supercharged 4.6l ?????

[stang869846]

i have a 98 gt with a vortech s-trim(12 psi), bbk h-pipe, flowmasters, 42lb injectors, and 4.10's. it makes 310.00 rwhp and 330 lb tq. i am putting 75mm throttle body, bbk upper intake plenum, shorty headers, intercooler, comp cams, and doing a p.i. swap. my question is when i do the swap i know it raises my compression ratio to bout' 10.5:1. would i have to lower my boost to say 8 psi even though im addin an intercooler or could i leave the 12 lb pulley on there? also how hard is it to do the swap? and about how much rwhp would i be makin after all of that? thanks to all that reply i kinda wanna know if there is anything i should look for when im doing the swap or is it pretty much just straight forward?
thanks
chris

 

[TweekedGT]

Becuase your vortech is a centrifugal blower it isn't as bad for your compression to be higher. Your full boost doesn't come on right away. You will defenitely have to run the highest octane fuel you can get your hands on. For the long run it will be best to pulley down a little. The PI swap is straight forward as long as you make sure you have all of the parts. You will need to tap a hole in the new PI manifold on the driverside aluminum crossover. The rest is plug and play.

 

[AmBo]

You were running 12psi non-intercooled? ...that does NOT sound safe.

 

[DBMSTNG]

adding an intercooler will lower your 12psi down to 10psi. use thicker gaskets to prevent your compression ratio from going too high and when you get it retuned, make sure they don't program too much timing.

 

[stang869846]

well i have heard that from everyone i have told about my car with 12 psi non intercooled and i dont see what the big deal is i mean it is a safe tune, it doesnt detonate and is totally reliable. i drive it everyday to and from work and school and it has 87,000 miles on it and the blower with 12psi was put on the car at 1,500 miles so pretty much its whole life its been blown and is still running good so im not gonna change it

 

[Gearbanger 101]

Your horsepower levels are really low for the boost levels you’re running. My guess is that the tuner pulled a lot of timing out of it and added a lot of fuel in order to keep you out of detonation. This would explain the low numbers. Ever consider just running the PI head parts (cams, valves, etc) in your non-PI heads and/or having them ported? Even an unported set of NPI castings will flow quite well in comparison to a set of PI's. It’s the valve train that kills the flow figures. Hell, if you want, Fox Lake will port your NPI’s to an exact duplicate of their ported PI castings. That way, you'll get to stick with the stock compression ratio and not have to pulley back or run race gas on those hot days. Combine it with the PI intake and all the other induction components you stated and you're next question will be.


...."where's the best place to have my short block beefed up?"

 

[stang869846]

so ur saying that just take p.i. intake and put it up to my n.p.i. heads? i thought they wont match up? and i didnt think that around 300 rwhp was to bad for pretty much a bone stock car stock exhaust manifold, throttle body, intake plenum, was to bad i mean hell these cars only make 180 rwhp stock and the supercharger added over 120 rwhp i mean i think thats pretty good i know it seems low for a blown car but i need to get it breathing right with headers bigger throttle body and heads and it needs to be intercooled too. but do u think if the tuner took alot of timing out of it because of the 12psi i could drop down to 8psi and see higher number is that what ur saying? would the more timing with the 8 lb pulley make more numbers than the 12 lb pulley and less timing? just curious.

 

[04DarkShadowGT]

I have a 98 GT with a PI Swap, I was told by the guys at MPH on their forum that with a full PI swap to not run more than 6psi. I guess if you go intercooler you could do an 8 psi pullery but I would definatly not use the 12 psi one.

 

[Gearbanger 101]

so ur saying that just take p.i. intake and put it up to my n.p.i. heads? i thought they wont match up? and i didnt think that around 300 rwhp was to bad for pretty much a bone stock car stock exhaust manifold, throttle body, intake plenum, was to bad i mean hell these cars only make 180 rwhp stock and the supercharger added over 120 rwhp i mean i think thats pretty good i know it seems low for a blown car but i need to get it breathing right with headers bigger throttle body and heads and it needs to be intercooled too. but do u think if the tuner took alot of timing out of it because of the 12psi i could drop down to 8psi and see higher number is that what ur saying? would the more timing with the 8 lb pulley make more numbers than the 12 lb pulley and less timing? just curious.

With your current set up, you could probably drop down to 8psi, have it retuned and make the same or slightly better numbers....yes, that's what I'm saying. Even spinning the blower as hard as you are, most of that additional volume of air is being backed up within the intake track and isn't making it into the engine. Not to mention being superheated. To give you an idea, most '99-up guys running 12psi (with some sort of aftercooling)through their stock cars with no other bolt ons are seeing in the 420rwhp range.

