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  1. #16

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    Quote Originally Posted by eschaider View Post
    Stefan,

    A couple of thoughts on your build.

    As long as you will be running E85 there is no reason not to settle in on a compression ratio of at least 10.5:1. Even with high boost you will be hard pressed to detonate the engine because of the extremely high detonation threshold for ethanol. Now, here is the caveat, E85 will change from summer to winter, not because of the weather but rather because of your European equivalent to what in the US we call the Department of Energy (DOE). You will have a similar regulatory authority. They will publish a book of their fuel formulations for summer, winter and potentially other times. You need to get that book.

    These regulatory agencies will publish a document that will show the ethanol content they mix for different seasons. It is important to know what they are doing and also what you just put in your tank. Injector Dynamics did an excellent write up on the use of ethanol as a fuel. I won't quote the entire article here but the upshot of the ethanol % content for fuels in the US is that if your engine tune was optimized at a 0.85 Lambda (λ) in winter by the time DOE gets done tinkering with the ethanol content for summer your 0.86λ tune will need to be modified to a 1.04λ tune for summer. Here is the link to the ID write up, it is excellent, =>Everything You Never Wanted to Know About Alcohol.

    A few more words about pistons. As you know I am a Gibtec bigot and for good reason. I believe the Gibtec offering is by far, the best possible piston for our engines. Additionally they will customize literally any part of the design you would like to change. I highly recommend not tampering with the design basics.

    More to why I brought this up. Gibtec will literally make a piston in any size (diameter) you want. This is very important for blown versions of our engine. I have yet to find a used block with bores that can be used as received. In the past that meant you had to bore the block to a 0.010" or 0.020" oversize. If you had a block that would clean up with a 0.002" clean up hone you literally could not do that because you had to accept a 0.010 or 0.020 oversize piston choice. Today some piston manufacturers have come around and are offering special custom sizes like that. Gibtec always has! Even more importantly, if you have a whoops, Gibtec can make an EXACT duplicate of the dead piston. If the bore needs an additional 0.001" or so to clean up Gibtec can make a piston that fits correctly and weighs the same as the dead one! that means no rebalancing — a big deal if you had to use heavy metal to balance the crank as most of us do.

    My suggestion on the pistons, beyond c/r, don't go any larger than you absolutely have to. Put the block on your engine stand put the heads on with old gaskets and torque them down. Leave out all the internals. Go in from the crankcase side with a dial bore gauge and measure each hole at TDC and then 3.5 inches down the bore. Take your measurements at 12/6 o'clock and 3/9 o'clock. Write them down or put them into an Excel spreadsheet. Look for the biggest bore. It should only be a thousandth or two different from all the others. That is the size plus 0.001" you want to make all eight bores.

    When you are overseas, as you are, I would just make the order for ten pistons and ask for piston #9 to be finished 0.001" larger and piston #10 to finished 0.002" bigger. It is way less expensive than doing it after the engine gets hurt — and you have the new soldiers sitting on the shelf just waiting in case you need them and already ready to accommodate a small clean up hone for the wounded cylinder.

    Before you hone out the bores have Gibtec make the pistons for you. When they arrive take the pistons and the block to your machine shop and have him hone each bore to fit a specific piston. This is more than a little disjointed, my apology. Despite the precision Gibtec has in piston manufacture you will find some pistons may be a gram heavier and others a gram lighter. Weigh your rods and get big end and pin end weights. Match the heaviest piston the the lightest pin end and the lightest piston to the heaviest pin end.

    When you have completed this and before you take the block and pistons to the shop for honing you have one more jig saw puzzle to solve. The big ends of the rods will not all weigh the same. You are going to do the same thing you did with the pistons and pin ends but this time you are going to match the heaviest big end with the lightest big end all the way to the end where you will match the remaining lightest with the remaining heaviest. Now mark the tops of the pistons with magic marker or equivalent indicating which bores you want them fitted to for the rest of their lives. Keep track of which rod goes with which piston so it is easy to put them back together when they came home from the shop.

    Now if you have kept good Excel records of what you are doing you can tell your crank balancer with absolute authority what your bob weight is for balancing. The calculation is all the rotating plus 1/2 the reciprocating weight, everything measured in grams. When you do the calculation remember you have to add the rod bearings to the rotating weight and you need to add the pins, locks and rings to the reciprocating weight. The easiest way to get the rod bearing weights is put all 16 half shells on the scale and divide the total by 8 to get the weight for a single rod — double it for two rods and add it to the rotating number for that pair. Same things for the rings. Put them all on the scale divide the total weight by eight and add it to the reciprocating number. Pins and locks are usually with less than a gram so they don't require all the fancy weighing foot work to get their weights. Just put them on the scale read the number and add it to the reciprocating weight you already measured. If you want to be certain weigh each pin individually. If you get a gram difference from heaviest to lightest use it to fine tune your reciprocating weights to be even closer.

