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09-22-2017, 05:06 PM #1
- Join Date
- Mar 2010
Another Engine Build Questions, Cams
Sorry for the long story, Stefan.
I'm in the process to build a new engine.
I have a 2003 Cobra which I rebuild the engine for a couple of years ago.
Many thanks for you here in this forum for your knowledge that made my decisions for parts quite easy.
That was done without any specific questions here.
I live in Sweden therefore planning of parts are really important, this due to heavy parts must go by container to save cost and they are not shipped that often.
In other words all that you buy, I have to pay 1.5 - 1.8 more than you.
This will be used for Street week here in Sweden which is similar to Drag week in USA.
This year I used my Cobra during Street week, but I know to be better I need to do something else and I like to keep that car in current stage.
Now I will build an engine for a Lincoln MKVIII which I have...., the Indian (it’s smoking like hell)
It will be a single turbo with approx. 30 psi may be 1000 hp.
It shall be backed up with a 6R80 auto and a Ford 8.8 (against what all using here).
Fuel will be E85, very common here in Sweden.
Good part this vehicle have a Teksid block, which I will be using.
So far the below is on order for the engine.
Crank Eagle stock stroke (more or less against Ed's choice)
Gibtec pistons 10:1, 0.010 oversize.
Molnar rods, turbo stock length.
Boundry GT500 oil pump.
Brian Tooley valve springs.
ARP bolts for main, head, crank bolt and flex plate.
King SI bearings, plus additional set to get fully flanged.
Now my concern..
Cams for the engine.
I have the stock 2003 Cobra cams, are they good to use in this combination?
I have tried to find 1996-1998 Cobra cams without any success, which I know is a better choice.
Help, any one with better cams that are for sale?
If I will be stuck with 2003 Cobra cams how to degree them.
What I’m looking for is to get boost soon as possible, I’m can give away high rpm hp.
Last edited by Tbird; 09-22-2017 at 05:11 PM.
09-23-2017, 02:27 AM #2
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.
Last edited by eschaider; 09-23-2017 at 02:42 AM. Reason: Spelling & Grammar
09-28-2017, 10:28 AM #3
- Join Date
- Jul 2006
what is your desired max RPM/Shift point?
converter stall speed?
No one can make cam recommendations without knowing these things.
Installing the stock cams at 100/103 will kill power up top. The stock cams are terrible and spending money on them to upgrade to 12mm bolts makes no sense.
09-28-2017, 05:34 PM #4
As you also know from his first post, he is in Sweden and as he indicates,
BTW the stock cams while not suitable for competition in a #/inch of displacement drag racing class are stunningly good performers for the type of usage Stefan is contemplating when properly phased to the crank.
09-28-2017, 07:44 PM #5
- Join Date
- Feb 2010
Custom grinds can actually help spool faster. I am unsure where this sudden stock or nothing kick came from Ed lol.
09-28-2017, 08:07 PM #6
I think you guys are missing the part about where this guy lives. Shipping parts over can get expensive, plus the premium price he is spending for something that he doesn't need. The stock cams degreed properly will get this guy what he needs and is asking for in the last line of his post. No sense in paying 1200+ bucks for a set of custom grind cams, then pay for shipping, taxes and customs fees when he can use stock cams and get what he needs.
09-28-2017, 09:04 PM #7
Custom cams are anywhere from $1,500 on up depending on where you go to get them. Put a 1.8 multiplier on that and suddenly the slight, if it exists at all, improvement in power becomes exorbitantly expensive. Now add to that the fact that there are only a handful of guys in this country that can actually spec a custom cam and I can count them on one hand with a couple of fingers missing. This is where the concept of adequacy and cost meet to steer you in smart directions but only if you are listening.
There are a bunch of guys that have ordered custom cams for folks that just didn't know what they were doing. What they thought they bought and what they bought were not the same. After they were installed the buyers remorse set in very quickly. You don't need that type of experience on the other side of the Atlantic — the parts and the experience are prohibitively expensive. This is especially true when the buyer's stated wishes discounted high rpm hp.
