400 at the crank is possible. My number was at the crank.

But whose dyno is correct! Everything I have heard about dynos is they can be as accurate as a Rain stick.

 

Looking at the Parts catalog online I see no different designations for X-51 versus Stock valve springs or valves.

If this is correct all Porsche did is port and polish the head.

 

There is no cams that I am aware of for the 3.8L, there are cams available for the 3.6L from Schrick. Schrik supposedly suppose to have some cams coming out soon. Contact FVD...they have the skinny on this.

Dave

 

The X51 head comes complete with the stiffer exhaust valve spring already installed on the head, hence no part number for it as the head is completely assembled when you get the kit. The valves are the same though.

Dave

 

Also thinking of X-51 headers. Do you notice much with GIAC?

Good luck

 

You broke my heart but I admite your honesty. Do you think CATS might release some of that power? Why didn't you swap those?

 

The reasons that cams aren't a popular quick modification are:

1) Cost
2) Time and special tools required to install
3) The need for a complete re-map - different cams totally change the ignition and fuelling requirements of an engine
4) New matching maps are rarely (if ever) available and any additional mods would make them redundant anyway
5) Driveability - cams tend to move the torque band further up the rev range
6) Given 5) above, the other mods to the engine (valves, heads, valve springs, cam followers etc.) to allow it to rev further safely
7) Different exhaust header requirements to match the new exhaust gas dynamics and altered peak torque and power points
8) Same for the inlet side of things

It's all rather more complex than just swapping cams! Have a look at 9ff in Germany, they offer crated engines with heads, valves, springs, etc. etc. (together with matching maps) up to 4.2 litres and 420BHP for the 997S.

Ian

 

Andre

There can be so many reasons for the disappointing result. One, as others have said is simply that the dyno was reading low - very uinrelaible devices in the wrong hands!

More likely is that the intake air temps and engine cooling temps weren't kept either properly monitored or controlled. Cooling flow over a car on a dyno is only a fraction of what the car gets on the road, no matter how many fans are used. Let these temps rise at all and the DME will immediately richen-up the mixture and pull timing to protect the engine. Result? Lots less power than you expect.

This article from Dinan (althought it refers to BMW) is definitive on this subject and applies equally to most modern cars.

http://www.dinancars.com/bmw/technia...ern-bmw-engine

Ian

 

Yes. Cats add HP they are probably the most restrictive part of the exhaust. I have AWE Headers and Cats with the stock muffler. I had the AWE Mufflers on but they were too loud for my tastes. With my set up I can listen to the stereo and still hear the engine.

Going under a bridge or through a tunnel at WOT is pure music with the windows down.

 

StrtSwpr996, how much have you spent , all together so far including the X51 Intake manifold?

 

I'm wondering since Porsche remaps the DME/ECU for the X51 engines if it is to work in conjunction with the X51 parts or a seperate performnace improvement all together or perhaps both?

It would seem to me if you are significantly changing the amount of air, fuel and or exhaust flow the DME/ECU should be remapped to be take advantage of the changes/enhancements.

 

That's fundamentally why it's re-mapped, yes. If you change the volume of mixture being burnt in the combustion chamber at a specific point in the engine's load/rpm range, the time for it to burn changes and the ignition timing needs to be altered to suit. An easy example of this is a car needing much more timing at part throttle for any given rpm than full throttle. The smaller, less-dense charge burns slower so must be ignited sooner to give best effect.

Other things in the remap are an increased rev limiter and doubtless some changes to the throttle map to work optimally with the bigger throttle plate.

Ian

 

Thanks for confirming this. I always thought that if I added all the X51 parts without the remap then I probably would not be realizing the full potential of the changes, correct?

 

I am really happy with the GIAC. Im sure none of us can actually feel 10 whp or even 20 whp and dynos are not always acurate so i decided to have a few runs with my friends modded M3. When i say Modded I mean pretty much any NA mod you can do to the car as well as light weight mods and 410 gearing. So we were dead even when I ran him before the GIAC, the next day I went and got it and ran him again... Easilyyyy walked him.. So i know it did something.

 

Well I havent gotten he X51 intake manifolds yet, I beleive i was told $432 a each? anyway, I think i probably spent around $2500 as far as performance parts goes.. I still plan on getting the x51 intake manifilods though aswell as some highflow cats probably AWE. BUt not really rushing into it just yet, Im thinking about routing a center exhaust GT3 style.