PI Swap AND Forced Induction - Need legitimate technical advice

[MyEarsHurt]

Hey Guys,

Its been a LONG time since I have been on here....the PI swap I did on my 98 GT vert has sustained me up until now - but of course I want more horsepower now and I am low on options but heavy on cash. I can afford to throw about $5000 at the mustang this summer and I was thinking about installing a procharger or vortech on my pony. I know that I have seen countless "don't do that" warnings for trying to add forced induction on top of the PI swap - but why?!?

My question becomes - what precautions do I need to have to do this safely and ensure that I am not gonna blow up my ****! This post is not to talk me out of putting forced induction on my pi swapped stang - so don't bother - but rather its to give me some pointers as to how I can do this in the best way possible. Thanks in advance guys!

 

[trinity_gt]

Hey Guys,

Its been a LONG time since I have been on here....the PI swap I did on my 98 GT vert has sustained me up until now - but of course I want more horsepower now and I am low on options but heavy on cash. I can afford to throw about $5000 at the mustang this summer and I was thinking about installing a procharger or vortech on my pony. I know that I have seen countless "don't do that" warnings for trying to add forced induction on top of the PI swap - but why?!?

I think the biggest concern is that swapping PI heads on the NPI shortblock results in a fairly high (~10:1) compression ratio. The higher the ratio, the more likely one is to see detonation which can easily harm the pistons.

With moderate boost (say, 8psi) and a conservative tune that give 11.5:1 or richer AFR you'll be okay, especially with a centri.

 

[Midnight2V]

Given your list of mods, you are right at the limit of what all the little bolt-ons can do, anything more is gonna be expensive just like you said. Given that you are ready to spend some serious coin, you should do it right so you only have to do it once. What I am gonna tell you may not be what you want to hear, but believe me it is in your best interests, especially long term. What I am suggesting is what I would do, if it were my car. Some people consider me to be conservative but that is me.

1. You need to get a forged lower end, the last thing you want to do is grenade your baby. I know, cuz it has happened to me. It will cost you about 3k but it will be worth it. Going forged will give you both the strength to deal with boost, and flexibility to choose what supercharger you want to use. You mentioned a couple of centrifugals, which actually thrive in high CR mills and work well with up to 10.5:1 CR easily. If you want to use positive displacement, lowering CR is probably a good idea. That 3k will get you forged + install.

2. Perhaps looking into a set of higher performance heads with a matched cam, or getting yours ported would also be a good option. Again it will be about 3k. A good set of heads and cams can get you to at least 320 at the wheels, which is quite a boost in its own right. You could do this even without going forged.

3. Combining 1 and 2 will give you the best of both but will put a bigger hit on your pocket than 5k. Trust me when I say it is well worth it. If this is the option you want, I would actually recommend you do your upper end prior to the bottom end. It will give you an immediate power increase as well as fuel economy. It will also feed the horsepower hunger

If you want any specifics, or some other options, let me know. I have plenty of experience with this stuff and enjoy helping others with "problems" like yours.

In any case have fun and enjoy the project.

 

[CobraRed_96_GT]

Given your list of mods, you are right at the limit of what all the little bolt-ons can do, anything more is gonna be expensive just like you said. Given that you are ready to spend some serious coin, you should do it right so you only have to do it once. What I am gonna tell you may not be what you want to hear, but believe me it is in your best interests, especially long term. What I am suggesting is what I would do, if it were my car. Some people consider me to be conservative but that is me.

1. You need to get a forged lower end, the last thing you want to do is grenade your baby. I know, cuz it has happened to me. It will cost you about 3k but it will be worth it. Going forged will give you both the strength to deal with boost, and flexibility to choose what supercharger you want to use. You mentioned a couple of centrifugals, which actually thrive in high CR mills and work well with up to 10.5:1 CR easily. If you want to use positive displacement, lowering CR is probably a good idea. That 3k will get you forged + install.

2. Perhaps looking into a set of higher performance heads with a matched cam, or getting yours ported would also be a good option. Again it will be about 3k. A good set of heads and cams can get you to at least 320 at the wheels, which is quite a boost in its own right. You could do this even without going forged.

3. Combining 1 and 2 will give you the best of both but will put a bigger hit on your pocket than 5k. Trust me when I say it is well worth it. If this is the option you want, I would actually recommend you do your upper end prior to the bottom end. It will give you an immediate power increase as well as fuel economy. It will also feed the horsepower hunger

If you want any specifics, or some other options, let me know. I have plenty of experience with this stuff and enjoy helping others with "problems" like yours.

In any case have fun and enjoy the project.

