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      07-17-2014, 08:33 AM   #1
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Post Build:E86 Z4M S54 3.4L Stroker + ESS VT525 Supercharger

I just placed the order for the VAC 3.4L Stroker kit and the ESS Stage 2 VT525 Supercharger Kit, and soon greatness shall be born. I was never meant to go down this path, but fate has lead me here. I've been fully satisfied with my aggressive NA set up for some while now (ca. 2 years), pushing 395hp. But as they say, all good things come to an end. It just so happened that a bearing came off the crank at high speeds and just messed up a whole bunch of my internals. At that point, buying a stroker kit seemed like the more cost efficient option, so that decisions was made quite easily. The supercharger on the other hand was a tough decision to make; anticipating myself going down that road in the future, i figured I might as well save a few bucks on labor while the engine is already apart, and just go for it like you'd take off a band aid.

So that is that, and let the fun begin!

Any questions or requests (in regards to the build) are welcome!

FS:
-CarTech CF Airbox $2300
-Any OEM replaced parts available (More elaborate list coming soon but includes engine and body: hood, wheels, suspension, cams, Euro headers etc.) PM for pricing.
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      07-17-2014, 11:07 AM   #2
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what a monster this is gonna be!
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      07-17-2014, 11:20 AM   #3
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In for results when available. What is your timeline? Love to see numbers as soon as you can. Best wishes =)
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      07-17-2014, 11:42 AM   #4
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This may sound like a stupid question but is the stroker kit using a higher compression ratio...if so you may run into problems now adding a blower. and you may want to opt if possible for forged pistons given the increased piston speed and wear that may occur with that setup.
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      07-17-2014, 12:29 PM   #5
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In my experience, stroker kit almost always means lower compression ratio if pistons weren't swapped, since the amount of air per cylinder to compress vs. the stroke is now decreased. Stroked and supercharged is usually a pretty popular options for hot rodders since it's like marriage made in heaven.

Of course, it's going to take quite a stroker to drop the compression ratio from what, 11.2:1 down to a more reasonable expectation for forced induction application.

I don't often say this, but when I do, you know it's going to be EPIC.

This build is going to be EPIC.

Although I would have preferred swapping a stroked S65 from Dinan if I had the choice (or the budget because they require a core).
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      07-17-2014, 01:10 PM   #6
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Quote:
Originally Posted by The HACK View Post
In my experience, stroker kit almost always means lower compression ratio if pistons weren't swapped, since the amount of air per cylinder to compress vs. the stroke is now decreased. Stroked and supercharged is usually a pretty popular options for hot rodders since it's like marriage made in heaven.

Of course, it's going to take quite a stroker to drop the compression ratio from what, 11.2:1 down to a more reasonable expectation for forced induction application.

I don't often say this, but when I do, you know it's going to be EPIC.

This build is going to be EPIC.
This basically sums it up...MORE BOOST

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      07-17-2014, 04:47 PM   #7
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Quote:
Originally Posted by The HACK View Post
In my experience, stroker kit almost always means lower compression ratio if pistons weren't swapped, since the amount of air per cylinder to compress vs. the stroke is now decreased. Stroked and supercharged is usually a pretty popular options for hot rodders since it's like marriage made in heaven.

Of course, it's going to take quite a stroker to drop the compression ratio from what, 11.2:1 down to a more reasonable expectation for forced induction application.

I don't often say this, but when I do, you know it's going to be EPIC.

This build is going to be EPIC.

Although I would have preferred swapping a stroked S65 from Dinan if I had the choice (or the budget because they require a core).
Hack:
I have been reading your informative posts for years, have always agreed, and have learned from your insight, this one, however I do have to disagree on. All else being equal (head gasket, piston shape, cylinder head etc...) your compression ratio will increase with increased stroke, as that is simply how its measured i.e. volume in combustion chamber measured from the bottom of the stroke to TDC. so naturally this will increase with an increased stroke length. Engine builders will often include a thicker head-gasket or specially shaped pistons to mitigate this increase in compression, esp on a motor already running a high ratio.

