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Thread: GT500 heads

  1. #31

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    Exhaust pressures historically have run much higher than intake pressures especially at initial blow down when the exhaust valve opens. That said the engine power output is simply the total amount of fuel and air that can be burnt per operating cycle. You want to optimize the intake and especially on a turbo application you have little you can do to change what happens after the exhaust valve opens.

    Newer design turbos can produce impressive boost (and therefore power) figures at lower exhaust pressures than their older siblings. These turbos may or may not spool as quickly as some of their higher pressure hot side cousins. You need to spend time with your Turbo supplier to optimize that metric for your build. That said you'll notice that rules making bodies focus on inlet side performance (boost) when attempting to normalize performance between cars with different types of superchargers. They don't do the same for the hot side design metrics — there is a reason. You've got to keep you eye on the ball and not be distracted by side shows. Other than keeping the hot side plumbing as short and hot (at the turbine) as possible along with minimizing unnecessary bends in the tubing your horsepower is intimately associated with the compressor side of the device.

    There is an argument that can be made that restrictive exhaust plumbing creates pumping losses that are paid for with horsepower that never gets to the rear tires but the real world numbers argue that the low hanging fruit, power production-wise, is on the inlet/compressor side.

    Don't try to over-science this process, you'll be much happier.


    Ed

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  3. #32

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    So Ed, what do you consider good flow numbers in that .200 to .400 lift range on a C head

  4. #33

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    Don't forget the low off the seat lift is equally important to the cylinder's filling efficiency. The Livernois flow numbers are a poster child for the low lift and also the 0.200 to 0.400 lift range. You are unlikely to find any "C" head measurably outperform them in this range and when you look at the graph in post #4 the trace that sits clearly aboven anyone else is the Livernois Stg 3 head.


    Ed

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  6. #34

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    New to Ford mod motors for performance.....I have a 98 Cobra that I road race in NASA American Iron. My current setup dyno'd at 319/309 at the rear wheel which is a little underpowered vs. the front runners. I would like to get to the 380-390 HP/TQ range. Can I get there with heads/valves/cams? If so, what heads should I be looking for (years/models)? I understand from the thread that I should be looking for porting by Livernois & +1mm SS valves from Manley. Which springs should I get (would like to get to 7500 redline) & which cams should I get? Obviously I will be staying NA & reliability is vital.

    Thanks!
    Rusty

  7. #35

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    Rusty,

    An OEM ECU and OEM COPS while they may be capable of being stretched to 7500 rpm, they are both well past their peak performance thresholds. You ought to be looking at an aftermarket ECU replacement and a COPs replacement as the first items in your quest for increased power. Your power will be found in increased engine operating rpm along with increased cylinder head flows. The factory ECU and OEM COPs will be out of their league.

    To make 100 FWHP a properly tuned, gasoline fueled engine needs to process 10 lbs of air per minute or 600 lbs of air per hour. A pound of air is physically a pretty big item. There are lots of excellent technical tools and calculators on the site here. One done by Black2003Cobra will save you all th noodling and paperwork to figure the rpm you will need for the power you are making. BTW in the FWIW bucket don't forget 319 RWHP is the same as 375 RWHP. so I am believing you are looking for 477 RWHP which translates into ~560 FWHP.

    To hit your target of 560 FWHP you will need 56 lbs of air per minute. Using a 110% Ve that will require 8900 engine rpm to hit your power target and an intake manifold optimized for operation in that rpm band. Your engine's entire appetite for air will only consume 750 CFM of air at that engine rpm — still easily within the reach of a stock "C" style head and certainly within reach for a stock head with the valve bowls cleaned up.

    Your next purchase should be replacement valve springs that are north of 300 #/inch spring rate. An excellent spring that fits this profile is the PAC 1223 springs and associated steel retainers. Before you get all whacked out over steel retainers consider the fact the PAC retainer for this spring only weighs 7 grams according to their catalog and when I weighed mine they came in between 5.5 and less than 6 grams! That is lighter than virtually all titanium retainers but with the durability of steel.

