Engine build rules?

#1

I am slowly finalizing my build plan, so I have couple of questions regarding the rules for the engine, as I will be re-building mine.

  1. While it says at
    “9.3.1.2.1. Machining for balancing purposes only is allowed.�
    And at
    “9.3.1.4.1. All valve sizes, seat dimensions and angles, etc., shall conform to factory specifications. “ ,
    I just want to ask/confirm that doing 3 or 5 angle valve job is legal. Is it?

  2. Can we change valve springs, either rate change or use something al a "bee hive" springs or …?

  3. I saw a reference in 9.3.1.1.2 and 9.3.1.5.1 relating to pistons, but just in case I want to confirm (or deny) legality of overbore MaxSil pistons. See http://www.bmwpiston.com/piston_kits.html

  4. What about wrist pins – are they ‘free’ or stock/OEM only?

While realizing that some of this questions might be daunting, I would rather ask now then be sorry later.
Regards,
Igor

P.S. Re-reading my own post I came to notice that it might sound as if I want to build a ‘specialty / supped up / etc’ motor – that is not the case. I will have to rebuild the motor on my 87 325is and just want to know all of the options available beforehand.

Post edited by: igor, at: 2005/08/17 14:51

#2

It would seem to me that in the spirit of the rules, no change can be made to your motor that would gain a performance advantage unless it’s listed as acceptable tollerences by BMW. For example, if the piston to wall clerance is listed as .020-.030 than you are free to run the motor at exactly .030 for more power, however if the car didn’t come from the factory with a 3 angle valve job, then you cannot add one.

I would think something like wrist pins would be fine provided they didn’t add a performance advantage. Nearly all pistons you buy will come with their own pins anyways.

#3

Leave it stock or go race somewhere else. I’d rather not get to the point where people even consider stuff like this. Or companies take a core and 5 grand to give you some horsepower. I’m sure if this series gets really popular we’ll have microfinishing of engine and drivetrain parts to free up that extra 5 horsepower too just like in spec miata. Lets not let it even get close to that point. Because I can win that game.

I’ll be using a 170k mile stock engine in my car. And I have access to alot more cool stuff than most of you(that I won’t be utilizing). I want to race cheap for fun using stock stuff and have everybody on the same plane prep wise.

Post edited by: robweenerpi, at: 2005/08/18 17:14

#4

Easy there bud – I was just asking because I have to rebuild the engine due to it’s current condition (tired, was neglected, leaking, blowing , etc… :S ). Because I realized how the original questions could be interpreted I added P.S. to the original post. While I very much share the sentiment that the series should be affordable and fun, I have no idea what everyone else runs, as I am physically located far from the majority of the runners (CA) and in the past I did not pay too much attention to the interpretation of the rules since I was on the fence if I will race or not. Now that I bought the car that I will prep, I am asking nitty-gritty questions so that I can have legal car.

Since overbore pistons are allowed, I am considering using them for rebuild if pistons/bores are not up to par (if they are I will use normal size pistons). Part of my plan is to cover as much issues and consequent options, before I start with the car build. So does anyone know if those MaxSil pistons are legal or not? (if no one knows I will call vendor and ty to determine if they have same dimensions as original pistons).

Regards,
Igor

#5

Igor:

It’s good that you are asking about the rebuild. Virtually everyone is running a stock 160k-plus engine so these questions haven’t come up, thus the lack of hard info from the group.

We’ve had one .020 motor and his car made 141 hp on the chassis dyno. That day, three other stock motors made 135, 136, and 137 at the rear wheels. The 141 hp car won both races that weekend (with a very good driver) but the 135 hp car was on his rear bumper at the checker on Saturday and slightly beside him (front bumper at right rear tire) on Sunday’s race.

I suggest you read the rules carefully and ask BMW if you have any questions about factory specs. And I’m planning to race in California next year so you better be legal! :laugh:

Carter

#6

[quote]Carter

Re:Engine build rules? - 2005/08/19 01:02

…
We’ve had one .020 motor …[/quote]

Who has the racecar with overbore pistons? I would be interested in brand, P/N and where were they bought?
At this stage of my race carrier, even if I had the ‘strongest’ car I don’t think that it would make me fastest guy on the track - I just want to build the car once and do it right (that’s the idea anyways :cheer: )

Regards,
Igor

#7

Igor wrote:

[quote]I am slowly finalizing my build plan, so I have couple of questions regarding the rules for the engine, as I will be re-building mine.

  1. While it says at
    “9.3.1.2.1. Machining for balancing purposes only is allowed.�
    And at
    “9.3.1.4.1. All valve sizes, seat dimensions and angles, etc., shall conform to factory specifications. “ ,
    I just want to ask/confirm that doing 3 or 5 angle valve job is legal. Is it?

  2. Can we change valve springs, either rate change or use something al a "bee hive" springs or …?

  3. I saw a reference in 9.3.1.1.2 and 9.3.1.5.1 relating to pistons, but just in case I want to confirm (or deny) legality of overbore MaxSil pistons. See http://www.bmwpiston.com/piston_kits.html

  4. What about wrist pins – are they ‘free’ or stock/OEM only?

While realizing that some of this questions might be daunting, I would rather ask now then be sorry later.
Regards,
Igor

P.S. Re-reading my own post I came to notice that it might sound as if I want to build a ‘specialty / supped up / etc’ motor – that is not the case. I will have to rebuild the motor on my 87 325is and just want to know all of the options available beforehand.Post edited by: igor, at: 2005/08/17 14:51[/quote]

Personally, just thinking about the purpose of this series, I would say these pistons would not be legal. The teflon coated piston skirt would be the kicker…assuming all other stock specs are met.

As others have told you already, get a used motor, run the piss out of it. That’s what we’re gonna do save some new gaskets at known leaking points. Run it til it blows up and then go to the junkyard to get another! ; )