PP NPI + S/C or PI Swap?

Blev · Feb 13, 2004

I have been hearing that if you PP the NPI heads they flow just as well if not better than the PI heads. If this is true, would it be better to PP the NPI heads and add a S/C since the added compression on the PI swap may blow out the lower end? What would make more HP, a PP NPI + S/C or a PI headswap with a 50 shot?

I'm trying to look down the road as far as power adders and want to plan smart rather than getting all gung ho and just start buying things. All INTELLIGENT input is appreciated.

Bone Racing · Feb 13, 2004

p+p and s/c

remember nobody can see a port job

JLstang351 · Feb 13, 2004

Iwas going to do the headswap but now im thinking about getting compucars 125 shot for $450. Otherwise I was going to be paying near $2k after the porting and long tubes. And the good thing about the headswap is everyone will think its stock until you bust off some high 12's-low 13's

hioc1098 · Feb 13, 2004

I have a set of Steen Racing ported heads I'm putting on with SHM cams and my SVO @ 9lbs. We'll see how she does. The heads flow 197/168 @ .500. That's right around SVO head range. Again, we'll see when my longtubes and gaskets get here.

Tim

Sam98 · Feb 13, 2004

Blev said:
I have been hearing that if you PP the NPI heads they flow just as well if not better than the PI heads. If this is true, would it be better to PP the NPI heads and add a S/C since the added compression on the PI swap may blow out the lower end? What would make more HP, a PP NPI + S/C or a PI headswap with a 50 shot?

I'm trying to look down the road as far as power adders and want to plan smart rather than getting all gung ho and just start buying things. All INTELLIGENT input is appreciated.

I have never regretted installing a blower on my car, but with non-PI heads you will be well below the power level others are at with similar blower setups on 99+ motors. A lot depends on how much you plan to spend and what power level you are targeting. You can port your stock heads and they will flow as well as, maybe even a little better than non ported PI heads, but that is all you will ever get out of the heads. You would be better off with ported PI heads on your block, and then install forged pistons/rods to bring the compression down when you are ready to install a blower. With the stock heads it is really difficult to get much over 300 RWHP and you have to do the same things that would get you 400 RWHP with a 99+ motor. Ported PI heads on your motor would get you real close to the power levels you'd see with a blower on your stock motor and you could always add a PA if you get the itch for more speed.

hioc1098 · Feb 13, 2004

Sam98 said:
You can port your stock heads and they will flow as well as, maybe even a little better than non ported PI heads, but that is all you will ever get out of the heads.

While I agree with 99% of your post, I'll have to disagree with the above assertion. Ported NPI heads will flow much better than stock unported PI heads; not just a little better. I know it's semantics, but it's a little misleading.

Ported NPI, Stock PI heads
Lift -Intake
.100-47.5, 50
.200-94, 93
.300-135, 126
.400-172.2, 148
.500-197.4, 158
.600-220, 163

Lift- Exhaust
.100-38.5, 48
.200-87.5, 91
.300-117, 117
.400-143.2, 134
.500-168.1, 141
.600-180.8, 145

These heads are fairly close to Steen Racing street ported PI heads. Now, where your assertion is most certainly true is these heads are pretty much maxed out. PI heads with larger valves and a good port job will leave these heads in the dust.

The key is where do you want to go with the engine. If you're looking to maximize what you have without dealing with compression increases or removing swirl dams to run boost, NPI heads can take you relatively far for very little cost (comparatively speaking). I know these heads are capable of pretty good numbers. In fact, they'll probably take me as far as I want to go with a 2v.

That being said, if you're looking for a sky's the limit head, the PIs are probably the way to go. Sam98, don't take what I'm saying as a flame. I think you're right. I just think you're selling the NPIs a little short.

Tim

cltgt · Feb 13, 2004

do headswap and s/c if you can swing it. Just get a set of Cometic gaskets to lower compression

Sam98 · Feb 13, 2004

hioc1098 said:
While I agree with 99% of your post, I'll have to disagree with the above assertion. Ported NPI heads will flow much better than stock unported PI heads; not just a little better. I know it's semantics, but it's a little misleading.

Ported NPI, Stock PI heads
Lift -Intake
.100-47.5, 50
.200-94, 93
.300-135, 126
.400-172.2, 148
.500-197.4, 158
.600-220, 163

Lift- Exhaust
.100-38.5, 48
.200-87.5, 91
.300-117, 117
.400-143.2, 134
.500-168.1, 141
.600-180.8, 145

These heads are fairly close to Steen Racing street ported PI heads. Now, where your assertion is most certainly true is these heads are pretty much maxed out. PI heads with larger valves and a good port job will leave these heads in the dust.

