which power kit do I get - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Jake Raby · 06-08-2010, 12:31 PM

Yet again we are talking generally here.. Some systems DO give some sort of gain, but the question is how much each one of those additional HP costs.

I sourced a set of expensive headers for my Wife's 996 Land Speed Car (that holds 4 records) and installed them.. I did back to back dyno work and no matter what I could not get back the 6Hp that they cost me, until I removed them and went back to stock. Using the data logger (DL-2) the 0-60 and 40-80 ETs substantiated what the dyno illustrated.

How much is 5Hp worth??? I can get 5-7 (RWHP) with a 225.00 pulley!

RandallNeighbour · 06-08-2010, 02:35 PM

Now I am no dyno expert, but I had a pro shop here in Houston do back-to-back dyno pulls on my boxster before and after I put on my cheap eBay headers and I had a nice HP and torque bump. The weather was stable that day too (in other words, it didn't start pouring down rain mid day which would have changed both temp and humidity factors)...I'm just sayin'

The loud, twin-chamber aftermarket muffler I added did not diminish gains from the new headers and stock cats. Makes the car sound more powerful than it is though and the cabin drone is deafening if you're stuck in traffic with the top up (ie, for rainy days) and moving through 2-3k RPM's a lot of the time.

I've dumped plenty of money into my car (arguably more than most every other forum member) and doing a high speed DE was hands-down the best way to discover my 2.5 doesn't need any more power. Holy crap it's got LOADS of power when driven right on a track.

A vast majority of us driving our cars in town light-to-light make us feel the car is underpowered and we want more torque. It's just not designed for this kind of driving... buying a 997 Turbo if you're rich or a Corvette (if you're not as rich) is the car for straight line performance.

Jake Raby · 06-08-2010, 03:09 PM

The cheap ebay headers aren't a bad deal.. Because you pay an adequate amount for the power they give.

Above that, I have been less than impressed.. If I have a chance tomorrow evening between appointments I'll drag up some of the dyno comparisons I did back in 2008 and post them.

Stroked & Blown · 06-09-2010, 07:58 AM

Quote:

Originally Posted by RandallNeighbour

Now I am no dyno expert, but I had a pro shop here in Houston do back-to-back dyno pulls on my boxster before and after I put on my cheap eBay headers and I had a nice HP and torque bump.

Randall,
Would you mind sharing the numbers?
I have some Chinese headers sitting on my shelf in fear of breaking header bolts for a minimal gain.
Your numbers may convince me to have someone do the install for me.

RandallNeighbour · 06-09-2010, 08:14 AM

Dyno graphs attached

Jake Raby · 06-09-2010, 09:27 AM

Randall's gains are less than I have seen with the Chinese headers.. But his power numbers are in line with all the cars I have had on my dynojet that were in good health.

Randall, which are the before and after direct runs?

Stroked & Blown · 06-09-2010, 09:28 AM

Thanks Randall
It looks like you saw ~ 10HP / 7TQ gain right away & it seemed to climb another 5HP as the computer learned the new breathing capabilities.
That's around 9% HP & 12% TQ gain. More than I expected. Looks like I need to do this.

Any other variables in play between runs 4/5 and 6/7/8?

Summary:
Baseline
Run 1 169.80 HP 149.56 TQ
Run 3 169.27 HP 147.91 TQ

Chinese Headers
Run 4 179.27 HP 165.85 TQ
Run 5 179.65 HP 164.38 TQ

Twin-Chamber Muffler + Chinese Headers
Run 6 181.29 HP 165.63 TQ
Run 7 182.51 HP 166.24 TQ
Run 8 184.24 HP 166.92 TQ

RandallNeighbour · 06-09-2010, 09:40 AM

Actually, it's not the breathing as much as it was adding the muffler.

The first run was a baseline. The second was after the Chinese headers were added. The third was after the muffler was added to the Chinese headers.

My butt dyno felt the bump in torque and the parts were free, so I couldn't lose on this deal... except for the twin chamber muffler being so freakin' loud with cabin resonance.

Jake Raby · 06-09-2010, 09:44 AM

If those are the comparable runs I'd say that Randall's engine was making less power than a normal bone stock 2.5 to begin with.

I've never seen a gain anywhere near 9Hp with the Chinese headers, in fact I've never seen a single system enhancement make that kind of power difference on that size engine.

What really tells the story is the data logged 0-60 and 40-80 MPH tests before and after the dyno with both systems at the same coolant and oil temperatures.