288/280 vs 280/272 cams.

[digger]

Strange: I have a factory modified head from BMW Motorsport at home (from the original P54B32) and BMW ported the combustion chambers, the valve seats as well as the intake side. Exhaust was not touched. Wondering if I should get that done beofre installing...

that’s probably because the exhaust side is not as important . The focus should always be the inlet side as in getting more air in to enable you to burn more fuel is the goal. It’s harder to get it in as the pressure differentials are much lower by orders of magnitude.

You do need a certain amount of exhaust time area (flow and cam duration) to exhaust appropriately for the power level, but you aren’t trying to maximise the exhaust flow at all as then you end up with too big, slow velocities and poor wave tuning. Too much exhaust flow capability (i.e. size) hurts torque. The balance point is not as much exhaust flow as people think like 60-80% of the inlet can work depending on the cam split and overwhelmingly the trend in top motoropsort is small effcinent exhaust systems and a 4V engine is rarely short of exhaust flow.

Head numbers at ~12mm/0.500” for stock S50b32 are 260/220 85% and s54b32 260/200 77% so the exhaust is not under done on S54 but is overdone on S50b32 and BMW were happy having less exhaust flow on the more modern engine, go figure as they made an extra 39hp with such a configuration. some of the earlier stuff ion 80's had exhaust the same as inlet so a defintive trend can be observed even in OEM.

Stock valve size numbers on the inlet can get to 280 cfm @ 28”, if you have those numbers a mild increase on exhaust is worthwhile but that probably doesn’t require much port work maybe just the valve seats, SSR and bowls with the main part of the port probably untouched as thats not where the flow restricton is anyway. Flow retsrction is where the bend is and most complex geometry

So to answer your question find a head specialist get them to put the head on the flow bench and evaluate it for your application. if they are any good they will look at flow but also velocity and bunch of other things. Most of the porting services for the S54 leave a alot to be desired so dont be going to the name brand ones.

[Altaran]

that’s probably because the exhaust side is not as important . The focus should always be the inlet side as in getting more air in to enable you to burn more fuel is the goal. It’s harder to get it in as the pressure differentials are much lower by orders of magnitude.

You do need a certain amount of exhaust time area (flow and cam duration) to exhaust appropriately for the power level, but you aren’t trying to maximise the exhaust flow at all as then you end up with too big, slow velocities and poor wave tuning. Too much exhaust flow capability (i.e. size) hurts torque. The balance point is not as much exhaust flow as people think like 60-80% of the inlet can work depending on the cam split and overwhelmingly the trend in top motoropsort is small effcinent exhaust systems and a 4V engine is rarely short of exhaust flow.

Head numbers at ~12mm/0.500” for stock S50b32 are 260/220 85% and s54b32 260/200 77% so the exhaust is not under done on S54 but is overdone on S50b32 and BMW were happy having less exhaust flow on the more modern engine, go figure as they made an extra 39hp with such a configuration. some of the earlier stuff ion 80's had exhaust the same as inlet so a defintive trend can be observed even in OEM.

Stock valve size numbers on the inlet can get to 280 cfm @ 28”, if you have those numbers a mild increase on exhaust is worthwhile but that probably doesn’t require much port work maybe just the valve seats, SSR and bowls with the main part of the port probably untouched as thats not where the flow restricton is anyway. Flow retsrction is where the bend is and most complex geometry

So to answer your question find a head specialist get them to put the head on the flow bench and evaluate it for your application. if they are any good they will look at flow but also velocity and bunch of other things. Most of the porting services for the S54 leave a alot to be desired so dont be going to the name brand ones.

I will likely not got to any names people on this forum know, since I am located in Germany. I do have an offer for a porting service of this head including exhaust side porting, matching my headers, grinding in new valves (planning on CSL Valves), and boring ITBs and matching them to the intake side. They did flow test other S54 headers before so I assume they can do it to this one as well.

[x Spades x]

I have done so many CSL airbox conversions here in NZ for others and I have never ever had a case of the so called hesitation.

I even made a video for someone in the States privately of my CSL trying to replicate the so called hesitation at various gears from 3000rpm and have not been able to replicate it at all.

i have however managed to replicate it via an Alpha N tune I received from the UK so I do know what it is and what it feels like.