The key is where do you want to go with the engine. If you're looking to maximize what you have without dealing with compression increases or removing swirl dams to run boost, NPI heads can take you relatively far for very little cost (comparatively speaking). I know these heads are capable of pretty good numbers. In fact, they'll probably take me as far as I want to go with a 2v.

That being said, if you're looking for a sky's the limit head, the PIs are probably the way to go. Sam98, don't take what I'm saying as a flame. I think you're right. I just think you're selling the NPIs a little short.

Tim

Stock non-PI heads outflow PI heads once the lift gets above .500 but that does not translate into more power. I don't know how much of the power increase with PI heads can be attributed to the larger exhaust valves and additional .060 lift or how much can be attributed to the intake manifold, but something clearly makes PI heads superior inspite of how the numbers look on a flow bench. Likewise, using PI cams in non-PI heads should be particularly effective because the additional lift is in the range where the stock non-PI heads flow better than PI heads, but in reality there isn't that much difference. I have seen my car on the dyno, and once the engine hits about 5000 RPM that's all the power you are going to get, even with the additional 4-5 psi increase in boost at the end. I would love to hear that I'm wrong, and all that is needed is a good port job, but there aren't many examples to look at. Even though non-PI heads don't produce big numbers on the dyno, I still have enough torque to light up the tires at will so I'm not complaining...

hioc1098 · Feb 14, 2004

I struggled with the same thought when I was thinking of either using NPIs or waiting until I rebuilt this fall and going with a complete SVO or PI setup. How are the flow numbers good (even at .500 - where my cams end), but no one is running good numbers with them? I think the answer to that is the existing paradigm. No one thinks these heads can do well, so they're not going with them. There may be some who are using them, but aren't running at the track. (How many PI dyno queens are there who never make it to the track?) Because almost everyone is running PI heads at the track, that's all we hear about. There are some t-birds who are now starting to run the numbers with the NPI stuff (Johnny Langton comes to mind).

I probably would've waited and went with a PI setup had it not been for two reasons.
1. I didn't want to have less power than when I had the Vortech, which was a possibility with the stock heads.
2. I found a pretty good deal on the Steen heads and I read about the guy making 482hp with them (dyno sheets were included).

If I wasn't going to start tuning myself, I'd have a dyno of my setup in April. As it stands, I'll probably dyno it sometime in the Spring, but it'll be on a Mustang dyno and those are a little disappointing. The proof - or lack therof - will be when I go to Estes this spring. Of course, I'll have to learn to drive again, because an SVO is much different than a Vortech.

In the end I hold to my previous statement. If you're on a strict budget, the NPIs can do pretty well. If, however, you're looking for a head that can take you to the sky, go with PIs and save your money.

Tim

Blev · Feb 14, 2004

ALOT of GREAT input guys!!

My concern is this. With PI heads I'm looking at like 1300 bucks and another 600 - 800 for the install (that's not PP). If I put a power adder how will the rest of the block hold up?

With PP NPI heads, 99+ intake manifold and PI cams what am I looking at for cost? Will this hold up better when I install a power adder?

What am I looking at in HP numbers on the two differant set ups N/A? I'll be adding a 75 TB, Plenum and a mid pipe.

I know it's hard to put numbers to this but I want to do this right the first time while being cost efficent and keeping this a daily driver.

I really appreciate your guys help and input!!

cltgt · Feb 15, 2004

If you go with NPI heads, you don't need a 99+ intake. the ports are not the same.

Blev · Feb 15, 2004

cltgt said:
If you go with NPI heads, you don't need a 99+ intake. the ports are not the same.

You must not be in the know....

That is all the rage right now... NPI guys are getting 10 - 20 HP gain with that mod alone!! Dyno sheets have been flashed! Trust me on this, do some searches.

hioc1098 · Feb 15, 2004

Blev said:
ALOT of GREAT input guys!!

My concern is this. With PI heads I'm looking at like 1300 bucks and another 600 - 800 for the install (that's not PP). If I put a power adder how will the rest of the block hold up?

With PP NPI heads, 99+ intake manifold and PI cams what am I looking at for cost? Will this hold up better when I install a power adder?

What am I looking at in HP numbers on the two differant set ups N/A? I'll be adding a 75 TB, Plenum and a mid pipe.

I know it's hard to put numbers to this but I want to do this right the first time while being cost efficent and keeping this a daily driver.

I really appreciate your guys help and input!!

