Multiple quetions about gears and PI

Black97GT

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First: I would like to change my gears..they are stock now but I do use my car for a lot of highway driving to and from school to home. 200 miles or so each way, I get about 25 mpg right now. At about 75mph my rpms are at 1900. How much would say 3.73's or 4.10's hurt the gas mileage and would it be worth it to go for the 3.73's over the stock ones.

Second: I have been reading a lot about the different combinations of PI heads cams and intake manifold. Some of the PI intakes that I see say I need PI heads in order to bolt it on. Then when I read the NPI vs PI thread it did not sound like that was the case. Also how hard is it to do each one of these swaps and is there a certain order that is reccomended to do it in? Heads then cams then intake or something along those lines? I was kind of hoping for a difficulty rating for swapping NPI to PI. What is the hardest (heads, cams or intake)? What is the easiest?

If anything is unclear just lemme know and I will try to clarify. Thanks ahead of time, If there are any threads you found useful feel free to post them. I have read most all on this site but others could be helpful.
 

DropTopPony

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Don't fear the gear! 3.73 will improve performance and not be a drastic drop in MPG....
PI swap is an improvement no matter what of the 3 parts you choose to buy.
If your gonna use your car as a daily driver and never supercharge it i'd do the full PI swap. It will give you a solid 45+rwhp gain and put a smile on your face. Its a weekend job with a buddy and there are a few step by step write ups to help.
 

Lightning Struck

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DropTopPony said:
Don't fear the gear! 3.73 will improve performance and not be a drastic drop in MPG....
PI swap is an improvement no matter what of the 3 parts you choose to buy.
If your gonna use your car as a daily driver and never supercharge it i'd do the full PI swap. It will give you a solid 45+rwhp gain and put a smile on your face. Its a weekend job with a buddy and there are a few step by step write ups to help.

+1
 

97GTS

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is ur car auto or manual?! either way go 4.10's esp. if you planning PI swap down the road. but if a positive displacement blower is in the future then forget the 4.10's but they would be ok with a centrifugal
 

Black97GT

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its a 5 spd and I am not planning on s/c right now...cant really afford it, heh its a stretch with PI stuff as it is :(
 

97GTS

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well good thing about PI swap is that parts can be had for pretty cheap nowadays
 

97vertstang

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3.73s at least but i would recommend 4.10s.i wish my car had 4.10s
 

281powered

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as for the gears i find my 3:90's to be a good comprimise between the 3:73 and 4:10s. i drive on the hwy all the time and it's no problem with gas milage, and they will put a smile on your face when you punch it ;D i've got the pi cams and intake with the npi heads and it works fine. the heads is the biggest job to do with very minumal gains. so if your planning stayin n/a then you don't need th pi heads imo. but if you wanna go crazy with your motor modding get them, or just get aftermarket ones, put you'll pay out of the ass for them :D
 

ALITL8

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mines a daily driver with 3.90's too but it doesnt see near the miles to and from that you do... its a blast to drive though ;D

id get a POS, gas saver for your commuting and use the money you save at the pump to build your stang ;)

hey, thats not a bad idea ???
 

Outlaw97GT

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281powered said:
as for the gears i find my 3:90's to be a good comprimise between the 3:73 and 4:10s. i drive on the hwy all the time and it's no problem with gas milage, and they will put a smile on your face when you punch it ;D i've got the pi cams and intake with the npi heads and it works fine. the heads is the biggest job to do with very minumal gains. so if your planning stayin n/a then you don't need th pi heads imo. but if you wanna go crazy with your motor modding get them, or just get aftermarket ones, put you'll pay out of the ass for them :D

I agree, The PI "heads" are just not worth it price wise. You can do just the PI cams and intake and only be around 10hp less the the whole head swap. And that HP is due to the compression jump.
Or for about the same price as a PI head-swap you could do comp 268H's and a PI intake and be about 15-20HP over the whole head-swap and have stock compression.

As for the gears, I love my 4.10's with my auto. Take-off is awesome and isnt bad on the highway. At 70mph Im @ 2600.
I do plan on a FRPP roots supercharger in the future so I will be going to either 3.55's or 3.73's when that happens.

But nothing like that is going to happen soon for me, atleast not till my wife is done with here cancer treatments. :-\
 

DropTopPony

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Outlaw97GT said:
281powered said:
as for the gears i find my 3:90's to be a good comprimise between the 3:73 and 4:10s. i drive on the hwy all the time and it's no problem with gas milage, and they will put a smile on your face when you punch it ;D i've got the pi cams and intake with the npi heads and it works fine. the heads is the biggest job to do with very minumal gains. so if your planning stayin n/a then you don't need th pi heads imo. but if you wanna go crazy with your motor modding get them, or just get aftermarket ones, put you'll pay out of the ass for them :D

I agree, The PI "heads" are just not worth it price wise. You can do just the PI cams and intake and only be around 10hp less the the whole head swap. And that HP is due to the compression jump.
Or for about the same price as a PI head-swap you could do comp 268H's and a PI intake and be about 15-20HP over the whole head-swap and have stock compression.

