*update* Experiment time: Police package Taurus heads on 96 N/A block in my '94 SC.

92bird

Registered User
Wow, why would I do that?

This is just a fun experiment using what i have laying around the garage.. My '94 SC has some rod knock, and money is tight so I'm trying something fun in the meantime. This bastard child 3.8L will be between the shock towers of my stock '94 daily driver SC for hopefully less than a year, while I take my sweet time doing something yet to be determined with the '94 block that I take out.

I am taking the engine from a '96 Thunderbird LX 3.8L that i had as a parts car (blown head gasket) and stuffing it in the SC.

I intended to use the whole 96 motor but valves and valve seats were rusted pretty bad from sitting with water/coolant and i didn't want to put money into a valve job just yet. But i'll hang on to these 96 heads for future endeavors..

I have a spare set of heads from a 1995 Taurus police package car, which have a D-shaped combustion chamber. This should lower the compression of the N/A motor by a bit, and give it a chance to survive in the SC until i can do something sweet with the '94 SC block.

Now these heads do not have the deck integrity of the SC or 96-98 3.8 heads, but they should be fine for a stockish application. Might be worth a few hp too because the valves are not shrouded as much.

I've attached a pic of the head differences.. 95 police package heads on top, and 95 N/A 3.8L heads on the bottom. You can see the chamber differences.

Any thoughts what this might run like? The stock '96 cam isn't horrible, specs are better than the '94 SC cam. Who knows what compression will end up being.

Hope to have this running in the next few weeks.

Jeramie
 

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One more thing to note, this engine is external balance.. I have the flexplate from the '96, and the SC crank pulley bolts up to the '96 NA balancer just fine. Everything should be in check.

I've got a spare '94 SC timing cover and water pump, the '96+ is different.

These heads are responsible for an additional 20hp and 5ft/lbs over the regular N/A 3.8L. These heads were used in the police package taurus, lincoln continental, and 1995 windstar.
 
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Ive always wondered about the winds on an sc motor...No idea if it be a performance upgrade of not...Nor do I know if any have ever been flow tested or compared
 
Like i said, this will be an experiment.. Also to see how well the NA bottom end will hold up with a blower. The '96 block is already even threaded for a knock sensor, just has a plug in it.

Jeramie
 
have seen things

one time a friend bough a sc that a month later start giving troubles.... when he got it the previous owner told him that fresh HG fixed... well yes it was but who ever did the job put some non sc heads ...... :rolleyes: so they crack at the cylinders 3 & 6 and the crack were not small.... at least 3 inches long right above the valves on the same place on both heads .... so this was just the heads that weren't sc parts.....;)
 
one time a friend bough a sc that a month later start giving troubles.... when he got it the previous owner told him that fresh HG fixed... well yes it was but who ever did the job put some non sc heads ...... :rolleyes: so they crack at the cylinders 3 & 6 and the crack were not small.... at least 3 inches long right above the valves on the same place on both heads .... so this was just the heads that weren't sc parts.....;)

Bet they weren't 96+ NA heads.
 
Got the Police package 3.8 heads surfaced, they were high in the middle cylinders and he had to take .006 off to get them flat.

Chambers ended up being just a hair under 71cc.

My estimate is about 8.6:1 compression with the 96 N/A bottom end.

Guides are good, and valve seats should clean up with a little hand lapping.

I'm excited to see how this runs, a lot of people have speculated the D-shaped combustion chamber should be better for boost.

Jeramie
 
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Got the Police package 3.8 heads surfaced, they were high in the middle cylinders and he had to take .006 off to get them flat.

Chambers ended up being just a hair under 70cc.

My estimate is about 8.6:1 compression with the 96 N/A bottom end.

Guides are good, and valve seats should clean up with a little hand lapping.

I'm excited to see how this runs, a lot of people have speculated the D-shaped combustion chamber should be better for boost.

Jeramie

Sounds like a fun project, race it until that NA bottom end blows up! :)

Did you want a 94 SC block? I've got one for you :):p:rolleyes:
 
If anything the dinky pistons and powdered metal rods will fail before the block does, lol..

In all seriousness, I think it will be fine at the stock SC power level. Compression is lower with these heads and i'll be running a stock '95 SC pulley.

Jeramie
 
The heads alone don't dictate compression ratio... there is numerous things including the block deck height, the stroke and the piston dish that affects overall compression. You may be running a higher compression than you think which will lead to detonation.

Fraser
 
The heads alone don't dictate compression ratio... there is numerous things including the block deck height, the stroke and the piston dish that affects overall compression. You may be running a higher compression than you think which will lead to detonation.

Fraser

I know the forumla for calculating static compression ratio. But the missing piece to the puzzle is the piston dish cc of the 96 pistons.

I know that engine with 62cc (stock heart shaped combustion chambers) is 9:1, so with the bigger chambers it should be less than that. By how much exactly, I do not know. The 8.6:1 figure was a guesstimate.

Up here in Denver (over 1 mile high altitude) I welcome the higher compression. A stock SC up here is a mid 16 second car :( It takes a 5% pulley just to see stock sea level boost numbers.

I also changed out the '96 N/A cam for a stock '92 SC cam. Specs looked a little better.

Jeramie
 
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I know the forumla for calculating static compression ratio. But the missing piece to the puzzle is the piston dish cc of the 96 pistons.

Looks to me like it can't be more than 3cc-4cc. The stock SC dish is something like 17cc, I think.
 
success... finished the engine swap today. Remember the '94 is completely stock, with only the freshly rebuilt 96 bottom end, 92 sc cam, and police package 3.8L heads. No tune, full stock exhaust, big 94-95 pulley, paper filter with silencer removed.

She fired right up on the first try, and runs fantastic.

Butt dyno says it pulls stronger than my 92 5 speed SC, which has a '95 blower and 89 pulley and high flow exhaust.

part throttle torque is nice, probably due to the higher compression.. The car pulls really hard in the midrange.

I'll have to get it on the dyno and see how much it puts down. No pinging at all, despite the slightly higher compression.

Jeramie
 
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Well 6 months and 7,500 hard miles later the '96 N/A engine is still holding up just fine.

It is getting unusually good gas mileage too :confused:

I'm getting about 20 mpg with less than 25% highway driving :confused: About 340-350 miles per tank.

A little street test shows its about dead even with my GTP, which I know runs consistant 14.6 in the quarter mile. This is at high elevation, just doesn't seem like it should be that fast. The exhaust is completely stock, resonator and all even..

I think those open chamber heads are worth something. I gotta get it on a dyno soon. It pulls very hard in the 3,500-4,500 rpm range, for what little is done to it.

Just thought i'd update everyone.

I think a resonator delete is the next mod. Hopefully with the stock cats and stock mufflers it will still be quiet.

Jeramie
 
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Do you have any pictures of the ports on those heads?

There is an attachment on the first page post showing the chambers. Other than the D-shaped chamber, the ports and valve sizes are identical to the SC heads.

The D-shape chamber really unshrouds the valves, it measured in at 71cc, which lowers the N/A bottom end compression to about 8.6:1
 
So could these heads be used as a performance alternative to the stock sc heads, on a sc motor...

just worndering if there would be any bennifits to them.
 
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