Im just curious what the minimum safe specs are for the connecting rod journals on the crank. Im thinking about having them offset ground for a little more stroke.
Very interesting, I have no idea, but am in here for further info. I'll check my manuals to see if it says anywhere.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Thanks, that would be awesome.
ive been looking into this... from what i have found we cant get large enough bearings for it to really work...
now, find a place to make a custom bearing or somewhere that makes larger than .75mm... then hell yes.
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well, doing a bit more research i found one hell of an article... it explains a lot and has great visualizations (something i need LOL)
Stroking Article
on a side note... i would say we could probably take some off the rod journal. reason being, we need to turn the mains down a TON to get them to fit into a 2.3 block for a stroker setup, i would think GM gave the rod journals a good amount of meat as well.
how the hell would you even test for that? sonic testing?
*thoroughly re-interested. thanks cory!
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I vaguely recall a company doing this many years ago...and it resulted in out-of-round cylinder bores (likely a result of increased normal force on the cylinder walls).
I have no signiture
Your welcome. That link was definitely a good read, thanks Brad. I think the best bet for finding out how much can be taken off the journal would be to find a standard crank that is junk, like a main bearing failure, and take it to a machine shop to dissect. The only thing that stinks about this is that by increasing the stroke we are decreasing the rod ratio.
As for the bearings I have come across places that make custom bearings, just have to pay to play lol. Ill have to search and see if I can find them again.
and whats the best way to increase rod ratio? tee hee.. longer rods.
for the minimal gains we THEORETICALLY "could" see by offset grinding our cranks possibly the small difference the slightly longer 2.3 rod makes could handle the difference. its all in the math... and i just so happen to have a junk (like spun a bearing so bad the journal is BLUE) standard crank lying around i could get tested.
out of round cylinders, brian? on an LD9 this was performed? must have been during the stone ages around here cuz i dont remember anything like that LOL you got any more info?
where's mcelvy... he's a wealth of old sckool knowledge.
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No, I don't have any info beyond that, brad. It might have just been an old rumor, but yes, it was an ld9.
I have no signiture
ok ive got some input...
we can get .75mm oversized bearings. with equates to around 1/32's more stroke if you offset ground the crank to match them.
my dad told me a small block chevy usually gains about 27 cubic inches for a 1/16th inch stroke increase. if you cut that in half sinze we have a four cylinder thats 13.5 ci, and since 1/32th's of an inch is exactly half of 1/16th's of an inch we come up with a cubic inch increase of about 6.75 cubic inches.
now, ive done the math, and on a STOCK LD9 with 146 cubic inches (2.39 liters) this would make an LD9 then 2.49 liters, which rounded up makes it a 2.5 liter twin cam. and mind you.. this is on a STOCK LD9, now... go ahead and bore the bastard to the max of the .080 she can take. can you say holy ballsack big boy motor?
someone please do the math on this and help me out cuz this seems way too good to be true, and well... i wasnt much of a math student so i wont be surprised if im off. but someone with some real skills please do this!!!!
brad = (stoked for stroked)
If it takes forever.... I will die trying. Underdog Racing
more i think about it no way its that easy LOL
cant be right...
If it takes forever.... I will die trying. Underdog Racing
Your math is way off, Brad. You can't use a completely different engine as some reference unless they have the exact same bore and stroke.
Displacement = (Bore diameter / 2)^2 * pi * stroke
Here are the results...
Stock
Bore Diameter = 9.0 cm
Stroke = 9.4 cm
displacement = 2392 cc (2.39 L)
Stroked (0.75mm)
Bore Diameter = 9.0 cm
Stroke = 9.475 cm
displacement = 2411 cc (2.41 L)
Bored (.080" / 2.03mm) and Stroked (0.75mm)
Bore Diameter = 9.203 cm
Stroke = 9.475 cm
displacement = 2521 cc (2.52 L)
I have no signiture
hahahaha i knew it couldnt be that easy. oh well, i didnt get to go to school for this stuff so thats why my ideas are half cocked sometimes. my bad, brian to the rescue again!
.2 liters more displacement for these bearings aint going to be worth it. i knew i had this figured out before... me and my machinist went through it awhile ago, i forgot the particulars.
FML i fail
If it takes forever.... I will die trying. Underdog Racing
it is cool to know that if you want a 2.5 all you gotta do is the .75mm bearings with an offset grind and bore it .060 though.
now, how about the regular stroker (quad block/LD9 crank).... bore a thicker cylinder walled rocket parts block to .060, and offset grind the crank .75mm. you'd have a real big bastard then.
it'd be worth it in a 96-98 LD9 with the dished pistons... cuz then you could cut like .015 off the tops of the pistons making them flat tops and they would still pop up out of the block .015 (due to the .030 more stroke), use the stock head gasket and have the clearance you need and basically get more stroke and .5 more compression.
so, you'd get a 2.41 liter with roughly 10:1 compression. be a real nice motor for circle track guys trying to hide mods.
Edited 1 time(s). Last edited Sunday, November 14, 2010 2:45 PM
If it takes forever.... I will die trying. Underdog Racing