A correctly converted car with a healthy engine just doesn’t have this issue. Period.

I have had my converted M3 with the csl airbox also for just over 3 years now and it has 189k km and I have not been able to replicate this issue either with it.

I concur. I had this hesitation when I first installed the EVOLVE airbox (alpha N). I converted to a Karbonius box with MAP sensor, air rail, CSL motorized flap and haven't gotten one hesitation in 70k miles (since 2015)... and my car has 194k miles on it now (original rod bearings btw - '05 ZCP).

[ATB88]

Slightly off-topic but not worth a new thread: to anyone who participated in the cam group-buy that Leighton ran back on the old m3f, what was the GB price for followers? Cheapest I can find them anywhere is $62/per. Was the GB price significantly better? Wondering if it might be worthwhile/possible to try and get a GB on rocker arms if there were many people interested in doing 288s in the future. Since each person would need 24 it might be easy to get a volume discount. If it were possible to get the price down to, say, $40/per, I might consider doing followers and 288s. Pretty unlikely, though Otherwise I feel like there's no way the difference between 288s and 280s could be worth another $1500 for followers, or risk of failure from not replacing, at least for a standard street/track build.

edit: would you look at that, Schmiedmann coming in clutch again... $52 per! https://www.schmiedmann.com/en/produ...1-33-7-833-259

[digger]

I will likely not got to any names people on this forum know, since I am located in Germany. I do have an offer for a porting service of this head including exhaust side porting, matching my headers, grinding in new valves (planning on CSL Valves), and boring ITBs and matching them to the intake side. They did flow test other S54 headers before so I assume they can do it to this one as well.

i doubt port matching to the headers is a good idea, what is the port exit size? what is the header primary ID at the flange and first tube OD? and how much power are you trying to make?I doubt they are pee shooter size.

the flow restriction is the valve seat area and areas 1" upstream and downstream thats where the attention should focus. the head you have may have had that area modified but they may have left the rest of the port untouched because they found it was big enough. Matching the port exit to the headers will unlikely help flow as that part is unlikely to be restrictive but depends on the actual size and on power level. having a step is often said to be anti reversionary and there are many proponents of keeping a step. IMO Ideally the first tube off the header matches the port size seamlessly to keep gas speed up then after like 8-10" it steps up in size.

[Apex_80]

This is true, i have them in my motor. I paid around 45 euro per follower from Leebmann.

Do you have a link to these?

[SUPREM3]

Is there a definitive solve for the Below 3k "CSL Hesitation?"

Having this issue now and thought it was a bad fuel pump.

Issue arrived after install of 288/280 Cams. Currently trying to figure out the issue so we can get back on the dyno to get better results (Currently 331whp on 91)

[Syfon]

So I'm looking at purchasing CAT 280/272 cams. I'm just about to pull the trigger on a carbon airbox, and since the motor is getting a rebuild, cams is a must.

After reading through this thread, my understanding is the 280/272 cams are a direct drop in? I have seen people recommending the followers be replaced, however it's not a necessity, right? FYI my motor had less than 60k miles when it spun a bearing (not sure if that makes any difference as the valvetrain is low mileage).

[mainstreamer00]

So I'm looking at purchasing CAT 280/272 cams. I'm just about to pull the trigger on a carbon airbox, and since the motor is getting a rebuild, cams is a must.

After reading through this thread, my understanding is the 280/272 cams are a direct drop in? I have seen people recommending the followers be replaced, however it's not a necessity, right? FYI my motor had less than 60k miles when it spun a bearing (not sure if that makes any difference as the valvetrain is low mileage).

I did the the mods above, and kept my old followers, which “looked good” on visual inspection.
Like many here, you’ll be able to run these without adverse issue.
Going to be a fun build!

[x Spades x]

So I'm looking at purchasing CAT 280/272 cams. I'm just about to pull the trigger on a carbon airbox, and since the motor is getting a rebuild, cams is a must.

After reading through this thread, my understanding is the 280/272 cams are a direct drop in? I have seen people recommending the followers be replaced, however it's not a necessity, right? FYI my motor had less than 60k miles when it spun a bearing (not sure if that makes any difference as the valvetrain is low mileage).

