(93)-95 Cobra and V8 Explorers

[chriswells78]

So I'm reading this book, The Official Ford Mustang 5.0 Technical Reference and Performance Handbook by Al Kirschenbaum. After I read through the 93 Cobra section, I began to realize just how similar these motors are to ours.

• GT-40 cylinder heads-they share the 1.84" intake valves but the Cobra has 1.54 exhaust valves where as the Explorer engine has 1.46 like an HO motor
• The Cobra has a 65mm throttle body, as do Explorers
• The Cobra has a 70mm MAF, Explorers (98+) feature a 75mm MAF but also feature a restrictive center blade that is not present in the Cobra MAF.
• GT40 style upper and lower intake manifold.
• The Cobra motor has 24# injectors where as Explorers have 19# injectors.
• The Cobra motor came with roller rocker arms where as the Explorer features stamped rocker arms.
• The Cobra came with smaller diameter crankshaft and water pump pullies. I do not know if they are the same but the pullies on my Explorer are smaller than those on my neighbors 90 5.0L LX.
• The Cobra came with a specific cam grind for the "GT40" motor. The Explorer cam is similar, however the grind is more torque focused. I have included the statistics on the E-303 camshaft since that seems to be the most popular aftermarket camshaft for Explorerforum members who have upgraded thier cam.
  ................GT40 Cam------Explorer--------E-303--------Stock 93-94 Truck---Mustang 91-95
  lift intake----.282-----------.264-----------.300------------.237----------------.278
  lift exh------.282-----------.280-----------.300------------.247----------------.278
  duration------270-----------256------------282------------244-----------------276
  IO------------19------------10--------------0--------------16-----------------20
  IC------------71------------66-------------40--------------48-----------------76
  EO-----------75.5-----------66-------------40-------------57----------------- 67
  EC-----------14.5-----------20--------------0--------------19-----------------19
  lobe I---------115----------118-------------110------------104----------------115
  lobe E--------121.5---------114-------------110------------111----------------116
• The 93-95 Cobra motor featured 63.4-66.4 combustion chambers as do 96-97 Explorer motors. The 97 1/4-01 (GT40P) feature 58.3-61.3 combustion chambers. The size vatriation is explaned later in the book as the difference in milled deck heights. The second number is the stock combustion chamber. The first number is the chamber volume if the head is milled down to the maximum 0.40".

The book also contains a blurb about Explorer motors in the Cobra chapter.

1996-2000 5-Litre Explorer Truck Years after the 5-liter V-8 was discontinued in Mustang service, the same basic engine was used to power Ford's 1996 (and later) Explorer and (L-M) Mountaineer sport utility (SUV) models. For these applications, the SEFI intake manifolding was redisigned to optimize the 5-liter's torque output.
Based on the GT-40's staggered round runner design, this two piece truck assembly features a right-side dog leg entryway passage. The cross-over section is tapered and reconfigured as an inverted "T." The runners are also taller and are tapered to maintain optimum flow velocity. Because the taller runners are also narrower (by .625 inch), the pair of front and rear through-bolt passages reamin clear of the runners feeding cylinder numbers 1 and 8. In addition, revisions to runner radii adventageously reconfigure the port floor and roof shapes for impoved air flow into cylinder heads.
Underhood packaging requirements dictated a flow-inhibiting 90* bend in the Explorer five-oh's EGR spacer. (The Explorer five-oh's EGR spacer weighs 2.3 pounds, twice as much as other versions.

If you are building a 5.0L Explorer motor, I recomend this book. I have picked up a lot of good information in the last 2 days I have been reading it. I wish I would have had it before I started planning my build.

This also makes me curious to see if 93 Cobra underdrive pulleys will work on our applicaiton.

 

[X6StringerX]

Very nice post... I'll have to check this stuff out.

 

[410Fortune]

the explorer timing cover is different I think and it also uses a high flow water pump.

Good info there!

I want to ditch my EGR elbows now hahaha
I also want to see the Cobra factory roller rockers installed on some GT-40 heads, I wonder if they are pedistle mount like our explorer's?

 

[chriswells78]

The book says:

OE Rocker Arms and Valve Covers.Although GT-40 cylinder heads acept an H.O. motor's production rocker arms, fulcrums, guideplates and fasteners, the 1993-95 Cobra's rollerized rocker-train is GT-40 specific. Developed by Ford and Crane Cams, the Cobra's nonadjustable, die cast aluminum roller rocker arms have a roller tip, roller trunnion, and a 1.7:1 ratio. Carried on GT-40 specific fulcrum guides, the OE Cobra's roller rockers are bolt on replacements for the high-friction sled fulcrum units used on 1978-and-later production 5-liter V-8's

The book does not mention a high flow water pump as a factory upgrade for the Cobra over the GT. It does mention the 14% smaller pulley that would make a production pump pump faster. It also does not mention an upgraded water pump in the "R" model either, only an upgraded 2 core radiator.

