[Taskmaster]

Originally Posted by Torgus

fun fun, any plans for building the head?

Why build the head, it’s far superior to the N54 and and N55.

[hassmaschine]

Originally Posted by scanspeak

I thought the manual transmission was the limiting factor.

they originally used the trans from a 328i/325i - the 330i trans would have been a lot stronger.

[Torgus]

Originally Posted by Taskmaster

Why build the head, it’s far superior to the N54 and and N55.

To rev it out safely to high rpms is the 1st thing to come to mind, 8k or higher would be fun to see..

Secondly, almost every head can use headwork from the factory for it to perform optimally in a high velocity/boost environment.

Custom cams if they felt the need to go for big numbers.

Finally, if they need or want to add larger valves that would in theory be an option.

Just a thought. The head has better for flow vs the n54, not sure how far it can rev out safely.

[Noir]

Originally Posted by hassmaschine

they originally used the trans from a 328i/325i - the 330i trans would have been a lot stronger.

o rly?
good for me!

[TheTallJS]

ooo maaan. more bwooost

[hassmaschine]

Originally Posted by Torgus

To rev it out safely to high rpms is the 1st thing to come to mind, 8k or higher would be fun to see..

Secondly, almost every head can use headwork from the factory for it to perform optimally in a high velocity/boost environment.

Custom cams if they felt the need to go for big numbers.

Finally, if they need or want to add larger valves that would in theory be an option.

Just a thought. The head has better for flow vs the n54, not sure how far it can rev out safely.

My buddy is looking at the head (BPC is lightly involved - they sent a "junk" head to him to play with, courtesy of Pete) - so who knows, but I agree. People speculate on larger valves, bigger cams, etc - but since we have no baseline at all, there's no way to know if any of that is needed or what would actually be an improvement.

As far as revving safely, we have a 7k redline stock, which is pretty high for a traditional BMW I6 (normally it was like 6200rpm). Only a 10% bump is 7700rpm - but the issue here isn't the strength of the motor, it's the tuning of the whole induction system which is not designed beyond the stock redline. See the power dive on the N52 using a 3-stage manifold vs an N54 manifold (which while likely not ideal, doesn't have the high RPM resonance issues).

Anyway, all of that is likely irrelevant on a boosted motor, which is probably not going to have an 8k redline anyway - but that's for BPC to answer.

[Phil@BPC]

Originally Posted by hassmaschine

they originally used the trans from a 328i/325i - the 330i trans would have been a lot stronger.

This project originally started out as a 2006 325i automatic. At the time no one had done a conversion to a manual. We were the first to break through that barrier and sourced a E90 325i manual to make sure everything would line up and have less of an issue. As Alice sits she has a 335i transmission. This is the transmission we have been using with the turbo installed. Its safe to say it has been holding up to our abuse and the power levels on the street and at the track.

After we did the swap we cut the stock manifold in half and ran the car as a make shift "ITB" application. This with some software tweaking and we revved the car to 8,000 rpms. We did this to help find limitations of the E90 N52 platform. With the turbo installed we don't have plans to rev it 8,000 rpms.

[JuniorB]

Although forged internals would be nice, it would be interesting to see what the limits are of a stock block. Seeing these don't have sleeves like there boosted predecessors, and that they are already equipped with forged rods, is this a nessary upgrade, what levels do you guys plan on taking to? Then again, the n55 is everything that the n52 could've had, I see another video comparison between the 52 and 55!

[Noir]

Originally Posted by hassmaschine

they originally used the trans from a 328i/325i - the 330i trans would have been a lot stronger.

how much stronger? asking for a fren..

[hassmaschine]

the 328i uses the GS6-17BG (170NM, 125ft-lbs) - while the 330i has the GS6-37BZ (370NM, 273ft-lbs). It's rated for more than twice the torque. The 335i is rated for 530nm, and is definitely stronger, but they tend to be pretty conservative.

Actually it's a wonder the 325i/328i can get away with such a light trans (they used the same one on 4cyls, lol), but I guess BMW felt it would work just fine. But obviously with 500wtq, the GS6-17BG wasn't going to last very long..

[Biginboca]

Originally Posted by hassmaschine

the 328i uses the GS6-17BG (170NM, 125ft-lbs) - while the 330i has the GS6-37BZ (370NM, 273ft-lbs). It's rated for more than twice the torque. The 335i is rated for 530nm, and is definitely stronger, but they tend to be pretty conservative.

Actually it's a wonder the 325i/328i can get away with such a light trans (they used the same one on 4cyls, lol), but I guess BMW felt it would work just fine. But obviously with 500wtq, the GS6-17BG wasn't going to last very long..

hassmaschine where did you get the 125ft/lb spec for the 328i transmission? When I did my research before modding my car and cross referenced the BMW part numbers with the Getrag website I got a much higher figure of about 258 ft/lbs.

[hassmaschine]

Its not a getrag - its a ZF. The data for the trans comes right from the BMW ETK.

[Phyrexia]

The GS617BG is a Getrag. I think the G at the end is for Getrag. I want to say mine has a stamp on the housing, but I only took one picture when I did my clutch.

Originally Posted by hassmaschine

Its not a getrag - its a ZF. The data for the trans comes right from the BMW ETK.

Here we are.

http://www.bimmernut.com/forum/archi...p/t-44824.html

and

https://www.newtis.info/tisv2/a/en/e...earbox/1RnIpsi

[hassmaschine]

Arg, you are right - im sorry, i was paying too much attention to the BMW part number but not enough. B = benzene (gas), D = diesel, Z = ZF and G = getrag.

