S54 Stroker Kits - PRO/CON

[usdmej]

Lithium batteries can drop 40 lbs without losing any capacity. You can even buy them from BMW or Porsche, as they used them stock, for street cars. I'm 6 years into owning my Lithium battery, and it has never acted anyway other than like stock-- works when cold, works when hot, works when parked, saves a ton of weight.

My stereo sounds better than stock and dropped the weight. It took (considerable) effort, but you don't have to lose the stereo.

... my M3's 1 piece seats are the most comfortable seats in any of my cars...? As in, I don't go around in the M3 wagon (stock M3 seats) adjusting the position. I adjust the position once to be correct, set the seat memory, and then I'm good forever. Similarly, if you get a 1 piece seat that's well matched to your body and position it correctly, there's no reason it should be any less comfortable than a stock seat. In my case, because I'm tall, it enables me to actually have a proper seat position without my head in the headliner, making it more comfortable than the stock M3 seat (or M5).

there's no under 10lb lithium battery on the market that has A/H capacity anywhere close to stock,
Once you're closer to a 20lb lithium battery is when you get what most people would consider OE like capacity

it's not saying much to say that an audio system is better than what the E46 came with stock, but like most car stereo systems, it was designed to sound the same from every position in the car and running fewer speakers than stock generally messes that up for someone in the car. this is ignoring the gaping holes /nvh you introduce when deleting speakers

1 piece seats are still 1 piece seats, it's pretty easy to see they're a compromise



most of the things we do to our cars are mods with compromises

[jet_dogg]

I've been wanting to start a thread on this topic for a while as I'm hard pressed to find a suitable resource on this issue. Since is the main forum I go to for advice, parts, knowledge etc this is the best place to appeal to.

Having a rough plan that will eventually lead me to cams (still unsure on 288s vs 280s) after everything I've done engine wise, I wanted to weight the options of getting a ground up build (or doing it myself should that opportunity arise). My goal is basically as close to 400whp NA on pump gas, while keeping some of the daily reliability.

On a pure cost benefit analysis for power NA vs FI is basically a non issue, unless you factor in the complete package (heat management, weight etc). Those are things I'm not willing to give up as the car will maintain its daily use and see probably 5 or more track days a year. All maintenance has been done, save for top side reinforcement of the RACP with which I'm struggling with as I want a 4 piece tie in to the factory bolts but don't really want a half cage due to weight (CMP has this but would like something that looks a bit nicer).

Main suppliers of stroker kits I've narrowed down to 3:
-Carbahn (Steve Dinan)
-VAC
-Lang Racing

Having had some quick correspondence with CarBahn, I like the idea of getting what is basically a zero mile stroked S54 (I think they only offer a 3.3L for street/performance uses) that also gets run on an engine dyno before shipping out. Power without any supporting mods is considerable with cams circa 370-390whp depending on metrics used. I'm not sure if they would also apply their correction to the crank for rod bearings that they talked about (Steve Dinan) in a recent Smoking Tire Podcast.

Things to consider beyond the new hotness of a stroker and its power are running costs compared to stock and reliability. Admittedly I'm a bit a novice to the platform having only gotten my car in 2019, but I dove in feet first and did my best to do it the "right" way. I don't mind the cookie cutter way of doing things if it's the best way to go.

I dont know of many members that have stroker kits on their cars but would definitely appreciate the feedback and their findings, as well as anyone else with work/use experience on the issue.

A few notes after a cursory glance at the carbahn website to clear up some information. They are not stroking the engines, the bump in displacement is soley from increased bore so this is not a stroker kit like the others (which I am assuming they are based on your info). They are also bumping the compression to 12:1 which means you'll have to run at least 93 octane at all times. Their engine is making 360hp using oem corrections so this implies their kit is making around 22 more (we'd have to ensure all power ratings are in the same units so this isn't an exacting calc, in this case I'm using euro spec hp). There is no mention of wheel hp anywhere, however, so it appears they are measuring hp at the engine without the use of catalysts. I don't recall what fuel bmw uses when they publish their engine specs (probably 93 aki equivalent) so the power is coming from higher compression and slight displacement increase.