    This weighing stuff will wear you out and piss you off. It will do the same thing to the guy who balances your crank at the machine shop. The big difference is when it pisses you off it doesn't cost any thing but your frame of mind. When it pisses off the guy at the balancing machine it will cost you additional money. More important it is good for you to do. You will begin to better appreciate how the insides of one of these engines work.

    While the 96/98 cams will have a small (very small) advantage over the stock 03/04 cams if you already have the 03/04 cams use them! Install them at a 100˚ centerline on the intake and a 103˚ centerline on the exhaust. You will be happy in the extreme. Be sure to upgrade the cam bolts to either 12 mm or 1/2" hardware. I just did a write up on how to do this for Matt (Jerry1200) in his thread, Build in Process, JRgoffin's Build Thread has Been My Guide Thus Far at the top of page 1 in the 03/04 forum. Go to post #30 and it will give you your options and chapter and verse instructions for each option.


    Ed
    Ed's directions are spot on for form taping the cams for 12 ARP bolts, mine turned out perfect!


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  3. #17

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    I'm glad but not surprised you had a good experience, Matt. Just like you, I was very impressed with the quality of the rolled thread the first time I used one of the taps. I became an instant fan of the rolled thread / thread forming / chip-less taps. When ever I have to drill and tap a hole now I always take the extra effort to get one of the thread forming taps. The finished threads are to die for.

    Glad you had the same experience


    Ed
    Last edited by eschaider; 11-29-2017 at 02:32 AM.

  4. #18
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    Bringing up this thread from the past.
    Time have evolved and I have Cobra 1996-98 cams in my hands.
    Wasn't able to build the engine last year due to much work.

    My question is how to set the 1996-98 Cobra cams.

    Sorry I can't upload the image.

    Can this be optimum?

    Intake opens -5 BTDC
    Exhaust close -5 ATDC

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  6. #19

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    How will this engine be built, Matt?

    Will you use turbos or a PD blower?

    I am presuming it will be primarily street driven. Am I correct?


    Ed

  7. #20
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    My name is Stefan.
    This will be a single turbo engine with 11:1 compression.
    Mainly a race car which will be street driven as well.

  8. #21

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    Apologies Stefan — mental dyslexia on my part.

    At 11:1 I am presuming E85 for fuel. My recommendation would be 102˚ Int C/L and 104˚ Exh C/L

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    The Cam Chart illustration is for a 102˚ Intake and 104˚ Exhaust cam phasing.

    The illustration below is a comparison of a 102/104 cam phasing with a 114˚. The dark red trace is the 102˚ cam phasing and the bright red trace is the 114˚ cam phasing. The model was built with a PD blower rather than a turbo so the turbo curve shape and peak power numbers will be greater because there is no engine power lost to driving the blower.

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    The comparison shows a slight improvement in both torque and power for the 102/104 phasing over the 114˚ phasing. For a turbo engine the -5˚ of overlap will not be an issue. With a PD blown engine that is street driven the idle vacuum will be down but likely manageable. The idle vacuum is significant for the PD blown engine because it is necessary for the proper operation of the idle bypass valve. An idle bypass valve that malfunctions will overheat a PD blower and lead to premature blower failure. Closer to -10˚ of overlap will produce improved idle vacuum and better idle bypass operation.

    I chose to use a PD blower for the cam phasing illustration because it was a more simplified model than the turbo model and provides a clear illustration of the impact of cam phasing on engine power output. When you select your turbo you will want to take the time and effort to discuss the turbo selection and trim(s) with the manufacturer. A single turbo, properly sized and with the proper trims will do very nicely for you. What you want to be sensitive to is the surge, choke and overspeed thresholds for any given turbo at the boost levels you will be running. Your compressor size, turbine size and A/R ratio will all play together in either keeping you away from those thresholds or putting you into a dance with the devil. Talk with your turbo manufacturer, but also employ some high quality engine modeling s/w that has your chosen turbo so you can test your ideas before you spend your dollars. It is much less expensive to discover what doesn't work in modeling s/w rather than buying parts and testing in real life.

    When you go the E85 route you will be able to use more advance and also sooner, which will produce more torque than a similar gasoline fueled engine. As a good rule of thumb you want to stop somewhere around 24˚ or 25˚ total. Even E85 can have a bad day above those numbers. When I built the PD blown models above I capped the advance at 21˚ which was 11˚ initial and 2.5˚ per 1000 rpm up through 4000 rpm. The timing chart looked like this;

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    Don't forget that either of the alcohols like to be a tad on the rich side both for max power and reliability. That means you are shooting for a lambda of 0.75 for E85. At that lambda you could discover the OEM COPS will begin to have difficulty firing that rich of a mixture. If they do you can back down the timing cautiously until the misfires disappear. When you do the max power achievable will come down also. If you want to maintain the power you will need to upgrade to Mercury Marine IGN-1A coils. The IGN-1A coils will need an aftermarket ECU to fire them. The OEM Ford ECU is incapable of firing those coils.

