RomRaider

What about M52B28 crank? Will it fit as well as M51D25 with 135mm rods?

compression could be a bit high...maybe with E85 or Aral 102 if you can get that?

A lad from Hungary did this. He removed 2,5mm from the top of the pistons what resulted in 11.5 CR. I'm not sute about it, but maybe it is safe to do so if 2.0 pistons are 3mm higher than 2.5/2.8?
https://www.youtube.com/watch?v=RbqBYfN6V8Y&t

Just had a look in my excel sheet.
With stock pistons and b28 crank with the 1,74mm headgasket i get 12,06:1
Using the thicker 2,04 oe gasket i get 11,63. (see picture attached)

So iam not shure if turning down the dome of the pistons is necessary. I think i would try it with the 2,04mm gasket for 95-98 octane fuels.

My setup with the tiny bit less stroke (82,8mm) is at 11,1:1 with the 1,74mm gasket.

Big thanks to you for the calculations. I didn't know about OE thicker HGs. Slightly higher CR isn't a problem as I'm running LPG gas in my E36 which is around 100 octane.
So, I'm starting to look for the best 2.8 crankshaft offer :p

I've collected every part needed + invested in the M54B30 intake camshaft. I'm kinda scared that there is a possibility for valves to collide with the pistons. Any tips how to measure if the do or don't? Sorry if I sound stupid but I have completely no education in stuff like this.

If you are unsure you should do a dry fit and test the clearence of the valves around tdc without valvesprings.
I just compared the stock b20 piston to deck vs the stroker. Because the stroker reaches tdc with more distance to the head there should be more room than the b20.

Cleaned up some old pink tops that were laying around and installed them today.
Max duty went from 70% to around 57%.<- incorrect due to very old logger-def, in reality much higher
trying E85 next tank (1,92€ for gas vs 0,75€ for E85)
Any pointers from people who dun it already are very welcome!

Quick Update on the E85:
Got the Pinktops running ok on E10.
Then switched to something like E76 on a nearly empty tank.
I started by multiplying fuel by 1.35. that was pretty close.
Then i went to top off and that got me to around E81
At WOT i run around 13 going a bit richer maybe at the very top.

Coldest to do a coldstart was a little bit over 10°C. There i added fuel to the cranking and cranking initial maps.
At the moment its not optimal. Sometimes when starting "cold" (13-20°C) it stumbles for 0,5s slightly before it fires correctly. maybe i added too much.
Will be revisiting this especially when it gets colder.

On the ignition side, beforethe switch i was pretty much on the knock limit at WOT. So i left the ignition map alone for now.
I thought to give it an extra 2 deg in the upper load cells (WOT).
But the question becomes wheres the point of optimal torque output...what do you guys think?

Would you recommend to get the RR dyno function working to tune the ignition correctly (is it precise enough)? Or bite the bullet and rent dyno time?

So far i used about 40-45 liters and i am overall happy with how it went so far

Update on the E85:
So far everything ok'ish. I ran a bit over 5000km with the E85. It starts good even with temps getting lower and its ultracheap now 60 cent/litre.
Since recently i have a problem where it feels like misfires in the range of 6000-7300 at WOT. I cant hear anything when it happens but the engine loses power for a split-second. It felt like some combustion cycles on some cylinders were not igniting at all.
Thats why i wanted to look at the plugs. I never saw plugs with a buildup like that. What is your guys 2 cents? Is this related to the E85?

From my experience whenever I had those small lags (losses of power) on top above 5500rpm it was always due to running too rich. I was chasing my tail for weeks before I had wideband O2 and thought it was perhaps due to ignition related. Running WOT with O2wideband reveavaled that running richer than like .86 lambda and those small jolts occur. Reduced WOT fueling to get to about .88 min. lambda and revs smooth.

However, this is with normal fuel e5. Did you log your wot runs with wideband?

Also, just for cross ref. here is a pic of my plugs after like 20K. All nice and brownish.

Hey thanks for your reply!
I run a WBO2. In the area where i have the problems its around 12-12.5 (gas-)AFR (ca. 0,82-0,85 Lambda) which should be fine for E85...
But no harm in doing a test leaning it out slightly!

Did a plug-read with new plugs today. But no real conclusion there, still some white deposits on there even after very short runtime (2 min). Did 4 WOT pulls with minimal idle time:


But in the logs i found something. In this one attached the RPM isnt rising steadily but has one small dip and quickly after that the lambda is showing it going lean:

This matches what i feel in the car. I have a hunch its skipping one or more injection cycles.
But the million dollar question the f*** why it does it remains

Does anyone know how loosing crank signal for maybe one revolution effects the ECU?
I have no codes so far...

While trying to search for a cause of the hiccups at WOT+high RPM i found that the IPW in my tune doesnt match what i capture in the logs
Thought about it for a while but cant see why
I picked WOT at 6000 rpm as an example. In this log i am at a little over 500 load, so i would think my IPW should be ca. 15,6 ms (from Basemap) plus 16,9% = 18ms. Plus Deadtime (but its just around 0,55-0,7ms).
That would be right at 90% Duty Cycle.

My log shows that injection time is 13.964 ms at this Datapoint huge deviation that i cant explain...

On the other hand the AFR is ok (Other than little leanspots with practically unchanged IPW->I think the cause for my hiccups)

I ve never looked at this in the past. Does anybody have an explanation for this tune-IPW vs logged-IPW?

EDIT: I had an old logger def from 2017 on the logging laptop...(old def used 0,004 vs new def 0,00534 as factor for IPW- 33,5% difference)
With the newest def from the thread its working. At 6000 with ca. 530 load the new log shows 20.255 ms.
(logged=20.255ms -0,55ms=Deadtime)/1,251=WOT_Enrichment=15,75ms ->matches the tune
Its running out of injector