I can appreciate the validity of going this route as I've done the same, but this is the direct opposite of his question. He's asking about boost on stock shortblock and PI heads, not considering a forged shortblock with ported heads - otherwise it wouldnt be a "problem" of a question because that combo wouldn't run into any problems.

There's a guy on theturboforums running a single turbo on his PI swap mustang with no problems. And lately with turbo's the trend has been high compression for fast sppoling, large cam overlap and low as possible back pressure - all of which make a sick combo.

My suggestion is this: You compression's around 10.3:1 - you're goals going to be to run in the 370-390rwhp range w/out running race gas or blowing up the internals right? Get an effcient form of FI (turbo would be best but centri should work) like a T trim and keep the stock pulley on so that peak boost comes in as late as possible and then put some blower cams up top. The blower cams will help you lower dynamic (running) compression while also depending on choice pushing peak psi up in the rpms. The cams will give you the extra hp/tq on a stock pulley without upping heat. Also an effcient/big intercooler is a must. Last is a safe tune, throwsome timing at it and even at stock pulley psi make it 11.5-11.8:1 A/F. And run cold plugs.

With these steps i dont see how you could run the stock pulley and see where that gets you. Just don't hunt for 410rwhp. Overall i'd recommend a single turbo small in size but big in flange or A/R. Plus compression helps turbo's.

 

[justinschmidt1]

To make a long story short you can do it if your careful.

I would say to go with a procharger kit since it will come with an intercooler.

Keep the boost down...around 8 psi should be enough to get you close to 400 rwhp.

Or you could go turbo....either way, your gonna need a good tune and an intercooler but you should be fine.

 

[bhuff30]

I've run boost on a high compression 2.3 before. It was around 9.7:1 and never made the power it should. Your compression is higher, so your problem will be even more pronounced. The problem is, to run the boost that you want, the timing will have to be severely retarded. This is bad for everything... bad for power, the EGTs go through the roof and that's bad for the engine. Not trying to change your mind, just stating the truth.
Since you are intent on running boost on high compression, then I very highly recommend a good front mount intercooler to keep the temps down. A meth injection kit would also help substantially. It will allow you to pick the timing back up to where it should be. With these 2 items, it should be very strong and reliable.

 

[CobraRed_96_GT]

I think we're all forgetting the stock compression on a 2001 mustang is 9.7:1 not 9.3 like 96-98. Plenty of people run boost on those. A .5 jump isn't going to wreck an engine

 

[2002BLGT]

keep the fuel rich and the timing under 14 is my advice

 

[trinity_gt]

I think we're all forgetting the stock compression on a 2001 mustang is 9.7:1 not 9.3 like 96-98. Plenty of people run boost on those. A .5 jump isn't going to wreck an engine

And they're on the edge for 8-10psi too. If your fuel's not fat and your timing not conservative you'll hurt those motors too. The extra compression of the PI-swapped NPI doesn't help and means the tune should be very conservative, perhaps moreso than the 99+ PI cars.

 

[CobraRed_96_GT]

And they're on the edge for 8-10psi too. If your fuel's not fat and your timing not conservative you'll hurt those motors too. The extra compression of the PI-swapped NPI doesn't help and means the tune should be very conservative, perhaps moreso than the 99+ PI cars.

Of course it needs to be safer, and of course 99+ cars need a safe tune to begin with. Im just saying an extra .5 compression wont ruin your day with the same goals of forced induction if you're smart about it.

 

[justinschmidt1]

Ive seen a lot of stock short block 99-04 cars running 10-13.5 psi....well over 400 rwhp too.

I think these motors are stronger than believed to be

 

[dastang2]

'm bringing this back to life. i just got a built motor. it has KB -17cc dish forged pistons, h beams, cobra crank. the pistons are .010 in the hole and the heads are 42 cc. with a .036 mls head gasket the compression should be around 9.8ish. the pistons also have small valve reliefs cut into them. i got a 3 inch pulley on my vortech v2sq with an intercooler. should i be ok under 12 psi

 

[CobraRed_96_GT]

'm bringing this back to life. i just got a built motor. it has KB -17cc dish forged pistons, h beams, cobra crank. the pistons are .010 in the hole and the heads are 42 cc. with a .036 mls head gasket the compression should be around 9.8ish. the pistons also have small valve reliefs cut into them. i got a 3 inch pulley on my vortech v2sq with an intercooler. should i be ok under 12 psi

Should be at 9.58:1 with those specs. Should be absolutley fine.
Also it should be noted that stock PI compression is 9.5, not 9.7 like i said a few months ago in this thread.