As for the gears, I love my 4.10's with my auto. Take-off is awesome and isnt bad on the highway. At 70mph Im @ 2600.
I do plan on a FRPP roots supercharger in the future so I will be going to either 3.55's or 3.73's when that happens.

But nothing like that is going to happen soon for me, atleast not till my wife is done with here cancer treatments. :-\

Good info :thumb:
I hope your wife recovers quickly....
 

Black97GT

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Outlaw97GT said:
As for the gears, I love my 4.10's with my auto. Take-off is awesome and isnt bad on the highway. At 70mph Im @ 2600.
I do plan on a FRPP roots supercharger in the future so I will be going to either 3.55's or 3.73's when that happens.

Would the rpm's be different in my 5spd? Anyone make an estimate about what they would be with 3.73's 3.90's 4.10's at around 75?
 

Dalamar

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Whether the PI headswap is worth it to you depends on the potential you want.

If you're happy in the 300 HP neighborhood, keep it NPI and bolt ons. (including a blower)

Used PI heads are pretty affordable. Add cams and stuff and you'll gain as much as you can from a blower on NPI's.
again, it depends on how far you want to go.

there's alot of info on the PI stuff in this thread:
http://www.sn95forums.com/forum/index.php?topic=1292.0
 

jpajkos

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Let me ask you guys a question. I was looking through summits catalog and there saying that these set of heads there selling for SN stang are 75 more horse power over stock. When your talking "P.I." are you meaning just the same intake, cams, and head from a 99-04 GT? I had a 1992 Fox GT and after I through on the Stage 3 Ported Cobra intake some E303 cams and world heads I got over 120 horsepower gain! Then I added some supporting mods such as a cold air, Throttle body, pulleys, MAF, etc and dynoed my fox it put out 354 horses @ 362 torque. Not trying to stir up any chit but its hard to fathem that new intake, heads, and cams only give you 45 more horses. I could be wrong and am just being a prick lol :thumb:
 

jpajkos

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just also wanted to add after 3 years putting those on I eventually slapped on a intercooled Paxton Novi, stroked out the 302 with the 347 rebuild kit assembley and had it tuned and was pushing 488 rwhp @ 498rwt. And for those who might ask where the car is. It was stolen from me gutted and recovered underneath a freeway 4 days later. :'( :'(
 

97vertstang

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jpajkos said:
just also wanted to add after 3 years putting those on I eventually slapped on a intercooled Paxton Novi, stroked out the 302 with the 347 rebuild kit assembley and had it tuned and was pushing 488 rwhp @ 498rwt. And for those who might ask where the car is. It was stolen from me gutted and recovered underneath a freeway 4 days later. :'( :'(
that sucks!!!!!!!!!that type of shit makes me mad.we pour our herat and soul for this just for someone else to steal it and sell it for crap!!!!!
 

ALITL8

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sorry to hear about your fox, man!

im afraid youre going to have to get use to spending more money to make less hp with the mod motor. the heads and intake from an 01-04 are more desirable but only yeild about 45-60 hp depending on your bolt-ons and tuning :dunno:

my understanding is: build a forged lower end (stroker, big bore, etc... IDK exactly), port the PI heads or get some performance heads, get a bullet intake or something equivalent, some ST1 or 2 cams (NA or Blower, depending on plans) and you might be close to happy with your hp.

on another note, im pretty excited that im making close to the 220 rwhp mark :dancing6: btw, i also make 299 ft #'s of torque ;D
 

jpajkos

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I understand what I got myself into when buying a NPI 4.6. All im saying is that there have to be better power gains then 40-50 horses from heads, intake and cams. I mean 40 horses for a new set of performance heads sounds about right if ported? In the muscle mustang fast fords anderson motorsports gained 60 more horses from a intake plenum and cams. Im not joking take a look for yourself. They then equiped it with a 75mm tb and pulleys and dynoed it at max power 267rwhp. I mean if this article is lying that sucks. About my fox I know its sad. Whats even sadder is I got a 3500 check for it from the insurance company. Thats hurt me the most. But hey better things will happen to me.
 

Dalamar

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Sorry about your car getting gutted. that sux.



Stock PI heads, with the stock PI intake and stock PI cams is 40-60 HP.

I did ported heads and cams with my PI's and got 95 rwhp, auto, high elevation...

you can get more with a more agressive cam.
a good tune and supporting mods will also add more.

there are guys on corral that got 130 HP gains, NA with porting and cams/tune.

another big factor is if you're adding a blower, the PI heads give you much better power gains
over NPI heads at the same boost. because of air flow restrictions and short valve stroke.
 

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