M Coupe LTW build

[Michael9218]

Originally Posted by racerbruce

Isn't the S54 OEM a "semi-dry sump" system?

Are you converting to a full blown dry-sump?

The S54 does have a very good wet sump system. I've heard it called semi-dry, but that's a bit of an exaggeration. It does have a scavenge feature moving oil from the front of the pan to the rear, but that's a far cry from a dry sump system.

Benefits of a dry sump in reverse importance to me:
You can run more oil. (Not needed if you have a good cooler)
Eliminates oil starvation due to g forces. (Dual pan is fine)
Creates a vacuum in the crankcase freeing up power (10-15hp in an S54).
Gives you a flat oil pan allowing for flexibility in motor placement in the chassis.

The cons are the cost and the need for customization to make it all fit. I like to build and fabricate, and I need a winter project..

[Michael9218]

So, what's wrong with this picture?



It's as if the BMW engineers intentionally moved the motor forward from where it should be in this chassis. Of course, the reality is they didn't want to invest in a solution that took full advantage of the chassis. They pulled an E46 subframe out of the parts bin, added an S54 and the motor placement was the by product. In an E46, this motor is tucked up under the cowl about as far back as it can go. In a Z4, not so much.

I'm of the opinion that the forward location of the motor in this shorter wheelbase chassis is why it is considered not to handle as well as an E46. The shorter the wheelbase, the more pronounced the weight imbalance impact. My car currently has 51/49 weight balance. I've talked to a couple chassis engineers and they agreed with this premise.

So, my project this winter is rather ambitious. I plan to move the motor back 3 1/4" - 3 1/2" to prove or disprove this theory. I mean, it should handle better, but it certainly won't hurt the handling. So why not? That measurement appears to be as far as it can go without cutting structural metal. The Z4 has a rather robust box section crowning the transmission tunnel entrance. If one were to notch this out, the motor could go back even further. But that would be risky. The last thing I want to do is compromise the wonderfully rigid structure of this chassis.

A dependency to moving this motor back is removing the dual pan wet sump oil system. It simply will not clear the steering rack. A dry sump system will give a flat pan and eliminate this restriction.

And so the fun begins...

[Michael9218]

After some research on the various dry sump solutions, I decided to go with Achilles Motorsports system. It's a Peterson based system with a pan of their own design that I posted above. I received the pan, and oil passage block off bracket, ahead of the rest of the system so I could begin by installing the pan so I could mock everything up in the chassis and take measurements.

With the OEM pump removed, one needs to either remove or secure the oil pump chain guide/tensioner. Removing it looked dicey so I elected to make a bracket and secure it. By dicey, I mean that if you remove the clip on the post and can't get it out, you're looking at removing the timing chain cover. That means removing the head...no thanks! To get the oil pump chain out, you just need to cut a link and feed it out.



Oil pan installed and taped to prevent blemishes while positioning in the chassis.

[Michael9218]

Decided I needed to wait on the pump to make sure I would have no clearance issues, so moved over to making room for my oil tank. I am going to have the oil tank sit in the engine compartment like OE systems. Less plumbing and since we don't have a trunk, this is the only option to keep it out of the cockpit.

A 3 gallon tank should fit nicely once the cabin air box is removed.

Work in progress, but here it is so far.







Next up is to make a patch panel to weld in and plug that rectangle hole. I'll lose my nifty cabin vents. Also need to make a fence across the top to seal to the underside of the hood.

[Vanne]

Howly cow Mick, what a project. It makes sense mate, move the donk back a inch or 2 and i would also guestimate that the handling will improve. Though already a really good handling chassis. Amazed at what your tackling mate. Subbed for more goodness.

in one word .. AWESOME!!!

[2skiddy]

OOOh, just spotted this! Michael, you are so right to remove that metal work, that is what they did on the VLN cars and moved the engine back a few inches. Yes the wet sump would hit the rack, so a dry sump got round it. The front subframe is totally bespoke on the race cars, but you can modify your own to suit. This is what I did, and maybe got the engine further back than even the Motorsport factory installation. I used an ARE sump pan BTW.

