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  1. #1
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    Turbo Cylinder head setup

    http://performanceforums.com/forums/...-cylinder-head

    Excellent thread from the best head guy in the country.

    Thought it was relevant considering the N54 head thread Click here to enlarge
    @Sticky you might not like what he says about factory high-po NA heads for turbo cars though Click here to enlarge
    boop

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    ported heads is something that is so overlooked in the enthusiasts realm, when people start modding they automatically get scared of head porting because it sounds too expensive and risky etc... IMO before any turbo work should be done, the heads need to get attention first, head porting is so important if you want to take your car to the next level, especially with the asthmatic N54 heads.
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    ported heads is something that is so overlooked in the enthusiasts realm, when people start modding they automatically get scared of head porting because it sounds too expensive and risky etc... IMO before any turbo work should be done, the heads need to get attention first, head porting is so important if you want to take your car to the next level, especially with the asthmatic N54 heads.
    Exactly

    The only numbers i can find, from dzennos head, show pretty huge gains, especially on the intake side.. And i wouldn't assume it's maxed out on the exhaust either. Coupled with that VAC dyno, just more proof.

    dollar for horsepower, there's far worse things people do... Just the head porting + valvetrain (if going there) does cost a fair whack of cash in one hit.

    stock turbos, sure, the housings are so tiny.. on one hand, you want to help them out every little bit, and like it's said in that thread.. any way you can reduce losses on either stroke help power production.. on the other, the path from head to manifold still flows more than the exhaust housing can.

    Ported heads with big boost singles.. Can't wait to see. By not doing it, it looks like you're leaving as much as what.. 8-9% power on the table.
    boop

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    Probably more than 8-9% from what I have seen with the N54 engine. I owned a 135 for 3 years that had basic bolt ons and chip and the car made a ton of power, the problem is it never really had that ass kick up top, even with a big turbo the heads are going to kick and scream past 6000 RPM.

    In fact pressure drop is inversely proportional to the FIFTH power of the diameter. So any increase in flow area of the ports will greatly reduce backpressure (by many many times, it is not one for one, more like one for thirty two if you double the flow diameter for example).

    Head porting also needs to be done by a professional who understands the physics of compressible flow at high speed, flow direction change, flow diffusion (expansion through a duct) and surface roughness all play a part in fluid delivery from the manifold to the cylinder.

    Dollar for dollar head porting will net you more gains for the N54 then an intake or mufflers, people just dont want to do it for some reason.
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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Probably more than 8-9% from what I have seen with the N54 engine. I owned a 135 for 3 years that had basic bolt ons and chip and the car made a ton of power, the problem is it never really had that ass kick up top, even with a big turbo the heads are going to kick and scream past 6000 RPM.

    In fact pressure drop is inversely proportional to the FIFTH power of the diameter. So any increase in flow area of the ports will greatly reduce backpressure (by many many times, it is not one for one, more like one for thirty two if you double the flow diameter for example).

    Dollar for dollar head porting will net you more gains for the N54 then an intake or mufflers, people just dont want to do it for some reason.
    Yeah, 8-9% was a guesstimation from the VAC thread numbers/graph.. 10% would be pretty spectacular - dyno at 700whp, swap head, dyno at 770 + rev higher for better in-gear. practically a bargain haha

    well at these 700+hp, there's probably GOOD gains to be seen with muffler/catback, unlike with the stock turbo power levels/RPM's... but yeah, near zero if not zero, otherwise. I've seen threads where evo's, 2j's, skylines, all wondering why they're not making more power.. to find out their muffler was the restriction, or something like that.

    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Head porting also needs to be done by a professional who understands the physics of compressible flow at high speed, flow direction change, flow diffusion (expansion through a duct) and surface roughness all play a part in fluid delivery from the manifold to the cylinder.
    yep, the more technical talk in the linked thread should highlight to everyone just how complicated it is/how important it is to have an experienced professional at it.. sure you physically could port your own head, and probably see SOME gains at certain lift, and if you're careful, not break things... but experience is the difference between 5hp and 50hp... plus the fact you can't do valveseats/multi angle valve jobs at home realistically.

    looking through TK's other threads, there's some where he's done the full build, and the calculations/simulations involved are intense and very comprehensive... working out to sacrifice some high lift flow for MUCH more midrange etc.
    boop

