Anybody hand-port their NPI heads?

DropTopPony

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lol

I always wanted those SVO heads but even when they went up for sale they got snatched up super fast.

Fox Lake is a great company, that is who ported my PI's.
 

OLD H2S

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I looked at the photo that 96BLAK54 put up dated 11-16 and could see the restriction he was talking about 1" down in the port, I could not get my first 2 fingers into it. I cut out the "tear drop" and turned the port more into a rectangle like the PI head shape. In this pic things are starting to get messy and I grabbed the camera before I was completely covered with chips, I can get both fingers down the port. Next I cleaned up the sides with a 1 1/2 long smoothing cutter. Someday I will pull off the heads and get to the bowl area and port these things to the moon. Now to find some GT roller followers and your cam suggestions and I will let you know how it feels. Your advice is welcome, flame on. And 96BLAK54 it's all your fault, thank you.
IMG_0448-D.jpg
 

DropTopPony

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If you screw them up no worries since another set can be had for next to nothing. Grind away!
 

96blak54

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You gotta get started somewhere! Just deem them heads junk with plans only to learn from. Its takes good practice to replicate 8 ports. Ill will say this though...these heads only need simple port work and a quench pad. Once you nail the ports with the head shown, pick up a set of F5 heads. They carry the thickest deck surface.
 

OLD H2S

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Are f5's the first for '96? For the top shape you can see the faint out line of the NPI gasket for a guide and the NPI gasket are huge, I could have gone much bigger to line the intake up. Flow is good but I think keeping the velocity as high as possible is the important thing. Flames, comments and suggestions are welcome... and cam choices.
 

OLD H2S

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This car MOVES now, positively squirrely in the rear end, WOO HOO. I can feel it run out of cam at 4600rpm+ What a difference, I can't thank you enough. The ports look rough in that pic but I measured the manifold runner size at 40mm wide and 46mm high, my ports are 42mm wide and 44 high, so I could go bigger to match things up better. Now the wife is kicking me in the ass for waiting 20 years to do this upgrade. The PI water pump nipple is leaking so I will tear it down again but with a smile on my face. Now I really need cam advice. THANK YOU!
 

lwarrior1016

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What are your plans for this car and what kind of cam are you wanting to get? The guys here will back me up when I say, the larger aftermarket cams will decrease your effective (dynamic) compression ratio. A good way to combat that is to increase static compression. You can do that fairly easily with a set of 4v pistons (Mark 8, Mach 1). Then your effective cam range gets a little bit bigger.
 

OLD H2S

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Well... That is a tough question. I would like to run this car At Summit Point more frequently, I did last weekend and it's weak points were showing. The last two cars I built from scratch, a 1969 Road Runner 440 and a Mercury Marauder 4v Terminator. Both cars were 4500 pounds and just over 500 BHP each, so I am used to big sleds that were not really good at road racing but fun to go 150 mph. Those two cars sucked up the last 20 years of time and money. This Mustang I bought new for the wife and have not done too much to over the years, just a Steeda stage 1 kit. Now she has a new car and the Mustang is a spare. It is 3400 pounds and 100 inch wheelbase with a V8, sounds like a BMW killer to me, parts are cheap and diverse which is a plus compared to the competition.
There were some other Mustangs there last weekend , all but one were dedicated track cars. The lone street car was 275 BHP and running in the advanced group and munching on 3 Porsche C3's. I have kept this car because it is so much fun to drive, you really have to work hard with only 170 BHP. I have had 2 Cobra motors so far, one was a Vortech and the other was an Eaton so I am over the need for speed.
I could do the Trick Flow heads but I like the NPI challenge, I have some used Manley H beam rods and a billet oil pump around, the stock cast crank is plenty good for a 300 HP build up, I am thinking of a stout, low HP, high RPM street car that I can beat on. Right now I am working on the brakes, handling and getting more seat time. This porting side job was just something to do while waiting for parts to come in, the valve seals are shot and it is burning oil bad so while I am in doing the seals I might as well do the cams and put in the good oil pump. My goal is to get the maintenance low so I don't have to jam between track days.
 

96blak54

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Back in the 2v days, the mustang mags did an apples to apples comparison with the npi and pi heads. Same compression ratio between the 2 heads, but both used pi intake and pi cams. Their was only a 10hp difference, the pi head being the better head.

Out of the box....untouched, the pi head is your best head. The npi head needs some love, but can be part of the competition and be competitive.
 

ttocs

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oh I see now after reading more closely. I thought that was a pic of what you had done. forgive me as I have been in the hospital again and I can't sleep here. Going on 40 hours of being awake and things are getting hazy now...
 

OLD H2S

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The ports are not as bad of a match when the gasket is on the head or looking at the manifold upside down with the gasket on it. Looking at the material left I can go bigger but do not have a long enough cutter, It will have to wait till I take the heads off to clean up the top side and do the bowl area. Do you think a set of PI cams will be OK ? Thanks for looking.
IMG_0455-D.jpg
 

96blak54

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Pi cams really help wake up the npi head. Actually the pi cams valve timing events are really close to a comp 262 (iirc). Although the 262 is an upgrade over the pi cam cause of lift values.

Take them heads off and deck the heads .080", reinstall, use the pi cams, pi intake. Do yourself a favor and dont port the bowls or anything under the valve seats. Port the valve guide boss out a little on the exhaust side
 

OLD H2S

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A big THANK YOU to you all for your advice. This morning I got everything back up and running, the idle is so smooth, no vibration in the engine, RPM sitting at 550. The wife came out and said "I have never heard it sound like that, that's better than new".
 

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