[Michael9218]

Originally Posted by 2skiddy

The front subframe is totally bespoke on the race cars, but you can modify your own to suit. This is what I did, and maybe got the engine further back than even the Motorsport factory installation.

Any details on your motor relocation? You modified the subframe rather make new motor mounts?

[2skiddy]

Hi Michael, you can fabricate new mounts, but for me at the time, using the original standard mounts was easier for just mocking up. The position of the engine and Quaife 69G box was to be determined by raising the unit up into the car and seeing how far it would go back and down. I had a space consideration for clearing the front ARB (sway bar to you), which is a chunky Motorsport item. This resulted in a 10mm ish clearance front and rear of the engine. I could have used the Motorsport subframe and the modified mounts that come with it, but these might have got in the way of the oil pump plumbing routing and the supercharger pipes. Everything was very tight in there, and I had to modify the left hand mount slightly to allow the steering shaft some room. In the end I modified the subframe for the mounts and inner suspension pick up points, and decided to see how that went and maybe fab some up later. I used hard race Vibratechnic mounts BTW, to give a little compliance. If I can find a picture or two, I will send them. Could you please message me your details? Cheers

[2skiddy]

Hi Mike, sent some photos over, hope these help?

[Michael9218]

Finished up the firewall modification, making room for the 3 gallon oil tank. Should work out really good with the nice flat surface of the firewall for ease of tank mounting.







Tank arrived yesterday just as I finished up. Fits nice. Like it was meant to be there...

[racerbruce]

Awesome!
The weight of the new tank and 3 gallons of oil (oil weighs appx 8 lbs per gal) will be appx 30 lbs?? As this is offset from center of vehicle, perhaps relocating the battery, or the enclosure for the cool suit system (if spec'd) could help balance this out?? Or, perhaps because the oil tank is over the "front axle" it won't matter as it relates to the "rear axle" and balancing out weight per corner of the car?? In my crazy math equation, deducting the weight of the air box removed and the addition of sheet metal you added (minor) could be included in the equation.

[Michael9218]

Originally Posted by racerbruce

Awesome!
The weight of the new tank and 3 gallons of oil (oil weighs appx 8 lbs per gal) will be appx 30 lbs?? As this is offset from center of vehicle, perhaps relocating the battery, or the enclosure for the cool suit system (if spec'd) could help balance this out?? Or, perhaps because the oil tank is over the "front axle" it won't matter as it relates to the "rear axle" and balancing out weight per corner of the car?? In my crazy math equation, deducting the weight of the air box removed and the addition of sheet metal you added (minor) could be included in the equation.

Interesting observations.

The weight of the remote oil tank is actually slightly aft of the wet sump. It is right of center, but the car has more weight on the left side. A 3 gallon tank will hold 2 gallons of oil to allow room for oil/air separation. So we're only talking about a few more quarts. At 7.3 lbs/gal, this is insignificant. The metal mentioned replaced the metal cabin air box, so likely no change.

But weight and placement of an oil tank is insignificant. The big objective is moving the 500 pound lump aft 3+ inches.

[racerbruce]

Originally Posted by Michael9218

Interesting observations.

The weight of the remote oil tank is actually slightly aft of the wet sump. It is right of center, but the car has more weight on the left side. A 3 gallon tank will hold 2 gallons of oil to allow room for oil/air separation. So we're only talking about a few more quarts. At 7.3 lbs/gal, this is insignificant. The metal mentioned replaced the metal cabin air box, so likely no change.

But weight and placement of an oil tank is insignificant. The big objective is moving the 500 pound lump aft 3+ inches.

Great - thank you.

[racerbruce]

Originally Posted by Michael9218

Interesting observations.

The weight of the remote oil tank is actually slightly aft of the wet sump. It is right of center, but the car has more weight on the left side. A 3 gallon tank will hold 2 gallons of oil to allow room for oil/air separation. So we're only talking about a few more quarts. At 7.3 lbs/gal, this is insignificant. The metal mentioned replaced the metal cabin air box, so likely no change.

But weight and placement of an oil tank is insignificant. The big objective is moving the 500 pound lump aft 3+ inches.

