Limits of cast pistons in T-bird 5.0

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Limits of cast pistons in T-bird 5.0

September 28, 2015, 01:06:24 PM

Hey all,

I recently found a good deal on an '88 t-bird LX with a 5.0 and a t-5 swap on my local craigslist.

For the time being, I wouldn't plan on doing much in the way of modification, but In the future I'd like to do some mild modification with a new set of heads and cams.

Upon doing some research, I found out that the T-bird 5.0's have cast flat-top pistons compared to forged pistons with valve cutouts on fox body mustangs.

Apparently there are some head/cam combinations that can work without worrying about valves contacting the pistons, but I'm curious as to what the power/torque limits of the stock pistons are?

I'm not really interested in doing any bottom end modifications, or going extreme with the power, but would 300rwhp be obtainable without worrying about damaging the piston heads?

Also, secondary question, is there any way to tell, externally, whether the short block is an HO or SO version without removing the heads and looking at the piston faces?

Limits of cast pistons in T-bird 5.0

Reply #1 – September 28, 2015, 01:53:54 PM

HO and SO have different firing orders, you could use your plug wires to determine.

Limits of cast pistons in T-bird 5.0

Reply #2 – September 28, 2015, 02:19:17 PM

If it's the stock block it more than likely has cast flat tops. Firing order won't tell you much as someone could have swapped in a different cam over the years.

To answer your question yes the cast factory pistons can support 300 wheel horsepower fine. What usually kills them is nitrous or boost.

Limits of cast pistons in T-bird 5.0

Reply #3 – September 28, 2015, 03:57:34 PM

Quote from: thunderjet302;451430

If it's the stock block it more than likely has cast flat tops. Firing order won't tell you much as someone could have swapped in a different cam over the years.

To answer your question yes the cast factory pistons can support 300 wheel horsepower fine. What usually kills them is improperly tuned nitrous or boost.

Fixed.

Limits of cast pistons in T-bird 5.0

Reply #4 – September 28, 2015, 04:24:22 PM

Also, Did the LX trim level ever come with the 5.0?

The poster claims it's an LX, but Wikipedia says that the LX has the v6, and the Sport had the 5.0

Limits of cast pistons in T-bird 5.0

Reply #5 – September 28, 2015, 09:00:46 PM

Yes, you could get an LX with a 5.0.

cheers
Ed

Limits of cast pistons in T-bird 5.0

Reply #6 – September 29, 2015, 01:10:52 AM

Quote from: magnanimous;451422

Also, secondary question, is there any way to tell, externally, whether the short block is an HO or SO version without removing the heads and looking at the piston faces?

The heads. An HO will have E7 heads, unless they've been swapped for GT40 or aftermarkets.

The upper intake...remove the plaque, there should be an "HO" that's part of the casting.

However, all this stuff is more cosmetic than anything and won't guarantee you're engine is an HO, or rather, disprove it as being the SO. The one true indicator of that is the firing order. Refer to post #2 for a good diagram.

As for the pistons, compared to what else you'd need for 300 HP, they're the least of your worries. Unless you plan to throw a 150 shot on it, then of course the pistons and fuel system will definitely be the weak link.

Limits of cast pistons in T-bird 5.0

Reply #7 – September 29, 2015, 03:03:54 PM

Quote from: jandmmustangs;451433

Fixed.

Yeah left out that part :hick:. With a proper tune it should work.

Limits of cast pistons in T-bird 5.0

Reply #8 – September 30, 2015, 09:28:36 AM

Either way, I'm not particularly interested in nitrous or forced induction, just maybe a decent set of heads, headers and cams to bring it up to a decent amount of street-friendly power.

But alas, apparently the bike I offered in trade wasn't big enough for the T-bird owner, so it looks like my search for four-wheeled transportation is still under way.

Limits of cast pistons in T-bird 5.0

Reply #9 – September 30, 2015, 11:05:49 PM

Quote from: magnanimous;451492

Either way, I'm not particularly interested in nitrous or forced induction, just maybe a decent set of heads, headers and cams to bring it up to a decent amount of street-friendly power.

But alas, apparently the bike I offered in trade wasn't big enough for the T-bird owner, so it looks like my search for four-wheeled transportation is still under way.

The E6 SO heads use the long reach plugs, E7 HO are std reach... Note '86 HO also used the E6 heads, but those pistons are forged and are perfectly flat(give 9.2 comp ratio, SO are 9.0), all the SO I've seen have a slight dish...

So much about nothing is made over the cast pistons, as mentioned unless you're boostin' or sprayin' they are fine...

Limits of cast pistons in T-bird 5.0

Reply #10 – October 06, 2015, 12:24:27 AM

I used to drag race with cast pistons and a 10.25:1 comp ratio, they are very forgiving in a n/a combo that is tuned properly even at elevated RPM.