A failed oil pressure relief valve was the impetus for falling far down the slippery slope known as "while I'm in there." Given the Duratec's lack of a keyed crank which makes timing the cams a PITA with the engine in place (or out for that matter), any job that involves removing the front cover is best done with the engine removed. Since the engine was coming out to access the oil pump I thought it was a great opportunity to key the crank and address this shortcoming. Logic dictates that if the crank is coming out the bearings should be refreshed, and if bearings are being refreshed it would be foolish not to also upgrade the rods and pistons. Of course why upgrade the rods and pistons, if I don't take advantage of the increased valve clearance that change affords and install more aggressive cams with greater lift and raise the redline? If raising the redline is an objective, then the bottom end should really be balanced, right? Lastly, why go to that much trouble and not replace consumables that are easy to access now, but much harder later like seals, gaskets, water pump, and clutch slave cylinder? Like I said, slippery slope.
Cam selection was a struggle. I'm not looking for big power and don't want a really soft bottom end, but those requirements seem to elicit suggestions for a 2.3L -- more torque than I want -- or assurances that radical cams capable of 290hp are "perfectly fine down low."
The table below shows how the various options under consideration compare. Cams that were DTEC10 equivalents, and any cams intended for at least 260hp were ignored. Given how much better the intake side of the Duratec head flows, a symmetric setup intuitively seems like the wrong approach. Kent, however, has staunchly adhered to that philosophy while everyone else has not; SBD, Piper, Cosworth, Crane and even the stock Ford cams have less lift and/or duration on the exhaust side.
Interestingly, Kent does time the two sides differently, but then again, the timing differs wildly for all of them. The DTEC35 gains it's advantage over the DTEC20 purely in overlap. Both setups have the least overlap and the most intake advance which are both good for low-mid range torque. The Piper has a lot more lift and duration on the intake side, and a lot less advance, but the exhaust has less lift than the Kent and just a bit more duration and advance. It also has a lot of overlap which means more potential idle and emission issues as well as more focus on the top end. The SBD has the most lift and duration on the intake side, ties for the most lift on the exhaust side, and has the most duration there as well. Overlap is in the middle, but leaning more towards the Piper.
Intake Exhaust
Cam selection was a struggle. I'm not looking for big power and don't want a really soft bottom end, but those requirements seem to elicit suggestions for a 2.3L -- more torque than I want -- or assurances that radical cams capable of 290hp are "perfectly fine down low."
The table below shows how the various options under consideration compare. Cams that were DTEC10 equivalents, and any cams intended for at least 260hp were ignored. Given how much better the intake side of the Duratec head flows, a symmetric setup intuitively seems like the wrong approach. Kent, however, has staunchly adhered to that philosophy while everyone else has not; SBD, Piper, Cosworth, Crane and even the stock Ford cams have less lift and/or duration on the exhaust side.
Interestingly, Kent does time the two sides differently, but then again, the timing differs wildly for all of them. The DTEC35 gains it's advantage over the DTEC20 purely in overlap. Both setups have the least overlap and the most intake advance which are both good for low-mid range torque. The Piper has a lot more lift and duration on the intake side, and a lot less advance, but the exhaust has less lift than the Kent and just a bit more duration and advance. It also has a lot of overlap which means more potential idle and emission issues as well as more focus on the top end. The SBD has the most lift and duration on the intake side, ties for the most lift on the exhaust side, and has the most duration there as well. Overlap is in the middle, but leaning more towards the Piper.
Intake Exhaust
Value |
Cam Lift (mm) |
Duration |
Full Lift at TDC |
Cam Lift (mm) |
Duration |
Full Lift at BDC |
|
Stock Mondeo |
9.87 |
256 |
8.45 |
252 |
|||
Kent DTEC10 |
10.46 |
260 |
110 |
10.46 |
260 |
105 |
|
Kent DTEC20 |
11.27 |
268 |
110 |
10.27 |
268 |
105 |
|
Kent DTEC35 |
11.30 |
280 |
108 |
11.30 |
280 |
106 |
|
Piper BP285 |
11.93 |
296 |
102 |
10.97 |
288 |
104 |
|
SBD DUR03 |
11.98 |
310 |
105 |
11.27 |
294 |
105 |
After speaking with lots of people and studying the lift and overlap differences between the options, I decided on the Kent DTEC20. It's a bigger step up from my current DTEC10s than those cams were to the stock Mondeo cams I ran for the first two years, which itself was a noticeable bump. And Kent was pretty blunt, telling me I would be unhappy with the bottom end of the DTEC35 as used in the R500. Although I question the symmetrical setup, they still seem the best option for my specific requirements. More to come...
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