ronnieabene

iTrader: (28)

cAN YOU BORE A lt1 TO 60 THOUSANDS SAFELY??

jarendt31

I've heard that 40 is as far as you want to go if you're going to lean on the motor at all. So I guess your end goals for the motor would have something to do with this.

Next level

iTrader: (5)

396 i think, atleast i enjoy mine.

Ray@Nitrous Outlet

396cid is still .030 over

.030 is safe
.040 max IMO

Next level

iTrader: (5)

.040 bore would be a 408 ?

The Engineer

I've examined and measured the cylinder thickness on an LT block with a .030” over-bore. The cylinder-wall to water-jacket thickness was .200” after the .030" over-bore. Therefore, you’re starting with only .230” side-wall thickness, basically less-than .2500” (1/4 inch). So, a .060” over-bore would only leave a .170” cylinder-wall thickness. Ouch!

WD

Ray@Nitrous Outlet

383 is 4.030 bore and 3.75" stroke
385 is 4.040 bore and 3.75" stroke
396 is 4.030 bore and 3.875 stroke
397 is 4.040 bore and 3.875 stroke

408 = 4.030 bore and 4" stroke...not recommended for the avg LT1 block

Formula350

iTrader: (3)

I thought an LTx block was basically the same as a GEN I with a few different provisions up front? If so, why can GEN I's handle .060?

Next level

iTrader: (5)

is the 397 really much different then a 396 ?
just curious.

Built LT1

iTrader: (3)

You forgot my engine!

388 is 4.060 bore and 3.75 stroke.

I did have my LT4 block "sonic tested" before going .060 over.

97Z28LT1

iTrader: (3)

I believe it has to do with the water jackets, but I am not sure. I know that is the "problem" with doing a 396, but plenty of people have done the 396 with no problems. The LT1 is also reverse-flow cooling so that could have something to do with it, since that is totally different than a regular small block. Someone else could probably give you a more definate answer. I have heard countless times not to take an LT1 over .040 over, but it sounds like it is a possibility, but not the ideal thing to do.

The Engineer

The issue with building a 396 "is not" the .030" cylinder over-bore, but clearancing the block for the rotating assembly without getting into the water jacket.

WD

slomarao

iTrader: (6)

anything past 40 over is really pushing it.

BlackScreaminMachine

iTrader: (17)

You can do 0.060" over, with no issues.

BlackScreaminMachine

iTrader: (17)

That is correct!

Formula350

iTrader: (3)

Just to updated list with exact numbers (and many more combinations, because I want to see someone mate a 4.3 with a 5.7 and have some freakish kids!)

Punched
349.8 = 4.000 bore / 3.480 stroke (Your stock 350)
355.1 = 4.030 bore / 3.480 stroke
356.9 = 4.040 bore / 3.480 stroke
360.4 = 4.060 bore / 3.480 stroke

Strokers
(Note:3.720 = stock crank + Baby LT1 rods, 3.990 = stroker crank + Baby LT1 rods)
374.0 = 4.000 bore / 3.720 stroke
377.0 = 4.000 bore / 3.750 stroke
379.6 = 4.030 bore / 3.720 stroke
381.5 = 4.040 bore / 3.720 stroke
382.7 = 4.030 bore / 3.750 stroke
384.6 = 4.040 bore / 3.750 stroke
385.3 = 4.060 bore / 3.720 stroke
387.0 = 4.000 bore / 3.850 stroke
388.4 = 4.060 bore / 3.750 stroke
392.9 = 4.030 bore / 3.850 stroke
394.8 = 4.040 bore / 3.850 stroke
398.7 = 4.060 bore / 3.850 stroke
401.1 = 4.000 bore / 3.990 stroke
407.2 = 4.030 bore / 3.990 stroke
409.2 = 4.040 bore / 3.990 stroke
413.2 = 4.060 bore / 3.990 stroke

Baby Strokers
(Note: Baby LT1 block & heads w/ above strokes)
305.8 = 3.750 bore / 3.480 stroke
326.9 = 3.750 bore / 3.720 stroke
329.6 = 3.750 bore / 3.750 stroke
338.4 = 3.750 bore / 3.850 stroke
350.7 = 3.750 bore / 3.990 stroke


De-Strokers
(Note: LT1 block & heads w/ Baby LT1 crank & rods (3.00 stroke), and w/ 350 rods (2.76 stroke), 6.2" longer rods (3.260 stroke)
277.5 = 4.000 bore / 2.760 stroke
281.6 = 4.030 bore / 2.760 stroke
283.0 = 4.040 bore / 2.760 stroke
285.9 = 4.060 bore / 2.760 stroke
301.6 = 4.000 bore / 3.000 stroke
306.1 = 4.030 bore / 3.000 stroke
307.7 = 4.040 bore / 3.000 stroke
310.7 = 4.060 bore / 3.000 stroke
327.1 = 4.000 bore / 3.260 stroke
332.7 = 4.030 bore / 3.260 stroke
334.3 = 4.040 bore / 3.260 stroke
337.6 = 4.060 bore / 3.260 stroke

If someone is REALLY that interested in it, I'll go through and factor in all the other SBC cranks with different strokes and multitude of different rods. Or even just 400ci 5.565" rods. (This has taken me long enough as is, anyone want to sticky it? heh)