Just get coated followers. It may not make a difference... but if it does, it will save your engine. I would never have a freshly rebuilt engine, and leave something like this up to chance. It's not like this is a mod you'll be removing, etc. Go in there, do it right one time, and never think about it again. I drive my car without a care in the world and I have 194k miles on an '05 ZCP SMG (changed the pump).

[Altaran]

i doubt port matching to the headers is a good idea, what is the port exit size? what is the header primary ID at the flange and first tube OD? and how much power are you trying to make?I doubt they are pee shooter size.

the flow restriction is the valve seat area and areas 1" upstream and downstream thats where the attention should focus. the head you have may have had that area modified but they may have left the rest of the port untouched because they found it was big enough. Matching the port exit to the headers will unlikely help flow as that part is unlikely to be restrictive but depends on the actual size and on power level. having a step is often said to be anti reversionary and there are many proponents of keeping a step. IMO Ideally the first tube off the header matches the port size seamlessly to keep gas speed up then after like 8-10" it steps up in size.

I haven't meassured yet. I won't pull the motor before the end of the year, so I am not in a hurry. Right now I am using SS V2 headers.

How much power? Have not really pinned down a number but 420 should be possible considering other mods to motor and drivetrain. In 2 or 3 years I will likely do some sort of motor swap (S65 / S85), there is just so much more power that can be made N/A with more cylinders so I am not going to go for the last micron right now. I just already have the motorsport cylinder head collecting dust so I may as well use it...

[i_love_japan]

Not affiliated to the below listing however I think the pricing is excellent if you’re able to get them for less than $1300 or so?

https://www.ebay.com/itm/SCHRICK-Performance-Camshaft-Set-BMW-S54-New/274423001732?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D225086%26meid%3Dd0b9ec3866484fccabd03a5d0d36e8d2%26pid%3D100675%26rk%3D2%26rkt%3D15%26mehot%3Dnone%26sd%3D274425519450%26itm%3D274423001732%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3A2083d2b9-c5d4-11ea-8a23-74dbd18000f6%7Cparentrq%3A4d7786a31730a4d626c7d16affe42fd8%7Ciid%3A1

[Rudbari]

How are cams with supercharged s54 , I see vac offer supercharged cam 280/272 .

[BBRTuning]

I re-used my 120k mile followers with my 288/280 install, using Dbilas cams (same spec as CAT/Shrick 288/280). Regardless of DLC coating or not, followers probably *should* be replaced along with cams, as they do interface together the same way a brake pad and rotor do. If only one is replaced, then one part will need to wear to match the other component's surface. However, I'm about 12k in with plenty of track days and have had zero issues with wear and all the lobes etc look good. Still, probably wouldn't recommend it to someone else, to be safe.

I posted about this a bit on M3F already, but HP/TQ results were interesting - almost identical to stock cams up until 6500 RPM where they start to split. Peak delta is just over 20whp. NOTE that my current setup is not completely optimised for these cams - I'm still on OE Euro short-tube headers, so going to a stepped header at this point of the build would certainly help. I'm also running 200cell Magnaflow cats, which likely don't flow as well as a high quality race cat such as HJS/GESI. Also still on 2.3x" exhaust system. Next up is going to V1 stepped headers, custom 2.5" section 1 with better HFCs, and dual full 2.5" system.

Tune was fully optimised both before and after cams, and dyno'ed within a few days of each other, so this is as accurate a comparison as possible for *JUST* changing cams. Again, just keep in mind that gains would likely be even better with the proper exhaust setup to really take advantage of these cams. This was also on a slight Ethanol mix for both runs, just to make the tuning process easier. Once I get these parts I will update with straight 91 octane and full E85 results!

JE pistons/Carrillo rod 11.5:1 S54
Dbilas 288/280 cams 12.75mm lift (some report these are the same as 12.5mm from other manufacturers)
Streamline CSL airbox
Euro headers / Magnaflow 100c cats section 1 / OE section 2 / SS Race section 3
AEM Infinity ECU tuned by me
550cc injectors

[bmw m3 s50]

I like to ask what about in a supercharged situation? Would the 288 make more sense than the 280 cams since you have much more air being forced in? Would 280 cams do just as well and retain stock driveability?