    Your last item will be your camshaft(s). You will want something right around 210˚ duration for the intake and exhaust. Turns out this is almost exactly what Ford built the 2000R Cobra cams to be. Ford went a little zippy on the valve lift at essentially 0.500" but the cams worked very well. If you were sourcing your cams and ran across a set of '00R cams I would snap them up. The bang for the buck is extremely hard to beat. Otherwise I would look for a set of aftermarket cams with 0.450" to 0.475" lift and 210˚ of duration at 0.050" valve lift.

    To get the power you are looking for you will need to run a n/a 4.6 fairly high in the engine speed to process the air you will need for the power you want. Small increases in Ve can lower the peak rpm required to process the air mass necessary to generate the hp.

    Don't forget to gear the car appropriately. If you use a triple crown winner Ito pull the Budweiser beer wagon it won't do as well as a Clydesdale ...


    Ed
    Last edited by eschaider; Yesterday at 05:38 AM. Reason: Spelling and Grammar

  8. #36

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    Great information Ed-a couple of questions:

    • Aftermarket ECU-do you have any recommendations? From what I see doing some quick searches, it looks like AEM is one of the main players out there.
    • Aftermarket COPs-do you think this would be a good choice? https://www.summitracing.com/parts/msd-8241


    Thanks,
    Rusty

  9. #37

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    I am running a Holley ECU system and have had good luck with it. Mine is the holley dominator with more inputs, but a Holley HP system would fit your needs. They also have a holley smart coil setup for the ignition that would take care of a higher redline as well. I'm running a completely different setup with different goals, but it revs cleanly on my setup past 7000 rpm with 30lbs of boost and no issues with spark.

  10. #38

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    Take a look at the MS3Pro Plug and Play ECU!
    Will still run all the factory gauges as well as a direct connect to the factory wiring harness.
    There are a lot of great features with it you may be interested in.
    Ed has a great write up and thread started regarding it.

    Ken
    Last edited by 4sdvenom; Yesterday at 09:01 AM.

  11. #39

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    Thanks-I'll look into the Holley & MS3Pro ECU systems.

  12. #40

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    The holley required a new dash on my 2003, it wasn't playing well with the factory stuff. I have it on a 1995 Cobra that is pre obd2 and it works like factory. So keep that in mind too when you're trying to figure this out.

  13. #41

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    Quote Originally Posted by RustyR58 View Post
    Great information Ed-a couple of questions:

    • Aftermarket ECU-do you have any recommendations? From what I see doing some quick searches, it looks like AEM is one of the main players out there.
    • Aftermarket COPs-do you think this would be a good choice? https://www.summitracing.com/parts/msd-8241


    Thanks,
    Rusty

    The guys beat me to the draw, Rusty. The Holley and MS3Pro - PnP systems are among the best options available to you right now. The Holley is an excellent system but will require a dash and some wiring harness building skills on your part. The MS3Pro PnP version will use all your existing OEM dash instrumentation, gauges, and sensors including the speedo and it literally plugs right into your existing OEM wiring harness where the factory ECU was. The PnP feature is a huge time saver and gives you the ability to pass emissions by swapping back the OEM ECU at emissions testing time.

    FWIW if you live in a state like California, then your underhood emissions equipment will need to be retained and maintained, for visual inspection by your testing station.

    If you like all the whizzy digital performance dashes, the MS3Pro also supports them. The pricing differences between the two systems can be compelling also. The MS3Pro PnP is $1359 vs somewhere north of $1999 for the Holley. I think (I have not installed a Holley) the Holley will come in somewhere North of $3K or so, possibly higher depending on what you choose to do or have done for you on your install, by the time you are done.


