996 Header System

[1turb993s]

I'm trying to get some input from anyone who has installed Race Headers on their 996. I have an 01', and I've been considering installing a set of Gemballa Race Headers. Some claim up to 30hp gains. Others claim around 5hp to the rear wheels. I already have high performance muffler system & Fabspeed intake, and chip. Just thinking headrs would complete the pieces. Any input would be welcomed.

Thx

Edited May 16, 2007 by 1turb993s

[wross996TT]

Just Port and polish the stock headers...for better flow. The length of the stock headers is perfect. Claim of 30hp is smoke and mirrors.

[Chuck Jones]

Were I you, I'd save my money. I've invested almost $4K into headers, mufflers, GIAC flash, PSS9's, EVO CAI....and I'm lucky if I've picked up 20 HP. Most of what you read on these forums about big HP increases are folks who haven't dyno'd the cars but "feel the increase in power". Yeah....I went thru that too...and I "felt" the increase in power just like the guys who went before me. Is it worth the $4K I've spent? I should have saved the money towards a twin turbo and spent more money on a nice car wax or detailing job. In all honesty, your best bet is a good set of performance suspension mods like the PSS9's or something similar, and some nice sounding mufflers to make it sound faster, meaner, badder or whatever. Everyone goes thru the mod stage....as I did. A lot of the folks will tell you it did something...but there's no scientific data to back it up. Regardless of what I or anyone else says, you'll probably go ahead and buy some mod that claims it's going to put 30 horses to your rear wheels...and hopefully you'll be happy with it. The best you can do is take good care of the car, keep it looking great, and revel in the compliments you get. Good luck....and I mean that sincerely. Chuck

[viper501]

I did a set of stainless headers *only* because I was able to find a nice set on ebay that were less than 300 shipped. I was a bit skeptical of the quality at first but was impressed when I examined the welds in person. They bolted up and fit perfectly. The engine seems a little brighter and sounds a lot more throaty. That said, I wouldn't expect any big HP increases out of them or any other header. There just isn't a whole lot to do with the header on these cars. While I disagree that the factory header is well engineered, it certainly is not 'badly' engineered.

[every day]

I'm considering a change as well and here's the text of an email I got from a shop I trust. My car's actually there right now getting some other work done...

http://www.gmgracing.com/tuning.shtml

In terms of exhaust here is what I recommend.

Mufflers make very little power mostly sound ( 5-7bhp) Cargraphic $2300.00

High flow cats- cargraphic 200 cell obd2 compliant ( 15hp) Cargraphic $2600.00

Exhaust manifolds help the power band come on sooner and fall off later ( 5hp) GMG 1900.00 Cargraphic $2300.00

[viper501]

With those prices, you may as well get a supercharger and get some real power.

[Chuck Jones]

Good God man....with those prices, sell your car and use the money towards a twin turbo.

[wdonovan]

You don't buy a Porsche to hotrod, you buy a Corvette. You can get parts for it. The parts don't cost $300 per HP. For $4000 you can put an extra 150HP in an LS1. For $7500 you can take the stock 350 to about 700.

An observation on headers. There was a discussion elsewhere on the web about Ebay headers. Dyno sheets showed a loss over stock 996 headers. Of course other buyers of these headers could "feel" the increase. Don't know about you but I can't feel 20 HP. Don't know anyone who can. Often when a car feels faster, it's slower. Feels slower.... could be faster. It's all in the power curve. Max dyno number mean nothing compared to the curve. Here's something to think about. Power to weight ratio. At 320HP and 3200 lbs. my 996 has roughly .1 HP per pound. To keep the same power to weight (and same acceleration) with 340 HP, you'd add 200 lbs. Anyone here feel there car accelerate slower when carrying a 200 lb. passenger?

[viper501]

Donovan, regarding the ebay headers, if you are referring to the thread where the guy did a before and after dyno IIRC he had the gasket on backwards and realized it after he yanked them off. Seeing that he'd fubared the install, he reinstalled the headers (correctly) but never reposted his dyno results.

My point about the headers, and other N/A mods is that there really isn't a whole lot to be gained by them. A few ponies under the curve here and there but nothing remotely near the standard $$ investment from our high margin aftermarket suppliers. Those boys are eating very well when the P-Car community is paying ten to fifteen times the costs of manufacture.

[wdonovan]

Vipe, I'm with ya all along. My point is ditto as your point.

The Ebay headers..... the guy did repost and said he flipped the gaskets and dynoed again, and it was still down, maybe 11HP.

I think even a turbo is not cost effective. Four to seven grand can buy a lot of NO2.

[ldfelix]

Vipe, I'm with ya all along. My point is ditto as your point.

The Ebay headers..... the guy did repost and said he flipped the gaskets and dynoed again, and it was still down, maybe 11HP.

I think even a turbo is not cost effective. Four to seven grand can buy a lot of NO2.

I happen to be in the same PCA club with Marc Reviel who owns http://www.turbowerx.com/ . He tested out a set of his new headers on my 996 and did before and after dyno tests at the wheels (where it counts). I noticed a few benefits and would suggest the upgrade. I had a bit of a power dip in the 5600-6600rpm range and the headers knocked that right out. I felt (seat HP) the improvement and think that if you know your car, you'll be able to tell even subtle differences. In my case I noticed a bit of power along the whole range. I dont work for the company but I am a believer. And at $800, it's far cheaper than other headers. I can say without any doubt this is a worthwhile upgrade.

All that and it's very shiny.

[wdonovan]

Sorry but I don't believe in seat-of-pants HP. I've been involved in drag racing for decades and many times when it "feels faster" it's slower, "feels slower", guess what.... best run of the day. What did the dyno say?