The takeaway is-
bigger bore
higher compression
no cats
93 octane
stock cams (so we can compare this rebuild to stock s54)
22hp increase

It doesn't seem like the above would be worth it unless rebuilding the engine in which case you could source the parts yourself and have your favorite M shop do the work on what would essentially be the same thing (fresh block). Assuming bmw tested with similar fuel and cats making around an estimated 10 hp difference, the increased bore and compression probably yields around 10-12hp (from 338 + 10 = 348 - 360 hp from carbahn). I would prefer this to stroking nonetheless.

[Obioban]

What exactly did this entail? (E.g. what connectors are on your harness, did you harvest them from your existing harness, etc). I’ve been thinking about a nav and harness delete / replacing with business CD but something like this seems like an option. Not like I ever use the stereo anyway but keeping a couple speakers as you did would be welcome.

The details are getting fuzzy with time, but the gist of it was...

The factory stereo wiring harness (which does all the ICE related modules-- bluetooth, speakers, CD changer, nav... all of it) actually only attaches to the chassis harness using one plug, which is behind the factory head unit. That plug gives you, mostly (fuzzy memory), constant power, switched power, ground, and ibus.

The very base stereo used in the e46 (non M) in Europe (nothing this low sold in the USA) had the amplifier in the head unit. I removed my entire stock ICE harness (which complete interior disassemble), adapted my chassis harness plug to be to the above spec, and plugged the speakers into it as it was stock in that config. The Avin came with an adapter for that chassis plug (as it'd designed to to work with all e46 variants) and has internal amps that it uses when wired up as such. Because that chassis harness also has an ibus cable, all the car integration features still work. Going forward, it's still plug and play with any head units designed to work with the base base base e46 stereo.

Equally exciting for me, this project also made my trunk bigger. On the left side BMW sold trunk liner for cars with nothing there:


And on the right side I relocated the battery to under the hood, as with the light weight it was no longer doing anything meaningful for distro, and the battery cable that runs to the trunk is 8 lbs. Happily, BMW made a bin that expands the usefulness of that space, as 4 cylinder e46 coupes had the battery under the hood stock:



Combined these made my trunk bigger than my M5 trunk, with factory fit and finish.

[Obioban]

there's no under 10lb lithium battery on the market that has A/H capacity anywhere close to stock,
Once you're closer to a 20lb lithium battery is when you get what most people would consider OE like capacity

it's not saying much to say that an audio system is better than what the E46 came with stock, but like most car stereo systems, it was designed to sound the same from every position in the car and running fewer speakers than stock generally messes that up for someone in the car. this is ignoring the gaping holes /nvh you introduce when deleting speakers

1 piece seats are still 1 piece seats, it's pretty easy to see they're a compromise



most of the things we do to our cars are mods with compromises

Generally, I'd say that...
-My battery is no more of a PITA than stock. I just don't think about it, other than plugging it in over the winter... which I did before I had one, as well. But, either way, you can get a 20 lb battery with zero capacity compromise compared to stock, and still save 30 lbs.
-I didn't leave any holes when installing the speakers-- the only holes that exist are the rear deck, and one side is plugged and the other side I have a stealthbox (with a light weight sub woofer swapped in). It probably does sound worse for people in the back seat, in fairness, but sounds better for people in the front seat (me). And, really... the back seat rarely gets used for people, with the M3 wagon and M5 around.
-I'm more comfortable in the M3 coupe than the M5 or M3 wagon, with stock seats, so this seems like a compromise for the better. They're even still heated, using the factory controls

[CrisSilberGrau]

A few notes after a cursory glance at the carbahn website to clear up some information. They are not stroking the engines, the bump in displacement is soley from increased bore so this is not a stroker kit like the others (which I am assuming they are based on your info). They are also bumping the compression to 12:1 which means you'll have to run at least 93 octane at all times. Their engine is making 360hp using oem corrections so this implies their kit is making around 22 more (we'd have to ensure all power ratings are in the same units so this isn't an exacting calc, in this case I'm using euro spec hp). There is no mention of wheel hp anywhere, however, so it appears they are measuring hp at the engine without the use of catalysts. I don't recall what fuel bmw uses when they publish their engine specs (probably 93 aki equivalent) so the power is coming from higher compression and slight displacement increase.

The takeaway is-
bigger bore
higher compression
no cats
93 octane
stock cams (so we can compare this rebuild to stock s54)
22hp increase

It doesn't seem like the above would be worth it unless rebuilding the engine in which case you could source the parts yourself and have your favorite M shop do the work on what would essentially be the same thing (fresh block). Assuming bmw tested with similar fuel and cats making around an estimated 10 hp difference, the increased bore and compression probably yields around 10-12hp (from 338 + 10 = 348 - 360 hp from carbahn). I would prefer this to stroking nonetheless.

