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Thread: So what are you Guys reving your 2.5L's to?

  1. #401
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    So what are you Guys reving your 2.5L's to?

    Ok I had to bring this post back from the dead, but for good reason. There has been some good information come about in the last 12 years. The 2.5s do like to rev and it has nothing to do with the rod ratio. This is my 2.5 stock bottom end, ported head, intake, header, and custom spec'd cam.. This thing loves the High rpms.. This is 6 psi / 11 psi / 15 psi


  2. #402
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: So what are you Guys reving your 2.5L's to?

    Agreed, nothing to do with rod ratio but breathing.

    I've found retarding stock cams helps move the power band to higher RPM.

    Thanks
    Randy


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  3. #403
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: So what are you Guys reving your 2.5L's to?

    Thanks for the graph. That is some serious action for 15psi to say the least.

  4. #404
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by cordes View Post
    Thanks for the graph. That is some serious action for 15psi to say the least.

    Yessir, made 410 on 24 psi. Again that was with the stock bottom end. Have not had it back on the dyno with the built bottom end, but the increase in compression made a HUGE difference. I would guess and say 450+ on 24lbs.

  5. #405
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Loudexploder View Post
    Yessir, made 410 on 24 psi. Again that was with the stock bottom end. Have not had it back on the dyno with the built bottom end, but the increase in compression made a HUGE difference. I would guess and say 450+ on 24lbs.
    What did you increase the compression to??
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  6. #406
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by chromguy View Post
    What did you increase the compression to??
    I just bumped it to 9.3:1

    I wanted to be around 10-10.5 but didnt want to wait on custom pistons


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  7. #407
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    Re: So what are you Guys reving your 2.5L's to?

    What fuel did you use?

  8. #408
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by tryingbe View Post
    What fuel did you use?
    E85


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  9. #409
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Loudexploder View Post
    I just bumped it to 9.3:1

    I wanted to be around 10-10.5 but didnt want to wait on custom pistons


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    Ah so it is now an interference engine but that is AOK.
    increased mine but still wanted to stay non-interference, for now

    So you are at 9.3:1 including chamber port?
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  10. #410
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by chromguy View Post
    Ah so it is now an interference engine but that is AOK.
    increased mine but still wanted to stay non-interference, for now

    So you are at 9.3:1 including chamber port?
    Im not sure if it is an interference engine or not as I havent checked that, but Id venture to say it was even before the new motor. The cam im using has a long duration and mid 500 lift which i think would cause interference.

    The 9.3:1 is static compression, measured from bore, stroke, deck height, piston dish volume, chamber volume, and gasket thickness.


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  11. #411
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    Re: So what are you Guys reving your 2.5L's to?

    While I used to take these tech articles seriously, nothing I've seen in winning engine combinations for drag racing has supported these claims. They specifically make claims about Drag racers wanting 1.8 rod ratios.

    Real advice about 4 cylinder power production is, obtain as much displacement as possible without having the bottom end scatter at up to 12,000 rpms. Some boosted combinations do better with lower rpms, probably because the rods get way too beefy vs a 12,000 rpm N/A combination.

    The idea that long stroke side loads the cylinder enough to hurt power production is wack. The pistons would all be wrecked in half a pass. Yes, rod ratio matters for the longevity of a road course or time attack car. Rod material quality has also improved over the last 3 decades.

    http://www.minimopar.net/perf/longrodengine.html
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@126 25 psi - Daily :eyebrows: Holset He351 -FT600 - 470whp 572ft/lb @26psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56 [SIGPIC][/SIGPIC]

  12. #412
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    Re: So what are you Guys reving your 2.5L's to?

    With built bottom end, my 2.5 made 509 on 27psi at 6700 rpms!!

    There are a few people who can vouch this thing likes to rev as they seen at SDAC.

    build it right and it'll make power.

  13. #413
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Thumbs up Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Loudexploder View Post
    With built bottom end, my 2.5 made 509 on 27psi at 6700 rpms!!

    There are a few people who can vouch this thing likes to rev as they seen at SDAC.

    build it right and it'll make power.


    yup. it revs.

    i mean if a k24 (not much less stroke... 3.9") can rev to 10k, a 2.5 can handle 7k.... hell, i money shifted mine in 2007 and hit 8800 without the bottom end coming apart. bottom end is still untouched since 2004. spit a few rockers on that exercise though....

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  14. #414
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Aries_Turbo View Post


    yup. it revs.

    i mean if a k24 (not much less stroke... 3.9") can rev to 10k, a 2.5 can handle 7k.... hell, i money shifted mine in 2007 and hit 8800 without the bottom end coming apart. bottom end is still untouched since 2004. spit a few rockers on that exercise though....

    Brian

    I have yet to spit a rocker, but I'm running some pretty stout springs. About 360lb open pressure.

    I seen over 8600 when I spun at the track. LOL

  15. #415
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: So what are you Guys reving your 2.5L's to?

    That's some engine speed for sure.

    Does anyone remember what Bill G's NA omni spun to? I seem to recall it being around 8K or so? I wonder what he did to make that happen. Granted, it was a 2.2, but I think the valve train modifications required would be the same?

  16. #416
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by cordes View Post
    That's some engine speed for sure.

    Does anyone remember what Bill G's NA omni spun to? I seem to recall it being around 8K or so? I wonder what he did to make that happen. Granted, it was a 2.2, but I think the valve train modifications required would be the same?
    Valve train mods would depend on valve sizing, size of camshaft, and ramp rate so that you can avoid valve float.

    2.2 would also require less camshaft go make power at the same rpm as a 2.5.


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  17. #417
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Loudexploder View Post
    Valve train mods would depend on valve sizing, size of camshaft, and ramp rate so that you can avoid valve float.

    2.2 would also require less camshaft go make power at the same rpm as a 2.5.


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    Interesting. Thanks for the info. Now I really want to know about Bill's ride. Hopefully someone can post up about it. That thing screamed.

  18. #418
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: So what are you Guys reving your 2.5L's to?

    Quote Originally Posted by Loudexploder View Post
    I have yet to spit a rocker, but I'm running some pretty stout springs. About 360lb open pressure.

    I seen over 8600 when I spun at the track. LOL
    yeah i remember you saying that.... (8600)

    I was running stock springs back when I tossed rockers.

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  19. #419
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    Re: So what are you Guys reving your 2.5L's to?

    Definitely one of the most interesting 2.5 builds out there.

    Will be very interested to see how it does as you approach 600whp.

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