02-04 4.6 Explorer Motor Swap in 96 Mustang - Legal?

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02-04 4.6 Explorer Motor Swap in 96 Mustang - Legal?

Postby blk96gt » Thu Apr 10, 2014 12:24 pm

While trying to figure out what path to go down for my dieing engine, I've found out that 02-04 4.6 Explorer engines are almost a drop in replacement. It's an aluminum Romeo block, with the main differences (that I can find) being the intake, oil pan, valve covers, and timing chain cover. All of those parts will swap right over from my current motor (96 GT Romeo iron block with 04 PI heads).

My understanding is that since our cars came with a class legal aluminum block (96-02 Cobras), this swap would be fine. There's varying information on whether the cams are the same, but I'm not too worried about that since I will swap my 04 heads onto the short block anyways. From what I can find the rotating assemblies are also the same.

So, is this legal? Seems similar to the truck 5.3 swap for the f-bodies.

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Postby Al Fernandez » Fri Apr 11, 2014 10:58 am

If the block and rotating assembly are the same part then they're the same part regardless of where they started life. If its just that theyre similar then the differences have to be evaluated and accounted for.
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Postby Supercharged111 » Fri Apr 11, 2014 11:16 am

FWIW I know the difference in cams on the DOHC Navigator vs. Cobra is negligible at best. I always thought the 2V engines used the same cams now matter what, but I could be wrong. The biggest difference I know of is PI vs non.
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Postby blk96gt » Fri Apr 11, 2014 11:56 am

OK so I did some more digging. The Mustangs came with a large variety of blocks over the years. I'll try to outline what I know here.

It seems the aluminum block in the 02-04 Explorers was actually a WAP (Windsor Aluminum Plant) block, which was used in the 01(99?)-02 Cobras and 03/04 Mach 1's. The 96-98 (99?) Cobra's used a Teksid block, which happens to be the same motor used in the DOHC Lincoln Mk VIII's.

There were a few different piston/rod/crank combos used in the 4.6 Mod motors, but it appears that all combinations were used at some point in the Mustang. Here is the breakdown of short block specs from 96-04 for the Mustangs that I know of.

SOHC
96-98 GT - Romeo iron block, 10.49 cc dish pistons, Non-PI heads, 51cc chamber volume, 6-bolt crank
99-00 GT - Windsor iron block, 18.1cc dish, PI heads (42cc chamber volume), 8 bolt crank
01-04 GT - Romeo iron block, 15.8cc dish, PI heads, 6 bolt crank

DOHC
96-98(99?) Cobra - Teksid aluminum block, 2.66cc pistons
01(99?)-04 Cobras/Mach 1 - WAP block, not sure about pistons

The 02-04 Explorer has the SOHC 4.6 with a WAP block which happens happens to use all the same bolt patterns as an iron Romeo block. It also uses the 6 bolt bolt crank. I'm not sure what pistons it had in it, but they were likely the same 15.8cc piston that came in the 01-04 GT.

So, there's some info. Clear as mud right? If anyone see's any errors in what I have above feel free to correct me.

Edit: Made some corrections. The 96-98 Cobras came with Teksid, 99 Cobra came with some other aluminum block, 01+ came with WAP blocks.

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Postby Al Fernandez » Thu Apr 17, 2014 4:36 pm

The 01 cobra and its aluminum block is legal. If that is the same wap block as used in the explorer then good to go just swap out other parts as necessary.
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Postby Dillon » Mon Apr 21, 2014 2:50 pm

Al Fernandez wrote:The 01 cobra and its aluminum block is legal. If that is the same wap block as used in the explorer then good to go just swap out other parts as necessary.

I read once that the part number is different. There are supposedly some very minor changes as well (quoted from a Mustang forum: The bolt locations for the left side motor mount is different. The Explorer engine has two raised bosses in the intake valley for a pair of knock sensors. Also the valley is much deeper in the Mustang engine.) Would either of those make it illegal?

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Postby blk96gt » Mon Apr 21, 2014 2:55 pm

I had read that as well at some point, but my understanding was this block was used in the Mach 1 as well. Looking at the rules it doesn't say that a Mach 1 is a legal car, so someone else will have to comment on that.

Either way, I don't plan on going this direction, but as Al said this adds another option for finding engine blocks, if it's deemed legal.

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Postby blk96gt » Mon Apr 21, 2014 3:06 pm

According to Wikipedia

"While the 2001 Cobra shares almost all the same components of the 1999, some changes were made including:

The engine block was changed from the Teksid block to the Windsor Aluminum Plant or WAP block. The WAP block is regarded to be weaker than the previous Teksid block. Some 2001s received the Teksid, either from the factory or as a replacement motor"

http://en.wikipedia.org/wiki/Ford_Musta ... 2001_Cobra

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Postby suck fumes » Mon Apr 21, 2014 5:50 pm

The Mach one is legal. It's just an 03-04 cobra engine without the blower.
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Postby Supercharged111 » Tue Apr 22, 2014 6:16 am

Changed my post after re-reading the rules.

blk96gt wrote:I had read that as well at some point, but my understanding was this block was used in the Mach 1 as well. Looking at the rules it doesn't say that a Mach 1 is a legal car, so someone else will have to comment on that.

