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Topic: Question about SO 5.0 pistons. (Read 2448 times) previous topic - next topic

Question about SO 5.0 pistons.

Newbie here,Are the factory SO 5.0 flattop pistons forged or cast?

Question about SO 5.0 pistons.

Reply #1 –
Cast.....  Welcome
[SIGPIC][/SIGPIC]
***** Project "EVOLUTION" 1987 Cougar LS  & 1985 Cougar Convertible *****
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5.0 HO 306 roller block, machined GT-40P heads, Wiseco dished forged pistons, Eagle forged floating I-beam connecting rods, Lunati pushrods, ARP bolts, Scorpion aluminum 1.6 rockers, Comp Cams Magnum 266HR, Explorer intake, 65mm TB, MAF Conversion, 19# injectors, Ford Racing stainless P-headers, 2-1/2" cat-less exhaust w/ Flowtech Afterburner lers , SC AOD with 2800 BDR torque converter, 3.73 T-Lok rear, CHE rear control arms, full 2-1/2" frame w/1" jacking rails & seat supports, Rear disk brakes, Turbine wheels, All original interior w/ floor shift upgrade .......
Pretty much every panel on my 87 is new, rebuilt, or re constructed. :D
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Question about SO 5.0 pistons.

Reply #2 –
Welcome , what he said ^^^^^^
Fox-less at the moment

Question about SO 5.0 pistons.

Reply #3 –
Also, factory SO pistons are NOT flat-tops...they have a considerable dish.
Project 3G: Grandpa Grocery Getter-'85 Crown Vic LTD 2-door, 351W with heavily ported/polished GT40 heads, heavily ported/polished Typhoon Power Plus upper & lower intake, Comp Cams 265DEH retarded 1*, FAST EZ-EFI, HD T5, 8.8" 3.73 trac lock with extra clutches, 3G alt. swap, '99 CVPI front brakes, '09 CVPI rear disc brakes, '00 CVPI booster&m/c + wilwood adj prop valve.

Parted & Gone-'88 T-bird Sport, 351W swap, ported GT40 heads

Question about SO 5.0 pistons.

Reply #4 –
Thanks guys,i've come across a complete 88 T-bird 5.0 from a wreck with 28k miles for $250. It runs great,i just didn't know about the pistons and how much abuse they could handle. What's the compression with that dish with E7 heads? I've got a bunch of old stock mustang engine parts,STD HO pistons,cams,etc collecting dust and was just wantng to know what was the same or diffrent.Thanks for all the info again,Great site! keep it up!

Question about SO 5.0 pistons.

Reply #5 –
With that little mileage, I'd say leave the SO pistons in it for now.  With the E6's compression was around 8.7-8.8:1 but the E7's have a little smaller chamber.  Figure around 8.9-9.0:1 with E7's....unless you send them to the machine shop and take .030" off.  Then you should be close to 9.3-9.5:1 depending on head gasket.
Project 3G: Grandpa Grocery Getter-'85 Crown Vic LTD 2-door, 351W with heavily ported/polished GT40 heads, heavily ported/polished Typhoon Power Plus upper & lower intake, Comp Cams 265DEH retarded 1*, FAST EZ-EFI, HD T5, 8.8" 3.73 trac lock with extra clutches, 3G alt. swap, '99 CVPI front brakes, '09 CVPI rear disc brakes, '00 CVPI booster&m/c + wilwood adj prop valve.

Parted & Gone-'88 T-bird Sport, 351W swap, ported GT40 heads

Question about SO 5.0 pistons.

Reply #6 –
If you're going to run anything more than an HO cam, the SO pistons will NOT work...not sure about some of the alphabet cams, but the HO cam will work with SO pistons.

Also, as an option, you can have them fly-cut, but for the trouble and cost, HO pistons would be better, plus you already have 'em...
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

Question about SO 5.0 pistons.

Reply #7 –
Quote from: Sick88Tbird;332857
Also, factory SO pistons are NOT flat-tops...they have a considerable dish.

The dish is 2.5 cc.

Quote from: ThunderbirdSport302;333530
If you're going to run anything more than an HO cam, the SO pistons will NOT work...not sure about some of the alphabet cams, but the HO cam will work with SO pistons.

