What's the maximum Reliable RPM Limit on the 4G63 Head

Posted by marck_c, Apr 24, 2008

Please Support Extreme Turbo Systems
  1. marck_c

    marck_c Proven Member

    11
    0
    Joined Nov 6, 2002
    kingston,
    Hi folks. I'm building a high rpm 4g61, with a 4g63 head. I'm curious to know what are your views regarding the maximum rpm limit is, based on the design of these cylinder heads. Please don't flood with comments about not needing to rev the engine high at all. This project is being built for a specific purpose, which necessitates high rpm operation. Look forward to your answers.
     

    Log in/Register to remove ads
  2. absolute_DSM

    absolute_DSM Proven Member

    1,552
    8
    Joined Jan 29, 2006
    Boise, Idaho
  3. 94_eclipse

    94_eclipse Proven Member

    150
    0
    Joined Jan 19, 2007
    Shelocta, Pennsylvania
    The highest i have seen is 10 grand, and it was a street legal car. Tacked out at 10 in first then 9 every gear after that... he ran a 10 sec. quarter mile. it sounded like a rocket, it was sweet
     
    My DSM:
    Loading...
  4. architechnik

    architechnik Proven Member

    609
    5
    Joined Jun 21, 2007
    Glad, Oregon
    The highest RPM for the head is entirely dependent on the springs, cams, and timing belt. The larger the cams the greater the risk of valve float, where the valve stays open longer than the optimal amount of time. If the springs do not have a high enough rate, then after the cams release pressure the valve will stay open very slightly.

    Increase the spring tension/rate and/or decrease the cams then you can keep revving until the cows come home or the bottom end blows out; whichever comes first. The optimal situation would be a conversion to double springs or those with extremely high rigidity and maintain a moderate or stock cam lobe.

    The only other concern would be if the timing belt will be able to maintain extremely high RPMs, although a kevlar belt should account for that.
     
    My DSM:
    Loading...
  5. marck_c

    marck_c Proven Member

    11
    0
    Joined Nov 6, 2002
    kingston,
    Here is the setup:
    The durabilty of the timing belt, and it's accuracy at high rpm, with the attendant stretching issues, were some of my concerns. What rpm limit have you guys seen these belts survive reliably at.


    My setup:

    Custom 83.5mm 10.0:1 Ross Pistons
    Carillo Rods w/ ARP Fastners
    ARP Head Studs, Mains, etc
    MLS Head Gasket
    Brian Crower Stage 3 Cams
    Ferrea Dual Interferance fit Springs, w/Ti Retainers
    [Adjustable Gears

    DNPerformance Tubular Header
    FP3052 Turbocharger
    Ferrea 1mm OS Valves
    Extrude Honed Stock Intake Manifold
    Ported and Polished 1g Head
    Fluidampr Harmonic Balancer
    Custom Moroso 3-Stage Dry Sump Kit
    Evolution 8 Intercooler
    Haltech E6X ECU
     
  6. architechnik

    architechnik Proven Member

    609
    5
    Joined Jun 21, 2007
    Glad, Oregon
    That sounds like a nice setup. I haven't heard of anyone going much over 10k for the simple fact that they're on the downward curve of the powerband at that point and the block/crank/pistons couldn't handle it.

    That was also on stock (Mitsu) timing belts, as the kevlar ones I've only seen come around in the past several months. I do not know what kind of duration the upgraded versions can get at those rpms, but the stock ones maintaining were always a concern and caused many broken hearts when frayed.

    Likewise with the Cower 3's and double springs, you'll be putting a good bit more wear/tension on the belt, so it may be of concern if you intend to keep it up there for any duration. What were you using this for?
     
    My DSM:
    Loading...
  7. marck_c

    marck_c Proven Member

    11
    0
    Joined Nov 6, 2002
    kingston,
    Road Race
     
  8. TunaTalon

    TunaTalon Proven Member

    779
    23
    Joined Oct 4, 2007
    Dittmer, Missouri
    I understand that the original question was about the limit on the head, but high RPM's causes high inertial loads on the rods and bearings too. Please see my StrokeOrNot document ( http://www.kidzuku.com/StrokeOrNot.pdf) for charts on the forces involved.
     
    Last edited by a moderator: Jun 5, 2014
  9. dsmfa9nutter

    dsmfa9nutter Proven Member

    780
    2
    Joined May 9, 2005
    Nowhere, Wisconsin
    12k.
     
