HP Gain After Port-n-Polish Head?

+ Reply to Thread
Results 1 to 15 of 15

Thread: HP Gain After Port-n-Polish Head?

  1. #1
    SupraForums Member
    Join Date
    Feb 2004
    Location
    San Antonio TX
    Posts
    34

    HP Gain After Port-n-Polish Head?

    Does anyone know what a realistic horsepower gain I can expect from porting and polishing the 7MGTE head? I have a BHG and am considering PnP the head while it is out. A local performance shop said between a 45 and 75hp gain. Anyone with experience in this department? (I didn't see any hp results in the searches I performed.)

    Thanks!

  2. Remove Advertisements
    SupraForums.com
    Advertisements
     

  3. #2
    boost freak drjonez's Avatar
    Join Date
    Sep 2001
    Location
    The Cheese State
    Age
    8
    Posts
    11,270
    that's hilarious. you'll NEVER see that sort of gain w/o a HUGE turbo or some HUGE cams.....the stock head is proven to 600rwhp+.....your $$ is better spent elsewhere.

    just my $5.

  4. #3
    Shawndude
    Guest
    The problem is, there is no clear definition of "port and polish". It is a catch phrase thrown around without much merit.

    Polishing alone is usually less than 2% improvement in flow. But it sure looks pretty, and most shops will call this "port and polish". Porting depends greatly what exactly is done. Some porting jobs take 20 minutes, some will take weeks or even months backed by flow testing, replacing valve seats, using larger valves etc etc.

    All in all, spend your money elsewhere. You already have a 4 valve pent-roof cylinder head, most domestic pushrod engine owners would kill for.

    Just get a good valve job done and take care of everything else that needs doing. That alone will cost plenty of money to do, and will provide huge performance increase over your old worn out engine.

    Some more information if you're interested:
    http://www.highperformancepontiac.co.../0210hpp_flow/

  5. #4
    SupraForums Member
    Join Date
    Feb 2004
    Location
    San Antonio TX
    Posts
    34
    I was leary about those kind of gains... hence my post. The person this shop contracts out to port heads worked for Lozano Brothers for 9 years. The shop has two display heads (from Eclipse's) showing three different stages of work. This guy does a good job: he enlarges the intake and exhaust sides and smoothes and streamlines the pathways. He also includes before-and-after flow testing measurements.

    The display Eclipse head looked like a fairly significant improvement-- larger, wider, smoother-- and the increased flow was supposedly equivalent to an upgraded cam. I searched Supraforums and found posts showing increased flow, but nothing about horsepower gains. If anyone has had a good port job done, I'd be curious what gains they saw. Otherwise, I'll put the money down on a hot date and partial payment for a Lexus AFM.

  6. #5
    sloopercat
    Guest
    The 7MGTE has such a tortured intake and exhaust path due to packaging. I think forcing more air in or opening up the exhaust , not smoothing the way through, would provide better return.

  7. #6
    ***ified? p5150's Avatar
    Join Date
    Jan 2003
    Location
    Lancaster, CA
    Age
    34
    Posts
    1,087
    opening up your head isnt going to give you a clear gain either way. The gain you see will be dependent on how much hp you expect to run. Sure, 500 hp is attainable with a stock head, but with it cleaned up nicely with quality valves - it wouldnt be difficult to see 525 with the same inputs.... Also to consider, the hp gains they talk about are seen on NA engines, which play by a different set of rules.

  8. #7
    Republican Ckanderson's Avatar
    Join Date
    Jun 2003
    Location
    Southbay.
    Age
    31
    Posts
    8,421
    I would deal with the stock IC piping, and routing (i.e. mk4 style...), more then some port and polish job, by billy joe...
    My HID GB has been shut down by SF staff due to a site sponsor confliction. Everyone who paid will be getting their kits without a question. Please PM me for more information.

    All kits ARE shipped.
    [/IMG]

  9. #8
    DDDDUUUUUBBBBBZZZZZZZZ suprafly1986's Avatar
    Join Date
    Nov 2003
    Location
    Charlottesville, VA
    Posts
    2,022
    On my friend's 7M-GE he turned out about 8 more HP and 8 more ft-lbs from a "port and polish" job from a local machine shop

  10. #9
    Shawndude
    Guest
    Originally posted by suprafly1986
    On my friend's 7M-GE he turned out about 8 more HP and 8 more ft-lbs from a "port and polish" job from a local machine shop
    Any other changes during that time? Like an engine rebuild, valve work, adjustment of valve clearance, exhaust, intake etc?

  11. #10
    25psi = 14" brakes :) adjuster's Avatar
    Join Date
    Dec 2002
    Location
    Boise, Idaho
    Posts
    2,306
    Heck, 8hp could just be a different barometric pressure from one day to another. (Or air temp changes etc.)
    I'd have to think larger valves, and porting to clean up any sharp edges near the seats, and casting joints should prove to be plenty. However, Defiant's porting guy has manged to get some very respectable flow numbers from the 7M head. It will be interesting to see if the 750.00 spent porting this head is worth the money in the end. (IF there is 75hp to be found, say from 3500rpm to redline, then I say it is. If not, I'll spend money on something else.)

  12. #11
    SupraForums Member 7M-rolla's Avatar
    Join Date
    Feb 2004
    Location
    Central Florida
    Age
    29
    Posts
    1,113
    well my brother had his ported and it was a great boost in power. Im guessing that you wont ntoice a difference. You might though. It all depends on how much work your engine has had and if you have a free flowing exaust. I hope i have had any help to your question.

  13. #12
    DEFIANT_7M
    Guest
    Originally posted by adjuster
    Heck, 8hp could just be a different barometric pressure from one day to another. (Or air temp changes etc.)
    I'd have to think larger valves, and porting to clean up any sharp edges near the seats, and casting joints should prove to be plenty. However, Defiant's porting guy has manged to get some very respectable flow numbers from the 7M head. It will be interesting to see if the 750.00 spent porting this head is worth the money in the end. (IF there is 75hp to be found, say from 3500rpm to redline, then I say it is. If not, I'll spend money on something else.)
    How are we going to figure what the head makes? So many things will be different and in place ie: compression change, stroke being the the two biggest other than the head work. We got stock numbers then this "INSANE" creation of mine. $750 is for the street port. Call me crazy I had a full race port/polish done, I'm in 1K^ land



    Allan
    Last edited by DEFIANT_7M; 02-22-2004 at 07:14 AM.

  14. #13
    boost freak drjonez's Avatar
    Join Date
    Sep 2001
    Location
    The Cheese State
    Age
    8
    Posts
    11,270
    easy: just send me your crazy head w/some stock cams and i'll dyno it!

  15. #14
    Dr Wheelspin Rh.D. Bishop92T's Avatar
    Join Date
    Apr 2002
    Location
    Red Stick Supras
    Age
    36
    Posts
    4,393
    You can slap a car on a dyno at 108F and then later at 40F, even with SAE correction the 40F will make a ton more power. Also just dyno'ing the same day a car can go up and down 10+hp, depending on what it's power level is.

  16. #15
    DEFIANT_7M
    Guest
    Originally posted by drjonez
    easy: just send me your crazy head w/some stock cams and i'll dyno it!


    LOL

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts