302 vs 306 ?

Discussion in 'Fox 5.0 Mustang Tech' started by undercover50, Jan 5, 2004.


  1. undercover50

    undercover50 New Member

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    I just found out that I need to rebuild my motor how much difference do you see in performance between a 306 and a 302 mustang motor. My mods are trickflow intake manifold e303 cam stock heads and 65mm throttle body along with bbk headers x pipe flowmasters pullies and 3:73 gears.

    What do you think my hp and 1/4 mile times would be with the 302 vs 306

    thanxs
  2. Boss 351

    Boss 351 Here sthhhhhhhheeeve take a picthh of my man flowe

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    I don't think there would be that much of a difference, just talking out of my butt here though. I guess you can increase the compression using some flat top pistons, that should hep some.

    One stupid question though, why not a 331 or 347 stroker kit while you have everything apart?
  3. undercover50

    undercover50 New Member

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    Good idea just send me the rest of the money and I will tell the shop to build me a 347 ..


    Email me so I can tell you where to send the money...


    I just love stang net.....lol
  4. cardudeusa

    cardudeusa Founding Member

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    In other words their just too damn expensive.
  5. Boss 351

    Boss 351 Here sthhhhhhhheeeve take a picthh of my man flowe

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    Oh I see lol... ahhhh DOH
  6. cardudeusa

    cardudeusa Founding Member

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    Why did you edit the part out about the supercharger? I was going to quote that LOL... Oh well since you edited it, what in the world is you aviator?
  7. mike keirstead

    mike keirstead New Member

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    There is a little bit of an increase in compression with a 302 vs 306...but its minimal. You would not see a difference. The reason people do it is just to freshen up the cylinder walls. If you want a power difference stroking is the way to go.
  8. IndyBlk5.0

    IndyBlk5.0 New Member

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    with bring a lower end into the shop, and i would need a new block probably too... what would be a estimated cost for building the motor with all my parts but stroking it to say a 327-331... and a 347?
  9. 5spd GT

    5spd GT "the 5.0 owns all" Founding Member

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    It looks like a longblock of somesort :nice:

    Somewhat on topic but....how much is a good estimate to rebuild a 306 if all the parts (pistons, bearings, connecting rods, crank, etc....) needed were supplied to the builders and just the 302 shortblock(allready torn down) was given to the rebuild place....Any estimates on the rebuild?

    David
  10. Look Its Aaron

    Look Its Aaron Your car looks like it came straight from Mexico. Founding Member

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    aviator and avatar are two totally different things... hehe



    :p
  11. 5spd GT

    5spd GT "the 5.0 owns all" Founding Member

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    Oops...I wasn't thinking...I just figured he misspelled avatar....lol :rlaugh:

    David
  12. 85_SS_302_Coupe

    85_SS_302_Coupe it sucks (I know) to be on the receiving end

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    Correct me if i'm wrong, but isnt a 306 just a slightly bored out 302, with the same size rods, same crank, just larger pistons? Just wondering, because i'm likely to do the same thing this summer. I want something reliable that's going to handle another 250k miles like my current 302 has on it. I'm likely to add a power adder someday also, so the size isnt quite as important to me as strength and a good amount of porting.
  13. mike keirstead

    mike keirstead New Member

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    Yes a 306 is a 302 with a .030 overbore.
    A 308 is a .040...thats what i have.
    A 310 is .060.

    All these numbers are rounded off cause mathmatically who wants hear that you have a 309.577373147943347193847987439....... :notnice:
  14. mike keirstead

    mike keirstead New Member

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    The only thing that is different is compression.
    A 306 has a little more compression than a 302 etc,etc.
    But its minimal.
  15. 1BAD89GT

    1BAD89GT New Member

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    306 is a bit more cu in. and has a tad more compresion both=HP

    what i would do for Budget Motor.
    Bore 302 .030 to a 306 then i would find me a set of 289 rods have the machine shop polish them to remove any fractures for strength (289 rod 5.155 stock rod 5.09) and choose a rebuild kit with flat top pistons TRW forged will probably be your best Budget forged piston and have .080 removed from top of piston and renotched with 2 valve reliefs.have the block decked so the piston sticks above the deck .005 and then have the heads milled down as much as possible while allowing for piston to valve clearances,according to cam etc.

    Cost of this rebuild right around 800-900$ parts and labor.
    Compression ratio should be right around 10:1
  16. Black331Stang

    Black331Stang Active Member

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    if u are really looking for power i would take the extra time and save the money u were being a wise ass about in the beginning. its not a rediculous difference in price, only a few hundred. but u never said u were in it for the most power u can get...if just want a nice little street/daily car 306 is the way to go. and a 306 lights peoples eyes so much more over a 302 when someone says "its a 306". theres basically no difference. good luck in whicheveer path u choose.
  17. 85_SS_302_Coupe

    85_SS_302_Coupe it sucks (I know) to be on the receiving end

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    That's why i dont concern myself with cubic inches as much as i do porting and good flow...think about mod motors, they're only 281s and they make tons of power when built strong and blown, of course SOHC and DOHC doesnt hurt.
  18. truly insane 87

    truly insane 87 Founding Member

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    LOL 302vs306 theres no difference unless you change to a higher compression piston.
  19. mike keirstead

    mike keirstead New Member

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    No your wrong....compression goes up a a little bit. Its a fact.
  20. 92GreenGT

    92GreenGT PEAT Founding Member

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    Whats the best 331 kit out for the money? I want a forged kit also, what would be the best way of going about buying this stuff? I think when I get into the heads and stuff I am going to do a rebuild and go with a 331.

    Dave

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