96-98 stock pistons, are they really that bad

slow98 · 03-30-2002, 05:14 PM

I was just wondering if the stock pistons in the 96-98 gts are as bad as everyone says, i know hammer has got alot of power on his but is this reliable? and what is the expect life of one of these engines modded like that,Ive also heard of people cracking them with a 75 shot, before i take my modding any farther i just want to know if there is gonna be a bad risk of blowing the motor and having to fork out a fortune to rebuild it,any suggestions/coments about this matter?

THANKS GUYS

esandes · 03-30-2002, 07:31 PM

The stock pistons are supposedly good for up to 400-450 HP. They are fine for naturally aspirated engines but if you go with boost or nitrous they can be the weak point in your engine. I'd hate to tell you that they would be ok for a 75 shot and then your engine goes so it's really a matter of piece of mind.

I have a 98 GT which I will mod to over 300 HP naturally aspirated and I won't get new pistons. With a 75 shot on a pretty stock GT your pistons should be ok. Forged piston upgrades are standard for blown cars to lower compression (dished pistons) and to make sure the new pistons don't go.

03-31-2002, 12:23 PM

So say that you are going to put a 8psi blower on your stang. Would I need to put new pistons in my car. And if so how much do new pistons go for ?

Also what if you are putting that 8psi blower on a set of PI heads that have been ported out , what kind of problems would I have then ?

Unit 5302 · 03-31-2002, 01:54 PM

stock 97GT, stock pistons, 99PI heads, and 8spi Supercharger = new engine.

esandes · 03-31-2002, 04:19 PM

When going to a blower it is best to get the heads and intake ported and also get forged dished pistons. The 99+ heads have a higher compression ratio than previous stangs so porting them a bit will help bring the compression down to make for a blower friendly engine. The dished pistons do wonders with a blower by lowering compression again by adding the extra cc's.

It's just a good idea to get stronger forged pistons when you get near 400 HP. I don't know how much 8 psi will get you for HP but I bet further down the road you'll tweak with the boost (more) and then you'll need new pistons anyways.

To make the most of a blown stang you really need some new cams too, x-pipes and cat back, long tube headers and a custom dyno tuned chip.

Unit 5302 · 03-31-2002, 08:11 PM

Porting isn't going to do anything for CR. You'll be sitting at 10.3-10.9:1 depending on how good the heads are cast from the factory. All porting does is change the intake and exhaust ports, not change the combustion chamber size.

Forged pistons with a 17cc dish, like the 99+ will give you a good CR to work with for a blower car.

If you stick a blower on with the stock pistons, you could have one cylinder sitting at nearly 11:1 CR and 8psi on top of that. With cast pistons, you're either going to lose the head gasket, or you're gonna lose a piston.

Hammer · 04-01-2002, 03:07 PM

Hammer says "Thank You God" for Ford Motorsport Heads and reasonable compression...

slow98 · 04-02-2002, 05:13 PM

so if you have the motorsports heads and they make the right compression ratio then they are made for the flat top 96-98 pistons right?but will the 96-98 intake fit or does the 99 up intake fit it, or do you have to get and aftermarket intake to go along with the heads? and about how much does it cost to swap with these rather than the pi heads

esandes · 04-02-2002, 05:20 PM

That's right...Motorsport heads give less compression than the 99+ heads. You require the motorsport intake for the motorsport heads or you can get the bullitt intake and just get the ports matched (some porting work there). The bullitt intake is almost half as much as the motorsport intake. The motorsport heads are around $900 (USD) each and the intake is over $2000 (USD) with the install kit too.

There is a big debate over which heads are better: the SVO vs. the 99+. Without any porting work, the SVO heads are the better ones, but with porting on each...it's hard to say. I personally think the SVO heads are the best 4.6 2V heads you can buy...what other heads bolt on more HP out of the box and without any custom work? None.

My 2 cents.

03-30-2002, 05:14 PM	#1
slow98 Registered Member Join Date: Apr 2001 Location: draper,va,us Posts: 206	96-98 stock pistons, are they really that bad I was just wondering if the stock pistons in the 96-98 gts are as bad as everyone says, i know hammer has got alot of power on his but is this reliable? and what is the expect life of one of these engines modded like that,Ive also heard of people cracking them with a 75 shot, before i take my modding any farther i just want to know if there is gonna be a bad risk of blowing the motor and having to fork out a fortune to rebuild it,any suggestions/coments about this matter? THANKS GUYS __________________ 1998 mustang gt/manual..373s,bbk offroad h pipe,flowmaster cat back,c&l 80 mm maf,steeda triax,eibach springs,steeda ud pulleys,upr timing adjuster,screamon demos coil packs,motorsports 9mm plug wires,steea aluminum lca's,steeda heavy duty uca's and just over 100 k on the clock

03-31-2002, 12:23 PM	#3
southernstang97 Guest Posts: n/a	how much do new pistons cost ? So say that you are going to put a 8psi blower on your stang. Would I need to put new pistons in my car. And if so how much do new pistons go for ? Also what if you are putting that 8psi blower on a set of PI heads that have been ported out , what kind of problems would I have then ?