    Ed


    p.s. The aftermarket COPs you want are either the IGN1 or IGN1-A coils like used in Mercury Marine race applications. The two coils put out essentially the same spark energy (~103 - 118 mj). The smart version, IGN1-A coils are in the 103 mj window and the dumb IGN1 coils are in the 118 mj window. Because the OEM coils on our engines are dumb coils the MS3Pro PnP will directly support the higher powered IGN1 coils. By way of comparison a good set of OEM style COPs will produce about 18 mj of spark energy on a good day. These IGN1 class coils are the same coils used on many ProMod cars — they have lots of suds. The IGN1-A coils are about $80 each plus another $16 for the wiring pigtail. The IGN1 coils are about $48 plus another $7 for the wiring pigtail.
    Last edited by eschaider; Yesterday at 12:06 PM. Reason: Added Post Script

  14. #42

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    Thanks again for the info. I found the IGN1 coils at DIYAutoTune, but not the wiring pigtail-I'll contact them & see what they say. Could I go ahead & upgrade to the COPs & ECU before I do the head work & get some gains?

    Another question regarding the heads-I contacted FPP to try to get the 2000R cam part numbers & the technician asked me why I didn't just upgrade to 2001 Cobra heads & intake. I found an article on SVT that said the 2003-2004 heads were the hot ticket. I'm sorry for asking dumb questions, but am a nube & trying to learn...….

  15. #43

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    Quote Originally Posted by RustyR58 View Post
    Thanks again for the info. I found the IGN1 coils at DIYAutoTune, but not the wiring pigtail-I'll contact them & see what they say. Could I go ahead & upgrade to the COPs & ECU before I do the head work & get some gains?
    There is a check box on the IGN1 coil page to add the pigtails to the coil purchase, it's just not real obvious. Here is the link to the pigtails => IGN1 Pigtail. The upgrade question answer is an absolute yes! You will need this technology no matter what you do so, get it before prices go up, it disappears or all inventory gets infected with corona virus or something worse.




    Quote Originally Posted by RustyR58 View Post
    Another question regarding the heads-I contacted FPP to try to get the 2000R cam part numbers & the technician asked me why I didn't just upgrade to 2001 Cobra heads & intake. I found an article on SVT that said the 2003-2004 heads were the hot ticket. I'm sorry for asking dumb questions, but am a nube & trying to learn...….
    The best head ever made for the non race, production 4.6L engine as delivered from Ford is the DC version of the "C" head. It was the last head Ford made for the engine and represented 20+ years of development work on the basic head design — there are no "C" heads that are better. The best '00R, FR500GT, GT500, Ford Factory race head is the late GT500 design. Ford added material to strengthen the decks and casting in general. Neither head has anything to do with the cam part numbers you were asking for. You should read through the Terminator Table of Contents (TToC) at the top of the 03/04 SVT Cobra Forum. It is a wealth of knowledge including part numbers for things like the '00R cams.

    In the FWIW bucket those cams ('00R) are not available anywhere today unless you find a used set. Get a set of Comp 106260 cams. They are 222˚ intake / 224˚ exhaust duration with 0.475" / 0.450" lift. They will serve you well.

    In yet another FWIW bucket that intake manifold the FRPP guy pointed you at is not tuned to the rpm range you will be operating your engine in. There is at least one, if not more, Coyote race intakes from Ford that are tuned for high rpm use. I believe Shelby Mike makes a set of adapter plates to mate those manifolds to Cobra "C" heads or perhaps GT500 heads. Find out which heads his adapters are for, get those heads, his adapters and one of the short runner OEM Coyote race intake manifolds.



    Ed

  16. #44

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    Thanks again for sharing your knowledge-the Coyote race intake sounds intriguing- I want to pursue that option. I have done several searches & can't find anyone with the name Shelby Mike on this forum. Does he go by another name or it is just a loose nut between the seat & keyboard here?

    Rusty

  17. #45

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    Shelbymikeracing.com

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