Bored & Stroked

chetwindell · 07-08-2002, 01:10 AM

What do these terms mean? i have heard of an engine being bored .0400 over or a "bored out v-8". But what does it mean? Also, what does it mean if it is a Stroked 302 or a stroker kit??? thanx for the help

Smokedawg · 07-09-2002, 08:24 AM

Boring the motor is just like it sounds. It bores out the sides of the cylinder walls to make them bigger. Stroking it is just changing the stroke that the crank is making.

chetwindell · 07-09-2002, 10:57 AM

What does the CI mean in your engine? cool indeed? just wondering

Smokedawg · 07-09-2002, 11:05 AM

347 cubic inches..

I bored my motor out .30 over and stroked it out to a 347...

302 LX Eric · 07-09-2002, 11:23 AM

Smokedawg's 347 cu. in. motor would have been only 342 if he had not bored the cylinders to .030" over.

Likewise, my 331 cu. in. motor would have been only 327 had I not had mine bored .030" over.

Obviously, in both cases, we had to get pistons that measure 4.030" to fit properly.

The more you overbore the cylinders, the more displacement you get, however there is a point of diminishing returns when you bore too much and therefore loose strength in the cylinder/block walls.

E

chetwindell · 07-11-2002, 05:06 PM

Quote:

Originally posted by 302 LX Eric
Smokedawg's 347 cu. in. motor would have been only 342 if he had not bored the cylinders to .030" over.

Likewise, my 331 cu. in. motor would have been only 327 had I not had mine bored .030" over.

Obviously, in both cases, we had to get pistons that measure 4.030" to fit properly.

The more you overbore the cylinders, the more displacement you get, however there is a point of diminishing returns when you bore too much and therefore loose strength in the cylinder/block walls.

E

ok, so if u have a 327ci engine bored .030 over it makes it a 331 and not a 330? do u not take the extra 3 from the .030 and add that to the ci of the engine like...
327ci+.030ci=330? why 331?

429mustang · 07-11-2002, 05:56 PM

because when you bore it out .030 over, you make the entire bore slightly bigger in diameter. Basically, with a 302, if you filled the cylinders up with water, then measured the amount it took to fill all 8 of them, you'd have 302 cubic inches of water. When you take .030 off the cylinder walls, then measure it again, it turns out to be 306 cubic inches. Does this make sence?

PKRWUD · 07-11-2002, 06:53 PM

To figure an engine's displacement, the formula is:

pi / 4 x bore squared x stroke x # of cylinders

Now, pi (3.1415927) divided by 4 equals .7853982, so the first part of the formula will always be .7853982:

.7853982 x bore squared x stroke x # of cylinders

Now, a 302 has a 4" bore, a 3" stroke, and 8 cylinders, so, by substituting those numbers, you get:

.7853982 x 4 squared (16) x 3 x 8 or:

.7853982 x 16 x 3 x 8 = 301.5929 cubic inches

With me so far?

Okay, now let's say you bore the engine .030" over, which means increasing the bore diameter of each cylinder to 4.030". Then the formula would look like this:

.7853982 x 16.2409 x 3 x 8 = 306.13375 cubic inches.

If you were to bore it .060" over, the formula would become:

.7853982 x 16.4836 x 3 x 8 = 310.70853 cubic inches

Get it?

Take care,
-Chris

PKRWUD · 07-11-2002, 06:56 PM

By the way, to help put it into perspective for you, .030" is approximately as thick as 10 sheets of notebook paper.

Take care,
-Chris

tarmon8r · 07-11-2002, 09:46 PM

Quote:

Originally posted by PKRWUD
By the way, to help put it into perspective for you, .030" is approximately as thick as 10 sheets of notebook paper.