04-01-2002, 03:07 PM	#7
Hammer AKA "Dr. Evil" Join Date: Feb 1999 Location: South Fork Ranch Posts: 1,721	Hammer says "Thank You God" for Ford Motorsport Heads and reasonable compression... __________________ Uncle Sam "What the hell is up with all the gauges? Calling Captain Kirk, your ride awaits... Phasers on stun...."

04-02-2002, 05:13 PM	#8
slow98 Registered Member Join Date: Apr 2001 Location: draper,va,us Posts: 206	motorsports heads so if you have the motorsports heads and they make the right compression ratio then they are made for the flat top 96-98 pistons right?but will the 96-98 intake fit or does the 99 up intake fit it, or do you have to get and aftermarket intake to go along with the heads? and about how much does it cost to swap with these rather than the pi heads __________________ 1998 mustang gt/manual..373s,bbk offroad h pipe,flowmaster cat back,c&l 80 mm maf,steeda triax,eibach springs,steeda ud pulleys,upr timing adjuster,screamon demos coil packs,motorsports 9mm plug wires,steea aluminum lca's,steeda heavy duty uca's and just over 100 k on the clock

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03-30-2002, 07:31 PM	#2
esandes Registered Member Join Date: Mar 2002 Posts: 72	The stock pistons are supposedly good for up to 400-450 HP. They are fine for naturally aspirated engines but if you go with boost or nitrous they can be the weak point in your engine. I'd hate to tell you that they would be ok for a 75 shot and then your engine goes so it's really a matter of piece of mind. I have a 98 GT which I will mod to over 300 HP naturally aspirated and I won't get new pistons. With a 75 shot on a pretty stock GT your pistons should be ok. Forged piston upgrades are standard for blown cars to lower compression (dished pistons) and to make sure the new pistons don't go.

03-31-2002, 01:54 PM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	stock 97GT, stock pistons, 99PI heads, and 8spi Supercharger = new engine.

03-31-2002, 04:19 PM	#5
esandes Registered Member Join Date: Mar 2002 Posts: 72	When going to a blower it is best to get the heads and intake ported and also get forged dished pistons. The 99+ heads have a higher compression ratio than previous stangs so porting them a bit will help bring the compression down to make for a blower friendly engine. The dished pistons do wonders with a blower by lowering compression again by adding the extra cc's. It's just a good idea to get stronger forged pistons when you get near 400 HP. I don't know how much 8 psi will get you for HP but I bet further down the road you'll tweak with the boost (more) and then you'll need new pistons anyways. To make the most of a blown stang you really need some new cams too, x-pipes and cat back, long tube headers and a custom dyno tuned chip.

03-31-2002, 08:11 PM	#6
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Porting isn't going to do anything for CR. You'll be sitting at 10.3-10.9:1 depending on how good the heads are cast from the factory. All porting does is change the intake and exhaust ports, not change the combustion chamber size. Forged pistons with a 17cc dish, like the 99+ will give you a good CR to work with for a blower car. If you stick a blower on with the stock pistons, you could have one cylinder sitting at nearly 11:1 CR and 8psi on top of that. With cast pistons, you're either going to lose the head gasket, or you're gonna lose a piston.

04-02-2002, 05:20 PM	#9
esandes Registered Member Join Date: Mar 2002 Posts: 72	That's right...Motorsport heads give less compression than the 99+ heads. You require the motorsport intake for the motorsport heads or you can get the bullitt intake and just get the ports matched (some porting work there). The bullitt intake is almost half as much as the motorsport intake. The motorsport heads are around $900 (USD) each and the intake is over $2000 (USD) with the install kit too. There is a big debate over which heads are better: the SVO vs. the 99+. Without any porting work, the SVO heads are the better ones, but with porting on each...it's hard to say. I personally think the SVO heads are the best 4.6 2V heads you can buy...what other heads bolt on more HP out of the box and without any custom work? None. My 2 cents.