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    I wish more people would get off their asses (mine included) and talk to some shops. It really doesn't have to cost a fortune to see decent gains. New valves, springs, retainers etc is going to set you back but aren't always required. Shops that know a little about porting just to touch up a few areas and to concentrate on the valves and seat area will get gains. I've spent plenty of time in performance and machines shops (from old school race V8's to multi valve engines) and most agree that the valves and valve area work gains the most. While a nice port job can be critical on NA race engines the gains are no where near as impressive on a boosted engine. Surprisingly I've heard some of the best porting shops could be at a local 2 stroke offroad shop, there porting is a cross between art, science and black magic where every single HP is a huge gain when your sitting on 300 lbs.
    2008 135i - Cobb AP, JB4 G5 w/2Step&FSB, MS DP's, Berk street exhaust, AMS IC, VTT Inlets, UR Intake, ER CP w/Tial BOV, Spec 3+ & Steel FW, CDV delete, Quaife LSD, DSS Axles, M3 control arms, M3 rear SF bushings, M3 Trans bushings, SS brake lines. Pics

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    brusk - I am told with the right engine, decent cams and sturdy rods and bearings with boost and decent fueling a great engine will produce remarkable whp and whtorque nos
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    Click here to enlarge Originally Posted by brusk Click here to enlarge
    . While a nice port job can be critical on NA race engines the gains are no where near as impressive on a boosted engine.
    you CAN see incredible gains on a boosted engine though, it's just completely different to NA porting. 10% power gain is pretty good to me haha.

    it's not even really enough to get a shop that's good at porting, you have to get a shop that's good at porting BOOSTED motors.

    I've tried contacting local shops, but they all close at 5 (even the ones only 20-30 mins away from work, i can't get to) and i work WAY after 5 most days...

    I want to send my head to TK, but again, hard to get in contact with, doesn't reply to PM's on forums.
    Last edited by Flinchy; 05-23-2014 at 02:31 AM.
    boop

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    On my spare motor, I will be having head work done to it. It won't be ready until next year since I've already used up my mod money for this year (BT) Click here to enlarge My builder expects decent gains from looking over the head upon initial inspection. This will be first N54 based motor he's worked on, but he has extensive experience with LSX cigarette boat race motors.

    Hopefully I will have some solid gains to talk about combined with my single turbo setup.

  10. #10
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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    you CAN see incredible gains on a boosted engine though, it's just completely different to NA porting. 10% power gain is pretty good to me haha.

    it's not even really enough to get a shop that's good at porting, you have to get a shop that's good at porting BOOSTED motors.

    I've tried contacting local shops, but they all close at 5 (even the ones only 20-30 mins away from work, i can't get to) and i work WAY after 5 most days...

    I want to send my head to TK, but again, hard to get in contact with, doesn't reply to PM's on forums.
    That's 10% for port and valves though right? I'd like to see the gains between full port and valve job vs just a good valve job.
    2008 135i - Cobb AP, JB4 G5 w/2Step&FSB, MS DP's, Berk street exhaust, AMS IC, VTT Inlets, UR Intake, ER CP w/Tial BOV, Spec 3+ & Steel FW, CDV delete, Quaife LSD, DSS Axles, M3 control arms, M3 rear SF bushings, M3 Trans bushings, SS brake lines. Pics

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    Click here to enlarge Originally Posted by brusk Click here to enlarge
    That's 10% for port and valves though right? I'd like to see the gains between full port and valve job vs just a good valve job.
    maybe someone could get both done, but flow bench done after the valves are done, but before the porting?

    that shouldnt be too much to ask i guess?
    boop

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    from headflow thread there is alot more than 10% hiding in the N54.

    flinchy you gotta ring him and he will get you to send it down and then youll be in the queue.....

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    I'd really love to see some serious valvetrain upgrades like lighter valves and bigger cams, rev this $#@!er out too 9000 RPM. Problem though is the N54 has a terrible piston/rod ratio and the piston speed at that engine speed would be very high. I do remember seeing a thread where a guy accidentally put his car into 2nd gear instead of 4th and brought it up to 9300 RPM Click here to enlarge stock motor
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    i wouldn't worry about rod ratio its not going to save the bottom end in that scenario a 5mm longer rod wont alter peak piston g's enough, the S54 strokers are worse for rod ratio.
    Only built engines would be looking to those rpm not those with stock bottom end and weakness would be addressed then

  15. #15
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    ^yeah, as long as it's balanced right.. lighter pistons etc. .. i'd say 9000+ is a bit of a pipe dream, and at that point the stock injectors likely won't keep up anyway

