I just picked up an S52 to build into an IP motor over the winter. 1995 M3 chassis, so no OBD1 conversion required. The plan is to use Sunbelt cams and just freshen up the ~70k or so motor with new bottom end bearings. My current S50 motor has a VAC head that we will most likely swap over (springs, retainers, etc, all prepared level stuff).

Anyone care to shed some wisdom or tips that you learned in the process? Pitfalls to avoid? Most of the IP motor issue threads are due to timing the Sunbelts correctly, and I think I have a good handle on how to do it. Anyone recommend the Dr. Vanos stage 2 w/ Sunbelt limiter?

I was planning on using the Bimmerworld software for the cams, is there a better option for a similar price? I'm trying to stick to a tight but reasonable budget.

Rules stuff: Also, it doesnt mention it in the rules and I know traditionally it would mean you cant do it, but are prepared motors allowed to be build "loose," as in increasing clearances beyond stock? Is there a defined limit? I was planning on doing this veeeerry mildly.

It cant find it explicitly in the rules, but I'd assume oil pan baffling is free?


Thanks for answering all my CR prep questions lately. :clap I know a handful of members here personally that are doing most of this this winter too, we appreciate the help.

Anyone recommend the Dr. Vanos stage 2 w/ Sunbelt limiter?


I have one very important tip - read the rule book. If you have a question, and think you want to tread out into the grey area, then be prepared to spend more money later when the grey area is clarified more conservatively. :)

On the statement above, would you consider limiting vanos to be a legal modification? I can find no instance in the rule book that would allow this. Yes, cams are free, but vanos is not a "cam". Other than the very limited engine allowances, the rules state "no other internal modifications are allowed."

It cant find it explicitly in the rules, but I'd assume oil pan baffling is free?


Oil pans are covered in the stock rules and are "free".

Gotcha. I've been reading the rule book for a few days, but I didnt even think of limiting Vanos. I know of at least one person using this in a prep car (not a member here)... Has anyone asked the rule gods about it?

I've heard time and time again, "No other internal engine modifications...," but does that go so far as clearances and building the motor loose? I'm not a motor genius, but this is done mostly to preserve a race motor since factory clearances just help street motors operate in all sorts of temperature ranges, correct?

I know I can justify it all day long but rules are rules yadda yadda.

I just picked up an S52 to build into an IP motor over the winter. 1995 M3 chassis, so no OBD1 conversion required. The plan is to use Sunbelt cams and just freshen up the ~70k or so motor with new bottom end bearings. My current S50 motor has a VAC head that we will most likely swap over (springs, retainers, etc, all prepared level stuff).

Are the S52 and S50 heads exactly the same? If not, I don't see any provision in the rules for mixing and matching blocks and heads in Prepared.

Was under the impression that they were exactly the same, am I wrong?


Edit: Real OEM says the same part numbers for (what looks like) everything except cams.
Edit 2: I just read one of the 1996 S52 heads had a different temp sensor for a short run. Every other one I'm seeing has the same P/N.

Sounds like you are good to go then...wasn't sure if there were any changes. It's been a while since we messed with any US S50/S52 stuff.

That isnt a bad thing. If I can find a S50B32 for a decent price, I will be HP so fast it'll make your head spin.... and blow that budget thing out the window.

Please continue to poke holes in my thought process, that is why I posted this. :D

I'm not positive but I think there's some mention of "blueprinting" or something like it in the rules. Most factory specs have a min/max. One would think you could take rod and bearing clearances to the max without issue. But nothing over unless specfically allowed, such as cylinder bore/psitons.

Jay

I just picked up an S52 to build into an IP motor over the winter. 1995 M3 chassis, so no OBD1 conversion required. The plan is to use Sunbelt cams and just freshen up the ~70k or so motor with new bottom end bearings. My current S50 motor has a VAC head that we will most likely swap over (springs, retainers, etc, all prepared level stuff).

Anyone care to shed some wisdom or tips that you learned in the process? Pitfalls to avoid? Most of the IP motor issue threads are due to timing the Sunbelts correctly, and I think I have a good handle on how to do it. Anyone recommend the Dr. Vanos stage 2 w/ Sunbelt limiter?

I was planning on using the Bimmerworld software for the cams, is there a better option for a similar price? I'm trying to stick to a tight but reasonable budget.

