[Noir]

Good press forward… interested in seeing where it goes! To confirm, would it be relatively 'easy' to fit internals from the n53 into the n52 without substantial modification?

[E92_William]

No idea. That's what I'm trying to find out. I suspect it will be okay. But who knows if it would even throw the rod/piston assembly out of balance or something like that. Another concern is how it will all fit when combined with MILVs if the pistons are reaching higher in the cylinder.

[cwlo]

How about an n55 crank in the N52. No idea if that would work, but the stroke of N52 is 88, N55 is 89.6

[E92_William]

Originally Posted by cwlo

How about an n55 crank in the N52. No idea if that would work, but the stroke of N52 is 88, N55 is 89.6

Interesting that could probably work aswell. I'd have to source an N55 crank to try that out. I believe the two engines share the same bearings so should fit right in.

[E92_William]

If anyone has a specific timing tool kit they can recommend or that they have laying around and would be willing to sell let me know. I bought this one from Amazon and one of the two cam locking tools is loose in place and the other barely fits. It all lines up like crap too once assembled.

[0l0dom0l0]

I checked on real OEM using my N53 330i and the
N53 crank shares the same part number as other N52 engines as does the head gasket.

The difference in compression will almost certainly come from the pistons themselves. Using the DI pistons on the N52 would be of no benefit at all because the tumble in the cylinder will be disrupted. The chambers on the N53 are to help with the stratified charge operation.

Have you thought about running something like some S54 throttle bodies on your car instead? I'd be interested to see if the N55 crank fitted also. Edit just checked pictures and no chance sadly. The oil pump drive is totally different.

[E92_William]

I had the opportunity to ask a few questions regarding these engines and this idea to Bisi from Bisimoto engineering which I'm sure some of the guys here know of, he's a well regarded engineer and engine builder with a lot of NA experience. He said it will be okay to run a piston with a divot in the center that came from a direct injection engine on an engine that uses port injection, even though airflow and propagation won't be perfect, the increase in compression will still be an improvement.

What he did recommend however was to calculate the current dynamic compression ratio of this engine as it sits. That way I know if I'm lacking compression or head flow or timing or who knows, I think flow is not an issue but we don't have numbers to back that up.

What did you see different in the N55 crankshaft? I just had a look and saw that the gears for the oil pump drive are indeed different but when that is removed as I saw in some listings, they both look very similar, maybe it could be swapped from the n52 crank to the n55?

[hassmaschine]

Huh.. stroker N52. I wonder if the N55 crank would still have rod bearing issues if used as an N/A build? or maybe that was a rod bearing issue itself.

Maybe that'd give me the motivation to do something with my N52 that's been sitting on a stand for 6 years!

[rjahl]

There are a few "stroker" kits available for the N52 and looking at the price, the cranks must be from other motors. I remember working with someone from Germany with a Z4 and a stroked 3.2 liter N52.

If I'm not mistaken the rod bearing issue on the N55 is related to oil starvation on hard turns. Sump was not designed for track use.

[E92_William]

Pretty sure the n55 uses the same rod bearings as the n52 so that issue has to come from somewhere else. Some people were saying the oil pump in those engines has some sort of electronic controls that might have an effect on that but I haven't looked into it

[2one3E90]

Hmm whats the redline on these n52? Does it make more power or just drops after 7?

[E92_William]

Originally Posted by 2one3E90

Hmm whats the redline on these n52? Does it make more power or just drops after 7?

Pretty sure 7k maybe there's some fuel cut before that. Power begins to drop off at 6500 with the 3 stage manifold and that's about where the n54 manifold takes it over to who knows what rpm it would stop making power at. Can't imagine revving an already undersquare engine which might be stroked even further with say an n55 crank, is any safe over 7k.

[hassmaschine]

N52 will easily rev past 7k. Valve start to float after 8k. My friend's N52 with the N54 manifold kept making power to redline - his is currently set to 7750. Hard to get a dyno number there, because it revved too fast and the soft limiter kept kicking in.

