Arke

Hi,

Iam fotis from Germany and a new member in this forum.

I currently have a convertible .01 996 C4 and a .08 Mini Cooper JCW.

Two weeks ago I went and did an ecu tune on my 996 and did a week later a Dyno run.

The Porsche made 276 hp at the flywheel and 325 Nm of Torque. The power at the wheels was around 235 hp. The Dyno used was a Dyno Jet. I can post the Dyno sheet too.

The problem is that my Porsch has eBay headers😅, high flow cats and a pipercross air filter and didn't even achieve the stock power figures.

The car currently has 127k km on the clock and the engine is at an excellent condition. No ims bearing fail or any oil leaks. It also runs great.

The car did run good/better with the hardware at the stock tune and was noticeably faster and more torquey after the tune.

Does someone now where this loss of power originates from? I suspect that the mafs sensor is the culprit.

The dyno is very accurate. I also measured my mini there and it made as the manic stage 2 map predicted 271 hp. Yeah my mini is faster than my sports car😅.


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Arke

Does no one has a suggestion?

Slakker

Ditch the eBay headers. What brand is the cat? There is some performance to be had there but not a lot. There is so much you can do to these cars to increase the enjoyment but HP upgrades are not one of them.

Arke

The cats are from magnaflow. Sure a n/a engine can't achieve much power trough performance mods, but we are talking about 30 hp less than the factory numbers even though the car got faster...

JimmyB

Sounds like you're in the right ballpark to me:

https://jalopnik.com/i-dyno-tested-m...les-1788130306

I wouldn't worry about the numbers - just enjoy driving the car

Slakker

My stock '99 is 245rwhp. So you aren't as far off as you think. My track car with stock headers, cat delete and magnaflow race mufflers was 265rwhp.

DBJoe996

2001 C4 brand new was rated at 296 HP, but I don't know where that was measured, i.e., engine, engine transmission, or at the wheels. It is logical that HP at the wheels would be less due to drive train losses. Actually, I don't think you are doing too bad at 235 HP at the wheels for a 17 year old car (you didn't state mileage which is also a big factor). As said, maybe ditch the ebay headers and get some real headers. However, HP gains are difficult to gain with these engines.
https://www.excellence-mag.com/resou...3#.WuieU5ch1hE

Arke

The mileage is around 79k miles, sorry I wrote it as kilometres. I knew that the Porsche have lower power ratings but I didn't expect it to be that low. Well the car drives good and I enjoy it. If everything is ok with the engine as you stated it, I wouldn't be happier.

Charles Navarro

What were the dyno figures before the tune? It's pretty hard to beat factory tune on these cars. We don't even flash the ecus when increasing displacement to 4.0 liters in most cases.

Arke

I can't tell you what it was before, but it definitely was 10- 15% less. I don't think it can be blamed at the age or the mileage because my daily has more mileage at a higher power per displacement ratio and still delivers the power numbers it supposed to do. I think Porsche is cheating on the power figures quite a lot.

Arke

I also run the car on the best premium fuel available in Germany. At an American rating it should be like 95 Ron.

Noz1974

I heard running the 3.8s manifolds is a lot better than the after market stainless types you get on eBay , I've got the stainless on mine at the moment and it's on my list to swap for the 3.8 s
Manifolds!

Arke

Sounds good. Are this the manifolds from the 997? Or the GT3 996?

Horsepwr

My guess is Porsche advertises the HP at the flywheel, you are measuring it at the rear wheels and this creates a big difference...

Charles Navarro

There is a difference in how they measure. I believe they use flywheel horsepower and DIN ratings, not SAE. DIN read higher than SAE and the % figure for drivetrain loss can vary on who you speak to. One of many reasons you might see a difference. Also, depending on the dyno, how it's strapped down, and other variables, the numbers can vary greatly from car to car and day to day.