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malachaihuffman
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09-29-2012

Okay here's the deal re though my original plan I really don't want that much for the street yet it wouldn't even hook lol. I have the whole motor harness from the Lincoln and the sohc ecm that I was going to get flashed then dyno'd for the 4v I pulled the valve cover and the motor looks like it might have 15k miles on it.. What are your saying I will have to change about the harness? It was originally a v8 so the dash harness and everything is there. Do you think the motor would be reliable on 8-10 psi? If so how much power est??
   
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El Caballo Corre
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09-29-2012

Welcome to the Mustang Collective Malachai. As you can see there are some very knowledgeable people here on the Collective that are willing to share their expertise with you. Any time you have questions or problems all you have to do is ask.


J&M Extreme Joint UCA and LCA's
JLT True Cold Air Intake
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Steeda Charge Motion Delete Plugs
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Personal Best
1/8 mile 8.05 at 85.38 mph
1/4 mile 12.66 at 106.89 1.64 60 ft
El Caballo Corre
   
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07mach
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09-29-2012

That is awesome for you that it is an original v8 chassis!!! You are correct that you can have the GT computer reflashed to do whatever you want (turbo, dohc, etc). What you cannot do however is use the MARK 8 engine harness. A stock 2001 GT harness will plug into the DOHC, with some temp sensor wires lengthened and a mod to the coil leads. You can go on ebay or where ever and get a GT sohc engine harness from 2001 and every plug will match. The Mark 8 harness connectors are made for the EEC-4 computers and your computer is an EEC-5 with OBD-2 status and nothing matches. Toss the Mark engine harness. Get the 1999 and newer COP valve covers and coils (watch out though, the Cobra coils have the + and - ends swapped compared to the GT, so just cut and swap the wires.

A Mark 8 engine can safely run 5-8psi of boost, but once you get over 8psi, the piston ring lands can break apart (had that happen twice) if your tune isn't 100% spot-on (no pinging). After the factory hypereutetic pistons weakness, the con rods usually fail over 500hp, although I never use them on rebuilds so I am not sure over 400hp (not able to resize easily due to cracked-cap design). I have used the cast cranks in high power deals, so unless you are going over 600hp, that cast crank is fine.

The ultimate DOHC you want might cost you $8000. That is a lot, and takes a lot of the "fun factor" out. It will hold about 900-1000hp, but your stock Mark 8 engine MIGHT hold just under 500. It will be sensitive to any detonation (pinging), so a bad tune will make it a grenade. But, if you keep the Mark 8 stock with under 10psi and play a safe tune from a legit tuner (I like Eric Brooks at brooksspeed) all you need is a remote tune ($250-350), 2001 GT engine harness $100-150, cop valve covers with coils and covers ($200-300), a 96-98 Cobra intake ($300ish), you can have a lot of fun before it lets go (may be reliable, may not be), bigger injectors, billet fuel rails to use the returnless fuel system. .

Last edited by 07mach; 09-29-2012 at 03:22 PM.
   
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malachaihuffman
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09-29-2012

so 450 on a conserative tune should be reliable? and im guessing that tranny will need a full overhual for that kind of power? and how well to they hold up to a man. valve body?
   
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07mach
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Reliable means you may get one season of hitting the track before you are death-smoking. Big factor is how worn the engine is to begin with. I don't know how many miles and what type of miles are on your setup (grandmom on the highway, or some punk who beat the crap out of a cheap Mark 8). Ring seal is a problem, valve stem seals are a problem, and people running 87 octane and pinging the engine all the time kills rod bearings and rings, etc.

As far as the trans goes, just Google "j-mod" for the Mark 8 and you will find tons of articles on how to make your shifts knock your tooth fillings out. Those articles may be old (I remember using one of those back in 2002 or something to give my Mark 8 a bark on the 1-2 and 2-3). I know I still have some of the springs and stuff to make the mod, but the valvebody mod is just drilling out holes. No "kit"worked better. Getting an aftermarket convertor is always a good idea - tell them what you plan to do with the car and they will likely weld anti-balloon plates on, etc.

One issue I just thought of though is; does your car have a stick or was it automatic? Reason is that the computer operates the transmission functions too. If the car had an automatic, you are fine, but if it was stick, you need a computer from an automatic car.
   
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malachaihuffman
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i pulled the valve cover today and you could eat off of that head and the cams have little to no wear so in your opinion it wont last very long as a weekend fun car?
   
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07mach
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Honestly, you can be happy that it is that clean. It means that someone changed the oil regularly. The problem is, that by looking under the v/c you haven't proved the bottom end to be solid. You could have a spun bearing or broken piston ring land and the top end will look beautiful. For the sake of your sanity, we can stay positive and say that everything should be fine.

My comment about lasting one year as a track car is that by boosting that engine and running it hard, that engine will slowly start losing ring seal and blow-by will start to become an issue. Also, pushing all the weaker factory parts- con rods, pistons, valvesprings to their limit will or may end in a bang.

The valvesprings on the 1993-1995 Mark 8 are notorious for breaking and dropping the valve into the cylinder. Ford made a change in 1996 to the "beehive" spring which fixed that problem. The easiest way to fix it is to spend the big bucks on higher pressure Comp Cams springs and their matching retainers. Remember, if you are running boost, you need more spring pressure, since the boost is trying to push the intake valve open. The spring has to control the valve or else the piston and valve will become close friends which again, ends in a bang.
   
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malachaihuffman
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yea i plan on looking at the bottem end its just sitting in a tire right now i need to buy another engin stand i sold the one i had after i rebuild my last 350 but i think my best bet will be to put it on a stand and start ordering parts and take a little longer but only have to build it once
   
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malachaihuffman
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and you said that crank is good for 600 would it be a complete waste of tim to just do rods and pistons?
   
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07mach
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For the sake of being straight-up with you, you have 2 basic choices; 1. you put it in stock with a Cobra intake 2. you spend tons more over a long period of time and go all out (possibly never getting it done-due to various other interests). Very few people just replace the pistons, rods, and rings because the crank needs to be rebalanced anyway, and likely resurfaced, so buying a forged Cobra crank is only a few bucks more.

Also, once you get the heads off and the crank, pistons and rods out, you might as well get the block honed, decked, cleaned, align-honed, and you might as well get the heads done, etc. So from a lot of experience I can tell you that nothing that starts with a simple rod and piston change ends under $6000 on these cars. All of those main cap bolts and head bolts have to be thrown out and replaced with either new TTY bolts or extremely expensive ARP studs.

I was the moderator on a huge modular forum from 2002 until 2010 and the biggest disappointment for most people was that they got the "core" Cobra/Mark 8 engine cheap, expected huge blown power numbers, but in the end spent $6000-$8000 to make it reliable at those huge power numbers, then lost interest and tried to sell off their stuff, losing their butt. Most of them had a year or two invested, but some had over 4 years of saving parts before they gave up. You have a nice car, I hate to see you get crossed up with it.
   
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