Dyno comparison with stock header and aftermarket

Last time I did a dyno with aftermarket header in July and here is the thread http://www.ferrarichat.com/forum/360-430-sponsored-yellow-compass-group/526878-dyno.html

Today I finally did another dyno but with stock header. Same place and same dyno. Weather luckily is about the same.

Dyno was done at Elite Performance in Burlingame.

The dynograph with 4 runs is attached.
Red line - aftermarket header and valve open - 452.8 HP
Green line - aftermarket header with valve closed - 373HP
Blue line - stock header with valve open - 415 HP
Green line - stock header with valve closed - 352 HP

The big difference other than peak HP, is the big dip on 4000 rpm - 5500 rpm on aftermarket header. From 5500 rpm the aftermarket header makes quite significant difference.

There was a 991 RS when I went to dyno today.
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That's a big gain from stock headers!
Are the IPE headers similar to Fabspeed?

What numbers are the 991 GT3-RS making?

 

Really interesting, over 35hp difference, wow. The big dip at 4k suggests the 4-1 design is not great for a street car. Race car yes when you would keep revs above 5.5k. looking at this If i was getting aftermarket headers I would go for try-y, 4-2-1 headers to bolster up that mid range as Capristo claim.

 

IPE, Fabspeed and AP are identical.

They did not dyno the RS. It was up for roll bar install and other stuff so he can take it to the track.

 

why the big dip between 4500 and 5500rpm ?
do you have the AFR chart ?

 

I don't feel that 50 ft lb dip in my car, interesting that it occurred and was repeated on 2 pulls. The addition of headers seems to provide a pretty significant horsepower increase, thank you for your testing.

 

I actually did 3 pulls on each scenario. 6 pulls total on aftermarket header and 6 pulls on stock header. I just took out the pulls so oh can see the lines cleared. They're on top of each other anyway.

Btw, I just realize there is a typo. The 373 hp is supposed to be 383 hp.

 

That is the fallacy of just looking at the top line number. Although it may be nearly 10% more, I would argue with a peak-dip-peak its a LOT less drivable than the stock and lap times could actually be slower...

If you watch the F1 races, you will see its only on flat out acceleration that they stay near the torque peak. The drivers actually use a surprisingly large rpm range throughout the lap.

 

If they could use more fuel those motors would rev much higher.

Did the owner feel any change in driveability between stock vs ipl headers?

 

It makes more power from 5500 rpm and on. For track driving if you see any rpm below 6000, you're driving it wrong.

For street, I agree, the stock header is better for drivability as you spend almost all your time at lower rpm.

It is about the area under the curve at rpm you are using.

That being said, on the street you have enough power with aftermarket header, even with the dip as you won't really go full throttle anyway.

 

Great info, Andrie. Thanks!

 

I would agree that maybe a Try-Y style header would prop up the low end torque without sacrificing much of the higher RPM gains achieved by changing to an aftermarket header. The Capristo header is a Try-Y design?? What are Capristos claims of Hp/Torque gains?

Thanks for sharing this information! It's great seeing some real, first hand numbers with dyno results to back up the claims.

 

Yes Capristo are 4-2-1 same as stock.

 

Just curious if the ECU was reset and the throttle targets set when the headers were swapped?
This allows the auto fuel trim to correct AFR to target tables this should be done every time you change a part that will effect AFR like headers/systems and air filters etc.

Do you have the AFR reading for the dyno pulls?

 

But I believe 4-1 headers is better for higher pitch sound.

 

Best without any wrapping or heat cover also but you need the shield to keep the heat out of the engine bay.

 

I've tried both capristo (4-2-1) and fabspeed (4-1) headers on my scud. From what I can tell, the IPE headers are identical to the fabspeed. Initially I didn't notice much difference in power/torque but after driving some more miles I do believe that the capristo 4-2-1 style headers have a bit more mid range torque and a flatter curve. This is just based on my butt dyno. I never did a tune or ECU reset.

In combination with 200 cell cats and the s-line xpipe, the fabspeed headers provide a slightly higher pitch at redline compared to the capristos. But they also tend to amplify engine noise which dirties up the exhaust sound. I can even hear this in some of the youtube videos others have posted. The capristos have a cleaner mid range sound.

Would be interesting to see someone compare both style of aftermarket headers on a dyno.

 

I wonder how much the pre-cat restriction creates back pressure that fills that dip on the stock headers vs aftermarket.

How many people have tuned their cars with headers? I wonder if this can be tuned out relatively easily.

 

you should check out various eras. Yes, the current generation is limited by fuel consumption/unit time which limits maximum rpm. But the V12, V10, V8 eras were not. And the drivability of the Renault V10 was at one time superior until the Ferrari dominated. Having a smooth torque curve meant drivability.

https://www.youtube.com/watch?v=46d3Z2DPdsQ
note how how most of Alonso's lap in Monaco is in the low-mid rpm range and not at 18,000 rpm!

 

It really depends on the track. Many F1 drivers struggle to keep it within 20% of redline...

Kimi:
https://www.youtube.com/watch?v=ggagn0vEmLM

DC:
https://www.youtube.com/watch?v=Gf1daEOS11g

Vettel:
https://www.youtube.com/watch?v=leipEzQS1D8

I would NOT want a dip in my torque curve like that!

 

If you actually race and analyze data logger, you'll find out, if you ever use under 5500 rpm on 8500 rpm car, you're either using the wrong gearing or you're starting or got bogged down by traffic and can't down shift. That's 35% off redline.

 

Yes having smooth torque curve is desirable. But not in the expense of 8% of Ho between the most usable range. It is always a compromise in racing especially those governed by rule.

 

Btw, this is for information only. Take it and do whatever you want with it. Given this is Internet, everyone will have different idea on what's ideal to them. It is natural as everyone also has different needs and priority. some people care only about sound, some people care about aesthetic, others about performance for street, the few about performance on track.

We are blessed that ice cream comes in so many flavors. It will be extremely boring if they only have vanilla.

 

Well said I like mint myself 👍 did you get an AFR reading from the dyno runs per chance?

 

No. I opted not to have the a/f reading since I have no means to adjust them. However, the ecu should trim the fuel based on your wide band O2.