Rules stuff: Also, it doesnt mention it in the rules and I know traditionally it would mean you cant do it, but are prepared motors allowed to be build "loose," as in increasing clearances beyond stock? Is there a defined limit? I was planning on doing this veeeerry mildly.

It cant find it explicitly in the rules, but I'd assume oil pan baffling is free?


Thanks for answering all my CR prep questions lately. :clap I know a handful of members here personally that are doing most of this this winter too, we appreciate the help.

Do you want a "built" IP motor or just a refreshed motor? Big difference in price. There is a lot you can play with in prepared motors.

As far as must do's.
All the head stuff, springs, retainers, and such but all stock weight.
Double pick up oil pan, ltw or euro. Pretty much a must have.
a good header, hehe
you've got the cams
then just a good tune

Thanks, Jay, sounds like a good (safe) idea. Anyone know where to get those specs from BMW? :dunno


On the statement above, would you consider limiting vanos to be a legal modification? I can find no instance in the rule book that would allow this. Yes, cams are free, but vanos is not a "cam". Other than the very limited engine allowances, the rules state "no other internal modifications are allowed."

Jon (or anyone) - Just read this part again, can we call Vanos a type of cam gear, or is this that grey area you were talking about? :D

"Cam gears and valve springs are free."

If cam gears and cams are free, it stands to reason that cam timing is free. If cam timing is free, vanos timing is free. No vanos modifications are needed to restrict the intake cam travel, you just time it to advance slightly less than it otherwise would.

Have you ever timed cams before?

Do you want a "built" IP motor or just a refreshed motor? Big difference in price. There is a lot you can play with in prepared motors.

As far as must do's.
All the head stuff, springs, retainers, and such but all stock weight.
Double pick up oil pan, ltw or euro. Pretty much a must have.
a good header, hehe
you've got the cams
then just a good tune

The head I mentioned before has all the head stuff you mentioned (maybe 10k miles old), so I guess that's why I'm thinking of it as just a freshening.

Double pick up is an absolute? Baffling kit (TMS or other) wont cut it?

Any thoughts on the good tune part? Is the included BW software (for Sunbelts) good enough? The $600+ tune and custom chip isnt worth the 5 hp to me or at least not yet.

And until you guys figure out the header thing with proof, I'm sticking to my TMS shorties. :D

If cam gears and cams are free, it stands to reason that cam timing is free. If cam timing is free, vanos timing is free. No vanos modifications are needed to restrict the intake cam travel, you just time it to advance slightly less than it otherwise would.

Have you ever timed cams before?

Matt - Yeah, I've done a bunch of these motors now. The Sunbelts have their own unique timing quirks, and as I understand it, the Dr.Vanos fix makes it simple and easy to get it right the first time. Your logic makes sense to me, but it goes back to the literal interpretation of the rules and "if it doesnt say you can, you cant." Like Jon said, I'd rather not ride the grey area and waste money if I dont have to.

If cam gears and cams are free, it stands to reason that cam timing is free. If cam timing is free, vanos timing is free. No vanos modifications are needed to restrict the intake cam travel, you just time it to advance slightly less than it otherwise would.

Have you ever timed cams before?

I like your logic pattern here. Like I said - I am not making a determination (not my place) just bringing up gray areas so we can talk about them.

I like your logic pattern here. Like I said - I am not making a determination (not my place) just bringing up gray areas so we can talk about them.


Same logic started pistongate and injectorgate.

I like your logic pattern here. Like I said - I am not making a determination (not my place) just bringing up gray areas so we can talk about them.

Well, I think if the Dr. Vanos uses a modification to the vanos unit to restrict the travel, then that may not be legal. But if you just time the vanos yourself so that it only advances the right amount, that would be legal.

Just my thoughts, probably not even worth two cents. :dunno

Same logic started pistongate and injectorgate.

I know what you are saying, but I see a distinct difference here. With the injector issue - they were simply NEVER allowed. Yes, big cams were allowed (those that could physically fit in the motor) but big fuel was NEVER allowed in prepared - so if you wanted to run big cams, then you took your own chance at running lean.

Here we have a situation where cam gears are free. Software tuning is free within the ECU (and this software controls the vanos actuation) thus controlling when cams are advanced or retarded. We allow you to place your cams within your motor in any orientation you want (cam timing).

That's my logic process.

