iX stroker turbo Questions

[SpecM]

don't get carried away with the v12 math, there...

you have to use either aftermarket (like MM) pistons with the "i" rods (135mm) or shorter eta rods (130mm)

[nando]

it's 6mm, not 3 - and they didn't just change the stroke to get more compression, they used different pistons as well. if you used the same pistons with 6mm more stroke you're going to hit the cylinder head long before you get to TDC.

[beamR X]

Cool.
So how much more stroke are we talking about? According to the spec sheet off of the main r3v page the "e" has 81mm stroke and the "i" 75mm. That 3mm gain on the compression. Is there enough room there for that or do I need a different connecting rod? ...specifically that I will have it resurfaced?




The M division played with 1mm on the S70.
I was studying the 850CSI V12 and I am starting to notice a bunch of parallels between the 325i "stroker" and the 850CSI "M" developed S70:

From this link:

http://www.bmwmregistry.com/model_faq.php?id=11

"DrivetrainHow is the S70 engine different from the M70 V12 upon which it is based?
When creating the 850CSi's S70 V12 motor, BMW Motorsport began with the standard 24-valve SOHC M70 engine and instituted the following changes:
-Increased bore (from 85mm to 86mm) and stroke (from 79mm to 80mm) for a new total displacement of 5,576cc (from 4,988cc)
-Lighter pistons
-Increased compression (from 8.8:1 to 9.8:1)
-More aggressive valve timing for increased high-rpm power
-Larger diameter exhaust pipes
-Variable rpm limit (6,400 in 1st+2nd, 6,200 in 3rd, 6,100 in 4th. 6,000 in 5th+6th)
-Adjustable throttle sensitivity via dual mode (Sport or Komfort) console-mounted switch
-Engine oil cooler (European-spec models only)

These modifications resulted in an increase in maximum power from 300 hp (DIN) or 296 hp (SAE) at 5,200 rpm to 380 hp (DIN) or 372 hp (SAE) at 5,300 rpm. In addition, maximum torque was increased from 332 lb/ft at 4,100 rpm to 402 lb/ft at 4,000 rpm.

This engine can be identified by the "Powered by M" inscription on the central cam cover between the two banks of cylinders."


So, reading between the lines: BMW "M" division made a 850CSI model and increased the size of the "stock" 5L V12 (pretty much 2 l6 2.5L blocks) to 5.58 L.

Hmmm.... What's more interesting is that they went from 8.8:1 all the way to 9.8:1 by increasing the stroke by just 1mm and advancing timing a bit.
Intriguing, since my Mark D chip already advances my timing so I have to run a minimum of 91 octane gas. I guess the "stroker" mod would pretty much do to 2.5 what the "M" division did to the V12. (less the bore, of course).
The torque gains are impressive. From 332 to 402. That's 70lb/ft!!!
Even if I 1/2 it that's 35lb. I don't know how much bore influences the torque in this motor, but I'd say a stoker on a 2.5 should bring at least 20-25lb/ft of torque...

How does this sound to you guys? Am I missing something? I find it hard to believe that by the same token I could gain 20-25 HP? I guess without lighter pistons that's not possible...

[SpecM]

So, excuse my total ignorance on the topic, but this means the ETA crank has simply a longer stroke,(hence the "stroker") which gives it more displacement and power all in a nice convenient package....
Cool.

yep, you got it

[beamR X]

Got'cha.

So, excuse my total ignorance on the topic, but this means the ETA crank has simply a longer stroke,(hence the "stroker") which gives it more displacement and power all in a nice convenient package....
Cool.

Thanx!

[nando]

You don't, you use the ix block with the e crank.

[gstuning]

Nobody needs a ETA block for a stroker conversion,
the 84mm m20 block from a IX is fine for any m20 based conversion.

200whp from a M20 isn´t the hardest in the world in N/A form but it´s not cheap either.

[beamR X]

recesitating the thread

So, nando, what does one do to the bottom end to marry the e block to the iX oil pump guts.

I am seriously considering building a stroker there are couple of tasty 325es for sale locally and I'm 1/2 way torn into my motor already (head gasket's pulled)

[nando]

nope - pump location has nothing to do with it. the ix pump is in the front of the block just like any other M20. the differences is an entirely different mount, pickup, reversed flow, and reversed intermediate shaft. the E28 block is the same as any other E30 block - it just has a different pan.

[aaron325ix]

e28 block

someone told me that a block from an e28 528e will work for my iX rebuild considering the oil pump location etc. Any ideas on this?

[aaron325ix]

I'm thinking I might just go with a stroker to start, break it in and see how I like it, maybe even put headers on and the like. When I get back into the mts., if I feel it is lacking I can still turbo it right?