Take care,
-Chris

simple yet effective.

props for the 100% correct answer

is there anything u dont know?

lol

peace

07-08-2002, 01:10 AM	#1
chetwindell Registered Member Join Date: Jun 2002 Posts: 10	Bored & Stroked What do these terms mean? i have heard of an engine being bored .0400 over or a "bored out v-8". But what does it mean? Also, what does it mean if it is a Stroked 302 or a stroker kit??? thanx for the help

07-09-2002, 08:24 AM	#2
Smokedawg Tires Fear Me... Join Date: Jan 2001 Posts: 867	Boring the motor is just like it sounds. It bores out the sides of the cylinder walls to make them bigger. Stroking it is just changing the stroke that the crank is making. __________________ 1990 Mustang GT- 347 Stroker-Tremec 3550-Compucar Nitrous, AFR, Systemax Intake, AFM, 30lbers, 70MM TB, 76mm MAF, full suspension and lots more 1995 Chevy S-10 406 SBC, Dual tunnel ram, Dart heads, Nitrous, full tub, 4-link, adjustable drag shocks, coil-overs, 9in rearend, 4.56 gears...etc

07-09-2002, 11:05 AM	#4
Smokedawg Tires Fear Me... Join Date: Jan 2001 Posts: 867	347 cubic inches.. I bored my motor out .30 over and stroked it out to a 347... __________________ 1990 Mustang GT- 347 Stroker-Tremec 3550-Compucar Nitrous, AFR, Systemax Intake, AFM, 30lbers, 70MM TB, 76mm MAF, full suspension and lots more 1995 Chevy S-10 406 SBC, Dual tunnel ram, Dart heads, Nitrous, full tub, 4-link, adjustable drag shocks, coil-overs, 9in rearend, 4.56 gears...etc

07-09-2002, 11:23 AM	#5
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	Smokedawg's 347 cu. in. motor would have been only 342 if he had not bored the cylinders to .030" over. Likewise, my 331 cu. in. motor would have been only 327 had I not had mine bored .030" over. Obviously, in both cases, we had to get pistons that measure 4.030" to fit properly. The more you overbore the cylinders, the more displacement you get, however there is a point of diminishing returns when you bore too much and therefore loose strength in the cylinder/block walls. E __________________ 1991 5.0 LX Coupe - 40,750 miles 331 cu. in. / Tremec 3550 / BFG Drag Radials 12.22 @ 114.31 mph - w/1.89 60'

07-11-2002, 05:56 PM	#7
429mustang Registered Member Join Date: May 2001 Location: westerville, OH USA Posts: 618	because when you bore it out .030 over, you make the entire bore slightly bigger in diameter. Basically, with a 302, if you filled the cylinders up with water, then measured the amount it took to fill all 8 of them, you'd have 302 cubic inches of water. When you take .030 off the cylinder walls, then measure it again, it turns out to be 306 cubic inches. Does this make sence? __________________ 1990 Notchback: BBK Ceramic Coated Full length headers, Dr. Gas 3"- 2 1/2" x-pipe, Flowmaster 40's/turndowns.

07-09-2002, 10:57 AM	#3
chetwindell Registered Member Join Date: Jun 2002 Posts: 10	What does the CI mean in your engine? cool indeed? just wondering

07-11-2002, 06:53 PM	#8
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	To figure an engine's displacement, the formula is: pi / 4 x bore squared x stroke x # of cylinders Now, pi (3.1415927) divided by 4 equals .7853982, so the first part of the formula will always be .7853982: .7853982 x bore squared x stroke x # of cylinders Now, a 302 has a 4" bore, a 3" stroke, and 8 cylinders, so, by substituting those numbers, you get: .7853982 x 4 squared (16) x 3 x 8 or: .7853982 x 16 x 3 x 8 = 301.5929 cubic inches With me so far? Okay, now let's say you bore the engine .030" over, which means increasing the bore diameter of each cylinder to 4.030". Then the formula would look like this: .7853982 x 16.2409 x 3 x 8 = 306.13375 cubic inches. If you were to bore it .060" over, the formula would become: .7853982 x 16.4836 x 3 x 8 = 310.70853 cubic inches Get it? Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-11-2002, 06:56 PM	#9
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	By the way, to help put it into perspective for you, .030" is approximately as thick as 10 sheets of notebook paper. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

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