I like the Npi's for our blown trucks too, as they keep compression down with the stock piston dish if you are not doing a bottom end rebuild with a head swap.
I spoke to fox Lake last year, and they will sell P&P Npi's for a good price, and even furnish cores for cheap. I would give them a call.
Look at this thread on corraldotnet regarding Npi cam lift. http://www.corral.net/forums/showthread.php?t=829076

My last post is a link to Crower's low lift cams for the Pi heads.

 

Thanks for the link

I like finding new NPI info, but not a lot of folks put too much effort into getting performance from NPI heads. The few who have put some work into them have provided some eye-opening data.

I was thinking that PI heads/lower comp. pistons were in my future, but I don't think so any longer. At any rate, I'm not doing anything until this motor lets o, and I hope that won't happen for a very long time.

 

If you are going to rebuild an engine you might as well rebuild the whole engine. The extra dollars you spend now will save ten fold down the road. If you plan on adding a supercharger then you must tell the engine builder that you are planning on doing so. The correct selection of parts is critical to the life of the engine. You do not want to go to your local wrench unless he has built performance engines before. And be sure to ask if he/they has/have built the Ford Modular engines. If they say no kindly thank them and run away. The good shops will offer turnkey options. Bring in the old engine and leave with the built engine. You would fair well to ask on the Lightning forum where they get their engine work done. Ask around locally. If your town has a Mustang club they should know. If you are going for aftermarket heads don't waste your dollars on non Pi heads. A redone Pi head will outflow a non Pi head. You can find tons of Pi intake manifolds in a scrap yard. Once the new engine is installed you will need tuning to make it all work. The computer has to be reprogrammed to adjust for the new hardware. I would advise you to contact Mike Troyer the Superchips distributor. Here is his contact info: Troyer Performance/Performance Products, Inc.
Truck & SUV Performance Specialists
Supercharging & Custom Tuning Experts - America's Oldest Superchips Distributor & 1st Superchips Custom Tuning Dealer
Web Site: TroyerPerformance.com
(540) 965-7123
Location: Covington, Virginia
Email: Sales@TroyerPerformance.com
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ASK US about our INTERCOOLED POSITIVE DISPLACEMENT SUPERCHARGERS for your 2004 & up F-150!!


JMC

 

JMC- Mike Troyer told me that NPIs can out flow PIs.
Good idea to hook up with him. He speced and sold me my cams, along with lots of other parts and help, and tuning of course.

 

From the Modular link that I posted above:

Here's the flow numbers(averaged at the lift points)for the last 3 sets of NPI's that Renegade ported:

* Lift..............Intake................Exhaust
.100"--------- 67----------------62
.200"---------120----------------97
.300----------165---------------137
.400----------193---------------152
.500----------210---------------164
.600----------222---------------175

and from his last 3 or 4 sets of PI's(averaged again)

* Lift..............Intake................Exhaust
.100"--------- 64----------------52
.200"---------116----------------94
.300----------162---------------130
.400----------192---------------160
.500----------213---------------178
.600----------217---------------185

That link is a good read if you're interested in NPI vs. PI.
AS you can see, when both are ported they are close.

Everyone assumed PI was better than NPI, but no one put any effort into NPI heads so there was not data. Once someone put some effort into the NPI heads, look at the data, it's interesting.

The few NPI guys out there are getting good results, some as good as the PI guys. They are in that lengthy thread if you bother to read it

But stock for stock, PI kills NPI.

Note that NPI gives pretty much zero choice for intakes - you're stuck with the cr@ppy factory intake if I'm not mistaken. I think the PI gives you an option or two, including a performance 4.6 intake if you use spacers like the one from Reichard racing...thogh I haven't seen any data to see what intakes work best for the PI.

 

From the Fox Lake site: Fox Lake Stage 2 P.I. heads flow a whopping 223 cfm intake and
195 cfm exhaust @ .550" with Manley or Ferrea valves!

Patriot Performance site :
Stage III 1020 Superflow Bench 3.552 Bore

Lift1.84" Intake Valve 1.452" Exhaust Valve

.100 68 cfm 53 cfm
.200 121 cfm 100 cfm
.300 169 cfm 138 cfm
.400 203 cfm 165 cfm
.500 219 cfm 186 cfm
.550 223 cfm 196 cfm
.600 226 cfm 201 cfm

JMC

 

HI!... I have FOX LAKE STAGE II heads upgraded to stage III and they kill the ported NPI heads. Go P.I or go home.

 

All well and good. It's easy to make a claim but I also think its interesting to look at the data.
Johnny Langton was laughed at with his NPI post, until his NPI T-Bird started beating Mustangs.

Different flow benches are like different dynos, IMHO the only way to make a true comparison is on the same flow bench, especially when the margins are so slim...we're talking a few CFM one way or the other.

I've only seen one data set where both PI and NPI were flow-tested on the same flow bench, and they are close. If you've got some totally conflicting data and not just anectdotal evidence, I'd love to see it. Though the PI's do have a slight edge, it's not a huge gap.

The Patriot PI hads are killer for sure.
But I won't just toss aside the Renegade Racing PI & NPI data that they've logged. They have a good reputation for doing good work, as well as the data to make some form of comparison.

I don't think the debate will be solved here. While there are a few NPI guys making big power and posting good track times even relative to their PI counterparts, almost everyone runs PI these days. I've been in touch with a few of the fast NPI guys, and believe me there are very few of them But they make competitive power and post fast times. They are just hard to find.

Point being: there are always gonna be a few guys running different combos, getting good results, just to be different.

I'll be the odd duck with a blown Expy in search of power.

 

I already ordered the Allen kit for my specific application, which is a '97 4.6L, aka NPI. The way I understand it, the kit replaces the intake manifold completely. In my case it sounds like I'm stuck with porting my NPI heads. After following that other thread, I have no problem with that.

The company I was going to go with is Motor Works. If you check their website, they appear to be on top of their game, and they are local for me. Since I'm taking the time to rebuild, I do indeed intend to do it right. That's why I'm posting bazillions of questions here.

Here's my loose plan at this point:
#1- Rebuild with forged pistons, balance.
(Are there other considerations here?)
#2- Include ported NPI heads.
(Apparently I have some choices at this point. What kind of cam for instance? I also don't have a clue about the valves. What is low lift? What should be my concerns?)
#3- Install Allen Kit.
(I understand this should work without a tune. That is until I chose to upgrade other components in the fuel/air delivery system. Correct?)

Remember, this engine is for daily driving and towing, NOT racing. I'm hoping to get VERY many miles out of it. They should be fun miles though too.

 

The stock pistons will get valve contact with lift approaching .5x, but you are putting aftermarket forged pistons in. If they are dished, then you may be able to run higher lift cams.

I'd touch base with Johnny Langton at Modular Depot for your cam questions. He started that link I posted above, and is extremely friendly. He has a lot of good NPI insights.

Since you have what appears to be a good local builder, I'd work closely with them. Tell them exactly what you expect.

Renegade ports what most people think are the best NPI heads, but they are pricey. Steen Racing has a good reputation for them, you may want to give them a call.

 

Many thanks to all!

As soon as that Allen kit gets here, I'm off to the rebuilder!