it. So maybe if you're looking to make 1000+ crank hp, you should look into forged pistons?

As far as the headgaskets being the weak point over the pistons, run whatever gaskets you want, they'll be the weak point. I have completely destroyed 2 sets of MLS gaskets and never had any sort of piston issue. I have a completely stock l36 shortblock and can't break the thing and i beat the **** out of it. I drive it daily with a Gen V and 2.7 pulley, 21.5 degrees of timing, and 13.2:1 afr.

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1999 Grand Prix GT 257,500+ miles.
XPZ, Heads, Pacesetters, S2 IC, Gen V, N* tb, UD pulleys, 160tstat, tune, etc...
11.682 @ 117.2 w/1.77 60', 379.9whp on 93 octane.

[This message has been edited by dbtk2 (edited 12-31-2009).]