Help Help Help Need answers fast!

[Bluesn95]

I am looking at buying a 98 longblock with a blown head gasket for $200. I just bought a set of pi heads to go on the motor. The reason for this is because my current engine uses too much oil ( about a quart every 2 1/2 weeks). My question is do all 96-98 4.6s have flat top pistons. I know that mine does but a local machine shop says that not all of them do. I am wanting to just slap the heads on the 98 motor and bolt it in but if the 98 motor doesn't have the flat top pistons then I don't want it. I was thinking that someone would know if this 98 4.6 out of a vert gt has them.

 

[justinschmidt1]

..96-98 all have the same pistons

 

[Jrgunn5150]

All GT engines, PI or NPI have a dish.

 

[Bluesn95]

With the engine code on mine "x" it shows to have flat top pistons. I haven't found anyone with this engine code yet.

 

[Jrgunn5150]

They ALL have a dish, regardless of year, PI, NPI, or engine code. They all have an X in the vin...

 

[Bluesn95]

All of my buddies cars have W for engine code

 

[Jrgunn5150]

I've only seen X's, anyway, W and X, both just mean, SOHC 4.6. They all have a dish, a flat top piston would give you a 12.5:1 c/r with an NPI head's bigger chamber.

Look up replacements, they almost all have a dish. At any rate, you are talking about a ten year old motor running junk rods an pistons regardless, if it's out, why not hone it and slap some decent stuff in there, are you in some kind of hurry.

 

[Bluesn95]

Well this engine is for sale online and he's only about an hour away from me. I need to do this swap at the end of april. This motor is going to sell fast and Iwant to know if I should buy it.

 

[Jrgunn5150]

I have no idea if you should buy it, but it's same as any other NPI motor, and all 2v motors have a dish in the piston,

http://www.musclemustangfastfords.com/tech/0302mmff_mixmatch/index.html

 

[Bluesn95]

I wanted to buy it to minimize the amount of time the motor was out of the car. But for some reason I had the idea that the 98 engines were a little different and that's y I asked if I should buy it.

 

[Jrgunn5150]

Once you are down to the longblock, they are the same. The head's may or may not be slightly better, huge debate, at any rate, you are yanking them in favor of PI like you should, so it doesn't matter.

 

[Bluesn95]

So should I just slap the heads on the 98 motor or tear it apart and do 30 over and install new pistons and rings? Im in college so I don't have tons of money but I don't want it to blow up on me.

 

[Jrgunn5150]

If the shortblock is in good condition, you can go ahead with sticking PI heads on it.

BUT, even if it takes longer, I would prefer to see you do some forged rods, .020 over pistons, and rings. And you can get less of a dish, get the compression up to around 11.5:1 and you'll have a grin everytime it fires, and have the added bonus of knowing whats in there.

 

[Bluesn95]

Isn't 11.5 to 1 getting in race gas territory ?

 

[blackgt4.6]

Isn't 11.5 to 1 getting in race gas territory ?

Yes it is getting close.

 

[Bluesn95]

yeah this is my daily driver and I'm in school on a budget don't need to be running race gas yet

 

[MustangMatt96GT]

11.5:1 can be run on 91 octane just fine... Race gas would allow for a more agreesive tune but thats about it.

 

[Jrgunn5150]

Isn't 11.5 to 1 getting in race gas territory ?

No, it's factory compression on alot of car's now.

 

[voidfinger]

lol the b16 vtec engine has like a 12.5:1 CR haha

Anyway, my dad's old 5.0 efi has like 13:1 cr and runs fine on 93

You just have to have the car tuned to keep it right. Also while there get a tune for race gas too since you might take it to the track and slap some 100 in there.