Porsche Motorsport Division X51 PowerKit (320 PS/235KW)

X51 3.4 - Engine Upgrade Install Manual showing the difference in the engine parts.

Continued,

Very interesting- thanks.

Neil, if you want a copy of the install manual drop me a PM and I will e-mail over.

From what I have been able to find out the X51 heads are no difference flow wise than the standard 3.4 heads, you more than most will know that the standard 3.4 heads flow well and there are only very marginal gains to be had from porting, polishing etc.

The additional flow comes in via the revised cams and valves, lift and duration. - The pistons are the standard 3.4 pistons that have been reshaped slightly to allow for the additional valve lift.

I'd really like to take a look at some X51 heads to see what they did.

Mike has found more flow from the stock heads, so whilst they flow well there are improvements to be found.

Interesting to read that they used lash-caps first, then went to longer valves. Suggests that the very first cars were a "lets see if this works".

I'm guessing from the instructions that the head is shaved a little to increase compression - between that and the longer valves/higher lift* you can see why they had to machine deeper reliefs into the pistons.

*If the X51 cams were higher lift, that's an assumption.

As your aware info on the X51 heads & cams is very thin on the ground, in the end I gave up, I have fitted everything bar the heads and their contents and will perhaps revisit in the future.

Below is the only Cam info I could find, it may mean more to you!

996 X51

LIFT DUR. OPEN CLOSE AREA
Lobe I1a ----- ------ ----------- ----------- ------
Centerline 100.00 ATDC 0.006 305.12 55.73 BTDC 69.39 ABDC 35.97
.050 Lift C/L 99.44 ATDC 0.020 266.80 35.78 BTDC 51.02 ABDC 35.71
Runout 0.00190 0.040 243.92 22.68 BTDC 41.24 ABDC 35.37
Peak Open Acc. 0.000832 0.050 237.74 19.43 BTDC 38.31 ABDC 35.23
Peak Nose Acc. -0.000308 0.100 214.98 7.75 BTDC 27.23 ABDC 34.33
Peak Close Acc. 0.000905 0.150 195.02 2.29 ATDC 17.30 ABDC 33.04
Lift @ TDC 0.1387 0.200 174.83 12.39 ATDC 7.22 ABDC 31.22
Minimum Flat 0.250 153.74 22.96 ATDC 3.30 BBDC 28.80
Follower Dia. 1.1585 0.300 130.85 34.43 ATDC 14.73 BBDC 25.59
0.350 104.70 47.49 ATDC 27.81 BBDC 21.29
0.400 71.59 64.05 ATDC 44.36 BBDC 15.00
0.44550 --- PEAK CAM LIFT ---
0.44550 --- PEAK VALVE LIFT ---

996 Standard

LIFT DUR. OPEN CLOSE AREA
Lobe I1 ----- ------ ----------- ----------- ------
Centerline 100.00 ATDC 0.006 300.87 51.06 BTDC 69.81 ABDC 38.05
.050 Lift C/L 100.02 ATDC 0.020 267.36 33.92 BTDC 53.43 ABDC 37.84
Runout 0.00210 0.040 254.97 27.50 BTDC 47.47 ABDC 37.66
Peak Open Acc. 0.001801 0.050 250.57 25.27 BTDC 45.30 ABDC 37.57
Peak Nose Acc. -0.000866 0.100 230.06 15.05 BTDC 35.01 ABDC 36.80
Peak Close Acc. 0.002106 0.150 209.15 4.77 BTDC 24.39 ABDC 35.49
Lift @ TDC 0.1728 0.200 187.65 5.84 ATDC 13.48 ABDC 33.61
Minimum Flat 0.250 165.50 17.00 ATDC 2.49 ABDC 31.12
Follower Dia. 1.1369 0.300 140.78 29.43 ATDC 9.79 BBDC 27.71
0.350 112.79 43.44 ATDC 23.77 BBDC 23.15
0.400 74.72 62.67 ATDC 42.60 BBDC 15.98
0.44140 --- PEAK CAM LIFT ---
0.44140 --- PEAK VALVE LIFT ---



