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1996 Ford Thunderbird LX (236k) 1990 Ford Thunderbird Supercoupe (74k)
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Discussion Starter · #23 ·
I don't have mufflers on my 4V .. I bought 03/04 Cobra mufflers with the spring bypass but never installed them. I was just responding to this ..
No mufflers would be completely fine with me if I need to cut them like my old ones. I would like mufflers for a bit since I usually am out driving past 3am but I don't mind it too much. Definetly not thinking of the manual swap that's too much for me right now.
 

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I am in the process of nearly the same power mod. My car is a 95 Cougar, and I used a 60k 1997 mark viii donor car.
So the Cougar was already OBDII and so was the Mark. Your 94 mark is not OBDII, your 96 bird is.

I went what I determined to be the path of least resistance, least time, and least cost. I used the OEM harness, PCM etc in the MN12 and made the Mark VIII engine work with the car.
The advice I got from Don Lasota was to always use the ignition and PCM that was in the chassis you are using.

Without going into great detail, none of this is simple, easy or cheap and every build seems to be a little different. There are a large number of builds chronicled here on TCCOA, and every possible variation seems to have been done at one time or another.

Of Note: Your 4v has IMRCs and your bird never did. Unless you plan on a very high stall converter that never sees 3000 rpm, and don't care much about fuel consumption, you need to make these work. They require an rpm window switch and a trigger to activate the IMRCs so it maintains induction velocity and is not "doggy".

I have both these items that I bought from another member which I will sell at my cost. My converter is 3800-4200 rpm and I don't care about fuel mileage at this point.

Your Mark exhaust is different. I modified the manifolds removing the left cat and deleting the EGR system entirely. The left cat received an aftermarket flange to accept cats in the usual configuration.

I have two Catted down pipes I made from the Cougar Cats and walker parts I put together. They terminate prior to the third cat where the pipe is nice and straight. These pipes are 2.25" and fit both the OEM cougar manifolds and the modified mark manifolds perfectly. The O2 bungs are very close to OEM positions.
These Catted down pipes are for sale, I no longer need them now that the car is an "antique" and no emissions are required for inspection here in NH.

You can re-use your Mark trans, it's a direct fit. Your Mark driveshaft is vastly superior to the bird although not the "best" you can get.

The aluminum carrier is a nice piece to use in the bird, a whole lot lighter. The Mark rear lower control arms will bolt on. Your front and rear hubs are identical, the Mark has larger front brake rotors.

For me, the donor car was a blessing. Having spare parts is great, saves time and money.

My car is not close to done, but I have a pretty big build planned for racing.
That said, I am running the original 95 trans that was pronounced dead twice but resurrected and j-modded anyway with the 4 valve engine installed. I have not yet tuned the PCM at all.

I can tell you that as is, my car is much more powerful than it was, and feels as if the 4valve engine belongs in it. When I do have it tuned, it should be remarkable;
Redline changes from 5400 to at least 6500...a lot of rpm I can't even get to now.
Shift points will be much more appropriate done properly.

As far as the 94 trans being "junk", I have to disagree if you don't plan on 400+hp. With a stock 4v, you might get to 300-325hp to the crank with bolt-ons, no more than that. That's unlikely to be more than the trans can handle according to Jerry W. The Ideal would be a new 2014 unit from a 2wd pickup or van and then bulletproof it to the Jerry W spec or get one from BCI, Pro-Weld or another vendor.

Eventually I will go to the 05-10 GT 5 speed upgrade, but that's a huge undertaking for another year for me. I plan to just rebuild my low mileage 1997 4R70W to the best it can reasonably be until the 5 speed mod. Reasonably, the stock differential is limited in power input so does it make sense to have a trans good for 750rwhp? I believe the 8.8 is limited to around 500rwhp, but I may be off on that.
Racecougar is very well versed in this and has some excellent articles in here, it would be wise to take his and others advice here. They are a bunch of good guys who been there, done that.

Best of luck, read a lot. Don't be surprised by lots of little expenses that come up. If you keep it pretty much stock, it won't be too bad. Once you start changing hubs, knuckles, brakes, suspension, transmission, and do power mods, it gets crazy.
 
