306 vs. 302

sodaking663rd

New Member

Oct 11, 2004

47

0

0

annapolis, md

Jul 21, 2006

#1

• Jul 21, 2006

• #1

I'm not a mechanic and correct me if I'm wrong about any of this but please enlighten me why a 306 stroker engine is that much more powerful than a 302. I understand that 306's probably have better components since it is built for power. Thanks!

 

grey5.0beast

Cookies should never be DUNKED!!!

Aug 3, 2004

0

1

0

atl ga

Jul 21, 2006

#2

• Jul 21, 2006

• #2

A 306 is just a bored out 302 by .030, making little to no power over a 302. The reason for doing this is to clean up the cylinder walls. Take a 302 with the same combo as a 306 and they would make very little power differneces.

 

srothfuss

Last night I stabbed the same guy 7 times in a row

Oct 17, 2004

1,796

3

0

Woodward Ave.

Jul 21, 2006

#3

• Jul 21, 2006

• #3

yup, greybeard said it just right... There is no noticable power increase between 302 and 306 cubic inches [using the same top assembly]

 

sodaking663rd

New Member

Oct 11, 2004

47

0

0

annapolis, md

Jul 21, 2006

#4

• Jul 21, 2006

• #4

interesting! thanks for the info.

 

Tonys96Cobra

professional deer "mounter"

Oct 28, 2005

19

9

29

Syracuse

Jul 21, 2006

#5

• Jul 21, 2006

• #5

Well, the main difference is that one is 4 bigger than the other one.

 

poneypower89

Now everyone in the world will know I wanna bang t

Dec 6, 2004

0

3

28

Indianapolis, Indiana

Jul 21, 2006

#6

• Jul 21, 2006

• #6

the only reason you have the impression that 306s make more power is for this reason:

Generally the only reason someone has a 306 is because the rebuilt their engine. Now, usually anyone who can rebuild an engine is an enthusiates... and when they DO rebuild the rebuild with better parts.. IE better heads, cam intake.. and therefore... the end result is more power

Generally... the proportion of stock setups in 302s is much much greater than the proportion of stock setups in 306s.


But, if EVERYTHING is same except one is a 302 and one is a 306.. the difference is minute and not worth mentioning.





306 is NOT a stroke.. the stroke is still stock.. its just an overbore in the cylinder wall. 327, 331, 347 <--- these are stroker sizes and DO make more power in general.

 

BlownFiveLiter

have car, will race....wait, it doesn't run

15 Year Member

Nov 29, 1999

3,133

18

108

Chicagoland

Jul 22, 2006

#7

• Jul 22, 2006

• #7

The 306 may make slightly more power than the 302, but the difference will be negligible. Some people say it makes more power because the larger bore unshrouds the valves.

 

8

8950HO

New Member

Mar 31, 2005

658

2

0

Jul 22, 2006

#8

• Jul 22, 2006

• #8

Those extra 4 cubic inches of displacement is all it takes to pin you in your seat under hard acceleration .

 

Coupe5oh

New Member

Jul 4, 2006

4

0

0

S.a. Texas

Jul 22, 2006

#9

• Jul 22, 2006

• #9

poneypower89 said:

306 is NOT a stroke.. the stroke is still stock.. its just an overbore in the cylinder wall. 327, 331, 347 <--- these are stroker sizes and DO make more power in general.

Click to expand...

Very true.

And you forgot the 342
which is a standard bore 302, but with a larger stroke.... sodaking fyi..
Late

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Jul 22, 2006

#10

• Jul 22, 2006

• #10

i hate when people think a 306 is something to brag about.

I have a friend who seems to think there is a noticable difference from a 302 to a 306, its 4 CI, hardly nothing at all...

 

FastDriver

I was uncomfortably high & wearing a helmet

SN Certified Technician

Sep 5, 2001

6,062

2,667

224

Vass, NC

Jul 22, 2006

#11

• Jul 22, 2006

• #11

Unshrouding the valves is worth like 50 hp, man.

BTW the 327 and the 331 have the same stroke. The 342 and the 347 have the same stroke. With an aftermarket siamese bore block, you can run more bore and can make some other interesting numbers like a 347 with the same stroke as a 331 etc...

Check out the July hotrod for every spec you'd need to make an 816 hp 374 c.i. SBF. It's a 302 block with a 4.125" bore and a 3.5" stroke. Fun stuff.

Chris

 

grey5.0beast

Cookies should never be DUNKED!!!

Aug 3, 2004

0

1

0

atl ga

Jul 22, 2006

#12

• Jul 22, 2006

• #12

I read that in one of the old mm and ffs. But I think the biggest you can go on a stock block is somewhere in th360 c.i. range, much past that and the cylinder walls get too thin.

 

85_SS_302_Coupe

it sucks (I know) to be on the receiving end

15 Year Member

Nov 11, 2003

6,945

1,597

223

Northern KY

Jul 22, 2006

#13

• Jul 22, 2006

• #13

You guys are missing a very important aspect that seperates the two, and why your typcial 306 WILL make more power than a 302.....they usually have aftermarket pistons, which usually have more compression and are lighter. Granted, this isn't going to be huge, but it's enough to notice it. Compression alone can boost power enough to feel it over stock.

 

Foxfan88

My Grandpa has great wood.

Sep 13, 2004

2,487

4

0

Miami, Ok

Jul 22, 2006

#14

• Jul 22, 2006

• #14

yeah but take 2 engines that are exactly the same... and the 4ci wont make a difference.

say if u rebuilt and engine and just got it bored .030 over and got a cheap flat top piston like stock but in a .030 oversize, that being the only change, i doubt you could feel a difference...