996 X51

LIFT DUR. OPEN CLOSE AREA
Lobe E1a ----- ------ ----------- ----------- ------
Centerline 106.00 BTDC 0.006 252.14 52.39 BBDC 19.75 ATDC 32.05
.050 Lift C/L 105.89 BTDC 0.020 239.76 45.99 BBDC 13.77 ATDC 31.97
Runout 0.00020 0.040 227.47 39.69 BBDC 7.78 ATDC 31.79
Peak Open Acc. 0.000896 0.050 222.40 37.09 BBDC 5.31 ATDC 31.67
Peak Nose Acc. -0.000314 0.100 201.14 26.33 BBDC 5.19 BTDC 30.89
Peak Close Acc. 0.001011 0.150 181.76 16.68 BBDC 14.92 BTDC 29.68
Lift @ TDC 0.0739 0.200 162.06 6.91 BBDC 24.84 BTDC 27.95
Minimum Flat 0.250 141.14 3.49 ABDC 35.37 BTDC 25.59
Follower Dia. 1.1943 0.300 117.67 15.14 ABDC 47.19 BTDC 22.36
0.350 89.54 29.16 ABDC 61.30 BTDC 17.78
0.400 48.40 49.71 ABDC 81.89 BTDC 10.01
0.42059 --- PEAK CAM LIFT ---
0.42059 --- PEAK VALVE LIFT ---

996 Standard

LIFT DUR. OPEN CLOSE AREA
Lobe E1 ----- ------ ----------- ----------- ------
Centerline 106.00 BTDC 0.006 342.75 61.74 BBDC 101.01 ATDC 34.39
.050 Lift C/L 105.51 BTDC 0.020 254.50 50.98 BBDC 23.52 ATDC 34.02
Runout 0.00150 0.040 236.61 43.51 BBDC 13.10 ATDC 33.76
Peak Open Acc. 0.000689 0.050 230.33 40.67 BBDC 9.65 ATDC 33.62
Peak Nose Acc. -0.000610 0.100 206.72 29.36 BBDC 2.65 BTDC 32.75
Peak Close Acc. 0.000640 0.150 187.51 19.89 BBDC 12.37 BTDC 31.55
Lift @ TDC 0.0877 0.200 168.35 10.32 BBDC 21.98 BTDC 29.87
Minimum Flat 0.250 147.96 0.03 BBDC 32.08 BTDC 27.57
Follower Dia. 1.2249 0.300 125.21 11.27 ABDC 43.52 BTDC 20.16
0.400 63.73 42.10 ABDC 74.17 BTDC 13.53
0.43700 --- PEAK CAM LIFT ---
0.43700 --- PEAK VALVE LIFT ---

I think it would make a lot more sense if formatted in a better way...

Lobe I1a ----- ------ ----------- ----------- ------
Centerline 100.00 ATDC
.050 Lift C/L 99.44 ATDC
Runout 0.00190
Peak Open Acc. 0.000832
Peak Nose Acc. -0.000308
Peak Close Acc. 0.000905
Lift @ TDC 0.1387
Minimum Flat Follower Dia. 1.1585

LIFT DUR. OPEN CLOSE AREA
0.006 305.12 55.73 BTDC 69.39 ABDC 35.97
0.020 266.80 35.78 BTDC 51.02 ABDC 35.71
0.040 243.92 22.68 BTDC 41.24 ABDC 35.37
0.050 237.74 19.43 BTDC 38.31 ABDC 35.23
0.100 214.98 7.75 BTDC 27.23 ABDC 34.33
0.150 195.02 2.29 ATDC 17.30 ABDC 33.04
0.200 174.83 12.39 ATDC 7.22 ABDC 31.22
0.250 153.74 22.96 ATDC 3.30 BBDC 28.80
0.300 130.85 34.43 ATDC 14.73 BBDC 25.59
0.350 104.70 47.49 ATDC 27.81 BBDC 21.29
0.400 71.59 64.05 ATDC 44.36 BBDC 15.00
0.44550 --- PEAK CAM LIFT ---
0.44550 --- PEAK VALVE LIFT ---

MC

11.3mm of lift?

I realize I am resurrecting an older thread here...but I recently found and purchased what I believe to be one of the X51 "Power Up" editions out of Japan. It is currently awaiting transport, I should be taking delivery sometime this summer. It is a MY2000 spec'd with the X51, M030 suspension, factory AeroKit, sport seats, XRL Sport Design wheels, etc. It looks exactly like the car in the brochure GT4 posted on this thread. It has some nice carbon/aluminum interior bits as well.

I am looking forward to receiving the car and found this thread to be a wealth of information. If anyone has any related documentation/files they can forward it would be appreciated.

Sorry to resurrect the thread but i've got one of these X51 equipped 3.6 c2's and this has been very interesting reading!

Blimey. Imagine paying £8725 in 2000 (£15,875 today) for +20hp! Yeah it comes with upgraded cooling + lubrication.. but still