Whatever Chris has figured out it works. The key word is "limiter". Figure out what that means and you will get the answer to the legality.

And what about the need to modify the lifter box or the 33mm/35mm cam tray to fit the sunbelt cam? I have been told by two builders who HAVE used them that this is needed.

That is certainly not legal.

And what about the need to modify the lifter box or the 33mm/35mm cam tray to fit the sunbelt cam? I have been told by two builders who HAVE used them that this is needed.

That is certainly not legal.

Not aware of that problem? Lots of myths surrounding these - they must be good!

This thread could turn out fun... :D

And what about the need to modify the lifter box or the 33mm/35mm cam tray to fit the sunbelt cam? I have been told by two builders who HAVE used them that this is needed.

That is certainly not legal.

:eatpop:

This thread could turn out fun... :D



No doubt. :D

I just picked up an S52 to build into an IP motor over the winter. 1995 M3 chassis, so no OBD1 conversion required. The plan is to use Sunbelt cams and just freshen up the ~70k or so motor with new bottom end bearings. My current S50 motor has a VAC head that we will most likely swap over (springs, retainers, etc, all prepared level stuff).

Anyone care to shed some wisdom or tips that you learned in the process? Pitfalls to avoid? Most of the IP motor issue threads are due to timing the Sunbelts correctly, and I think I have a good handle on how to do it. Anyone recommend the Dr. Vanos stage 2 w/ Sunbelt limiter?

I was planning on using the Bimmerworld software for the cams, is there a better option for a similar price? I'm trying to stick to a tight but reasonable budget.

Rules stuff: Also, it doesnt mention it in the rules and I know traditionally it would mean you cant do it, but are prepared motors allowed to be build "loose," as in increasing clearances beyond stock? Is there a defined limit? I was planning on doing this veeeerry mildly.

It cant find it explicitly in the rules, but I'd assume oil pan baffling is free?


Thanks for answering all my CR prep questions lately. :clap I know a handful of members here personally that are doing most of this this winter too, we appreciate the help.


It sounds like you have the cam choice done correctly. Timing the Sunbelts isn't as tricky as everyone may think. I've been running them with very good results for two seasons now in my OBD1 S52.

Your IP motor build is pretty straight forward:

1. Cams + supporting "kit" components (24# injectors, M50 manifold, 3.5" HFM, 3.5" CAI, etc.)
2. Get some decent headers...and I wouldn't even know where to begin to recommend a setup for your build. Search for recent lively threads on this subject.
3. Get good tuning. I had AA due my OBD1 tune and I'm happy with the results.
4. You'll need to do a few sensor swaps on your S52 to drop it into your 95 chassis. It's all pretty simple stuff.
5. Freshen up the head and replace what is worn and improve your reliability.
6. At minimum, baffle your oil pan or spend the money and get a dual pick up pan and pump.

Good luck.

If cam gears and cams are free, it stands to reason that cam timing is free. If cam timing is free, vanos timing is free. No vanos modifications are needed to restrict the intake cam travel, you just time it to advance slightly less than it otherwise would.

Have you ever timed cams before?

Let me preface this statement with the following:

<<I'm not sure what the Dr. Vanos change is or requires.>>

If cam gears are free and cams are free, that means you can replace the factory cam gear and the factory cam with aftermarket items. No more, no less. The freedom to replace either of these parts does not mean timing is free. If the rules wanted to say timing was free, they would say it.

It only means cam timing is free in as much as the new cam gear or cam that are swapped into the engine might be different than if it had been the factory parts, or, it is free within the tolerances of how you time the cam using these new parts. Set and forget.

Since programming the dme is allowed, you could affect time camming in this particular case by having the vanos solenoid operate on or off at a different rpm.

Any modification to the solenoid, the freedom of motion of the solenoid, or any mechanical limiting of its action is not allowed specifically, therefore, I would NEVER do it and expect that its free by the logic posted above.

Alex. (my 02 worth after having been in CRAC for a couple of years and watching how rules discussions go)

Not at all meant as a personal attack on the person being quoted, not intended to imply he/she can't read the rules, I'm not trying to say anything about his or her car or its legality, or the legality of anyone who has done these things.... I'm just calling it as I see it, and not trying to pick a fight.

Thanks for the input everyone. Like I said, I posted this to have you all poke holes in it.