oem l67 rods stress rating - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-23-2005, 10:22 PM   #1
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Default oem l67 rods stress rating

how much hp can the rods from a 95 ssei handle in stock form, after shot peening, and after shaving?
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Old 12-23-2005, 10:59 PM   #2
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The stock rods UN-modified can handle more than you can throw at them. I've never seen a single Series 1 L67 rod fail.
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Old 12-24-2005, 11:05 PM   #3
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My motors hasnt even batted an eye , even with a 100 shot on it. You've gotta figure with a 2.1 pulley and 100 shot, its probably making over 400 lb ft of torque and hp in the 350 range.. If not more. Even the tranny is holding together.
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Old 12-24-2005, 11:40 PM   #4
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The amount of stress exerted at the 1-2 shift on the Series 1 is BRUTAL. Even a mildly modded Series 2 can't compare. And we have yet to see a stress related bottom end failure here on an L67 Series 1.
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Old 12-25-2005, 02:57 AM   #5
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Lets just say a stock series 2 bottom end can handle 9s, and there not much difference in series 1 or 2
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Old 12-25-2005, 02:59 AM   #6
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Put it this way, if my Bottom end couldnt take the stress, i would be doing all the top end work to my car that i am.
These engines are top notch.
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Old 12-25-2005, 12:07 PM   #7
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I have seen 2 3800 Bottem ends go out, Or thrown rods...

An LN3 because the owner neglected to put more oil in the engine... Rod went through the block...

The other had to be a factory flaw on an L36, as the rod broke in two... Wasn't twisted in any way... Just a good jagged break in the middle of the rod...

Other than thos 2 I have pretty much never seen a 3800 toss a rod... I have seen a couple run from the cops and put those 3800'* through their paces...

I have seen a couple L27'* knocking ( bad oil pump stupid Owner ), But those never threw a rod,

If we looked at OSG'* car the piston broke into many pieces but the rod was still all there and intact with the wirst pin...

After seeing the bottom ends of the Ford 3.0 and 4.0 60* V6 engines I'd say that the 3800'* came with some pretty decent internals...

And there is a good diffrence in the way the power is produced between the 3800 Series I and 3800 series II engines...

The series 1 produces all of its torque in a hurry, added length of the piston/rod assembly in motion make a diffrence in the way the engine will produce force... Keep in mind that the series I'* have more reciprocating mass than does a Series 2 engines.. So we can't say that they are the same, they may make almost the same power, but they do it in a diffrent manner...

As well the series 1 and series 2 engines are very diffrent beasts, Bore and Stroke were the 2 things that stayed identical...

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Old 12-25-2005, 01:22 PM   #8
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What he said.






Every now and then Don gets on his soapbox and makes us all wonder WHERE THE F*** DID THIS GUY COME FROM?

Glad he ended up here though.
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Old 12-25-2005, 11:26 PM   #9
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Quote:
Originally Posted by jr's3800
I have seen 2 3800 Bottem ends go out, Or thrown rods...

An LN3 because the owner neglected to put more oil in the engine.....The other had to be a factory flaw on an L36, as the rod broke in two Wasn't twisted in any way.....Other than thos 2 I have pretty much never seen a 3800 toss a rod.....I have seen a couple L27'* knocking ( bad oil pump stupid Owner ), But those never threw a rod.....
Likewise I have seen very few Gm 3800'* with bad rods all of the one'* ive seen due to Gross maintenance negligence/mechanical/oil system failure...
to be specific...3 with crushed oil pans (restricted oil intake on each-half crushed) 2 failed at highway onramp speeds after leaving a certain jiffylube (less than a mile from our shop ) and let loose with massive system damage...but only one rod would fail and it would F%$k up the inside of the block but they never puncked a hole in the block!, 1 failed rod (rod and cap intact 1 bolt had heated up and relaxed It miced at over .030 longer than any of the other bolts literally the rod nuts vibrated off and rod halves seperated...just put a hole in the pan with the shoulder)
and those are SI engines
i have seen 2 SII failures both due to oil starvation...both blocks had holes...

this is why i am checking bulkhead thickness'* between the different SI/SII engines we have in Al'* garage