 

[Turdle]

the explorer timing cover is different I think and it also uses a high flow water pump.

Good info there!

I want to ditch my EGR elbows now hahaha
I also want to see the Cobra factory roller rockers installed on some GT-40 heads, I wonder if they are pedistle mount like our explorer's?

Jamie-you posted a link for custom egr elbows at one time--and I can't find it-
Could you please post it again?

 

[CDW6212R]

Good stuff for newbie's. The most important cam specs you did not list, why? The advertised duration and lift are irrelevant for stock or mild cams/engines.

Concern yourself primarily with the @0.050 duration numbers, that is when 90% of the airflow enters the engine. The stock cams will be in the very low 200 range, like 204. All of the Ford Motorsports cams are over 220 degrees duration for the intake valves. That is a huge difference, and that is why those FMS cams are all poor choices for a 302 truck with a 5000rpm limit.

Find cams with @.050 specs on the intake around 210 degrees, duration for the exhaust can be 220 or so for a 302 truck/stock application.

FYI, the 95 Cobra roller rockers will bolt onto any stock late 302/351 engines. They are pedestal mount, and they should mount under short valve covers. That is their best feature, being short. My friend has a used 95 Cobra engine that was traded to him. I sold the man my rebuilt 91 LSC engine with Edelbrock heads/intake. That's the engine which I have the used cam from. I got it back to use in my Mountaineer test 302, with 212/22 duration. Regards,

 

[Turdle]

That is a huge difference, and that is why those FMS cams are all poor choices for a 302 truck with a 5000rpm limit.

Well, Don-we'll just have to raise the rev limiter --

My camshaft has 232 degrees duration at .050"-it performs very well with stock tuning. I'm anxious to see what really happens-
The trick is to not skimp on the torque converter--

 

[CDW6212R]

Yes, the @.050 duration directly affects the needed torque converter, the stall speed. Low rpm torque falls fast with bigger cams. Are you sure that you've got 232 degrees intake, that's a stout rpm cam for a 347. I've got an unused 236/242 Cleveland cam that was chosen for a 5800rpm 408 engine.

I think that you need to "...just have to raise the rev limiter --."

 

[chriswells78]

I posted the cam specs listed in the book except overlap because there were no specs on the FRPP cam. I will add the listed 92-93 Ford Truck cam specs. The 94-96 specs are stated to be the same as the stock Explorer.

I would scan the page with the chart for all to se but I think I'm probably pushing the copyright thing far enough as is

 

[Turdle]

Yes, the @.050 duration directly affects the needed torque converter, the stall speed. Low rpm torque falls fast with bigger cams. Are you sure that you've got 232 degrees intake, that's a stout rpm cam for a 347. I've got an unused 236/242 Cleveland cam that was chosen for a 5800rpm 408 engine.

I think that you need to "...just have to raise the rev limiter --."

Where did I come up with that number--

here is the ford racing specs--

PART NUMBER ENGINE DESCRIPTION PEAK RPM DURATION (6) VALVE LIFT
TORQUE BHP. INT. EXH. INT. EXH.
M-6250-E303
(1) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 2500 5500 282° 282° 0.498" 0.498"
220° 220°
M-6250-F303*
(3)(4) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 2800 6000 288° 288° 0.512" 0.512"
226° 226°
M-6250-B303*
(3) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3300 5100 284° 284° 0.480" 0.480"
224° 224°
M-6250-X303*
(3)(4) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3500 6200 286° 286° 0.542" 0.542"
224° 224°
M-6250-Z303*
(3)(4)(5) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3500 6300 290° 290° 0.552" 0.552"
228° 228°

M-6250-E303

 

[CDW6212R]

Well look at those mess of numbers. Here is how they should be displayed, then you can see what to compare that means the most;


"PART NUMBER ENGINE DESCRIPTION PEAK RPM DURATION (6) VALVE LIFT
TORQUE BHP. INT. EXH. INT. EXH.
M-6250-E303
(1) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 2500 5500 282° 282° 0.498" 0.498"
220° 220°

M-6250-F303*
(3)(4) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 2800 6000 288° 288° 0.512" 0.512"
226° 226°

M-6250-B303*
(3) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3300 5100 284° 284° 0.480" 0.480"
224° 224°

M-6250-X303*
(3)(4) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3500 6200 286° 286° 0.542" 0.542"
224° 224°

M-6250-Z303*
(3)(4)(5) 1985-95 302 with Roller Tappet Cam
(1)(2) Hydraulic Roller Tappet 3500 6300 290° 290° 0.552" 0.552"
228° 228°"

The "E" cam can be a good choice for a hot 347 with high compression, but not for a stockish 302 and low compression.