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  1. #1
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    Lack of high lift Schrick N54 cam results due to needing aftermarket pistons?

    The Schrick N54 cams have been out for some time but few results are posted and those that have been posted have been on built motor applications.

    I'm thinking the reason for that is if you go for the high lift cam spec you need aftermarket pistons or an engine build? This is due to the piston clearance I assume?

    Maybe someone like @alex@ABRhouston can clarify but that would explain a lot regarding the lack of results on stock internal N54's with cams.

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    I thought that josh guy has a stock bottom end with a built head? I could have sworn he has shricks. Jtswole his name on here is like jt05 or something

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    Click here to enlarge Originally Posted by daedoe Click here to enlarge
    I thought that josh guy has a stock bottom end with a built head? I could have sworn he has shricks. Jtswole his name on here is like jt05 or something
    Yeah but the question is which Shricks? The more mild profile works on the stock N54 internals I believe.

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    True... im trying to find the thread its on this board somewhere. @jt0407

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    Well I cant comment on a stock piston but...peak lift has nothing to do with PTV clearances. When the cam is at or near peak lift the pistons are halfway down the bore. PTV clearance issues come down to two things, one being duration, but to be more precise valve timing (specifically during overlap) and radial clearance which you would encounter going to larger oversized valves (pocket is deep enough but not wide enough).

    So to reiterate the overlap event is the only time when the valve is anywhere near the piston. This is when the exhaust is closing and intake is just starting to open. With vanos you could simply limit the overlap (actually maintaining same as stock) by advancing the exhaust and retarding the intake events each a few degrees where it is could be tight and in actuality the valve to piston relationship would be close to stock.

    Another way of looking at this is the often used term "interference motor". Our motor (stock) if it skips timing enough will bend the valves. So even our stock cams at or near max lift will hit the pistons if the timing is too far off.

    So with Vanos on a stock piston I would not worry the slightest bit with PTV personally if you go into the vanos tables and remove a bit of duration from the extreme ends of the exhaust and intake during the overlap event. I do have JE pistons in my build and did not compare the valve reliefs to a set of stock pistons so I couldn't say if there actually is a physical difference or not. I would personally be worried more about radial clearance if I went with oversized valves. My head guy suggested staying with the stock size valves to keep as much material in the seats as they are rather tiny and we were not doing much port work.

    I can tell you having finally gotten the time to get my engine running that the Schrick Hi Lift cams did not cause any Vanos faults or drivability issues whatsoever. I have even used them with the off the shelf JB4 BEF for single turbo twin scrolls while trying to trouble shoot some fueling issues I was having. Turns out THESE CAMS WORK! My new base tune could not keep up with the fueling and airflow that the new motor has seen. I made a base tune with vanos changes I felt were appropriate and the Trims were pegged as soon as it spooled, duty cycle is up and I had to make some LPFP changes. I barely get a few hours a week to work on it unfortunately so progress has been slow.



    Just my experience so far. In my research I did come across some stock shortblocks with these cams posted here and there so I suspect with proper vanos maps PTV is not a problem.

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    Click here to enlarge Originally Posted by ninjacoupe Click here to enlarge
    Well I cant comment on a stock piston but...peak lift has nothing to do with PTV clearances. When the cam is at or near peak lift the pistons are halfway down the bore. PTV clearance issues come down to two things, one being duration, but to be more precise valve timing (specifically during overlap) and radial clearance which you would encounter going to larger oversized valves (pocket is deep enough but not wide enough).

    So to reiterate the overlap event is the only time when the valve is anywhere near the piston. This is when the exhaust is closing and intake is just starting to open. With vanos you could simply limit the overlap (actually maintaining same as stock) by advancing the exhaust and retarding the intake events each a few degrees where it is could be tight and in actuality the valve to piston relationship would be close to stock.
    Ok so it seems Schrick recommends for whatever reason on certain high lift BMW cam options (which implies more duration) to not use stock pistons but VANOS tuning can address potential issues?

    What about when VANOS is deleted in certain applications? Pistons are a must then?

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Ok so it seems Schrick recommends for whatever reason on certain high lift BMW cam options (which implies more duration) to not use stock pistons but VANOS tuning can address potential issues?

    What about when VANOS is deleted in certain applications? Pistons are a must then?
    Yes, Vanos tuning can address the timing issues on these motors during overlap. If you locked out vanos and the cam timing was fixed then you are basically old school and claying the pistons to check ptv and either notching or using aftermarket pistons with deeper/larger reliefs.

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    What happened to the people that said BMW cam tuning was easy and anyone could do it?