    8k, though..

    i've accidentally taken my N52 to a hair over 8k a few times haha

    Click here to enlarge Originally Posted by digger Click here to enlarge
    flinchy you gotta ring him and he will get you to send it down and then youll be in the queue.....
    yeah just a pita to get on the phone in business hours -_-.. i'd expect a couple month wait with him haha.
    boop

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    I would love to see the N54 breath up to 8k, I don't even know if this is physically possible due to the heads. If you just cannot port the heads due to water jackets, or bolt holes being in the way of the port, you just wont be able to use the heads past a certain limit. I wonder what that size limit is for this head. The N54 has been out for 7 years now and we still dont really know, do we??? Anybody?
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    Can't see why not, dzenno's heads flowed over 30% more intake, something like 12% more exhaust.

    that can't ALL be in the valve job?

    no, no one knows except businesses like VAC. 2014 seems to be year of fuelling and breathing lol.
    boop

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    VAC's pricing is very very high for what they offer. A DOHC head is a DOHC head. Shop around, folks.

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    Click here to enlarge Originally Posted by Dietcoke Click here to enlarge
    VAC's pricing is very very high for what they offer. A DOHC head is a DOHC head. Shop around, folks.
    It's probably not more or not much more than a good shop will charge you for the same work (or better)

    $2k in parts (actual pricing of all valves, springs, retainers) leaves the VAC head having $2k in labour, and THAT part is maybe the part that's on the high side.
    boop

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    It's probably not more or not much more than a good shop will charge you for the same work (or better)

    $2k in parts (actual pricing of all valves, springs, retainers) leaves the VAC head having $2k in labour, and THAT part is maybe the part that's on the high side.
    His original statement stands Click here to enlarge That's VERY expensive.

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    Click here to enlarge Originally Posted by Sered Click here to enlarge
    His original statement stands Click here to enlarge That's VERY expensive.
    heh, true, not cheap. gotta pay to play regardless though.
    boop

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    Click here to enlarge Originally Posted by Dietcoke Click here to enlarge
    VAC's pricing is very very high for what they offer. A DOHC head is a DOHC head. Shop around, folks.
    VAC who refuses to give flow numbers or tell us what the head can safely rev out to. And the crappy dyno they used they didn't even rev out the stock head which just makes the gains seem that much more questionable. As they don't mention oversized valves I assume they are just stock size when Dzenno fit larger which I would have to assume is part of his gains. Screw that option.
    E92 Bren Tune / E90 PTF Tune / E70 Twin Turbo Diesel JBD

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    Click here to enlarge Originally Posted by Torgus Click here to enlarge
    VAC who refuses to give flow numbers or tell us what the head can safely rev out to. And the crappy dyno they used they didn't even rev out the stock head which just makes the gains seem that much more questionable. As they don't mention oversized valves I assume they are just stock size when Dzenno fit larger which I would have to assume is part of his gains. Screw that option.
    yeah, for a company that has a strong reputation for being at the top in this game, they're not doing anything in their favour.. almost purely relying on 'we offer this and... WE'RE VAC Click here to enlarge'

    VAC does +.5mm valves, which, i just realized, actually makes their head even worse value, because their $4k price doesn't include new seats, where the $4k price (or less) from anywhere else includes +1mm and new seats to suit... even if it's marginal, half a millimetre matters.

    i'm glad you agree with me re:revving out on stock head.. then claiming a certain 'delta' which isn't quite reality. their stock dyno was flattening but was not YET flat.
    boop

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    Click here to enlarge Originally Posted by Torgus Click here to enlarge
    VAC who refuses to give flow numbers or tell us what the head can safely rev out to. And the crappy dyno they used they didn't even rev out the stock head which just makes the gains seem that much more questionable. As they don't mention oversized valves I assume they are just stock size when Dzenno fit larger which I would have to assume is part of his gains. Screw that option.
    There is no 'safely rev out to' such a thing does not exist. The RPM capability of the head is limited by valvetrain weight and stability, as well as boost pressure. The more boost, the less effective the valve springs are at controlling the valves. Either way the simplest solution is to add a stiffer spring or shim whats already in there. Top end RPM is a non-issue to be honest.

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    Click here to enlarge Originally Posted by Dietcoke Click here to enlarge
    There is no 'safely rev out to' such a thing does not exist. Top end RPM is a non-issue to be honest.
    This guy here lol.
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