Like I said, the PI hardware in your current NPI heads and/or having them ported would be the way to go. That way, you get all of the flow benefits and compression ratio remains in the 9:1 range. The PI intake will bolt up to the NPI heads. All you need to do is run a thin bead of RVT around the water/port passages of the head along with the PI gaskets to guard against leaks. Literally hundreds of pre-99 Mustang and T-Bird/Cougar guys are doing this with 100% success.

If you're still not comfortable with that idea, Fox Lake Racing will open up and port a set of NPI castings to the same port shape and flow potential as a set of Ported PI's. There's enough meat around the ports in order for them to do so. If cost is an issue, keep in mind that the money you would have sunk into buying a set of PI heads will pay for over half of the port job. In the end you'll make more power with a set of properly ported NPI's that you will with just a strait PI swap. As for the rest of the cost.....a set of good flowing heads and intake will yield you more gains than pretty much all of the other bolt-ons you previously listed put together. Hell....cams alone will run you about $600....and with the kind of compression ratio a PI swap brings, all you're pretty much going to gain out of them is a lumpy idle.

 

[mr. jones1]

confirmed-my 98 with NPI heads (stock), a PI manifold (with my plates to match ports) and a vortech at 6lb+ 70mm TB and a catted x-pipe stock mufflers, 30lb inj., 85mm MAF makes 320rwhp.

 

[stang869846]

yea thats kinda not good news cuz i bought my PI head swap last week for $1300 and i was just hoping that i could use thicker gaskets and maintain somewhere around the stock compression i mean thats what i heard and i talked to a local speed shop and they said 12 psi with PI head swap would work fine but i dunno hope he's right i mean these guys do it for a living so hopefully he knows what he's talkin bout. thanks for all the input guys

 

[Built98GT]

Sup man! I met you on Saturday night after 39th street I got pulled over again for my exhaust after we left that parking lot! I think our mustang club is gonna get together before we go cruise this next saturday and make some car videos if you wanna join.

 

[Built98GT]

Dont leave your NPI heads on go ahead and just run lower boost because after talking to you on saturday I dont think your modding is going to stop after you get this pi setup on. You will eventually build your block like we were talking about and run lower compression pistons so you can run alot of boost and thats when the pi heads will really come to life!

 

[Gearbanger 101]

yea thats kinda not good news cuz i bought my PI head swap last week for $1300 and i was just hoping that i could use thicker gaskets and maintain somewhere around the stock compression i mean thats what i heard and i talked to a local speed shop and they said 12 psi with PI head swap would work fine but i dunno hope he's right i mean these guys do it for a living so hopefully he knows what he's talkin bout. thanks for all the input guys

In that case, I'd probably wait until you were able to afford to build up a decent short or at least swap out to a set of lower compression pistons to keep things boost friendly. For now, I'd drop your boost levels to a more street friendly 8psi and have it retuned. At the very least, it will make things easier on gas and add a little life to your current blower and engine until you can get things sorted out with the other set up.

 

[98GTVortech]

Run methanol injection you can raise your timing and gain a good amount of power. See my sig below for my mods and HP/Torque numbers. I think yours are pretty low considering you don't have much more bolted on then i do???

 

[four six]

NPI heads + Blower=

Get PI heads and internals then get blown= mad power

 

[Gearbanger 101]

NPI heads + Blower=

Get PI heads and internals then get blown= mad power

Read this before you decide to continue with that one sided mind set.....

Q: Are '99+ non-PI heads worth using? You know, the ones off Crown Vic's?
A: Sure, if we port them they come out exactly like our ported PI castings. They are cast a with smaller ports than the PI heads, but there is enough metal to fully port just like the PI head and they end up the same.

http://www.foxlakeracing.com/index.php?src=faq

This holds true for the Non-PI '96-'98 Mustang and '96-'97 Thunderbird, Cougar heads as well. Plenty of meat to work with, so why wouldn't you spend the money to have them ported? They'll easily outperform stock PI castings, perform as well as ported PI castings and still allow you to retain a 9:1 compression ratio for a blower application.

As a matter of fact, the only reason I could see someone wanting to swap out to PI heads would be because they're on a bare bones budget (in which case modifying their car to any extent should be questioned), or because they want the additional compression for a built N/A or Nitrous application.

 

[stang869846]

hey man were are yall meetin saturday i might just go ahead and go i mean i am still not running right cuz i need spark plug wires and i dont think they'll be here by then but just let me know where ya'll are meetin and i might go or just gimme a call 923-6799 my names chris by the way. yea i think im stayin with the PI swap i mean i already bought em' and im buildin up my shortblock anyways to lower the compression.