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    Click here to enlarge Originally Posted by Sticky2 Click here to enlarge
    What happened to the people that said BMW cam tuning was easy and anyone could do it?
    I don’t know these people and I don’t think just anyone can change their own oil let alone mess around with cam timing events. There are people who make a living out of just that. I’ve only had a chance to work on some part throttle stuff and can tell you there are gains to be had with these. When I started on the WOT stuff I quickly ran out of fuel and needed to address my LPFP side of things. I don’t know how many sets of these cams are out in the wild or who has tuned them anymore than you have. I only know what others have posted but this platform doesn’t really welcome people who post experiences. Oddly enough it doesn’t seem as bad these days thiugh. Wonder what’s changed. I have some time Sunday to start turning up the boost and RPMs. I have company at the house the following week so my progress will be slow. I do have a dragy though so I’m looking forward to that.

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    1 out of 1 members liked this post. Yes Reputation No
    I would limit the phaser travel in any case if they have kits on the market just as a redundancy.

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    high lift cams will contact stock pistons, from what we've measured.
    We need to know if high lift cams are to be used before building the bottom end- we end up having to fly cut the pistons to create additional valve clearance.

    Messing with the vanos tables WILL get you in trouble- we've seen it first hand.

    A lot of people don't understand you shouldn't just throw cams in a head. Installed spring height, valve guide to retainer clearance, seat pressure and other factors go into a smooth running head.
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    Maximum intake valve lift usually occurs around BDC.
    Maximum exhaust valve lift occurs at TDC and can cause PTV issues.

    Obviously changing the timing events with VANOS will make this different and could cause PTV issues.
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  13. #13
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    Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
    Maximum intake valve lift usually occurs around BDC.
    Maximum exhaust valve lift occurs at TDC and can cause PTV issues.

    Obviously changing the timing events with VANOS will make this different and could cause PTV issues.

    i wonder if conversely changing the timing events could make ptv clearance better... I wish there was some way of knowing which way was what but this damn n54 is unlike any other engine ever built lol.

    What we we really need to know is what the sweep is during the vanos self check the car allegedly does.

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    Gut two Vanos gears, set up cam degree wheels on both and on crank, and measure em.

    It took me about 2 weeks of fiddling to see what I needed to see lol
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    Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
    Gut two Vanos gears, set up cam degree wheels on both and on crank, and measure em.

    It took me about 2 weeks of fiddling to see what I needed to see lol
    The ranges I have seen published in a few places, I was wondering about software wise if the DME does a full sweep on startup. A friend who was a Tech for BMW says yes. If that's the case then using Vanos timing to help with PTV wont work. Do you know what tables define that sweep on startup? Would a phaser kit as mentioned above cause a fault if installed on the system to physically limit the travel? More curiosity then anything personally.

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    A physical VANOS angle limiter/stopper should be used IMO. Stock VANOS can be advanced hugely for EGR but you don't need anywhere near that much for performance.

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    Click here to enlarge Originally Posted by ninjacoupe Click here to enlarge
    The ranges I have seen published in a few places, I was wondering about software wise if the DME does a full sweep on startup. A friend who was a Tech for BMW says yes. If that's the case then using Vanos timing to help with PTV wont work. Do you know what tables define that sweep on startup? Would a phaser kit as mentioned above cause a fault if installed on the system to physically limit the travel? More curiosity then anything personally.

    unless the table is adjusted, if the vanos doesn't go to the specified position, it'll toss a fault and limp home mode.
    A limiter may work, but if tables can be adjusted accordingly, then it wouldn't be needed.... but then you'd be back to the beginning of my sentence lol
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    Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
    unless the table is adjusted, if the vanos doesn't go to the specified position, it'll toss a fault and limp home mode.
    A limiter may work, but if tables can be adjusted accordingly, then it wouldn't be needed.... but then you'd be back to the beginning of my sentence lol
    The tables can be adjusted. The limiters are just a redundancy to potentially save your motor if something happens with the solenoids or oil pressure. But I haven't found where the cam's parked centerlines are yet.

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    Click here to enlarge Originally Posted by alex@ABRhouston Click here to enlarge
    unless the table is adjusted, if the vanos doesn't go to the specified position, it'll toss a fault and limp home mode.
    A limiter may work, but if tables can be adjusted accordingly, then it wouldn't be needed.... but then you'd be back to the beginning of my sentence lol
    I would never, ever depend on software only to not have a valve strike a piston. You just never know what type of self-learning or failsafe operation might cause it to go outside of what the main DME tables specify. You absolutely should have a physical limiter.

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    I have some sort of cams going in the motor Vargas out together for our 135i. Hopefully, the matching springs hold out. Click here to enlarge
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    Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
    I would never, ever depend on software only to not have a valve strike a piston. You just never know what type of self-learning or failsafe operation might cause it to go outside of what the main DME tables specify. You absolutely should have a physical limiter.
    I agree- what i was saying is the snake would be eating its tail if you didnt have software to control it w/ limiters.
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