PI Headswap Before/After Results at the Track

5spd GT · May 18, 2008

I went to the track finally, after completing my PI Headswap.

Before with Bone Stock NPI 1998 GT (5spd - 3.27 gears - 110k):

2.356 - 60 ft.
6.332 - 330 ft.
9.647 - 1/8 ET
74.89 - 1/8 MPH
12.30 - 1000 ft. ET
85.32 - 1000 ft. MPH

After with 2002 PI Heads/Cams/Intake (5spd - 3.27 gears - 133k):

2.159 - 60 ft.
6.032 - 330 ft.
9.255 - 1/8 ET
76.98 - 1/8 MPH
11.82 - 1000 ft. ET
88.15 - 1000 ft. MPH

Difference of:

.197 - 60 ft.
.300 - 330 ft.
.392 - 1/8 ET
2.09 - 1/8 ET
4.80 - 1000 ft. ET
2.83 - 1000 ft. MPH

Same track, similar conditions, untuned. This gives a ballpark of what you can expect to gain with a NPI to PI Headswap.

BurningRubber · May 18, 2008

Nice, get it dialed in and watch the numbers drop even more.

On top of that, getting off the line harder as it is could drop you down to a 9.0 id say.

5spd GT · May 18, 2008

BurningRubber said:
Nice, get it dialed in and watch the numbers drop even more.

On top of that, getting off the line harder as it is could drop you down to a 9.0 id say.

Thanks.

I have only ran, in NPI and PI version, once each.

For the daily driver and a stock T-45, I do not like to race it much.

Stock tires, and everything else is stock. I prefer to look at the MPH gain, because it takes out the launch factor.

I think the results are pretty realistic with just swapping over the parts with no tune or bolt-ons/exhaust on the vehicle.

BurningRubber · May 19, 2008

Not bad at all. I didnt realize the car was stock aside from just the swap.

If you do decide to add more down the line it will really benefit from the swap.

Just be careful, it is easy to get hooked on going to the drag strip, lol.

5spd GT · May 19, 2008

BurningRubber said:
Not bad at all. I didnt realize the car was stock aside from just the swap.

If you do decide to add more down the line it will really benefit from the swap.

Just be careful, it is easy to get hooked on going to the drag strip, lol.

This is not my first time to hit the track. I got a hefty stack of timeslips from my current and other mustangs I have owned in the past.

From just looking at the MPH gained, 2.8 MPH, that is around 28 HP or so, as a rule of thumb with everything else being stock.

BobHyatt · May 19, 2008

5spd GT said:
Thanks.

I have only ran, in NPI and PI version, once each.

For the daily driver and a stock T-45, I do not like to race it much.

Stock tires, and everything else is stock. I prefer to look at the MPH gain, because it takes out the launch factor.

I think the results are pretty realistic with just swapping over the parts with no tune or bolt-ons/exhaust on the vehicle.

that data really is not useful then. You need several runs just to get some consistent idea about what is happening. Driver performance is just as important as car performance in the 1/4 mile, and you can't tell anything with just one run before/after... You need 10 or more each to see if there was any significant difference.

Winters98GT · May 19, 2008

Good times, get that 60 foot down a bit. I would have expected more mph out of your car. Where are you shifting?

The 60 foots are way off from one another. I understand the improvement in the hp creating a better 60 foot, but that npi run had wheelspin, throwing off the mph of the run. Eitherway, congrats on the install!

I dont think you need 10+runs to get a good comparison. 2-3 runs with similar 60foots should be good.

5spd GT · May 19, 2008

Winters98GT said:
I dont think you need 10+runs to get a good comparison. 2-3 runs with similar 60foots should be good.

I agree with you.

I actually ran the NPI version twice. It was consistent.

Bob, it is fairly accurate. I try to be as consistent as possible.

It was just to give an idea. I am not worried about the 60 foots. I look at the MPH, and I shifted as close to the same speed as one can.

Remember, this is with no tune, no bolt-ons, no exhaust, and everything is stock.

This is not my first merry-go-round.

Winters98GT · May 19, 2008

its cool to see somebody go for the real power right away. Good foundation for going fast later.

I was curious about where you shifted because the I shift about 800rpms different with a PI setup than I do with an NPI one.

Keep us posted on the progress.

bhuff30 · May 19, 2008

Thanks for sharing the results, great info for sure.

It is important to compare the mph each run, but it is also true that a poor 60' time will inflate the mph to be higher than it actually is. The best explanation I've seen, is a slower 60' time gives more total time to gain speed. Yeah, doesn't make much sense but it's true. So the true gains are higher than the difference in trap speed indicated there.

Also, you said you shifted at the same speed. Let that PI engine rev! I shift my basically stock NPI at 5000 on the nose. Let that PI engine rev out to 5500-5800 and you'll probably pick up even more!

5spd GT said:
I agree with you.

I actually ran the NPI version twice. It was consistent.

Bob, it is fairly accurate. I try to be as consistent as possible.

It was just to give an idea. I am not worried about the 60 foots. I look at the MPH, and I shifted as close to the same speed as one can.

Remember, this is with no tune, no bolt-ons, no exhaust, and everything is stock.

This is not my first merry-go-round.

5spd GT · May 20, 2008

I was shifting in the 5,700-5,800 RPM range, according to the stock gauge.

Thanks for understanding the reason why I posted. I figured it is best to post something, rather than nothing when I had a little comparison here.

mrvax · May 20, 2008

Very nice. Using the 1/8 mile to 1/4 mile converter, you went from about a 15.05 to a 14.43 1/4 mile ET.

That is usually over a 50rwhp increase.

The link for the conversion is here:
http://www.blownstangs.com/misc/times2.html

PI Headswap Before/After Results at the Track

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