Most BMW engines are undersquare and they rev fine. The S54 is a good example of that. Maybe an ATI damper is a good idea - but his next problem is his power steering, it's boiling the fluid on the track. lol

If you have a 3 stage, there's not much point in raising the limiter, except in lower gears so you don't end up bouncing off it.

[hassmaschine]

Originally Posted by rjahl

There are a few "stroker" kits available for the N52 and looking at the price, the cranks must be from other motors. I remember working with someone from Germany with a Z4 and a stroked 3.2 liter N52.

If I'm not mistaken the rod bearing issue on the N55 is related to oil starvation on hard turns. Sump was not designed for track use.

It has the electronic pump too (it's mechanical, but there's some sort of oil control system connected to the DME). Maybe those couple % fuel savings are not worth the risk..

[Biginboca]

Originally Posted by hassmaschine

If you have a 3 stage, there's not much point in raising the limiter, except in lower gears so you don't end up bouncing off it.

hassmaschine I respectfully disagree with you on this. And it’s not just you I have seen this repeated time and again when discussing raised redline on this platform. Raising redline is always an improvement in performance with a manual transmission because it enables you to stay in the lower gear longer.

This has 2 advantages.

Firstly…
You ride out the increased torque of the lower gear longer before shifting. You are making substantially more torque in the lower gear than any power drop off the engine sees as it nears redline. Look at these gear ratios for the 328i manual transmission (GS6-17BG)


1st Gear 3.69:1
2nd Gear 2.06:1
3rd Gear 1.31:1
4th Gear 1:00:1

First gear is almost double the torque of second gear. Staying in 2nd gear you are still making almost 40% more torque than you will after you shift to third. Staying in 3rd you are making 30% more torque than after you shift to 4th.

These huge torque advantages far exceed any power drop off of the engine as it goes the extra 300-500rpms for a typical raised redline.

Secondly…

After the shift you will land at a higher RPM in the new gear, which will typically put you deeper in the meat of the powerband post shift (such as 5,500rpms instead of 5000rpms, or 5000 rpms instead of 4500, etc)

With an N/A car unless traction is an issue you are pretty much always better off staying in a gear as long as you can. The transmission’s relatively large torque split between gear ratios is the reason why.

Btw have you had any chance to mess with the exhaust cam rollers yet?

[2one3E90]

Originally Posted by Biginboca

hassmaschine I respectfully disagree with you on this. And it's not just you I have seen this repeated time and again when discussing raised redline on this platform. Raising redline is always an improvement in performance with a manual transmission because it enables you to stay in the lower gear longer.

This has 2 advantages.

Firstly…
You ride out the increased torque of the lower gear longer before shifting. You are making substantially more torque in the lower gear than any power drop off the engine sees as it nears redline. Look at these gear ratios for the 328i manual transmission (GS6-17BG)


1st Gear 3.69:1
2nd Gear 2.06:1
3rd Gear 1.31:1
4th Gear 1:00:1

First gear is almost double the torque of second gear. Staying in 2nd gear you are still making almost 40% more torque than you will after you shift to third. Staying in 3rd you are making 30% more torque than after you shift to 4th.

These huge torque advantages far exceed any power drop off of the engine as it goes the extra 300-500rpms for a typical raised redline.

Secondly…

After the shift you will land at a higher RPM in the new gear, which will typically put you deeper in the meat of the powerband post shift (such as 5,500rpms instead of 5000rpms, or 5000 rpms instead of 4500, etc)

With an N/A car unless traction is an issue you are pretty much always better off staying in a gear as long as you can. The transmission's relatively large torque split between gear ratios is the reason why.

Btw have you had any chance to mess with the exhaust cam rollers yet?

Have u ever shifted without the clutch? During autoX i forgot to press the clutch and went from 1st to 2nd. It shifted, I let off the gas like usual but didnt even press the clutch. It shifted good to. Can u do that often?