Quote:
Originally Posted by jr's3800
After seeing the bottom ends of the Ford 3.0 and 4.0 60* V6 engines I'd say that the 3800'* came with some pretty decent internals...
Agreed! we all have to remember that in the end this engine is HEAVILY related to the odd and even fire Buick V6...and the GNX
remember how much power some of those engines are making on STOCK shortblocks! makes you realise that though the Buick and SI(EV6)/LN3/LG3 (as the Oz guys call "buick v6" as the series II are called ecotech) have only 2 bolt mains vs the SII 4 bolt cross bolt mains...remember both blocks are deep skirt blocks and believe it or not have a whole LOT in common...which i have to say the tall deck/long rod features of the SI shortblock have a bigger advantage over the Supposedly stronger SII 4 bolt mains and lighter rotating/reciprocating weight...the dwell at TDC with a long rod engine is comparativly longer, less rod angularity, less thrust loading of the cylinder rods.... and with a tight ringpack and good pistons you could get longer custom rods with better (lighter) metalurgy and improve upon this further
also the SI block is better suited to stroker crankshafts...which face it in the next few years as 3800 racing gets faster...displacment will increase...and every little increase in mechanical engine efficiency will matter.

a while ago i rebuilt the 3800 in my 92 Chrysler Imperial...a 60* design...that engine was built! it went on a rodknock (i bought it cheap that way! ) for close to 12,000 miles and the rod still had a round big end bore!...the fords...eh i wont get into those...but i can tell you this i have been thinking heavily about dropping the Mopar 3800 into the back of my sisters old 87 Lebaron GTS (2.2L turbo 4 cyl) very well built and should handle a turbocharger fairly well stock...
Mopar 3800 Borexstroke 96 x 86.9 mm'*
Gm 3800 borexstroke 96.52 x 86.36 mm'*

Quote:
Originally Posted by jr's3800
And there is a good diffrence in the way the power is produced between the 3800 Series I and 3800 series II engines...

The series 1 produces all of its torque in a hurry, added length of the piston/rod assembly in motion make a diffrence in the way the engine will produce force... Keep in mind that the series I'* have more reciprocating mass than does a Series 2 engines.. So we can't say that they are the same, they may make almost the same power, but they do it in a diffrent manner...

As well the series 1 and series 2 engines are very diffrent beasts, Bore and Stroke were the 2 things that stayed identical...
and again, Ditto! the small ports of the SI engines maximizes low end Tq! but overall from some research i have done even extremly worked over SI heads will not flow more than ported SII heads...and when you get into large valve lift numbers the SII heads shine better than heavily modified SI heads with larger valves (shrouding is an issue...as with the SII head)

I am a firm believer that at some point the aftermarket WILL come out with heavily modified factory heads or aluminum heads...
with the modern "WetFlow" flowbenches (Rehermorrison)
Quote:
The shape of the combustion chamber also has a significant impact on performance. A conventional chamber with deep reliefs around the valve seats and a relatively flat valve seat angle can produce terrific flow at .200 to .300-inch valve lift. Today a state-of-the-art chamber typically has 55-degree valve seats and steep walls that guide the air/fuel mixture into the cylinder to enhance high-lift flow......
....Engine technology in all forms of motorsports is converging around smaller, high-efficiency combustion chamber designs. You can see the result in lower brake specific fuel consumption (BSFC) numbers, which indicate improved engine efficiency. Twenty years ago, a racing engine with a .48 BSFC was considered very good; today'* competition engines produce BSFC numbers in the neighborhood of .35. This means that a given quantity of fuel is being atomized and burned more effectively to produce more power. A cylinder head'* combustion efficiency can't be measured on a flow bench, yet it has a huge impact on performance.....
the new wetflow flowbenches have shown that a small "guidefin" in the port design can help "homogenize" the fuel air mixture and promote swirl around a centrally located spark plug... less Knock tendancies and with well designed quench area'* to provide added mixture turbulence right at TDC...many engines in the engine masters challenges have found extreme gains by closing the head to piston gap under .060 many ran less than 2-3 hundrenths of an inch!
and start exploring modern canted valve heads, by either "moving" the valveguids in the heads (factory) or with a custom designed after market aluminum cylinder head (full advantage in CNC operations to produce the excelent (modern) heart shaped combustion chambers/valvetrain technology)...unshrouding of valves as the valve moves through its travel...and....
for the stock heads...take a look at hotrockers...
http://www.hotrocker.com/


imagine something like this but with some modifications...
VARIABLE VALVE LIFT!...have that giant beast of a camshaft...but with the drivabilty and low end tq of a tamer one

I think that with a little bit of work i can get the SII heads that have a much better engineered package, port configuration/crosssection, combustion chamber design, to work on the tall deck SI block and yield an engine with overall much better mechanical efficiency to make a better "Mouse trap"
and all with factory parts i might add
Regards, James
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Old 12-26-2005, 12:23 AM   #10
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WOW That hot rocker thing is crazy. Any idea on price? It'* probably a fortune.
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