limit on non-PI heads?

Teen'93stang5.0

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Jan 12, 2004

#1

• Jan 12, 2004

• #1

whats the roof on the non-pi heads? ive heard some say its as low as 210hp, and some say 275........what is it?

 

asthmaticZeater

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Feb 6, 2003

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Jan 12, 2004

#2

• Jan 12, 2004

• #2

http://forums.modulardepot.com/showthread.php?s=&threadid=2634&highlight=npi

long read, but well worth it. decide for yoruself.

 

R

Rio96

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Sep 11, 2003

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Jan 13, 2004

#3

• Jan 13, 2004

• #3

Keep in mind that the intake manifold's small runners,
restrictive muffler, low camshaft duration, and
dubious ignition timing, also affect performance of the 96-98 era GTs.
My suspicion is that Ford made choices that were knowingly less than optimum,
so that 99-up years could be 'improved'.

 

asthmaticZeater

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Jan 13, 2004

#4

• Jan 13, 2004

• #4

not too mention that alot of the NPI cars came with 2.73 rearend gears. which kill alot of potential.

especially on a no low end power engine such as the 4.6

 

LI98GTStang

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Jan 13, 2004

#5

• Jan 13, 2004

• #5

asthmaticZeater said:

http://forums.modulardepot.com/showthread.php?s=&threadid=2634&highlight=npi

long read, but well worth it. decide for yoruself.

Click to expand...

That link is very interesting to us 96-98 guys, so another recommendation here.

You don't say with or without porting or staying N/A or not either. Those would make a huge difference in the ceiling on the NPI heads. Well I'm at 218 SAE rwhp on stock NPI heads right now and feel there is more to go before the engine/heads has reached it's limits. With LTs, Off road X, P&Pd, VT or Comp Cams, lower and upper intake, Chip/tune I would say the limit at the upper level of your number range. It only takes money.

 

Teen'93stang5.0

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Jan 14, 2004

#6

• Jan 14, 2004

• #6

hmmm, its staying N/A, but i want to max out the heads before i do the swap.....but i need to know what that is N/A, untoutched heads and runners, so i can decide what i need to do

 

asthmaticZeater

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Jan 14, 2004

#7

• Jan 14, 2004

• #7

no one knows. thats why i said for you to read that thread and come to your own conclusion. everyone does the PI swap and hasnt really tried anything NPI.

 

D

david l gary

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Jan 14, 2004

#8

• Jan 14, 2004

• #8

Power from non PI heads


I have 211 hp and 291 tq on non-pi heads. Most every bolt on. More power is on tap. Have not touched the long block. Our intakes are the biggest choke point. Install the PI cams and valves. I was looking at maybe putting the PI intake on a non pi car. I know it would have a large port miss match but it might help. Any one else have any other ideas?

 

asthmaticZeater

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Jan 14, 2004

#9

• Jan 14, 2004

• #9

im doin a PI intake swap on my nPI headed car. i already have PI cams and some boltons. im taking my heads off though for a port match to the PI intake, just because i can do the labor myself, and know a local guy who will do the portmatch for me for a lil bit of nothing. im hoping to get a before and after dyno on it also. this will all be taking place over the next few weeks so keep an eye out for the results beginning of feb sometimes.

one of the tbird guys just dynoed his NPI headed car at like 302rwhp or so. had to take it to SAE numbers to break the 300rwhp mark, but still, he did it. not to mention it was done through an auto tranny and IRS. you can search MD for more info on that too.

 

Teen'93stang5.0

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#10

• Jan 14, 2004

• #10

david l gary said:

I have 211 hp and 291 tq on non-pi heads. Most every bolt on. More power is on tap. Have not touched the long block. Our intakes are the biggest choke point. Install the PI cams and valves. I was looking at maybe putting the PI intake on a non pi car. I know it would have a large port miss match but it might help. Any one else have any other ideas?

Click to expand...

i didnt know that they even matched up, i thought you could ONLY use the PI on the PI and nPI on nPI

 

asthmaticZeater

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Jan 14, 2004

#11

• Jan 14, 2004

• #11

they will only fit on their respective heads. without modification.

on the one dyno ive seen of this before, they used epoxy to shape the exit of the PI intake to the shape of the NPI ports.

the way im doing it is reversed. im getting the heads portmatched to the PI inake.

if you do one of those 2 things the intake will fit no problems.

also, a heads up. livernois is working on a PI intake right now. and where the ports meet the heads, theyve machined the plastic intake down, and made an adapter that puts the runners back to stock length, but has a trasition to the shape of the NPI ports.

 

T

tangerine

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Jan 14, 2004

#12

• Jan 14, 2004

• #12

I was fixin to have a spare set of npi heads port and polished and I was going to do the same thing with the intake. I have always heard that a npi head when ported to the max and pi heads ported to the max that the NPI heads flow more cfm than the PI heads. I am going to do it because not many people do it because they have always been fad that if you bolt on a set of PI heads then you will gain more power than you ever will off of non PI heads. on the 96-98's there is a lot of restrictions besides the heads also. like the exhaust for one example. some big company needs to do a big comparison in all aspects and put it mm&ff or 5.0 mustang. I am going to try it. if it really sucks then I am not going to be worried about it because it is just money it is made to spend.

 

LI98GTStang

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Jan 15, 2004

#13

• Jan 15, 2004

• #13

asthmaticZeater said:

they will only fit on their respective heads. without modification.

on the one dyno ive seen of this before, they used epoxy to shape the exit of the PI intake to the shape of the NPI ports.

the way im doing it is reversed. im getting the heads portmatched to the PI inake.

if you do one of those 2 things the intake will fit no problems.

also, a heads up. livernois is working on a PI intake right now. and where the ports meet the heads, theyve machined the plastic intake down, and made an adapter that puts the runners back to stock length, but has a trasition to the shape of the NPI ports.

Click to expand...

Did you hear any release dates on that adapter plate or any guinnea pigs going to be needed to make sure the kit works? My PI cammed NPI head desperately needs to breathe better up top.

Also are they doing the port match while the heads are on the car somehow or are the heads coming off. If that's the case, why not just get the PI heads and save on the labor costs. I know it would be interesting to know, but you already know what the stock PI heads are going to get you.

 

asthmaticZeater

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Jan 15, 2004

#14

• Jan 15, 2004

• #14

nope, the last i heard about it was in a thread on MD and a livernois rep said soemthing like they should be ready in a few months, and they had just done their first dyno. havent heard anything else.

im removing the heads for the port match. labor is no big deal, i can do it myself. im actually looking forward to taking my heads off again. im not going to PI heads cause i have no plans to stay 2v any longer than this year. thats a large chunk for something im gonna sell next winter. so im just gonna duke it out for the NPI guys till then.

total, PI intake, head gaskets, headbolts, etc. this swap is costing me total $200. i found a great deal on a PI intake and some other stuff on ebay. i get the port match job done for $30 by a local guy i know who does that kinda stuff. i figure a lil over $200 for what im hoping will be a 15rwhp gain isnt bad. the dynos will prove for sure what i gain. and from the looks of it, it should make my car a lot more livable with for the next year.