I hope the combo works, its always great for the community for someone to try something innovative and share the results. I have no doubt people have been running the combination on other engines, The tuner just has to take all this into account when calculating boost and timing as not to blow the head gasket or cause premature detonation.

Here is a quick link to an excerpt on building a stoker motor in general, not specific to the S54
http://www.mre-books.com/biginch/biginch2.html
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      07-17-2014, 04:57 PM   #8
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looking at the VAC website, it appears they have different pistons (increased dish to decrease ratio), to accommodate for what the desired compression ratio would be, using their kit.
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      07-17-2014, 05:24 PM   #9
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Really? I'm used to dealing with rodders and the common knowledge/understanding is stroking an engine decreases compression ratio. I've always thought that compression ratio is calculated as the volume at the bottom of piston travel divided by volume at the top of piston travel, therefore if you simply increase the stroke of the engine, compression ratio decreases since you're not changing the amount of movement of the piston.

Say, for example, the S54 has a bore of 87mm and a stroke of 91mm, with a compression ratio of 11.5:1. To stroke it to a 3.4L, you would add a 4mm spacer on the cylinder head to get to a 95mm bore. That 11.5:1 compression ratio means, the piston travels from fully extended to fully compressed is 91mm-(91mm/11.5)=83.1mm. At a 95mm stroke, the compression ratio is now (fully extended)/(fully compressed) which is 95mm/(95mm-83.1mm)=7.9*

I'm using the formula of volume = Pi*r^2*h, since Pi*r^2 stays constant in this instance, compression ratio can be calculated straight from the change in height.

If my math is correct, a small increase in displacement from 3.2 to 3.4L would yield quite a significant decrease in compression ratio, at nearly 8:1 it's PERFECT for a supercharging application.

Like I said. EPIC.

EDIT: Huh. Maybe I should start hanging out with people who mod newer engines...Apparently it's far more common to increase the stroke of the engine by actually increasing the movement of the piston vs. spacer plates on top of blocks. Guess I was WRONG.
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Last edited by The HACK; 07-17-2014 at 05:45 PM..
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      07-17-2014, 05:54 PM   #10
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To stroke (or destroke) a motor you primarily change the crankshaft, and hence the stroke length of each piston (from BDC to TDC), as opposed to boring out the each cylinder as a way to increase the displacement. The calculation for compression ratio is as follows:

Cr = (((3.141/4)*b^2)*s + Vc)/Vc,

Where Cr = compression ratio, b= bore diameter s = stroke length, Vc = clearance volume i.e. volume in chamber incl head gasket at TDC.

You can add a thinner or thicker head gasket as a way to change the compression ratio, but unless you change the crankshaft you are not changing the stroke of the motor.

I'll confirm with Mike at VAC tomorrow and report my findings (I've been wrong before)
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      07-17-2014, 05:55 PM   #11
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oops, didn't see your edit, as I was attempting to write this formula in... regardless, I will confirm with the guys at VAC tomorrow.
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      07-17-2014, 07:24 PM   #12
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Who is doing the tuning ? That's going to be a PITA to get right . make sure you are getting large enough injectors from ESS , have adequate cooling , and I'd recommend keeping the revs under 8k, probably 7800 . I'm seeing rapid bearing wear with track use of a 525 kit with optimal cooling on a standard S54 revving to 8k . I'm running a 34 row Setrab oil cooler and a larger radiator to keep temps to the 240's on track . Its every 15k bearing replacement at my power level and heavy track use . With the stroker and boost there will be no need for 8k so you won't be missing anything .
George
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      07-17-2014, 10:31 PM   #13
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If the vac kit includes pistons, which I assume it does, it will take care of the comp ratio. Surely this would be info that vac makes available. Better yet, offer a few options for differing compression ratios as is common practice.