09-28-2017, 09:07 PM #8
09-30-2017, 12:45 PM #9
- Join Date
- Jul 2006
I'm not against stock cams, but putting 03/04 cams at a 100/103 is not a good option for any combo. 96/98s cobra cams offer more intake duration and have 12mm bolts which is a good thing. Their duration split id much more turbo friendly and when installed at 107/110 offer an excellent powerband: quick spool and power up top.
Last edited by na svt; 09-30-2017 at 12:48 PM.
09-30-2017, 10:52 PM #10
In most situations I would agree with you about the 96/98 cams, Todd. In this instance the OP has indicated he has searched unsuccessfully for the 96/98 cams. At that point you are confronted with either the cost and acquisition challenges of new aftermarket cams from overseas or making best use of what you have at hand — which in this case turns out to be the 03/04 variety cams
In most but not all applications, properly phased 96/98 cams would outperform similar 03/04 cams — however not always by as much as some might suspect. Given the prohibitively high cost and potential delay in acquiring new aftermarket cams from overseas and the potential for a charlatan to misrepresent a used part, the rephased stock 03/04 Cobra cams make a lot of sense. Will they outperform an optimized install of 96/98 cams? Not always but, they sure have made believers out of a surprising number (not all) of the people that switched from optimized 03/04 cams to 96/98 cams. The oh so important (for most guys I have worked with) seat of the pants dyno, could not distinguish difference.
For the small potential improvement associated with the 96/98 cams, smart money is on rephased 03/04 cams. Especially if you are overseas and confronted with the time, shipping and cost considerations that someone like Stefan is.
Last edited by eschaider; 10-01-2017 at 04:08 PM. Reason: Spelling & Grammar
11-27-2017, 08:00 AM #11
- Join Date
- Mar 2010
I will continue this tread.
Have decided to make a trip to US early spring to pick up parts (heavy suitcases).
what intake manifold? Cobra 1999.
what is your desired max RPM/Shift point? A good guess 7-7500 rpm.
turbo dia/AR? Turbo is not decided yet. Most likely a large single turbo.
converter stall speed? Not decided yet but will be after turbo is decided.
trans brake? I will use US shift which doesnt have transbrake (yet).
I have the whole time consider not to use the Cobra 03-04 cams due to the 10mm fastener.
There is some cost to upgrade to larger fasteners.
So why not to put this money to another set of cams.
I have now found 2 different sets for sale.
Cobra 1996-98 cams
Bullet racing cams
Intake 223 deg duration @0.050, lift 0.480 and specified timing events @ 0.050, open 1.5 close 41.5
Exhaust 227 deg duration @0.050, lift 0.480 and specified timing events @ 0.050, open 51.5 close -4.5
For me the Bullet cams look pretty good or I'm wrong?
11-27-2017, 08:18 AM #12
- Join Date
- Jul 2006
The 223/227 cams are not good for a turbo. Seeing how you would be spending a good amount of money on travel to the state I can sell you a set at my cost if you are interested.
99 cobra intakes are not good, get one from a 01 Cobra or Mach 1. I have a friend selling a powder coated 01 Cobra intake; $400
What is your power goal?
11-27-2017, 01:28 PM #13
Couple of things to consider here Stefan;
We have had several site members go the small(er) twin turbo route. One was a street driven car that never was raced. He made 780Hp on 91 octane, get it at the pump gas. The car idled well at about 800 rpm had 17 inches of vacuum with an extraordinary driving experience that had near PD blower throttle response. He used stock 03/04 cams.
The second member has twin 64's or 67's I don't recall which anymore. His car was a race only car, TH400, stall converter etc. He used a set of the Ford GT cams that are 189˚ Intake and 190˚ Exhaust with very gentle lift. Intake lift was 0.424 and exhaust was 0.448. His car ran eight second quarter miles at 160 mph or so.