You are correct in that there's no mention of whp anywhere, however, at this particular link, graph and tables are provided for power and tq https://carbahnautoworks.com/product...ngine-rebuild/

I would be hard pressed to think that these are crank rather that whp numbers, but again language is confusing here. Financially this doesnt make sense, like a lot of stuff we do. And for whatever reason I misstook the increased bore to stroke by 1mm. S54 has decidedly little room for increased bore. IF it is in fact whp numbers, then it would make sense for me only if stock, or relatively stock running costs and maintenance intervals are maintained. At minimum an engine tear down, full clean and polish cant really be a bad thing can it.

The main point of the thread was if proper internal engine work storker or otherwise makes sense in terms of power gains, maintenance, running costs etc. and getting information from those that have gone this route. Seeing as there is little information about this thought it was a good idea to get the ball rolling on it. For a car, like mine, that will see way more street duty than all out track it may not make sense. It's also fun to learn and spitball ideas. I hope to keep seeing contributions regardless.

[jet_dogg]

If there's no mention of wheel hp then it's not wheel hp, nothing confusing about that. They use an engine dyno https://www.instagram.com/p/CHRMb-mJXER/

One mm bore increase and half a point compression don't yield 80 hp.

Sorry to burst your bubble but give them a call and educate yourself about their product rather than making assumptions from their sparse literature. Good luck.

[Obioban]

Interesting-- I never actually looked in depth at Carbahn's offering, and assumed it was a stroker. Not being one actually makes me interested in this, when the day comes that my engine needs a rebuild. Lighter pistons/rods, 12:1 compression, and a slight boring sounds like exactly the kind of bottom end upgrade I'd actually want in my car!

[tnord]

On any kind of overbore of this block I'd be nervous about the headgasket. There's so little material between cylinders, and resulting HG material to seal, that any further reduction I think would warrant some sort of stronger HG material/construction and maybe even head bolts to hold a more consistent clamping force? I'd guess that's why there are stroker options for this engine, though increasing piston speeds and bearing loads is also concerning.

I don't know, but often times mfgs even offer OE parts (piston sets etc) for .20 and .40 overbore rebuilds. If there are BMW offered pieces for an overbore of equivalent size to what Carbahn offers, you're probably fine, and would totally make sense during a rebuild. I'd still want to address the HG issue in every way possible if I did that however.

[Obioban]

The Carbahn setup includes a MLS head gasket.

[CrisSilberGrau]

Interesting-- I never actually looked in depth at Carbahn's offering, and assumed it was a stroker. Not being one actually makes me interested in this, when the day comes that my engine needs a rebuild. Lighter pistons/rods, 12:1 compression, and a slight boring sounds like exactly the kind of bottom end upgrade I'd actually want in my car!

Yah it seems like this is the most plausible option in the car for an eventual full refresh/rebuild.

[jet_dogg]

Bmw offers 20 over factory pistons.

[DropTopKingM3]

Don't get VAC. Ever. Seriously.

This has been asked before and you nonchalantly ignored the question.. What's the issue with VAC? They seem like a great company and very knowledgeable when it comes to BMW in general. Plus the e9x guys rave about their rod bearings. Let us know... If there's something that you saw maybe you can open the eyes of the other members on here.

[digger]

Vac gets cranks from arrow so shouldn’t have an issue as they didn’t develop it.

VAC is mostly overpriced and products “over sold”

[Feffman]

A fellow M3 racer had his engine rebuilt by Engine Services (https://engineservicesga.com/) in Georgia. When inquiring about a stroker setup, they told him don't bother as the extra money offered negligible gains. He did, if memory serves me correctly, do to the wider crank bearings and I know for a fact forged rods & pistons along with what little head work remains to improve the S54 cylinder head.

Feff

[jbfrancis3]

A fellow M3 racer had his engine rebuilt by Engine Services (https://engineservicesga.com/) in Georgia. When inquiring about a stroker setup, they told him don't bother as the extra money offered negligible gains. He did, if memory serves me correctly, do to the wider crank bearings and I know for a fact forged rods & pistons along with what little head work remains to improve the S54 cylinder head.

Feff

The wider bearing on the stroker crank is unique to Lang Racing, no?