Either way, I don't plan on going this direction, but as Al said this adds another option for finding engine blocks, if it's deemed legal.


7.11.1 Any 4.6 Ford, 5.0,(302 Ford or 305 GM), 5.7 liter LT1/LS1 GM V8 production engine, in OEM stock configuration unless otherwise stated in these rules, that was originally offered in an eligible model car is legal. Cobra R model engines (Ford) and LT4 (GM/Chevrolet) engines or engine components are prohibited. Additionally, early GM cars may run any LT-1 from the 93-97 Late GM cars as long as the stock LT1 engine controlling electronics are maintained.

It's not otherwise stated, therefore it's (Mach 1) legal. Like Al said, if the Explorer block was ever used in the Mustang (sounds like it was), it's legal too. You will have to run Mustang electronics, and though the rules don't explicitly state you must run a Mustang intake manifold, I think that'd be the intent. Kind of like sticking a 5.3 in a Camaro, you have the run the Camaro's intake and accessories and management.
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Postby Dillon » Tue Apr 22, 2014 12:54 pm

Supercharged111 wrote:...though the rules don't explicitly state you must run a Mustang intake manifold, I think that'd be the intent. Kind of like sticking a 5.3 in a Camaro, you have the run the Camaro's intake and accessories and management.

I looked into this swap a while back in case I ever needed a replacement, and IIRC aside from the differences already mentioned, the longblock (including intake) is identical to a 99+ GT, so no need to swap. I think the Exploder engines had slightly different power ratings because of the headers / exhaust. So, good to know this would be a viable alternative. Read that it's close to 80 lbs. weight savings.

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Postby Al Fernandez » Tue Apr 22, 2014 4:14 pm

Just for clarity, its not kinda like the 5.3 at all. The 5.3 is a set of parts that are explicitly allowed even though they were never offered in an elligible car. The aluminum 4.6 from an explorer is legal on the premise that it is the same exact block as what was used in the Mustang. That doesnt mean anything else on that explorer's engine assembly is legal (like the exhaust manifolds for example). The rules do indeed state you have to run a stock mustang intake, just one from any of the eligible models due to the update/backdate within models rule.

Hope that helps :D

By the way its not a weight savings at all, check out the minimum weights table :wink:
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Postby Dillon » Wed Apr 23, 2014 2:46 pm

Al Fernandez wrote:Just for clarity, its not kinda like the 5.3 at all. The 5.3 is a set of parts that are explicitly allowed even though they were never offered in an elligible car. The aluminum 4.6 from an explorer is legal on the premise that it is the same exact block as what was used in the Mustang. That doesnt mean anything else on that explorer's engine assembly is legal (like the exhaust manifolds for example). The rules do indeed state you have to run a stock mustang intake, just one from any of the eligible models due to the update/backdate within models rule.

Hope that helps :D

By the way its not a weight savings at all, check out the minimum weights table :wink:

Just to clarify, you would have to run a Mustang intake even if they're exactly the same (except maybe part number)? And true, it's not a weight savings, but you have much less weight up front, which I have no idea if that helps on Mustangs, but I'd take it :) That's all I meant, I imagine it's a bit like the difference between LT and LS powered cars...

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Postby ShadowBolt » Wed Apr 23, 2014 4:22 pm

Dillon wrote:
Al Fernandez wrote:Just for clarity, its not kinda like the 5.3 at all. The 5.3 is a set of parts that are explicitly allowed even though they were never offered in an elligible car. The aluminum 4.6 from an explorer is legal on the premise that it is the same exact block as what was used in the Mustang. That doesnt mean anything else on that explorer's engine assembly is legal (like the exhaust manifolds for example). The rules do indeed state you have to run a stock mustang intake, just one from any of the eligible models due to the update/backdate within models rule.

Hope that helps :D

By the way its not a weight savings at all, check out the minimum weights table :wink:

Just to clarify, you would have to run a Mustang intake even if they're exactly the same (except maybe part number)? And true, it's not a weight savings, but you have much less weight up front, which I have no idea if that helps on Mustangs, but I'd take it :) That's all I meant, I imagine it's a bit like the difference between LT and LS powered cars...


Been there done that and it's not worth the extra weight you are required to put in the car if you run the aluminum block.

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Postby Camron70 » Tue Oct 21, 2014 9:59 pm

My understanding is that since our cars came with a class legal aluminum block (96-02 Cobras), this swap would be fine. There's varying information on whether the cams are the same, but I'm not too worried about that since I will swap my 04 heads onto the short block anyways. From what I can find the rotating assemblies are also the same.
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