I don't know if I'd want to be the pioneer with a supercharger and PI intake on NPI heads. As far as I know the only guys who have done it have done it to N/A cars. The concern (and there's a decent debate on ModularDepot) is about the RTV that you use for some of the coolant passages blowing out (or in) on a supercharged car. Certain things I'd like to be a pioneer on, but this isn't one of those.

You can get the heads ported and polished by Steen Racing for $750. The install kit will cost you the same as the PI swap, so there's no savings there. You can always do it yourself and save that money, but you need to be halfway mechanically inclined.

The numbers you're looking at with the non ported and polished PI swap is about 256-270 rwhp. Guys with a decent port job and cams are pushing 300. If you went with the non ported PI heads, you won't be very blower friendly anymore without either thicker headgaskets, or worked swirl dams (but you won't see the benefit of the added compression N/A so the numbers will be lower).

I can't tell you what you'd see with ported NPIs and PI intake, because I've never seen it done yet on a Mustang. You're looking at about $1000 for total parts costs. If you're hellbent on a supercharged car in the future, this may be a good option. Theoretically, you should see about the same numbers N/A, but I don't think the PI cams can take advantage of the ported NPI heads. If you do a search on ModularDepot on Johnny Langton, you'll find the numbers he's putting down. I'm pretty sure they were in the 250 or so range and he's running in the 12s N/A in a heavy T-bird. Just my $.01.

Tim

Sam98 · Feb 15, 2004

Blev said:
ALOT of GREAT input guys!!

My concern is this. With PI heads I'm looking at like 1300 bucks and another 600 - 800 for the install (that's not PP). If I put a power adder how will the rest of the block hold up?

With PP NPI heads, 99+ intake manifold and PI cams what am I looking at for cost? Will this hold up better when I install a power adder?

What am I looking at in HP numbers on the two differant set ups N/A? I'll be adding a 75 TB, Plenum and a mid pipe.

I know it's hard to put numbers to this but I want to do this right the first time while being cost efficent and keeping this a daily driver.

I really appreciate your guys help and input!!

I have been running with a blower on the stock block now for almost 2 years and have not had a problem. With any power adder even a slight amount of detonation can crack a piston so you will need a conservative tune. With the PI heads your power level will be up by around 100 RWHP over what it will be with non-PI heads. That additional stress makes the engine more likely to break but that doesn't necessarily mean that it will. As it is, I always have enough power to satisfy that urge, and I rarely have to punch it; when I do, I usually end up smoking the tires and attracting more attention than I want. I don't have enough power to stay up with the PI headed, blown GT's, but I can still put most ricers to shame. I guess that's good enough until I can afford to get a forged bottom end and the car sounds damn good too.

cltgt · Feb 15, 2004

Blev said:
You must not be in the know....

That is all the rage right now... NPI guys are getting 10 - 20 HP gain with that mod alone!! Dyno sheets have been flashed! Trust me on this, do some searches.

well, there were no matches doing a search on piintake and it won't look up pi intake, so point me in the right direction on this development. I would like to know so i can do it myself!

Sam98 · Feb 15, 2004

I have heard rumors about using a PI intake with non-PI heads but I wouldn't trust it. You would probably be far more likely to develop vacuum leaks and it could end up being a real PITA...

Blev · Feb 15, 2004

cltgt said:
well, there were no matches doing a search on piintake and it won't look up pi intake, so point me in the right direction on this development. I would like to know so i can do it myself!

Here ya go man.

Intake Swap

Numbers

cltgt · Feb 15, 2004

Thanks for the info! looks like I might have something to do Monday after all....

LI98GTStang · Feb 15, 2004

Sam98 said:
I have heard rumors about using a PI intake with non-PI heads but I wouldn't trust it. You would probably be far more likely to develop vacuum leaks and it could end up being a real PITA...

Here is another link.
http://forums.stangnet.com/showthread.php?t=424554

If your not convinced that the seal will stay for any length of time, you can always order a kit that includes adapter plates that allow for an easier transition from PI intake to NPI heads (you will pay though). Gaskets on either side should give a solid seal.
http://www.livernoismotorsports.com/product.phtml?p=457&large=1

Lastly, adapter plates are being developed aside from a kit that would include the PI intake. Check out this link. I believe he posted on stangnet in one of the threads asking about interest as well. If interested he is looking for people to pm him.
http://forums.tccoa.com/showthread.php?s=&threadid=33763&perpage=10&pagenumber=1

Sam98 · Feb 16, 2004

I'll keep it in mind if my stock intake ever cracks...

PP NPI + S/C or PI Swap?

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