[Taskmaster]

350nm torque - which is 258ft-lbs.
The 330i is 27x

[Phyrexia]

Hey, I get it. I'm never wrong. I thought I was, once, but I was mistaken.

Originally Posted by hassmaschine

Arg, you are right - im sorry, i was paying too much attention to the BMW part number but not enough. B = benzene (gas), D = diesel, Z = ZF and G = getrag.

[Noir]

Originally Posted by hassmaschine

the 328i uses the GS6-17BG (170NM, 125ft-lbs) - while the 330i has the GS6-37BZ (370NM, 273ft-lbs). It's rated for more than twice the torque. The 335i is rated for 530nm, and is definitely stronger, but they tend to be pretty conservative.

Actually it's a wonder the 325i/328i can get away with such a light trans (they used the same one on 4cyls, lol), but I guess BMW felt it would work just fine. But obviously with 500wtq, the GS6-17BG wasn't going to last very long..

Damn. /:

[tom.gnade]

Originally Posted by Biginboca

hassmaschine where did you get the 125ft/lb spec for the 328i transmission? When I did my research before modding my car and cross referenced the BMW part numbers with the Getrag website I got a much higher figure of about 258 ft/lbs.

That is very interesting that 350nm is the limit on the transmission because I just confirmed the limp mode limit is set at right around 360nm by checking the torque limit fault code data at a shop.

[atmosphericM]

That is interesting. I wonder where this TQ limitation is being measured? At the crankshaft/flywheel/clutch/tranny input shaft (yes I said it), I'm guessing? I'm assuming that the TQ force should be about the same across all of those components.

This all has my brain on overdrive. I'm thinking.. OK so how does the DME even know what TQ is being produced? Perhaps it is measuring the acceleration of the flywheel and then crunching the numbers based upon it's size and weight, sort of like a dyno does. If that's the case though, I wonder if simply switching to a lightweight flywheel would cause the car to go into the over-TQ limp mode. Then again, I suppose if the clutch was engaged, a lightweight flywheel overall wouldn't make a large enough difference in the entire drivetrain to change the acceleration all that much. But if we are already riding the edge, as it seems we are when tuned/FBO, it could cause issues. Ha can you imagine going into limp mode by just revving your engine??

Furthermore, I'd imagine that an immediate, great increase in TQ (an increase in value over a set, small period of time) would have a much higher chance of damaging things, so you'd think that the DME would be looking out for that a lot more than it does overall TQ. Maybe it is.

I wonder if Getrag's published limit is really the overall TQ capacity of the transmission, or if it's a "safe" value because they are keeping in mind how immediate TQ could wreck things. Maybe the real physical limitation of the transmission is higher than 350 nm, however an increase from 0 TQ to 350 immediately (within reason) is actually the limitation they are referring to.

Fun stuff.

[tom.gnade]

Originally Posted by atmosphericM

That is interesting. I wonder where this TQ limitation is being measured? At the crankshaft/flywheel/clutch/tranny input shaft (yes I said it), I'm guessing? I'm assuming that the TQ force should be about the same across all of those components.

This all has my brain on overdrive. I'm thinking.. OK so how does the DME even know what TQ is being produced? Perhaps it is measuring the acceleration of the flywheel and then crunching the numbers based upon it's size and weight, sort of like a dyno does. If that's the case though, I wonder if simply switching to a lightweight flywheel would cause the car to go into the over-TQ limp mode. Then again, I suppose if the clutch was engaged, a lightweight flywheel overall wouldn't make a large enough difference in the entire drivetrain to change the acceleration all that much. But if we are already riding the edge, as it seems we are when tuned/FBO, it could cause issues. Ha can you imagine going into limp mode by just revving your engine??

Furthermore, I'd imagine that an immediate, great increase in TQ (an increase in value over a set, small period of time) would have a much higher chance of damaging things, so you'd think that the DME would be looking out for that a lot more than it does overall TQ. Maybe it is.

I wonder if Getrag's published limit is really the overall TQ capacity of the transmission, or if it's a "safe" value because they are keeping in mind how immediate TQ could wreck things. Maybe the real physical limitation of the transmission is higher than 350 nm, however an increase from 0 TQ to 350 immediately (within reason) is actually the limitation they are referring to.

Fun stuff.

I've been thinking about this too. How are they measuring actual torque? Is it an instantaneous value or sustained over some number of milliseconds? Is it based on a ramp rate, or just based on a single threshold value? Is there an RPM map for expected torque? If we go much over 350nm are we going to be blowing GM transmissions? Somehow I think that's a very conservative value but if the transmission really is that much lighter than the one in a 330i, maybe we're closer to the safe limit than we think?

[hassmaschine]

Originally Posted by tom.gnade

That is very interesting that 350nm is the limit on the transmission because I just confirmed the limp mode limit is set at right around 360nm by checking the torque limit fault code data at a shop.

actually it was 268nm based on what you posted - the value the DME saw was 360nm, which is why it triggered the error.

IIRC it's the instantaneous torque that the DME tracks internally. I'm not sure if it's 100% accurate or not - probably depends on how good the calibration is..

[tom.gnade]

Originally Posted by hassmaschine

actually it was 268nm based on what you posted - the value the DME saw was 360nm, which is why it triggered the error.

IIRC it's the instantaneous torque that the DME tracks internally. I'm not sure if it's 100% accurate or not - probably depends on how good the calibration is..

Agreed, the limp mode threshold is 358nm apparently? Also, if the torque sensor is accurate then wouldn't there be a way to output actual engine torque to a file and get a cheapo flywheel dyno chart, at least an approximation? Could use that to a/b test changes like milvs and bbtb pretty easily if someone with enough skill could monitor it via odb2 while the car is operating.