BTW It counts at the flywheel too <LOL>

[Izzy]

Donovan,

So you don't buy the Butt-O-Meter measure tool? Me neither, but follow the link above the picture, has the dyno test in the website. I did, and it looks like max peak 20 hp gain at some point above 5K rpm. But for the rest of the powerband is closer to 4-5 hp (hard to read graph) increase, sometimes 10. What the dyno test did not cover is if the mufflers or intake where also modified or not, which could make a bigger difference.

[wdonovan]

Verrrry interesting. This graph shows the huge "power dip" that Idfelix describes. This dip is (maybe intentionally) omitted in any Porsche documentation of the 996 engine. I suspect they oversmoothed the data to eliminate it. More than a dip, the HP actually flattens then climbs again starting at 6000 RPMs. This is something that I can definitely feel in my 02 C4 Cab. Until I saw this graph, I was puzzled by this phenomenon.

If anyone's interested, this dip then recovery is typically caused by either intake tract, exhaust plumbing, or valve timing being mismatched where they are tuned for different peak power RPMs. The result is that the engine has 2 (or 3) different RPMs where it has the most volumetric efficiency (breathing ability). The most famous occurence of this was the old Indy cars (I think) that had different 2 different length velocity stacks. The practise was adopted to reduce the power dip between "happy" RPM ranges. The OEM header on the 996 is like a 3 pronged "F" where 2 of the 3 primary pipes are the same (effective) length but the 3rd is different. If I had to bet, I'd put this as the most suspicious cause of the dip. Installing an equal length header apparently clears it up providing the header is of other geometry that the engine likes.

[Chuck Jones]

I think Donovan explains it rather well....but the bottom line is that I don't believe that for the $800-1000 that you'll end up spending...that you'd get much more than "it feels so much better". With all the "stuff" I've done...I should have saved the money. Just buy an really nice muffler and it's going to sound so much faster...you'll love it.

After spending an inordinate amount of money chasing mod horsepower in my 99 996, I've come to what I feel is the inescapable conclusion that the best mod I can buy is a 996 Twin Turbo with the X50 package in it.

[phillipj]

Just wanted to add my own experience to this discussion.

I have a 99 996. It has GIAC chip, Fabspeed mufflers, cold air kit and K & N filter. All of these after market mods were done by the previous owner (So I didn't pay for them.)

After I got the car I fell for the hype of the headers and Cat bypass pipes for more claimed power. ( So I bought them.)

Lets just say that the car ran so poorly (with the Headers and bypass pipes) that I complianed to loudly to the manufacturer that I got my money back!

The car had lost it's low end torque and just wasn't fun to drive.

I tried it with just the headers, just the bypass pipes and both combined. It sucked. So I took them off.

On the good side.......

The mufflers are awesome but it is just for the sound (which I love.)

I have driven my friends bone stock 996 (and he my car.) We both agree that my car is quicker and has better throttle response.

I agree with the other that the money required for all of these exhaust mods is not worth it and the HP claims are silly.

I also agree to just enjoy the car and save your money for a GT3 or a Turbo if you want to go faster!!

Just thought I would try to save some people some money. Or if you have to have them look for a guy who has spent his money on them and has to sell the car and take the loss on the mods.

Phillipj

[c70Pete]

anybody try 200 cell cats... I hear that *is* a worthwhile upgrade and lets your engine rev faster beyond 4000 rpm....???

[aehsani]

I'm trying to get some input from anyone who has installed Race Headers on their 996. I have an 01', and I've been considering installing a set of Gemballa Race Headers. Some claim up to 30hp gains. Others claim around 5hp to the rear wheels. I already have high performance muffler system & Fabspeed intake, and chip. Just thinking headrs would complete the pieces. Any input would be welcomed.

Thx

Loren has addressed this issue very eloquently in his blog. You may wish to review this.

BTW, the claim "up to 30 hp" is really meaningless, as the purpoted gain encompasses the range from 0 to 30 hp. Having said that, I am aware that there are reputable tuners (RUF, Manthy and others) whose products can give a decent but modest gain in peak hp, i.e., 20-25 (perhaps even more) for the NA engines. In fact, the factory Porsche power kits for 996 increase the maximal hp by 20 and 25 for the 3.4 liter (which was not available in the US) and 3.6 liter engines (which was available in the US), respectively.

Please consider that: 1) these kits include multiple components that should work in harmony to acheive the targeted gain, and 2) they are expensive. It is unlikely that a single product can produce a consistent 20-25 hp gain in peak power, particularly WITHOUT a decrease in power in the low-mid RPM

[ldfelix]

Donovan,

So you don't buy the Butt-O-Meter measure tool? Me neither, but follow the link above the picture, has the dyno test in the website. I did, and it looks like max peak 20 hp gain at some point above 5K rpm. But for the rest of the powerband is closer to 4-5 hp (hard to read graph) increase, sometimes 10. What the dyno test did not cover is if the mufflers or intake where also modified or not, which could make a bigger difference.

The car is actually bone stock. No funny business. On the low end there a smaller HP gain but I do notice it and it's stronger off the line. As far as peak HP, I dont run my car at 6K+ RPM all day so where the HP matters to me, that 4000-5000 range where I tend to do a good part of my foot mashing, it's an obvious difference. The before and after dyno image is a little small but the header did make a real difference and considering the price point, I've seen people pay a lot more for a lot less gain. I know that chasing HP leads people to buy things they dont need and for people who make products to claim results that just dont add up but you have to admit, there are some upgrades which simply allow the engine to add more power.