You are far away from the parts sources for your given engine choice that we are so close to. It is very easy to overbuild one of these engines especially if you are coming from a non-4V, non-supercharged space. If you do, the cost to fix the judgmental error will approximate the price of another engine because of where you are located. If you fall 5 or 10 percent short of your power target (which I genuinely doubt) you will never feel it and most importantly you will enjoy the dickens out of your car — all the time.
Talk to your transmission builder of choice. He will undoubtedly also offer converters. Explain your intended usage, your desire not to overheat the trans on the street and listen to what he says. Then go to a converter only source like Neil Chance Converters and repeat the process. The difference this time will be that you are already more educated from your first discussion. Give the advice from Neil Chance or whoever you choose more weight in your decision process.
Remember for the cost of drilling and tapping you can comfortably sit on a 780Hp engine with excellent cold start and operational characteristics all year long that will give you years of driving satisfaction.
11-27-2017, 04:48 PM #14
- Join Date
- Mar 2010
Thank's for the response.
As I mentioned from the beginning, this will be a type of a race car (drag week in US and street week in sweden) that can run decent on the street.
The 6R80 transmission can have lock up from the second gear (even though I prefer from third with locked up converter).
Circle D have multiple discs to hold it up.
I will be the transmission builder, just upgrade all clutch packs and add a upgraded intermediate shaft.
For the cams, I doesn't want to "over cam" but I like to have something that work in the whole range especially when needed on the drag strip.
Street driven and then working as well on the drag strip. Yes I know this is not easy choise.
Therfore I'm asking here.
About the intake manifold. I thought after some reading that most/all 1999 cobra intakes have been upgraded. Either extrude honed or acid dipped.
After that they are compatible to the Cobra 2001 and Mach1 2003-2004 intakes. Correct?
I know that I will spend a lot of money in this engine. So far I have had.
For me is the biggest question mark the cams (so far).
To many directions, Ed you suggest towards original and Todd to something other which is unknown.
I will be using MaxxEcu for engine management ( yes swedish made and what I know the first that can support variable cam timing for the Coyote engines).
This engine will be run with E85 and I looking for at race day for max 30psi, but on the street much less.
11-27-2017, 08:39 PM #15
Fuel specific power improvements not withstanding, the question you should try to develop an answer for is how much power and performance are you looking for. The one drag race Cobra I spoke to above that runs in the eights at over 160 might be a good data point. There have been any number of site members that have had very good experiences with the OEM components.
An other site member of ours, WV_Snake holds the stock block record on this site (and probably a good many others) for 03/04 Cobra's. He ran 8.70's at 170 or nearly 170 on a 10 year old stock long block (as delivered by Ford) that he added a Whipple, injectors etc to. I think you want to focus on whether or not you want to have something like they have or something else. My suspicion is you would be hard pressed to improve upon their performances.
There are a lot of Cobra owners over the years that have been seduced by various forms of marketing mischief only to discover they like the tone of their exhaust and wonder where their performance went. They usually discover this shortly after they race someone they used to easily defeat.
The 03/04 SVT Cobra engine with a good supercharger (Screw, Turbo or Centri) a proper tune and suitably strong internals will not only perform beyond your wildest expectations but will do so with consistency and reliability. Can more power be had on top end with carefully selected cam profiles — absolutely! Is it going to make a difference in 99.9% of your races absolutely not!
You are building a very nice and very desirable car. Don't do things that will cause you to increasingly dislike the product of your efforts the more you drive it. You will be absolutely pleased as can be with a good set of small twin turbos, a properly phased set of OEM cams, all the E85 that engine can consume along with an apropriate E85 tune. While anything can be improved upon that engine will give you 98 to 99% of what you are looking for, do it for a fair price and do it reliably for a long, long time.
In the end only you are capable of making the choice of which direction to pursue. I know it is a tough call but if there ever was a time to fall down on the conservative side of the decision line this is it.
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