Depending on what heads are being utilized; this may not be true. 
You'll never know 100% for sure unless you measure PTV clearance.

Example: Trick Flows TW heads, flat tops, no valve reliefs, .565" lift and roughly 225 degrees duration @ .050" lift....  LOTS of clearance.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Question about SO 5.0 pistons.

Reply #8 –
Quote from: V8Demon;333548
The dish is 2.5 cc.


Quote from: ThunderbirdSport302;333530
If you're going to run anything more than an HO cam, the SO pistons will NOT work...not sure about some of the alphabet cams, but the HO cam will work with SO pistons.


Depending on what heads are being utilized; this may not be true. 
You'll never know 100% for sure unless you measure PTV clearance.

Example: Trick Flows TW heads, flat tops, no valve reliefs, .565" lift and roughly 225 degrees duration @ .050" lift....  LOTS of clearance.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Question about SO 5.0 pistons.

Reply #9 –
You should go to the CoolCats.net and read about the H.O. conversion it will probably answer a lot of your questions.

Question about SO 5.0 pistons.

Reply #10 –
Quote from: V8Demon;333548
The dish is 2.5 cc.



Depending on what heads are being utilized; this may not be true. 
You'll never know 100% for sure unless you measure PTV clearance.

Example: Trick Flows TW heads, flat tops, no valve reliefs, .565" lift and roughly 225 degrees duration @ .050" lift....  LOTS of clearance.....


Right, I forgot to put that in my other post...better to err on the side of caution any which way. :D
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

Question about SO 5.0 pistons.

Reply #11 –
i'm running a B303 cam with stock flattops and stock e6 heads so thats another one that clears...
Currently Birdless but never Foxless

86 Mustang GT

Question about SO 5.0 pistons.

Reply #12 –
The factory E6 heads have their valves recessed much further into the head than E7's or other factory Ford heads.
Project 3G: Grandpa Grocery Getter-'85 Crown Vic LTD 2-door, 351W with heavily ported/polished GT40 heads, heavily ported/polished Typhoon Power Plus upper & lower intake, Comp Cams 265DEH retarded 1*, FAST EZ-EFI, HD T5, 8.8" 3.73 trac lock with extra clutches, 3G alt. swap, '99 CVPI front brakes, '09 CVPI rear disc brakes, '00 CVPI booster&m/c + wilwood adj prop valve.

Parted & Gone-'88 T-bird Sport, 351W swap, ported GT40 heads

Question about SO 5.0 pistons.

Reply #13 –
A local machinist told me he prefers the e6 turbo swirl design chambers to the e7's. He basically said the e7's are junk and everyone gets too caught up with flow numbers of cylinder heads in general. If you know what to do, the e6's could be made to out perform the e7's in his opinion with the better combustion chamber design.
[SIGPIC][/SIGPIC]88 t-bird: 5.0ho, gt40y, crane 2031, fms 1.7, paxton@5#, aod wide ratio, tci stall, performer rpm upper, 70mm bbk, pro m 60, 42#s, 3.73 7.5" posi, jba shorties, borla, upr x. 13.4 @ 104mph. cbaza, moates, tuned by decipha

Question about SO 5.0 pistons.

Reply #14 –
Right, because E6's flow better and make more power than E7's is why Ford switched in 1987 on trucks, Stangs, and Mark VII's. :rolleyes:

Hey, if E6's are so darn good, I've got a set (or 3) I'll sell for an all time low price of just 79.99 each! :hick:


Somewhere online is a flow chart of E5, E6, E7 and later 5.0 heads....E6 actually do flow worse than any other 5.0 head made since '69 or so. Proven.


Of course, I see in your sig you have a paxton on yours, with a little air pressure i suspect there's not a hell of a lot of difference.

Take a stock '87-'93 HO, swap stock E6 heads on, dyno it, and get back to me. ;)

torque will be down (a lot), horsepower will be sucked out of the engine, and it won't make power over 3500-4500 max.

So I will kindly disagree with your machinist, in regards to stock E6 heads being superior to stock E7's.
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)