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Another thought:
My Cougar responded to the gear set change immensely, and in my opinion a higher numerical of any order and traction lock is the best mod for your money.
If you are lucky, your Mark may have 3.27:1 gears already in the aluminum housing. If you are lottery-lucky it may have traction lock but that would be very unusual.
I paid about $250.00 for the R and P, about $100.00 for gaskets, seals, friction modifier and gear oil. A used T-L carrier and the Cobra clutch kit was about another $100.00 Professional installation was $300.00, he did it for $250.00 and a half gallon of maple syrup.I am brave and was intending to rent the tools to do the ring and pinion myself. Then I downloaded the FRPP instruction set, read it, and found $250.00 and syrup for the man. I am not THAT brave.

The second best major power improvement was the full exhaust kit from TRUBENDZ even without headers. I am not paying $1500.00 for 3/4 length headers from Kooks, no matter how sexy they are. (CANT SEE EM ANYWAY) Another member has a setup to modify full length Cobra headers in a MN12 with a 4 valve installed for reasonable cost. (the steering shaft is in the way of 7&8. The factory true dual upgrade in the Mark states a 10hp gain. My seat of the pants Dyno with the Trubendz kit disagrees; it feels like twice that or more.
I will also state that once the cats are out, and the larger dual pipes are installed you will re-consider the need for mufflers. I repurposed 2 OEM resonators and installed them as mufflers which definitely reduced the sound level. That was not enough by half to make it tolerable in the neighborhood. I had to fab up two motorcycle baffles wrapped in glass and stuffed into a 2.25" pipe that I shoehorned into the very end of the pipes. He baffles come out by removing 2 bolts in each. The baffles cut the harshness and the sound level a lot at low rpms so it is tolerable. It takes 10 minutes to remove or install them roadside. Without mufflers of any type (I tried it) the sound was painfully loud with a real bite in it. With just the resonators, every head turned every time, it had a real snarl to it. With the silencers in it's about like a stock mustang V8 until you step on it.

My plan is to combine 3 mods next spring or summer. I want to pull the '95 transmission and install the rebuilt 97 transmission.
Pull the exhaust manifolds and downpipes, and replace with modified Pace Setter full length long tube Cobra headers.
Remove all my new leather mark 8 seats and the interior flammables, and weld in the Main Hoop, door bars, shoulder bars and back bars of the 6pt Roll Cage.
I hope to reduce shop time combining the mods. My biggest sponsor gives me shop time in his shop but it has to be minimized as that's his livelihood when not on the road.

Ultimately, I went with the 4Valve because my baseline is about 300hp stock and weighs like 200pounds less. The cost and the work involved to make a cast 2 valve 300hp did not seem worth it. It ends up with no room to improve easily beyond 300hp and is overweight in comparison. For what I paid for the entire Mark VIIi, you couldn't buy the gaskets to rebuild the 2 Valve.

it did take parts and work to make the 4 valve fit. A set of gen 1 valve covers modified, a different coolant pipe, window switch, trigger card I reverted the COP to wasted spark, lengthened the harness, replaced the injector harness, manifold modifications..
even after all that and lowering the cradle 1/4", I had to cut out hood supports to be able to close the hood.

Ford left lots of room for improvement in the MN12 and that makes the build very gratifying.


Just your engine swap has amazing supporting numbers..where else can you get a 50% power gain and a 200 pound weight reduction in a bolt in modification/swap.
That's going from 41 watts/pound to 61 watts/pound. A 50% power to weight improvement, and it bolts in sort of. Thank you Ford for making us heroes.



 

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Just to correct some bad advice; the latest transmission we can use is a 2003, the later ones have no vss gear on the output shaft . It's difficult to swap.
 
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97 Thunderbird 4.6, 98 Mark VIII LSC
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Another thought:
My Cougar responded to the gear set change immensely, and in my opinion a higher numerical of any order and traction lock is the best mod for your money.
If you are lucky, your Mark may have 3.27:1 gears already in the aluminum housing. If you are lottery-lucky it may have traction lock but that would be very unusual.
I paid about $250.00 for the R and P, about $100.00 for gaskets, seals, friction modifier and gear oil. A used T-L carrier and the Cobra clutch kit was about another $100.00 Professional installation was $300.00, he did it for $250.00 and a half gallon of maple syrup.I am brave and was intending to rent the tools to do the ring and pinion myself. Then I downloaded the FRPP instruction set, read it, and found $250.00 and syrup for the man. I am not THAT brave.
Setting more of the record straight...