[hassmaschine]

Originally Posted by Biginboca

hassmaschine I respectfully disagree with you on this. And it’s not just you I have seen this repeated time and again when discussing raised redline on this platform. Raising redline is always an improvement in performance with a manual transmission because it enables you to stay in the lower gear longer.

This has 2 advantages.

Firstly…
You ride out the increased torque of the lower gear longer before shifting. You are making substantially more torque in the lower gear than any power drop off the engine sees as it nears redline. Look at these gear ratios for the 328i manual transmission (GS6-17BG)


1st Gear 3.69:1
2nd Gear 2.06:1
3rd Gear 1.31:1
4th Gear 1:00:1

First gear is almost double the torque of second gear. Staying in 2nd gear you are still making almost 40% more torque than you will after you shift to third. Staying in 3rd you are making 30% more torque than after you shift to 4th.

These huge torque advantages far exceed any power drop off of the engine as it goes the extra 300-500rpms for a typical raised redline.

Secondly…

After the shift you will land at a higher RPM in the new gear, which will typically put you deeper in the meat of the powerband post shift (such as 5,500rpms instead of 5000rpms, or 5000 rpms instead of 4500, etc)

With an N/A car unless traction is an issue you are pretty much always better off staying in a gear as long as you can. The transmission’s relatively large torque split between gear ratios is the reason why.

Btw have you had any chance to mess with the exhaust cam rollers yet?

well, with the 3 stage, it's not a smooth decrease in power like you'd expect - it feels like hitting a brick wall, lol. It looks that way on a dyno chart too.

I agree with you in principle, and I still have mine set to 7500 or something for the same reasons you mention. But there's no power to be had there without a different intake. That was my real point. With the N54 intake, you can rev as far as the engine can handle and power will not hit a wall like it does with the 3 stage.

of course if you have an automatic it's going to shift regardless of what you do with the redline in the DME.. so that sucks.

edit: I have poked around the rockers coming up with a plan of how I'm going to measure stuff, but I haven't disassembled the exhaust cam tray yet. I'm finally done with a project I've been working on for over a year at work, and should have some free time again. It'll definitely happen in the next couple weeks (my family are taking off on a mini vacation next week, and I'll be here by myself).

[hassmaschine]

Originally Posted by 2one3E90

Have u ever shifted without the clutch? During autoX i forgot to press the clutch and went from 1st to 2nd. It shifted, I let off the gas like usual but didnt even press the clutch. It shifted good to. Can u do that often?

it's possible but it's hard on the synchros. I wouldn't make a habit out of it.

[2one3E90]

Originally Posted by hassmaschine

well, with the 3 stage, it's not a smooth decrease in power like you'd expect - it feels like hitting a brick wall, lol. It looks that way on a dyno chart too.

I agree with you in principle, and I still have mine set to 7500 or something for the same reasons you mention. But there's no power to be had there without a different intake. That was my real point. With the N54 intake, you can rev as far as the engine can handle and power will not hit a wall like it does with the 3 stage.

of course if you have an automatic it's going to shift regardless of what you do with the redline in the DME.. so that sucks.

Put this then

[2one3E90]

Originally Posted by hassmaschine

it's possible but it's hard on the synchros. I wouldn't make a habit out of it.

Is downshifting and blipping the throttle always when dropping gears bad on the synchros?

[hassmaschine]

no, that should be fine, it's actually better for the transmission since you're matching the input shaft speed with the engine speed between gears. I rev match every time I drive (because it's fun), heck my E30 has like 350,000 miles on the transmission.. lol

[Biginboca]

Originally Posted by hassmaschine

edit: I have poked around the rockers coming up with a plan of how I'm going to measure stuff, but I haven't disassembled the exhaust cam tray yet. I'm finally done with a project I've been working on for over a year at work, and should have some free time again. It'll definitely happen in the next couple weeks (my family are taking off on a mini vacation next week, and I'll be here by myself).

Awesome… Really looking forward to your findings, thanks!