  10. Spyder4g64

    Spyder4g64 Proven Member

    257
    1
    Joined Mar 9, 2005
    Wallingford, Connecticut
    You don't need to Rev anywhere near 10k for Road Racing.. IMHO
     
    My DSM:
    1998

      manual
    Loading...
  11. diambo4life

    diambo4life Proven Member

    978
    53
    Joined Apr 18, 2002
    Oklahoma City, Oklahoma
    I will agree with the poster above...especially on that setup. No need to put unnecessary wear and stress on the motor. 9k is plenty on the 3052. :|
     
    My DSM:
    1991 Mitsubishi Galant VR-4

    Street Build

    710 whp   501 lb/ft
    1991 Eagle Talon TSi AWD (sold)

    10.56 @ 136.45 MPH
    Loading...
  12. UofACATS

    UofACATS Proven Member

    649
    13
    Joined May 11, 2004
    Tucson, Arizona
    And I will disagree.

    Do we know what track he runs? Or what corner he's thinking about not having that extra shift? Or maybe he hits 170 on the front straight, and right now he's RPM limited. :) Point is, he wants the extra RPMs to play with for a reason.

    I'm building a head for higher revs and I can think of a couple corners where I'll be able to stay in second instead of the quick upshift to third, then back down to second. That's worth it to me.

    Just a thought.

     
    Loading...
  13. Spyder4g64

    Spyder4g64 Proven Member

    257
    1
    Joined Mar 9, 2005
    Wallingford, Connecticut
    Point taken. I do understand that the higher the rev, the better off you are..

    I wouldn't rev past 10k though. That's what i was trying to say, regardless of what type of race it is..
     
    My DSM:
    1998

      manual
    Loading...
  14. dsm-onster

    dsm-onster DSM Wiseman

    8,218
    78
    Joined Jul 11, 2004
    Bloxom, Virginia
    Are you asking at what point the head becomes a restriction? Because you've purchased more than enough valvetrain hardware for 9-10K.
     
    My DSM:
    Loading...
  15. marck_c

    marck_c Proven Member

    11
    0
    Joined Nov 6, 2002
    kingston,
    Your forgetting about the 75.5mm stroke and the 83.5 bore.
     
  16. 92awddsm

    92awddsm DSM Wiseman

    3,934
    79
    Joined Jan 17, 2004
    Chesterfield, Virginia
    Well, in drag racing, if you get fast enough, you get to a point where you dont have a chioce with the stock type tranny.
     
    My DSM:
    1992 Eagle Talon TSi AWD

    12.320 @ 115.440 MPH
    Loading...
  17. jrohner

    jrohner Proven Member

    2,551
    9
    Joined Sep 25, 2004
    Willmar, Minnesota
    I don't see how the head itself would have some issue at a certain RPM. The head isn't moving; it just sits there and goes wherever your car goes unless your engine falls out or it gets stolen.

    You've got the good valvesprings. Get a good timing belt if you're worried about that.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    11.415 @ 119.59 MPH
    1998 Mitsubishi Eclipse GSX

    414 whp   459 lb/ft
    Loading...
  18. lacroixdp

    lacroixdp Proven Member

    695
    3
    Joined Aug 3, 2004
    Columbia, South Carolina
    You'd better throw a manual timing belt tension device in there as well. I've seen the hydraulic one compress at high-rpm operation and throw the belt. Also, IMHO, there's better FMICs for the money than the Evo 8 one.
     
    My DSM:
    Loading...
  19. dsm-onster

    dsm-onster DSM Wiseman

    8,218
    78
    Joined Jul 11, 2004
    Bloxom, Virginia
    Nope. I'm not forgetting. You're moving air with less velocity using a tiny stroke vs. a stock 4g63 stroke. The stroke determines piston speed. Piston speed determines velocity. The velocity determines the required port and valve diameter. The stock stroke and matching velocity starts to see a mach number that exceeds ideal for the stock valve diameter after 9K with an 88mm 4g63 stroke. So I would assume you're ok, without putting the effort into the math.
     
    My DSM:
    Loading...

Share This Page

Loading...


Log in/Register to remove ads

Support Vendors who Support the DSM Community
Ace Race Parts Advanced Fuel Injection Archer Fabrication Boostin Performance ECM Tuning Extreme Turbo Systems ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions Jackson Auto Machine JNZ Tuning Magnus Motorsports Miller Import Parts Morrison Fabrication & Design OHM Racing Race Components Inc RockAuto RoadSurge Spultronix Performance STM Tuned Strictly Import Motorsports VR Speed Factory