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Can X51 Plenum & Intake manifolds be retro-fitted or has anyone do

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Hi there

First things first I have a 2006 C2S and it already has X51 manifolds, PSE, Centre Radiator kit, X51 undertrays etc.

I now want to add:-

X51 Intake manifolds

X51 plenum

X51 Throttlebody

X51 carbon intake

Other stuff required, sleeves, hoses, tank vent hose etc.

This will give me pretty much the full kit all I shall be missing is the cylinder heads which are pointless as Porsche did so little to them and changing these turn a 4-6hr job into one two to three times longer, making it a lot more expensive.

I can do the above for about $4500 cost in parts and can do the installation myself, as I am capable with such stuff.

But when I look at images of the X51 intake design and standard I see a problem, check these images:-

Stock Engine Varioram design



X51 Engine - Varioram deleted



My Questions

So this question is to those out there who know how these engines work:-

1. Would installing the X51 plenum/Intake manifolds throw a CEL/Check engine light as its essentially deleting the Varioram, as I believe the stock none X51 design has butterflies/secondary plenum to help torque, wheras the X51 design deletes this. Can anyone confirm this or will it all run OK on the stock map without any check lights?

Obviously getting the X51 map would be ideal to get maximum potential from the added components.

2. Is any modification to the DME/Pins required if installing the above, I've looked at the X51 installation guide and not come

across anything, but I don't know the ins and outs of how these engines work. Here is the installation PDF if anyone wants to download and view it:-


If anyone knows the answers to my questions or can put me in touch with someone who has done this or knows what is required it would be hugely appreciated, if its a case of it will no way run on the stock map without throwing CEL's then I need to see if Porsche would be willing to load my car with the X51 map for a free or a fair charge. I am buying the parts from US and Germany as they are vastly cheaper than buying from UK. Shame the UK is so expensive really, its crazy I can buy it from the USA and Germany and its more than half the UK price even after adding shipping / taxes.

Thanks in advance :)

P.S. I could just get an IPD competition plenum/GT3 throttlebody as many are running this on stock map without issue, but that is goodbye warranty! Its also obvious the X51 plenum and intake manifolds are a big factor in the improved horsepower. I've asked Porsche the above questions and they are unsure is the answer. Obviously someone will know its just asking the person knows.......

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X51 cars have different camshafts and valvetrains too, so without that your dollar to horsepower advantage may be very low. As you have a bottle neck. Also, these 3.8 motors have design weaknesses in cooling, hence why the X51 needs the extra radiator, its because when they bored the 3.6 engine out to the 3.8 the coolant passages got smaller. And Porsche went cheap and went from left and right dependent head gaskets with coolant holes sized differently to control the amount of coolant that each cylinder received, to a generic head gasket that fits both sides, with coolant holes all the same size. Add that to the bad design of putting the oil squirters on the bottom of the pistons instead of the top where gravity can work to cover the whole piston, and you get a motor with some serious weak points. Increasing the horsepower just exacerbates the problem. Make sure and change out your thermostat to a cooler unit too. You want to keep these motors as cool as possible, and I would maybe even add an additional oil cooler too if you're going to increase the power. If your motor has over 25,000 miles on it, Porsche says that the Crankshaft Main Bearing and the connecting rod bearings MUST be replaced, and the cylinders need to be inspected for the above mentioned cylinder scaring and connecting rod Bushings scaring before installing the X51. I think too that the MAF plugs are different, and the DME plugs are different, and the DME has to be completely reprogrammed, Porsche even goes so far as to give it a new part number when they're done. Its a bold undertaking for sure. Good luck!

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