B35 hibernation mode with MS3X

[Bearmw]

I am liking the 3.73 diff so far. It is perfect for back roads and I stayed in second gear the entire time on the course. It is a little buzzy on the highway at 70 mph but liveable since the car was built primarily as a mountain car and less of a highway cruiser. I also like to 205/55/15s as the steering effort feels better (slightly less) than with the 225s. The car feels almost effortless in any gear now.

https://www.r3vlimited.com/board/attachment.php?attachmentid=121775&stc=1&d=1528680268

[Bearmw]

I decided to recalculate my fuel economy after the most recent tune and gear changes. I am pleased to see that even with the 3.73 rear and plenty of hard driving there is an improvement ( however sleight). The beast used 36.9 gallons to travel 694 miles which comes out to 18.8 mpg compared to the previous 18.27.

[CharMick]

Similar idea

I'm in the middle of putting my B35 into the engine bay (time to start bashing the firewall). I have Garagistic mounts and Treehouse-style CABs. My megasquirt2 is built (almost...logic drivers and PWM for idle valve left to install) and using LS2 truck coils like you. My car is an auto with a 4.10 Torsen LSD from a Z3...probably not as fun as stick but should move OK.

I like what you did with the coils and it looks like you might have the same injectors I got (23 lb/hr?). I also have the vibrant resonator and a high-flow cat but I went with a borla muffler i got for next-to-nothing...all 3-inch...I hope that wasn't a mistake.

Where did you find a base tune for your MS? Do you have a picture of your MS board showing the idle circuit...MS documentation is a bit sketchy in this area.

Awesome build and pictures, BTW!

[Bearmw]

I think that I am using Bosch 0280155715 injectors that flow about "24 lb" at 49 psi. My FPR is 3.5 Bar so that is about 50.76 psi. I believe they give me ample reserve capacity for my motor. The 3" exhaust is a recommended size for most turbo M30s so it might result in a bit less exhaust velocity with a NA motor. Hopefuly that won't result in a reduction In torque? I came up with a base tune by looking at some fuel and ignition plots on mye28 and then guestimated what numbers would be most applicable to my combo and reduced the timing due to my higher compression. I also read the SA books Engine Management Advanced Tuning and Designing and Tuning High Performance Fuel Injection Systems to give me a better idea of what I was doing. I took the easy way out by not building a MS board (hence no pics of it) and instead bought a pre-made MS3X unit from DIYautotune. Once I got the base tune so it would ldle I let auto tune do a lot of the rest until I got on a Dyno.

What else is going into your build and how do you plan on using the car?

[CharMick]

It will just be an around-the-town cruiser for my wife, mostly. Occasional stop-light sprints, nothing too extreme. It probably won't be driven on the highway much (seatbelt slaps the heck out of your arm at speed) although I do have a hardtop i got on CL a year ago. From my recent entry in the M30 role call...

In final stages of assembly (I hope)...
Low mileage 91 cabrio, black
92 M30B35 from a 735i with 110K miles
4.10 Torsen LSD from a Z3
E46 steering rack
E36 tie rods
Condor Speed offset cabs
Bilstein fronts and KYB Camaro shocks rear
E32 aux fan for cooling
Z3M radiator
Transcool transmission cooler
Megasquirt2 DIY
Six LS2 Truck coils using crank-fired ignition
23lb mustang injectors
3 inch single exhaust with Vibrant Quiet resonator, high-flow cat, and Borla muffler
14.7 wide band O2
E32 intake with AFM delete
Garagistic mounts with 635i rubber bushings
M30 torque converter and bell housing with E30 4HP22 (or is it a 24?)
Style 18 BMW wheels from an E36 that I will mount once i can save up for a set of 42 Draft Design adapters
UUC braided brake lines
Garagistic rear shock mount reinforcement
Battery relocated to rear...50lb ballast removed
Drilled and wired cam oiler banjo bolts
AC delete
PS retain

[CharMick]

Just got the m30 on its engine mounts today after some firewall bashing and there is about 1mm of clearance between the AC pulley and the Z3M radiator. Since I am not reinstalling AC and I will be distributorless I think I am going to split the AC pulley down the middle (in the valley) and remove half of it. Should have about 10-12mm of clearance. Any other suggestions? e28 535 radiator?

