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Thread: Port and polish

  1. #21
    Join Date
    Mar 2003
    Location
    Spring Hill, Fl.
    Posts
    14,199
    have you seen how poorly a 5m head flows? there are head flow graphs out there. the exhaust is especially bad. honestly, if you want to stay n/a, the best bet is to do a 2jzge swap. the engines are very cheap(~$400ish complete with harness and ecu etc...) and the stock head flows more then a ported 5m head. header, exhaust, intake etc.. and your movin some air. the stock maf is the same as the 7mgte so wont be restrictive like the flapper afm the 5m has.
    william
    http://www.cardomain.com/ride/2042690/1 black 84 7mgte, MS2, truetrac, bbk, etc...soon to have 2jzgte and t56
    http://www.cardomain.com/ride/2117186/1 blue 85 beater
    http://www.cardomain.com/ride/2965297/1black 86 triple weber 6m in the works!

  2. #22
    Join Date
    Mar 2003
    Location
    Clifton NJ
    Posts
    2,641
    P&P can improve 5mge headflo. go here http://www.supramania.com/forums/sho...Z-2JZGE-2JZGTE) to see results. I'd try to contact one of the porters to see if they could offer any recommendation(s).
    84 mt 6mge with intake, exhaust, suspension, brake, and wheel mods
    85 mt 6mge stock

  3. #23
    Join Date
    Jul 2003
    Location
    Houston, TX
    Posts
    16,603
    165whp 6MGE here, completely stock head (no porting, no cams). I am of the persuasion to leave the head alone, as I've never seen more than a couple hp gain (example: Wes Hetrick's 5MGE did 146whp w/ similar mods to my old 5MGE plus port/polish, and my motor made 144whp).... but then again I'm not a math wizard by any means and am stubborn in my old school ways ^_^

    as for the 6M/2J debate, I suppose that would depend on your goals (realistic) and your finances and patience. 2J won't be a simple drop in like a 6M, but finding a 6M (a real one) is a PITA and expensive.

    also, 2JZGE for hp goal, 6MGE for torque

    I really can't find many 2JZGE dynos, as most everyone goes turbo, but the ones I have found were between 175-185hp and similar tq.

  4. #24
    Join Date
    Mar 2003
    Location
    Clifton NJ
    Posts
    2,641
    Just cause headflo is higher doesn't necessarily mean that VE which determines performance is higher. From what I've read I believe that porting is an art. That's why I suggested that contact with Toysport, who claims increased performance from p&p, would be beneficial.

    Headflo is a static measurement. Filling cylinders through the intake valves is a complicated process that involves a number of transient flow phenomenae. Pressure inside the cylinder varies as a function of stroke position. Reflected shock waves due to other intake valves closing and intake plenum and runner dimensions tend to stuff additional charge into the cylinder. Flow pressure increase due to lower charge velocity increases VE and additional turbulence causes better fuel/air mix. (Charge velocity is not constant from the port input to the intake valve. It's purposely slowed to increase pressure at input side of valve.) Surface roughness helps mixing but turbulence it causes reduces cylinder charging pressure. Charge column momentum near end of stroke where piston velocity is slowing increases VE. Things are so complicated that we could easily have a whole forum just on porting.
    84 mt 6mge with intake, exhaust, suspension, brake, and wheel mods
    85 mt 6mge stock

  5. #25
    Join Date
    Mar 2004
    Location
    Indianapolis, Indiana
    Posts
    1,122
    Gentlemen & Tanya,

    I thought I would throw my 2-cents in, since we are here! I have ported & polished all of my heads since the mid-1970's. I ported/polished my 5MGE and I did not notice any performance drop-offs at all. The only mod that adversly affected my performance was the Gude cams. They were terrible when it came to low-end torque.

    Now while I did spend a fair amount of time on R&D for the 5MGE top-end, I still ended up with a completely stock bottom-end (never got the pistons, etc.).

    So with a completely stock bottom-end 5MGE I made around 185 RWHP while using a modified AFM and stock ECU.

    Once I removed the AFM and ECU I bounced up to 193 RWHP. I think I could have eclipsed the 200 HP mark, since I only dynoed once after installing the stand-alone. But after my Intake cam gear became damaged I decided to pull the plug...

    I included my last dyno with AFM/ECU run and my last run with no AFM/stand-alone... A couple of things to notice, the increase in power through the mid-range and the relatively flat powerband in the upper RPM's...

    P.S. Toyota/Yamaha designed their heads for a specific purpose in mind, daily driver! So for performance, I port & polish everything!

    Regards,

    Carlos


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