100WHP by installing an N52 exhaust cam in an N55.

Bnks334

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And your earlier comment (#107) acknowledges you're making assumptions about the n55 cam profile (since you don't have one).

Exactly. I have an N55 cam measured. Waiting on an N52 cam. I can assure you Mike's numbers in post #107 for the N55 cam are wrong. He seems to be using N54/N55 interchangeably and they are not. N55 uses unique to it rollers as well which I believe changes the rocker arm ratio. I will measure that tonight to confirm. I will then post all the numbers I have once the N52 cam comes in. Then you guys can speculate and rip it apart lol. Donations will be welcomed to fund my out of pocket for the cam and taking the time to post the actual numbers.
 
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PureFthirty

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'Cause we haven't seen a good comparison of someone running an n55 cam versus n52 cam to judge whether it's an improvement on the curve. Just the other guy's single sketchy comparison. And your earlier comment (#107) acknowledges you're making assumptions about the n55 cam profile (since you don't have one).
😂😂 "Will someone please spend 40+ hours documenting these results for me so I can sit on my couch and judge every aspect". Not happening. Just move on dude...
 
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PureFthirty

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Exactly. I have an N55 cam measured. Waiting on an N52 cam. I can assure you Mike's numbers in post #107 for the N55 cam are wrong. He seems to be using N54/N55 interchangeably and they are not. N55 uses unique to it rollers as well which I believe changes the rocker arm ratio. I will measure that tonight to confirm. I will then post all the numbers I have once the N52 cam comes in. Then you guys can speculate and rip it apart lol. Donations will be welcomed to fund my out of pocket for the cam and taking the time to post the actual numbers.
Good luck lol!
 

ShocknAwe

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😂😂 "Will someone please spend 40+ hours documenting these results for me so I can sit on my couch and judge every aspect". Not happening. Just move on dude...

Not sure anyone cares how long you spent making that video. You could have spent 3 minutes coming here, copy, paste, link pictures and have been done. Time spent isn't an indicator of quality.

Kudos for the initiative on the video format but I hope you take pleasure in knowing that you made it and aren't looking for external gratification.
 

PureFthirty

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Not sure anyone cares how long you spent making that video. You could have spent 3 minutes coming here, copy, paste, link pictures and have been done. Time spent isn't an indicator of quality.

Kudos for the initiative on the video format but I hope you take pleasure in knowing that you made it and aren't looking for external gratification.
That's cool. I do take pride in the fact I was the first to do this swap. I take pride in that a 3rd party tuner has already publicly acknowledge he saw positive results from another swap that already happened. I have quite a bit to spend my time on and arguing and proving what I already know on a forum is unfortunately not one of those things. However, I do read the comments.
 

ShocknAwe

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That's cool. I do take pride in the fact I was the first to do this swap. I take pride in that a 3rd party tuner has already publicly acknowledge he saw positive results from another swap that already happened. I have quite a bit to spend my time on and arguing and proving what I already know on a forum is unfortunately not one of those things. However, I do read the comments.

Doing a good bit more than simply reading comments, if that's all you intend.
 

PureFthirty

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Doing a good bit more than simply reading comments, if that's all you intend.
We can just plan to leave it here until someone else is willing to take to take on the job, and I mean job, of proving it. I can't go back in time to correct throttle cut and whatnot.
 

Bnks334

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Good luck lol!

It took me literally all of 5 minutes to measure the cam and Google the cam profile from the n55 e gine pdf. Shockingly simple. Yet here we are 8 pages later and no one has provided accurate numbers. Just a lot of fake bs which just unfortunately has done nothing to support the OP. It sheds doubt. That doesnt mean there arent gains to be had but damn how do you want people to react when you claimed 100whp... bpc still cant be reached for comment? They couldn't get you basic cam measurements?
 
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PureFthirty

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It took me literally all of 5 minutes to measure the cam and Google the cam profile from the n55 e gine pdf. Shockingly simple. Yet here we are 8 pages later and no one has provided accurate numbers. Just a lot of fake bs which just unfortunately has done nothing to support the OP. It sheds doubt. That doesnt mean there arent gains to be had but damn how do you want people to react when you claimed 100whp... bpc still cant be reached for comment? They couldn't get you basic cam measurements?
Do it dude and comment. Let's see your results. Measure away.
 

scrllock

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40 hours, nah, I don't care about YouTube views. I'd buy a cam and try it but the results so far don't seem to justify it. $800 for the cam, guessing a good 10 hours of labor for the swap, waiting around on tune revisions, Dyno time before/after, likely to get results within the margin of error for runs? Not to mention the temptation to do a lot more "might as wells" with the motor open. Would rather spend that effort on my fuel or suspension and get far more appreciable results. Based upon many many dynos, I'd get results on par with yours simply adding meth or tuning for a higher ethanol mix on my setup. And for people without a ps2 already, well, they can and should just spend that difference on a stage 3 single kit instead and *actually* get the extra 100hp.

I'm not saying it's not going to work, just that the results you've presented aren't compelling enough to make me or most people drop the time and money on it.
 

9krpmrx8

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The other tuner (owner of BigBoost) who claimed the cam helped never backed up that statement really, and the car is making 100WHP less than my buddies 435i with the same kit so making claims of gains is pretty silly.
 

