Naturally Aspirated street/track car

[morcheeba]

PEI - silly question (and I apologize for not looking it up myself).... are those rings on the valves stock? I remember on my E30 they weren't & the folks at Metric Mechanic had a service where they'd add them.

Totally unrelated ... I'm going to berlin for a conference... I found out they make BMW motorcycles there... and the disc brakes for the cars. Dec 31st is my tourist day - the plant is probably closed :-(
http://www.bmw-werk-berlin.de/berlin...ndex_home.html

Glad to hear the next car is in the planning stages!

[PEI330Ci]

Originally Posted by morcheeba

PEI - silly question (and I apologize for not looking it up myself).... are those rings on the valves stock? I remember on my E30 they weren't & the folks at Metric Mechanic had a service where they'd add them.

Totally unrelated ... I'm going to berlin for a conference... I found out they make BMW motorcycles there... and the disc brakes for the cars. Dec 31st is my tourist day - the plant is probably closed :-(
http://www.bmw-werk-berlin.de/berlin...ndex_home.html

Glad to hear the next car is in the planning stages!

Thanks!

To be honest with you, I don't know if the valve seats are stock or not. There were supposed to be new valve guides and valve seats installed in the head along with port work, valve job, and decked mating surface. The valve job on every single valve was so bad that there was a visible gap between the valve and the valve seat with the valve closed. There was no port work done to any of the runners, and while the head was decked, it was found not to be straight. Being that so much was wrong, I'm not confident that either the valve seats or valve guides were replaced with the "super alloy" that was sold to me over the phone. Live and learn.

I'm working with someone extremely reputable in Sweden on my new heads using parts that I have sourced myself. Including what's in Sweden right now, I've got 5 heads in play. Work has already started.

[PEI330Ci]

Another busy month, but I'm not ready to get into details yet.

Projects on the go right now are:

- CF intake (The complete intake)
- Head work
- Modified valvetrain
- New Headers + Exhaust
- Radical new nitrous system
- Engine management (It's looking like a PAIR of ECUs)
- Drivetrain (Trans, clutch, diff)

I've also been looking for a doner car, preferably a 2001 325Ci w/o Zenon with a blown engine. While I can re-use my original chassis, I need so many trim parts and odds and ends that it would be a lot easier and cheaper just to strip a complete car down.

[PEI330Ci]

2010 is going to be a very fun year.

A donor car has been sourced, but it's in 100% running condition. As a little surprise, it's not what people will be expecting.

We're going to start the adventure all over again, except this time with even more weighing, measuring, dyno testing, and track testing. And if that isn't enough, HD Video capture and higher resolution images. (Enter the Macro lens!)

All of the existing development projects will continue in parallel.

[PEI330Ci]

I guess the cat's out of the bag now, and a change of thread title might be in order.

The 330Ci is going to be rebuilt as a tube-frame race car with a 4 link rear suspension and a GM 12 bolt center section. The engine will be a highly developed M54B30 block and head, with a centrifugal supercharger feeding a modified BMW Motorsport P54 intake manifold. A WON direct port nitrous system will also fitted which will be capable of flowing over 4000 lbs/hr of nitrous. (I'll let you nitrous gurus figure that one out) The transmission will a V-gate shifted 5 speed, with a carbon/carbon clutch system.

The "donor car" will become a street toy for me to enjoy while I build the above monster. Although an automatic transmission, I've decided to fit a Technique Tuning stage 1 turbo system to the car to keep things fun. Here's the new toy prior to being shipped cross country (literally) to my home on PEI:

[PEI330Ci]

Ever wanted to design a piston from scratch?

That's the fun I've been having for the past month or so, and let me tell you the M54B30 doesn't make life easy.

Probably the most important spec to look at when designing a piston for an engine is "compression height". This is the measurement from the center of the wrist pin to the crown of the piston. In the case of the M54B30, we need to do a little backwards math to find out what are limitations are in this area.

The distance from the center of the crank to the "deck" of the block is 211mm.

89.6mm crank throws the center of rod journal up 44.8mm.

The connecting rod is 135mm from center to center.

This gives you a "compression height" of 31.2mm from the center of the wrist pin to the deck of the block.

The wrist pin on all M54s (and most other BMW engines) is 22mm. This brings us to 20.2mm of space to work with above the wrist pin on our custom piston design.

