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Formerly known as 89 steeda
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Discussion Starter #1
I built a 83 Tbird Tc with a 97 Explorer motor,t5 and a 8.8 w/3.55 gears. Car is light for a TC but havent weigh it yet so Im guessing a race weight of 3300 with me in it.

Here is the motor I built.
Shortblock is a fresh stock rebuild
Untouched P heads with Alex spring upgrade for .550 lift cams
TFS stage 1 cam
stock lifters,pushrods,rockers,intakes,throttlebody
BBK 1 3/4 long tubes
24lb FMS injectors and a MircroSquirt from EFI Source Im tuning myself.


Car has a 2.5" Y-pipe into a 3" single full exhaust. And I have real 17" street tires on 93 Cobra wheels. I didnt build it as a race car so I know my tires and gears are killing its full potential but I really thought it would MPH better than it does.

On tow different days it ran almost identical passes. Here are my two best slips.
2.09 60ft 13.93 at 102
2.16 60ft 13.94 at 102

im holding 3rd gear through the traps and crossing at 6200.If I short shift to 4th it drops 3mph every time but still runs in the 13.90s

So what IS a good mph for a mostly stock GT40P motor? I see a few guys on here pushing past 110mph with not much more motor than me.

I guess I was thinking it would be closer to 105mph and Im hoping maybe its low just because of the gear choice.
 

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Not bad all things considered. Bet your race weight is over 3,400 lbs and that explains the ET. A better 60' would do wonders for ET.
 

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Not too shabby. I would run either a ported stock lower or throw on a GT40/Cobra/Explorer intake. Should wake up a little more. Maybe throw that cone in the fenderwell also.
 

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Formerly known as 89 steeda
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734 Posts
Discussion Starter #4
Not bad all things considered. Bet your race weight is over 3,400 lbs and that explains the ET. A better 60' would do wonders for ET.
I really need to weigh it because it has a UPR k-member,deleted all the a/c stuff,no power steering,Flaming River rack,removed the cruise control parts and power antenna. Ford info says a stock 83 TC had a 3000lb shipping weight.

Not too shabby. I would run either a ported stock lower or throw on a GT40/Cobra/Explorer intake. Should wake up a little more. Maybe throw that cone in the fenderwell also.
It is a Explorer GT40P motor top to bottom. Only thing that isnt front the Explorer is the cam and headers.
 

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When my car still had to go through emissions I was forced to run a single 3" exhaust like you. That was a long time ago, but going from full exhaust to open collector was worth a good bit. I still have the log... just dug it up.

Date: 11/28/97

Best pass, open collector: 13.57 @ 102 with a 2.03 60' (street tires)
Only pass with full exhaust (at the end of the night; spun unfortunately): 14.34 @ 99 with a 2.21 60'.

Even taking into account the spin, the exhaust was choking off 4 tenths and 3 mph. I had 1.5" longtubes on the car at the time.
 

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Formerly known as 89 steeda
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734 Posts
Discussion Starter #7
There is noway my exhaust is holding back the car. I have 1 3/4 tube long tubes, 2.5" homemade Y out of mandrel bends, into a Flowmaster 2.5 to 3" merge pipe,3" Magnaflow straight thru muffler and a Stinger Performance 3" TurboCoupe mandrel bent tailpipe kit. I barely make 300hp with this 5.0 and my Ranger that had a 2.3 Turbo made 382 to the wheels thru a full single 3" exhaust. Same truck gained nothing with an open downpipe.
 

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So what IS a good mph for a mostly stock GT40P motor? I see a few guys on here pushing past 110mph with not much more motor than me.
You say they don't have much more engine than you, but there are many things you can do inside the engine to find a lot of "free" horsepower (non-compromise horsepower). Thin/low restriction ring packs, special Torrington bearings on the cam gears and cam, special main/rod bearings, amazing valve jobs, the list goes on and on.

For reference of what other people with P heads do: my old 302" with new moly rings, P bearings, stock cam, 1.84"/1.55" GT40p heads with TFS springs, explorer intake manifold, 1.72 rockers, FMS shorty headers, 2 chamber mufflers, 3.73 with a T5, and stock intake tube ran 13.45 @ 105 with a 2.23 60'.

Look into and read about the Factory Stock P head engines the NMRA guys are running. You'll see cam durations approaching 240/250 degrees @ .050, amazing valve jobs that put the seat right on the very edge of the valve, more compression than you would think possible for iron heads to run, and a lot of other secret stuff that is very hush hush.
 

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Formerly known as 89 steeda
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Discussion Starter #9
Well my new plan is Im going to swap in some 3.73s in the morning and I picked up some cheap 15x8 Weld knock offs to mount some 26x8 ET Drags on and see if this thing will come close to the 12s and break 105mph.

More people I talk to seem to remind me for a basically stock 5.0 with a cam and exhaust upgrade Im doing pretty good I guess. I still hear about guys with similar mods in other foxbodies not coming close to this mph
 

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I would think 102 is not bad given bone stock heads/intake/compression.
what are you shifting at? Over-reving will hurt et and mph.
 

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Formerly known as 89 steeda
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Discussion Starter #11
Shift light set to 5900. 1-2 shift shows anywhere from 5900-6100 in my logs depending on if it was spinning or not. 2-3 shift is always right at 5900 and most passes I run 3rd out the back door.
 

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i would "guess" the car would be more happy shifting lower... if it were mine I would experiment with 5200 and work up till it starts slowing down.
That combo should be pretty tolerant to lower shift points...
I'm thinking the TFS-1 cam is not the best choice, but, cam swap is quite a bit of work... so, again, were it me, I'd work with what you have.
Slicks and 3.73's should do wonders... don't be afraid of 5000rpm launches. Slicks and a manual you want a little wheel spin... not a dead hook. Dead hook = broken parts. I would start with high rpm launch, looking for wheel spin, and work down till it's just rolling the tires over a couple times coming out of the hole.
 

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+1 ^^^

We have comparable setups, and mine dyno'd peak at 6000. I started out shifting at 6100 and worked down. I ended up shifting now at 5600-5700 and gained 4 mph from first run. Each car will be different though.
 

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Formerly known as 89 steeda
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Discussion Starter #14
Well I went back to Milan yesterday for a private rental and I put 13 passes on the car trying all kinds of things.

I made two changes to the car since last time. I swapped in 3.73 gears and brought along a set of 26x8 ET Drags.

The first two hours I ran my 17" street tires and tried different launch rpms and tried different shift points. I wanted a real apple to apples between the 3.55 and 3.73 gears. I found that by dumping the clutch right off idle would let the tires hook and it blew my mind when it pulled a 1.96 60ft. My best pass was a 1.96,[email protected] That was shifting at 5900-6000 and when I tried short shifting at 5500 it slowed to the 13.80s. Logs showed I cross the line in 4th at 5000rpm with the 3.73s

The last two hours I swapped on the slicks and tried launching between 3000 and 4000 rpm.They worked great. The 3000 launch wasnt enough and it bogged with a 1.92 60 but the 3500-4000 launches resulted in four passes between 1.74-1.78 and 13.33,13.37,13.34,13.41 all in a row and all at 102mph.

I datalog every pass and only needed to make minor adjustments as my tune is as about as good as it can be since no adjustments ever made any real change in the mph numbers.


Felt pretty good with these numbers for a car set up to throw around corners and not built to drag race.
 
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