    In fairness once you make the jump to E85 it is well worth the investment to go to an aftermarket ECU. My three favorites are Motec, Haltech and MS3Pro-Ultimate. Everything down stream from the ECU costs about the same no matter who you use, more on that in a bit. In order of decreasing price Motec is the highest priced, Haltech is the second most expensive and the MS3Pro-Ultimate is the least expensive.

    Haltech will require you to use their sensors. Motec would like you to use their sensors but will provide you a relatively wide range of other sensors they have characterized or they will characterize a sensor or even an injector for you if it is not in their library. Megasquirt (MS3Pro-Ult) will allow you to use any sensor you want and gives you the capability to calibrate the ECU to work with it. Motec is pure elegance (at a price), Haltech is stunningly capable (at a somewhat lower price), and Megasquirt (MS3Pro-Ultimate) is the poor mans equivalent of the other two.


    Ed
    Last edited by eschaider; 02-21-2019 at 10:26 AM. Reason: Spelling & Grammar

  9. #22
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    Thanks Ed for the help.
    I will follow your recomendations and later this year I will follow up with the results.

    Yes, this car will be on E85 and no it's not a 2003 Cobra.
    It's a Lincoln MkVIII 1993.
    Yes it will be a after market ECU, most likely Maxx Ecu http://www.maxxecu.com/
    The ignition coils will be Chevrolet square ones with cooliling fins, really good ones (don't have the part number in my hands).
    Not the optimum turbo to begin with, but good for a shake down of the chassie.

    Yesterday I picked up the the tubing for the cage (8.50).
    I'm using Docol R8 which is from Sweden and now legal in NHRa and other seies in US.
    Nice for a change to pick up some parts localy, Docol R8 is manufactured here in Sweden.

  10. #23

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    I saw the Docal tubing at their PRI booth last December. Very innovative. The ductility and weldability are quite impressive. Unlike the commonly used 4130 chrome moly tubing it is more ductile even in the heat affected zone adjacent to the weld, meaning stress related fractures / failures are less common.

    The tubing, as I understand it is a rolled product that uses a weld along its length to finish the rolled tube rather than a drawn over mandrel product like the seamless 4130 and 4340 airframe tubing. Normally I am a seamless tubing fan but I have to admit the Docal approach definitely captured my imagination.

    Strength wise the R8 version's 116ksi tensile strength and improved ductility are a pleasant improvement over 4130 tubing that is typically somewhere around 96 to 98ksi. The additional strength is certainly attractive in creating torsional rigidity in a chassis. Moree significantly, to my way of thinking, the weldability and ductility adjacent to the weld really ring my chimes.

    In the past when we needed better tubing we would always default to 4340 which has a stunning tensile in the 185 to 190ksi range along with some equally impressive toughness characteristics. Like 4130, however you should back purge with an inert gas through the tubing as you are welding it. When I asked the guys at the show about the need to back purge R8 as it was welded they were not certain if it was required or not.

    Back purging not withstanding, R8 is impressive and anytime the source for something is local to you, there is a proximity benefit that is very real.



    Ed

  11. #24
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    It's a flat steel rolled to the dimension and then welded and then the weld tops are ground off.
    No back purging is required. Easily to weld and very easily to weld to car sheet metal.
    Mats Eriksson who is a chassies builder and owner of ME Racing have used Docol R8 for a long time in the chassies except for the cage which is wasn't certified for.
    He have finally convinced and get Dovol approved as a subsitute for chrom moly 4130 tubing.
    Here is more info.
    http://www.meracing.com/tubes--ror/docol-tube-r8__1201

  12. #25

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    I was impressed with it when I discovered R8 at PRI and I continue to be the more I learn about the tubing. Very innovative product and approach.


    Ed

  13. #26
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    Hi Ed,
    One more question.
    What vacuum in/hg is exspected when setting the cams at these values.
    The reason for the question is that I will buy a blow off valve and then have order it with the correct spring rate.

    Thank's so far for all answers and suggestions.

  14. #27

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    For cam phasing with between zero and ten degrees of negative overlap (both intake and exhaust valves closed) you will see vacuum in the middle teens. As you get closer to a zero overlap the vacuum will decrease. At zero overlap with cams like the the 96/98 OEM cams you will likely see about 7 inches of vacuum, give or take, with the shift more likely to the take side. This type of cam phasing will require a larger idle throttle opening and an increase in injector idle pulse width to maintain idle.

    For a PD blown car with an idle bypass valve this is problematic because it impairs the normal functioning of the idle bypass valve. Both KB and Whipple offer special purpose built diaphragms for use on engines with weak idle vacuum signals. If the idle bypass valve is lazy opening or doesn't open consistently on the PD blown engine, the blower will operate at a higher temperature and require more frequent maintenance to avoid a premature failure. Turbo cars do not experience this phenomena.

    The other characteristic that low idle vacuum brings is a sixties style idle — which many people find attractive. By and large that style idle while reminiscent of muscle cars of years past does nothing for the daily driving experience and in fact makes the car less attractive to drive as a daily driver or in traffic. Additionally and perhaps most significantly it does not necessarily bring better performance and usually brings worse performance — but it is reminiscent of the '60's muscle cars.


    Ed

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