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tuning jtd - cam lift and duration and head porting.

Has anyone or does anyone know what the standard jtd cams are in terms of lift and duration.

Anyone had them re-ground?

Anyone done any head work for flow?

Just got to thinking, what makes the BMW diesel so good? especially with its broader rev band - and engine that revs past 5k, responds to a remap very well and without smoke, even with the dpf removed.
Is it the cam profiles that allow it to rev so well? (the power does start a little later than the jtd)

I know the usual turbo nutters route is fmic, big turbo, remap, perhaps clean up some smoke with water/meth etc etc, but has anyone ever played with cams and head porting?
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Doesn't the BMW diesel run much higher boost?
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Quick search shows some of the newer 177hp 2.0 ran 1800bar rail and the latest are 2000bar and piezo injectors. So id guess the rail pressure before was similar to the jtd at 1500bar or 1600bar. Better injectors maybe im sure tribesman has posted a duration map for a bmw somewhere.
Cant find much info on the net tuning wise with real data.
I think the turbine i have in my turbo is from bmw spec the largest vnt17 at 43mm inducer and 39.5mm exducer, this probably helps a fair bit.Seems they run 1.2-1.3bar boost standard.
Found no cam data.
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The BMW has far better designed bowls in the pistons..
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Cam tuning will be better for N/A tuning.
If more power is needed bolting on a far larger Turbo will dish out much better power.
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Quote:
Originally Posted by jasons View Post
Has anyone or does anyone know what the standard jtd cams are in terms of lift and duration.

Anyone had them re-ground?

Anyone done any head work for flow?

Just got to thinking, what makes the BMW diesel so good? especially with its broader rev band - and engine that revs past 5k, responds to a remap very well and without smoke, even with the dpf removed.
Is it the cam profiles that allow it to rev so well? (the power does start a little later than the jtd)

I know the usual turbo nutters route is fmic, big turbo, remap, perhaps clean up some smoke with water/meth etc etc, but has anyone ever played with cams and head porting?
Imo, the 2 basic factors to achieve this are:
- enough air, so turbo capable of high flow at high rpm
- enough fuelflow, high inj pressure and/or large nozzles

I tried a C&B cam on my JTD 8v a few years back, it did make a difference in airflow at high revs but very small, only about 1-2%.

Ofcourse head flow of the BMW could be better, meaning that at the same boost pressure (measured in the intake manifold) the result is more mass flow.
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Quote:
Originally Posted by JS JTD View Post
Imo, the 2 basic factors to achieve this are:
- enough air, so turbo capable of high flow at high rpm
- enough fuelflow, high inj pressure and/or large nozzles

I tried a C&B cam on my JTD 8v a few years back, it did make a difference in airflow at high revs but very small, only about 1-2%.

Ofcourse head flow of the BMW could be better, meaning that at the same boost pressure (measured in the intake manifold) the result is more mass flow.
Only 1-2% air flow gain with C&B cam?Do you have data logs after and before? I'm going to upgrade the camshaft with 272 C&B , my car is overfueled at hig rpm 4000-5000 when w/m is on but the performane is only 1-2% more flow is a waste of tim e and money
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What did you expect? +20%?

This is the same tuning NA engine... a lot of investment for small gains.
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8V head seems to be choked on the exhaust side, so you can await bigger gain (than those 1-2%) with additional mods. I'll tell you in few weeks :-)
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Quote:
Originally Posted by JS JTD View Post
I tried a C&B cam on my JTD 8v a few years back, it did make a difference in airflow at high revs but very small, only about 1-2%.
1-2% more MAF measured airmass, not considering the additional airmass in exhaust gasses reentering the cylinder in those 49 of both valves opened (inlet valves opens 28 before TDC, exhaust closes 21 after TDC. So in real you can run a bit richer mixture than before.

Also you tried it with stock turbo, JS JTD. With bigger turbo (with lower backpressure), the MAF measured airflow would be even more higher.

Last edited by yan.ko; 05-09-12 at 08:18.
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Quote:
Originally Posted by yan.ko View Post
1-2% more MAF measured airmass, not considering the additional airmass in exhaust gasses reentering the cylinder in those 49 of both valves opened (inlet valves opens 28 before TDC, exhaust closes 21 after TDC. So in real you can run a bit richer mixture than before.

Also you tried it with stock turbo, JS JTD. With bigger turbo (with lower backpressure), the MAF measured airflow would be even more higher.
That is ofcourse true. With a bigger turbine it's possible to achieve the crossover effect (intake pressure higher than exhaust backpressure) and cylinder filling can increase with higher overlap.
Therefore I'm curious what the C&B cam does with a GTB2056v unit. Can you determine the actual difference or did you make more modifications at once?
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Unfortunately I did more mods at once (on head and plenum).
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