I have a concern about splitting that pulley...I don't want to unbalance the crank.

[Anthony B]

If you split the pulley you would need to rebalance it, I was look at that yesterday on mine while I have it pulled apart & decided against it. The e28 rad is thinner it will give you about 2cm & with no distributor you’ll have around 3-4cm at the top.

3” may drone I’ve got a 3” setup on mine & will be redoing it out of 2.5” drones terrible at 110km/h however below that it’s throaty & pretty fun

[Bearmw]

Since I elimnated power steering I am just using the alternator and water pump pulley of the harmonic damper. I was under the impression that these motors are internally balanced and the damper ( metal bonded to rubber) just dampens out crankshaft torsion harmonics. So far I have noticed no I'll effects from the missing pulley. I did no crankshaft modifications but lightened the rods at the big end and balanced them. My pistons are a bit lighter than stock as well. My flywheel is an early 533i unit that is fairly light at around 17 lbs. It spins up pretty quick but am still thinking about a lighter flywheel for the hell of it.

[Anthony B]

The issues with not rebalancing is more killing the damper or the damper mount giving up the ghost, it’s more of those it could happen but may not. I’ve gone with the mrt crazy trigger wheel & ati damper setup & will be balancing it all together.

I’ll be running Rama’s rhd light flywheel I have a mate with one behind his m54b30 & the rev response is insane, hopefully with knife edged crank, s38 rods, lighter pistons, & the mrt damper I hope I can see this thing find 8000rpm

[Bearmw]

Wow Anthony that sounds like a crazy build and not cheap! My cam runs out of steam at just over 6 grand (and I don't redline it too often) so I am less concerned about damaging vibration. I guess the old M30 race motors would rev to 7 or 8000 RPM and made up to about 370 hp so with modern technology it seems doable but I would think high compression and race gas is necessary toward that end. Are you running E85? I run 93 octane which is the best we have where I !ive without going to racing fuel.

[Anthony B]

I’m tossing up e85 or at least running a flex fuel sensor & have the ability to run e85(not many service stations have e85 on pump) I can run 98octane pretty easy will just knock back rpm limit & timing to avoid detonation

it’s setting me back a few dollars but it’s been a long project now just chipping but by bit, itbs/ecu/ & built head will end up on my oe bottom end shortly, & I’ll be building the short block in the mean time(machining, & ordering pistons to go)

[Bearmw]

What compression ratio are you shooting for?

[Anthony B]

Aiming at 11:1, will be getting pistons made to suit need to see if the block is going out to 93mm & using forged 144mm s38 rods

[Bearmw]

What are your thoughts on using a b34 block over a B35 due to it's thicker deck? The b34's are supposed to be less likely to crack around the head bolt/water jacket area. Similarly the "early" B35 blocks ( not sure which ones these are) are also considered stronger. Also, are you considering modifying the block to improve coolant circulation between cylinders 5 and 6 to mimic the long raised coolant passage on the driver side that the m90 blocks had? These two considerations might be over kill for a mild N/A build (like mine) but if I was to build a turbo or next level N/A motor I would use a b34 block and modify it for an extra coolant passage (via external hose attached to fittings added to the block) to lessen the chance of having to pull the motor back out to deal with a crack.

[Anthony B]

I have an m90 block stored at my parents place which is a weird one no raised cooling passage(late m90), however correct bore sizing, 84mm crank, flat top pistons not pianos. It’s however got lots of coolant build up in the channels so when I hit up the machine shop I’ll be taking both the m90 & m30b35 blocks whichever’s the better slate I’ll be running with that.

I’m looking at using the older rear drain from the head, I have the outlet piece thanks to the m90 this should see the cooling improve(I haven’t helped mine by pulling the heater box).

The b34 would be a better option for forced induction more so due to the 8.1:1, I don’t think the N/A build will push the b35 hard enough to crack the block(hopefully). I’m running a reasonably sized oil cooler setup, & looking at crank scrapers. In theory if the oil pressure, oil cooling, along with water circulation the block should run pretty consistent heat cycles.

I should probably update my build thread rather that rambling in yours haha. But I digress, how is your car going currently? mine seems to be getting pulled further & further apart currently