Which brings up the question's: What pistions should i go with? I think I'm set on MM for sure with the non interferance, but you said 10:1 wont be good to turbo later on right? So I should still consider getting some 8.5:1 made from them, and still be happy with those if I decide to stay NA?

As far as everything else, I would still want to overbuild, welded coolant channels etc. and with stroked I can still use motronic right?

[nando]

very good info, thanks for that. I'm sure I dont have to ask if it is fun to drive. how are you on reliability, and smooth idle and things of that nature? I like how you moved the oil cooler to behind the kidneys, that is one of the things I was wondering about.

reliability - that's the reason you build it well, don't skimp on important peices of the puzzle. I can't speak for issac, but my idle is just as good as it was with motronic - I'm using MS2/extra's PWM closed loop to control the stock ICV.

With the stand alone, does your OBC still work like stock, do you need an adj FPR? Welded coolant channels I am still unfamiliar with as well.

No, the OBC won't work, unless you can figure out a way to input the VSS and a calculation for the present fuel rate (econogauge). An adjustable FPR is pretty much a waste of money, but a gauge is a good thing to have - if you happen to find a AFPR with a gauge, pick one up and just set it to stock (43.5psi). Welding the head means welding the coolant channels to be more like the late M30 head - early M30s and all M20s have really wide coolant channels that are uneccesary for cooling and cause the head to flex quite a bit (this is bad on a turbo).

My current motor isnt exactly dead yet, but I am at the point where i am starting to collect parts, infact I am thinking of buying some pistons soon. I was thinking of MM 86mm. I figure that is a good starting point, one of the most expensive parts,and go from there, so when the motor shits the bed I can be ready to rebuild.

You can have MM make you 86mm pistons, but keep in mind their off the shelf pistons are 10:1 - but they are willing to build you lower compression or any bore diameter really. I don't know if it works on turbos but it's pretty nice to have the deep valve pockets for non interference :)

Side note: I was planning on getting a IE cat back like next week as i am sick of my B&B tri-flo(too loud). Will the IE be good enough for what i am potentially planning, or should I hold off and wait or get something different? Thanks again.
AW

I would wait, or get something cheap (stock muffler maybe?). you're going to want a single 3" exhaust pretty much, a cat back isn't going to do you any good with a turbo.

[aaron325ix]

very good info, thanks for that. I'm sure I dont have to ask if it is fun to drive. how are you on reliability, and smooth idle and things of that nature? I like how you moved the oil cooler to behind the kidneys, that is one of the things I was wondering about.

With the stand alone, does your OBC still work like stock, do you need an adj FPR? Welded coolant channels I am still unfamiliar with as well.

My current motor isnt exactly dead yet, but I am at the point where i am starting to collect parts, infact I am thinking of buying some pistons soon. I was thinking of MM 86mm. I figure that is a good starting point, one of the most expensive parts,and go from there, so when the motor shits the bed I can be ready to rebuild.

Side note: I was planning on getting a IE cat back like next week as i am sick of my B&B tri-flo(too loud). Will the IE be good enough for what i am potentially planning, or should I hold off and wait or get something different? Thanks again.
AW

[backtrail69]

I went serious overkill on overbuilding. I would get an eta crank, bore 1mm, forged pistons 8.5:1, re-bushed i rods (or any other 135mm length rod), Everything else standard rebuild, oil pump, bearings, seals etc. For the top end ARP headstuds from VAC, MLS head gasket or an o ringed block with stock HG, a new stock valve train. If you have the ability get the water channels welded, but if you don't I wouldn't worry much.

For electronics a full standalone w/ 42#+ injectors w/ a walboro 255 and a wideband go a long way.

Charge Piping: stick to 2.5in AL piping with NICE multi layer couplers with T bolts.

IC: Ebay bar and plate works wonderfully.

Exhaust: 3in with whatever muffler you deem appropriate.

Drivetrain: lengthen that front driveshaft and get new guibos, also a strong clutch, I am running a sachs 618 PP and a clutchnet sprung 6 puck and it is holding 331 whp with no problems.

Turbo/Manifold: I like my HX35, but any reasonably sized Genuine Garrett t3/t4 will work for a first setup, I whole heartly recommend the jon volk adapter, great unit. Stick to external WGs as they are generally more reliable and keep boost levels in check, I like TIAL.

That is just some of the things I thought I would touch on. You can see how to build your car over the top in my motor build thread...

http://www.r3vlimited.com/board/showthread.php?t=101610

[aaron325ix]

Good advice, I think the 2.8 sound more practcal. But, would I need to do more to it than say what you did to yours in order for it to be turbo suitable. You mentioned "overbuild". Should I look at blacktrail69 for a good model? Thanks again.