Truth about NPI vs PI

[Todd in KS]

Thanks for finding that. Has anyone done any performance comparisons? That looks like a nice intake. I have a friend at work who is a panther platform guy and we were discussing intakes the other day. He was saying the performance goes "old"PI, "new"PI (the new ones are a little different?), and NPI. He has an Edelbrock on his motor but wouldn't recommend it for a daily without 4.11s

 

[96blak54]

And he is right about the edelbrock. Its an rpm intake. The new pi versions dont perform like the old pi, but it is an intake option.

 

[Todd in KS]

He building a beast of a Vic. The motor has a bigger TB and MAF, long tubes, cat delete, cams, 5spd, big brakes, etc.

 

[Fawls]

I had to use the search bar on the Speedmaster website. I typed 4.6l and searched

Ford 4.6L EFI 1999-04 Mustang MidRise Intake Manifold Satin

SpecsBrand:SpeedmasterPart Number:1-148-020-01Part Type:Intake Manifold, Fuel InjectedProduct Line:MidRiseEngine Block Style:Stock/OEM standard deckInjection Style:Multi-portBasic Operating RPM Range:1,500-6,500Intake Section Included:CompleteEGR:YesInjectors Included:NoFuel Rails...

www.speedmaster79.com

View attachment 47350

Well done, thanks for the link.
If I ever need to replace my manifold this will be top of my list.

 

[ctandc]

Aluminum crossovers did NOT come on the 99 and most 2000. You are in luck tho because there are still some used factory manifolds out there! The factory pi manifolds are the best performers with an otherwise stock/bolt ons engine and can be sourced from crown vics, marquese, and town cars after 2003. Your plastic crossover manifold will crack eventually. Its a good idea to have a replacement on hand even if you dont want to change out the manifold just yet. Ford is now offering a new style pi replacement, but it doesnt perform like the original. Speedmaster company is offering an all aluminum manifold, no plastic. Should out last the car! It can be scored new for $500

The problem also applies to the later redesigned PI intakes as well. They will all eventually fail - it's where the plastic meets the cylinder head underneath the alum coolant crossover. Age / miles and heat cycles. Last Summer I hit up several local junkyards and a friend and I pulled intakes from 4 or 5 later model Ford/Merc/Lincoln 4.6 PI engines and all of them had signs of coolant leakage / cracking at the plastic.

Just replaced the intake in my '04 GT because of a very slight loss of coolant, only under pressure. Took a pressure tester to find it was leaking just enough to cook off coolant under the alum crossover. I ended up going with the Summit replacement intake. It's IDENTICAL to the Ford replacement intake. The only difference is one has FOMOCO molded in the plastic the other has Summit. The instruction sheet and hardware are IDENTICAL. $340 vs $199. If I hadn't of found the Summit I was leaning Speedmaster, but I have heard some concerns with how bad the casting flash is on the Speedmaster, whether that's the case or not I don't know.

The newer PI intake does lose some power over the original - but my 04 is a NA 2V and my daily for now - and I highly doubt anyone could tell any difference driving the car.

The problem area for the old redesigned PI intake:





The new version - it's definitely not a Dorman copy - I forgot to get pics.





The Speedmaster would have definitely been in the running if I was dropping $340+ for the Ford version. I didn't look a bunch, but I ran across a lot of "out of stock" messages when looking initially at the Speedmaster intake FWIW.

 

[Fawls]

Great find.

 

[ctandc]

The original issue with the 4.6 intake was the all plastic coolant crossover.
The "Solution" was for Ford to have one of it's suppliers modify the front of the intake to accept a bolted on aluminum coolant crossover.

Problem solved. Right?

Well you've still got plastic in direct contact with coolant and now in contact with metal on both sides. Add in age and heat cycles. Ever had a 4.6 with a hint of sweet coolant smell when it's at operating temp, but no visible coolant leaks?



This is very common with the later PI intake. So for those who want to get a 'good condition' used intake? Good luck. This engine had less than 100K on it. Age and heat cycles.

 

[96blak54]

Great write up! Good job with the comparison!

Yeah, sure the new intake design doesnt deliver the performance like the original did, but truth be told most new vehicles today outrun and out perform these mustangs. Im with you though, no reason to pursue king of the street status with a stock 2v 4.6l......just drive it and enjoy the ride.

 

[ttocs]

I totally understand the idea behind the heat transfer for intake temps being better with a plastic intake vs the old aluminum yet the lack of its ability to last has always made me shake my head.

 

[07GtS197]

I had a typhoon intake on my old 02 gt and I have the Speedmaster intake on my current 01 gt. Even with stock gearing it definitely feels like it pulls harder than stock and the intake really comes alive over 3k rpm’s. Even if I needed another intake, I don’t think I’d pick any other intake due to the material. I’m sure this metal intake probably doesn’t perform that much better than an original pi intake but being metal I know it isn’t going to fail like the stocker.

 

[ctandc]

I totally understand the idea behind the heat transfer for intake temps being better with a plastic intake vs the old aluminum yet the lack of its ability to last has always made me shake my head.

It's more an issue, in my opinion, of the engine / intake manifold design, rather than the limitations of of the plastic intake manifold itself. Look at all the high mile LS based GM engines around the world. I've owned multiple that were 200K plus. My current truck has a 4.8 with over 250K. Untouched except for plugs and wires (and those went almost 200K) with zero issues with the intake. I had a LS engine in a project car that was beat on like it stole something from me, including tons of 1/4 rips, and it ran a plastic intake with zero issues.

 

[ctandc]

I had a typhoon intake on my old 02 gt and I have the Speedmaster intake on my current 01 gt. Even with stock gearing it definitely feels like it pulls harder than stock and the intake really comes alive over 3k rpm’s. Even if I needed another intake, I don’t think I’d pick any other intake due to the material. I’m sure this metal intake probably doesn’t perform that much better than an original pi intake but being metal I know it isn’t going to fail like the stocker.

Fair point. I just wanted other folks to know that the new Ford 'service part' and the Summit intake do not have the same failure point as the previous versions.