In concert with the pursuit of changing the large weight mass aft, perhaps assessing lowering the center of gravity....is it possible to locate the oil tank lower in the chassis? Possible to lower the battery lower in the chassis? Perhaps lowering the seat height a touch?

All of these may be on your radar already.

[2skiddy]

Racerbruce, the oil tank can't really go any lower as you have sheet metalwork of a structural nature right below it. The Z is not a big car and packaging various components is a real challenge. The location of that oil tank is correct, as the Motorsport guys at BMW did the same, but with a bigger tank. I made one up to fit there on mine and to clear the extended cage structure, took a bit of doing, but just fits in.

[Vanne]

I wouldnt change it, nor the other bits. The oil can and the batt/freezer are probably good offsets for driver weight.

[Michael9218]

What they said...

The only other option would be to locate the oil tank in the passenger footwell behind the firewall. But that would take a lot of fabrication to box it in so that it would not be technically in the cockpit. Not worth it for the 20 or so pounds of the tank and oil. Since there's room in the engine compartment (unlike E36/46) one would be crazy to complicate things by moving it back. One also has to consider that the further you run hose, the larger the hose needs to be to allow adequate flow. Longer larger hose also means more weight.

The driver seat is basically as low as it can go. At 6', I'm so low in the car that I'm having a challenge with markers on track that I've used for years. Can't see over the hood like I could in my old E36.

With the oil tank and the oil cooler now on the passenger side of the car, this should help with the weight balance.

Been noodling a solution for my Achilles dry sump kit. Their placement of the pump isn't going to allow the under pump fittings to clear the steering rack. I need to get creative...

One small bit of disappointment is the Achilles pan requires the motor to be 4mm higher up than I had it with the stock pan. Now to be fair, I was using AKG aluminum mounts that drop the motor 10mm. Their pan is designed to be compatible with most of the aluminum mounts that drop the motor 5mm. I suppose I could notch it, but where I'd need to notch it there is an oil galley for the forward scavange point...no one said this would be easy.

[2skiddy]

Mike, The ARE pan and Pace pump worked OK, I wouldn't want to modify the pan, might be better getting a different one? Raising the engine slightly is acceptable as you have already lowered it!

[Michael9218]

Originally Posted by 2skiddy

Mike, The ARE pan and Pace pump worked OK, I wouldn't want to modify the pan, might be better getting a different one? Raising the engine slightly is acceptable as you have already lowered it!

As far as I could tell from their website, the ARE pan looks to have no more clearance. 10mm drop is probably just too much. So I may just settle with 5-6mm drop.

[Michael9218]

Finished up the motor mounts and successfully test fit the motor and trans.

After a LOT of measuring, I decided 3.25" is as far as I can go without the need to cut structural sheet metal. Just not worth it for 1/2" to 3/4" I could get for the effort. 3.25" fits like it was meant to be that way!

To make the motor mounts I started by making a jig of the old mounts. To that jig, I mounted a bolt forward the 3.25" I want to move the motor back. I opted to use 3/16" plate for the base and feet. The arms are 1"x2"x1/8" rectangle tube. I gusseted with 3/16" plate where I felt it needed it. Each mount only weighs 1 pound more than the aluminum mounts. Hopefully these mounts will be stout enough. I believe they'll be stronger than the cast aluminum mounts. If they do fail, steel tends to bend where the cast aluminum mounts just snap.



Learning to weld, so no critique of the welds...






And now some before and after showing the fitment in the chassis.









Now with the motor in the car and the trans supported with a floor jack, I'll fabricate the trans mount.

[2skiddy]

Hi Mike, IIRC, I swapped round the starter motor bolt, as it would be quite inaccessible. All the other bolts I could just reach with the correct tools. I fitted a thread insert into the bell housing and drilled out the starter to take the bolt. I know I am stating the obvious, and you probably have done this already, but thought I would mention it......
Cheers

[ga41]

This thread is amazing. We all know that similar extensive mods were already done on various M3s but to see this amount of work on such a rare platform is really cool. Thank you for posting!