Bnks334

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There were quite a few assumptions being made so I purchased an N52 cam and measured it against an N55 cam. The numbers help give a much better idea of how the cam swap will affect an N55. Quite a few of the assumptions in this thread are wrong... including some of my own. Post #67 mixes up the pictures. N55 is left and N52 is right. Post #107 has a lot of assumptions that don't seem to hold true. What I did find with my own measurements was that while the N52 and N55 share very similar exhaust cam profile in their respective engines, there are some other part differences that will produce much different profiles when the cams are swapped.

Cam Comparison.png


You can see the previously stated roller ratio of 1.64 can't be true (based upon my measurements). Resulting valve lift would only be 9.27mm. We know the exhaust valve lift for all three engines is 9.7mm so we can use that information to deduce the actual rocker/roller arm ratio for the N55 to be 1.72. It was hard to measure this ratio by hand because as little as 1/64" difference can swing the ratio from say 1.68 to 1.71. The math is simple though and the cam measurements are pretty accurate. 5.65*x=9.7 ==> x=9.7/565 ==> x=1.72. Do the same basic math for the N52 cam and you get a rocker arm ratio of 1.66.

This is important because the ratio play a direct roll in overall valve lift. Multiple the lobe lift provided by the N52 cam by the N55 roller ratio of 1.72 and you get a resulting valve lift of 10.03mm (5.83mm * 1.72 ==> 10.03mm). This is an increase of .33mm lift over stock N55 cam. The exhaust valve will also open earlier and close later. How much? That is not something I plan to try to figure out. It would require more measuring equipment and time than I have.

The general theory would be that more duration and lift out of the exhaust valve could potentially increase whp at high rpm while sacrificing a bit of torque down low. How much? certainly not 100whp. This kind of cam change would be chasing 10whp at best is my assumption. Maybe on an 800whp build you might pick up 50whp... That is reality of making small changes to the exhaust cam especially so with leaving the intake cam stock. Exhaust port restrictions are still there as well.

There are also a few things that need to be considered when doing the swap such as, Spring travel/bind, piston to valve clearance, hydraulic lifter preload/travel, torque on the cam ledge, etc. Most of which might be considered moot since it's a working swap. Stock springs have the travel from what's been measured by others... not too sure what kind of issue might pop up with the lifters.

here is a link to the pics and spreadsheet: https://drive.google.com/open?id=1R-GaBRBd7Gw6xIL5_GlULuCk3DTbD2O1

Maybe @CobraMarty or someone like @MOTIV Motorsport can be so kind as to share some opinions/speculation?
 
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Weehe

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Based on that I wonder if the N54 exhaust cam is the same as the N52.
 

Bnks334

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Based on that I wonder if the N54 exhaust cam is the same as the N52.

I don't think so. The cam lift just needs to be the same to result in the same overall lift since they both use the same roller ratio. It's just one piece of information in the grand scheme of complex cam tuning lol

I can also say that all of the cams appear to be symmetrical. No speculation there... I can also say that there is probably other reasons why BMW moved to a smaller cam with a higher roller ratio. Some of the basic premises are discussed in this easy to follow article: https://www.knowyourparts.com/technical-resources/engine/performance-rocker-arm-history/
 
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Weehe

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I don't think so. The cam lift just needs to be the same to result in the same overall lift since they both use the same roller ratio. It's just one piece of information in the grand scheme of complex cam tuning lol
Based on the part numbers you listed, the N54 and N52 cams have to have the same lift since they have the same part numbers for everything. Unless I'm misunderstanding something. Hopefully Cobramarty can chime in with N54 measurements to compare to yours.
 

Bnks334

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Based on the part numbers you listed, the N54 and N52 cams have to have the same lift since they have the same part numbers for everything. Unless I'm misunderstanding something. Hopefully Cobramarty can chime in with N54 measurements to compare to yours.

Cam lift is just base cam lobe measurement - cam base circle measurement. Just to put numbers to it... 42-40 = 2 and 36-34 = 2. both cams would produce the same valve lift when multiplied by the same roller ratio. There could still be a lot of differences though. Cam centerline, rate of the valve opening and closing, duration, etc. I do not think the N54 uses the same cam as N52.
 
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ShocknAwe

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From previous information:

N54 are
Intake 245deg 9.7mm lift
Exhaust 261deg 9.7mm lift

N55 is
Intake: 255* / 9.9mm lift
Exhaust: 261* / 9.7mm lift

I have the N53 cam specs saved somewhere, I'll see if I can find them.
 

Bnks334

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From previous information:

N54 are
Intake 245deg 9.7mm lift
Exhaust 261deg 9.7mm lift

N55 is
Intake: 255* / 9.9mm lift
Exhaust: 261* / 9.7mm lift

I have the N53 cam specs saved somewhere, I'll see if I can find them.

Yes, if you look at my picture I have all those specs in there (except N53). This information alone isn't really all that valuable when you start talking about putting the cam into another engine with different valve-train geometry. The numbers do indicate that N52 and N54 cams are different. N54 cam is likely in-between an N55 and N52 cam. This is getting off topic though...
 
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Bnks334

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Found this gem from Franken turbo in a "cat cam" post. Just reposting it here for those looking to dig into the N54 cam. Looks like he had the N54 cams measured:

Note that he found the rocker ratio to be 1.667. Close enough to what I deduced. Definitely not the 1.64 posted in #107. Numbers seem a hair off vs what BMW is stating in their BMW academy docs. Probably due to human error trying to measure the exact degree the valve started to lift off it's seat. Or, old tired springs etc..

Intake:
N54-camshaft-card-BMW6R-INT.jpg


Exhaust:
N54-camshaft-card-BMW6R-EXH.jpg


Graphed:
N54-camshafts-curves.jpg
 
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