Who's tuning it for you? What fuel will it be run on? On the right fuel you can do wonders with high comp and boost.
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      07-22-2014, 05:21 AM   #14
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Quote:
Originally Posted by gmd2003 View Post
Who is doing the tuning ? That's going to be a PITA to get right . make sure you are getting large enough injectors from ESS , have adequate cooling , and I'd recommend keeping the revs under 8k, probably 7800 . I'm seeing rapid bearing wear with track use of a 525 kit with optimal cooling on a standard S54 revving to 8k . I'm running a 34 row Setrab oil cooler and a larger radiator to keep temps to the 240's on track . Its every 15k bearing replacement at my power level and heavy track use . With the stroker and boost there will be no need for 8k so you won't be missing anything .
George
Did I just read that right? You're having to replace your rod bearings every 15k miles?!
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      07-22-2014, 06:12 AM   #15
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Quote:
Originally Posted by sixspeed
Quote:
Originally Posted by gmd2003 View Post
Who is doing the tuning ? That's going to be a PITA to get right . make sure you are getting large enough injectors from ESS , have adequate cooling , and I'd recommend keeping the revs under 8k, probably 7800 . I'm seeing rapid bearing wear with track use of a 525 kit with optimal cooling on a standard S54 revving to 8k . I'm running a 34 row Setrab oil cooler and a larger radiator to keep temps to the 240's on track . Its every 15k bearing replacement at my power level and heavy track use . With the stroker and boost there will be no need for 8k so you won't be missing anything .
George
Did I just read that right? You're having to replace your rod bearings every 15k miles?!
15k hard track miles yes.
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      10-16-2014, 06:24 AM   #16
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Here's an update and a more in-depth list of the mods going into this project.

The engine build is being carried out by a local and very professional shop in Switzerland called Speedy Garage SA. The expertise and bimmer knowledge has mostly come from CA Automotive in England, who have been on top of it since day one, with some help from VAC -- with that said, it was left to their professional expertise to precise the compression ratio's with both the stroker and SC kit.

All the parts arrived and the build has begun -- so far the crank, clutch assembly and lightweight crank damper have been balanced and the crank and connecting rods been placed into the block. (photos attached)

As for the in-depth list, here its:
-ESS VT525 Supercharger (All ESS system components)
-VAC 3.4L Stroker Kit (97mm stroke crank, 87mm bore JE Piston heads, AP rods, and ARP hardware)
-OEM gaskets.
-VAC Upgraded oil pump.
-Going back to OEM cams with Schrick DLC Cam followers (previously Schrick 288 / 280 11.6mm Lift)
-Brand New UUC segmented kevlar Clutch and flywheel.
-Lightweight crank damper.
-Brembo 6-pot GT Kit (Front only)
-UUC urethane engine and tranny mounts.

Any questions, comments, inputs, suggestions are welcome as always!
Updates soon!!
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      10-16-2014, 07:59 AM   #17
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Way cool man. Are you going to drive it at all with the stroked engine before the supercharger goes in?
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      10-22-2014, 06:55 PM   #18
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warning, I've heard that lightweight flywheels don't work well with supercharger kits. don't remember why for sure


very excited to see what power levels you'll have
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      10-23-2014, 05:21 PM   #19
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Quote:
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warning, I've heard that lightweight flywheels don't work well with supercharger kits. don't remember why for sure


very excited to see what power levels you'll have
Ha that would be me ! That's my destroyed 500 mile clutch due to high rpm vibration lol .
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      10-25-2014, 09:23 PM   #20
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exciting stuff. in for updates
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      05-19-2015, 05:48 AM   #21
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any updates on this? how did the VAC stroker kit turn out? any issues? looks like sex on a stick though..
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      12-13-2015, 05:19 AM   #22
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Hey there everyone...sorry I took a while to get back with more info. The cars been done since May 2015 (took a year to build) and the tune was soooomewhat of a PITA but nothing unusual for such a build. I got quite lucky the person who was meant to do the tune got sick and my contact had to source another tuner...ended up with the the dude who turned the M4 for BMW Germany...not too shabby for a replacement!! Anyhow with all the work done and the car running just perfect, it pushes 550hp to the wheel @ 527Nm @ about 7 RPM. Anyone let me know if you'd like more details!!
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