So the next step is to figure out the ring package that we want to run. Normally for N/A engines, you'll see top and second rings in the 1mm - 1.2mm area. For FI, it's recommend to run a thicker top ring. So for my "nitrous engine", I've chosen a 1.5mm top ring, and 1.2mm second ring. The oil scraper ring is dependent on a number of variables in the oil system, as well as the stroke of the piston. The more stroke, the more oil there is to shear off the wall and you need somewhere to store this before it bleeds through the breather holes. Luckily, the M54B30 has a modest stroke and moderate amount of oil being cycled onto the piston wall. This means that we don't need to be on the high end of the oil scraper ring scale (5mm for big blocks for example) and can get by with a good 2.5mm ring.

So the combined ring stack is 5.2mm, giving us 15mm of space to place the ring lands. Assuming we are placing the oil ring directly on top of the wrist pin bore, this gives us 3 ring lands to specify

Top Land
Top piston ring
Middle Land
Second piston ring
Bottom Land
Oil scrapper ring

Probably the most critical as far as strength is concerned will be the top land. The more material we can place here on an F/I piston, the better. So this means we want to minimize the land size for the middle and bottom land to give as much as possible to the top land.

On advice from industry experts, I went with a middle land of 3mm, and a bottom land of 2mm. This leaves us with 10mm above the top ring. Sounds like a lot right? Well we still have to design the piston crown, and that's where we have to account for the valves.....

So recounting a bit of math:

Top Land = 10mm
Top piston ring = 1.5mm
Middle Land = 3mm
Second piston ring = 1.2mm
Bottom Land = 2mm
Oil scrapper ring = 2.5mm

Wrist pin radius = 11mm
Connecting rod length = 135mm
Crank stroke radius = 44.8mm

So we've used all of the 211mm of space with the reciprocating assembly.

Some might point out that the head gasket can be adjusted so that we can run the piston above the deck before it will hit the head. This is true, and to be honest, we can get gaskets 3.5mm thick. (0.140") But when you are producing maximum cylinder pressures, do you want to run that pressure against more gasket surface area or a solid cylinder bore? Most top level engine builders when not constrained by deck-height rules, will chose to run the thinnest head gasket possible. So in this case, the piston design will respect a 0.030" head gasket.

If you want to flow lots of air through moderately sized valves, you need to hold them open a long time. The peak lift value isn't as important as the average lift value in cranking degrees. With the custom camshafts I have, this means that the valves are open when the piston reaches TDC at the end of the exhaust stroke and beginning of the intake stroke. With the cams "centered" in the middle of the VANOS adjustment range, this figure is around 4.5mm for both sets of valves. Retarding the exhaust camshaft will increase this value, as well as advancing the intake camshaft. In fact, it's feasible to see lift of nearly 9mm @ TDC at the far end of the VANOS adjustment range for both the intake and exhaust camshafts. This gives you 2 options for designing the valve reliefs:

1.) You mechanically lock the cam position for what you estimate will be the best cam timing position, and design the piston to clear the valves at that position.

2.) You allow the full range of VANOS adjustment, and design the piston to clear this.

A third option is to limit the VANOS range with the ECU, but then Murphy's law is bound to show up with some glitch that ruins the engine.

I went with option #2, and had massive valve reliefs designed into the piston crown. I reasoned that being able to manipulate exhaust cam timing was going to do more to control chamber heat than running the extra material in the crown above the top piston ring. Hopefully, with some of the other tricks I've got planned, it works.

Clearance for the intake valve is 9.62mm @ TDC with a 0.030" head gasket.

Clearance for the intake valve is 8.92mm @ TDC with a 0.030" head gasket.

The result of the valve relief cuts are 2 "low" areas above the top piston ring measuring just 4mm thick across a 5mm area on the intake side, and 5mm thick across a 4mm area on the exhaust side. It's a compromise, but one that I'm willing to accept to maintain mechanically safe clearances in the event of over-reving or ECU failure.

So where does this leave the compression ratio?

11.4:1 with a 0.030" head gasket, which is actually low for nitrous race engines running race fuel.

[morcheeba]

wow! This'll be fun!

[PEI330Ci]

Originally Posted by morcheeba

wow! This'll be fun!

I hope so too!

I "think" I figured out how to hold cylinder pressure reliably past 500rwtq. Time will tell...

[Madhatter22]

Hey pei, im new to the forums. The work you have done to your cars is great, and have accomplished some very helpfull diu. I have a silver 2002
330i automatic. I was wondering if you had any thoughts on what additions i should begin and work with. Thanks
~joshua

[PEI330Ci]

Originally Posted by Madhatter22

Hey pei, im new to the forums. The work you have done to your cars is great, and have accomplished some very helpfull diu. I have a silver 2002
330i automatic. I was wondering if you had any thoughts on what additions i should begin and work with. Thanks
~joshua

Forced induction!

The brakes and suspension are pretty good in stock form. For FI, you've got a choice between 2 types of supercharging, and a turbo kit. All are pretty close in price, but have different features.