All Mark VIIIs have an OPEN differential in an aluminum housing. Base Mark VIIIs had a 3.07 - the LSCs all had a 3.27. It has nothing to do with luck - and if you find it has a TL, it was added by a previous owner. No Mark VIII left the factory with one.

The second best major power improvement was the full exhaust kit from TRUBENDZ even without headers. I am not paying $1500.00 for 3/4 length headers from Kooks, no matter how sexy they are. (CANT SEE EM ANYWAY) Another member has a setup to modify full length Cobra headers in a MN12 with a 4 valve installed for reasonable cost. (the steering shaft is in the way of 7&8. The factory true dual upgrade in the Mark states a 10hp gain. My seat of the pants Dyno with the Trubendz kit disagrees; it feels like twice that or more.
Headers and exhaust respond very differently based on the cam in the car, and one exhaust does not equal another. The LSC duals don't have an X-pipe like the mandrel bent kits do; a stock 4v will benefit from the additional scavenging offered by an X-pipe but unless there was a clog somewhere in the previous exhaust, you're not going to pick up 20 HP from an X-pipe with the factory cams. X-pipe and headers though, sure. The stock exhaust isn't great but it's not THAT bad either. In a nutshell, show me the dyno graph.

Ultimately, I went with the 4Valve because my baseline is about 300hp stock and weighs like 200pounds less. The cost and the work involved to make a cast 2 valve 300hp did not seem worth it. It ends up with no room to improve easily beyond 300hp and is overweight in comparison. For what I paid for the entire Mark VIIi, you couldn't buy the gaskets to rebuild the 2 Valve.
There actually isn't much difference between the weight of the 4v engine vs. the iron block 2v engine. The extra weight of the cylinder heads on the 4v motors offsets just about all the weight savings afforded by the aluminum block. Getting 300 HP out of a 2v is easy with TFS heads these days, cheap though, not as much. :)
 

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A set of cams is probably the cheapest upgrade, and duals and a pi intake with pi cams will make a 2v rock. And they're cheap.
I noticed a nice improvement
 

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2v to 4v swap has been done thousands of times. Depending on your wallet, skill level, and tools/equipment it could be easy, or it could get complicated. I've done it several times and been happy with the results. EVTMs are an absolute necessity imho. One thing i ran into was that the factory ECMs are all pretty old at this point, i had an ECM that some leaking caps.
 

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The hardest part to me was finding a combo that will clear the hood.
Matt's build, with c- heads and a mach intake is best, imho.
B head intakes are hard, but the 93 will work with some hood mods, and a hammer. :)
 
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The hardest part to me was finding a combo that will clear the hood.
Matt's build, with c- heads and a mach intake is best, imho.
B head intakes are hard, but the 93 will work with some hood mods, and a hammer. :)
+1 on the C heads and Mach intake. That's what i have on my Zephyr. Mach intake won't fit on Teksid with factory knock sensors installed tho.
 

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1994 Cougar XR7 DOHC/5-Speed
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The hardest part to me was finding a combo that will clear the hood.
Matt's build, with c- heads and a mach intake is best, imho.
B head intakes are hard, but the 93 will work with some hood mods, and a hammer. :)
Oh yeah it clears the hood鈥 with 3/4鈥 spacers between the frame and K member 馃榿
 

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Well, Yeah, but you didn't have to cut a hole in the hood.
 
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I keep thinking of the tragedy that was goldbird.
 
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1994 Cougar XR7 DOHC/5-Speed
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I keep thinking of the tragedy that was goldbird.
I never got that goldbird hood cut unless it was to show the copious amounts of bling. Fundamentally it鈥檚 just a bullitt/SVO intake and centrifugal combo, and I have definitely seen 96-97 steel hoods clear similar setups with just trimming of the inner braces, k shims might even reduce some of that need


I figured the only tragedy that was Goldbird is that it got sold off non running.
It was a project car being built since before I joined the forum and was still that when it was sold! I feel gypped frankly I never saw it finished lol Long term non running projects seem like they never get finished as plans just keep escalating and that car might just be the poster child. In my experience done is better than perfect.
 

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97 Thunderbird 4.6, 98 Mark VIII LSC
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It was such a cool build, then there were issues, Then it got badly overheated and basically destroyed. It got sold off for 5 g's. IDK what it sold for, but no one ever got it running after that.
 
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