S54 Build Decisions: Turbo vs. High-Revving NA – Seeking Experienced Opinions

[George Hill]

If I was in it solely for the RPM I would consider an S52 deal. The Rabid Racing Development guy and his crew are really pushing that package and turning those engines a bunch of RPM and making a lot of whp with them.

Not saying an S54 can't do it, but for the money the option is pretty intriguing.

[maw1124]

I haven't done either and hate turbo cars. But I own a supercharged V8 and have spent significant time in supercharged M3, though not on track (E46M and E9XM). To my view the supercharging of these NA engines brings you everything you're looking for and none of what you're not.

So I'd say supercharge + weight loss + chassis improvements = where the money is. Turbo seems like a never ending science project, which is to say "buy a Porsche if you want a turbo car."

maw

[digger]

if you want to mess around with turbos you need something OE based otherwise IMO it going to be problematic non responsive aftermarket junk. i.e. you'd better off to start with B58/S58 based with Xdrive so you can actually put the power down properly

[Altaran]

With these targets, sell the car and get a Cayman GT4. At 420 hp, that meets the power goals and has the overall driveability. It will likely be cheaper in the end as well.

9500 rpm and reliable, that just won't go along.

I've gone the NA build direction and there are some basic restrictions that prevent the motor from being a true powerhouse.
- stock crank is too heavy for much higher revs. Even with forged rods and pistons, the engine will reach its sweet spot from 8k to 8,5k rpm. For more you will need a lighter crank, most likely billet with a shorter stroke, bringing piston speeds to an acceptable level.
- overbearing is only possible in a very limited way die to the wall strength, so no big numbers here.
- valve train at 9,5k rpm is another challenge. Readily available aftermarket valves & springs are good for 9k max, more is possible I guess but with more risk to blow up. Developing a new valve train for this is going to be ridiculously expensive and anything but reliable, because you are in essence the test mule for it.
With all other factors considered, it's a ton of money for ever diminishing gains.

Turbocharching ruins the engine. May as well do an S58 swap or buy an M2 or similar...

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[jvit27]

If I was in it solely for the RPM I would consider an S52 deal. The Rabid Racing Development guy and his crew are really pushing that package and turning those engines a bunch of RPM and making a lot of whp with them.

Not saying an S54 can't do it, but for the money the option is pretty intriguing.

I don't know who that is, but it sounds like the same absolute nonsense that comes along every few years from some new 'tuner' who gets everyones hopes up with their bs marketing.

Why are you returning the S52 turbo to stock?

It's a nice example and I just don't use it much anymore. Time to move on to something else

[JeremyJames]

NA is the expensive way to go slow.

To do it right, would require an entire rebuild of the engine, addressing all parts of the rotating assembly... lightening pistons, rods, and crank, forged internals, bigger cams, stronger valve springs, headwork, intake, exhaust... it's a lot.

Turbocharging will be far cheaper, with greater results.

That being said, I can't stand turbo charged cars, they have no soul. My E46 is supercharged, which I feel gives the best of both worlds... high revs and no turbo lag, but it pulls hard at high RPMs. (Some would argue that it's actually the worst of both worlds, but that's an argument for another day)


Ultimately it's up to you and your checkbook. If money was no option, I would love to build a fully built S54 with velocity stacks. Big cams, custom header, revs to 9K RPMS... The problem is the most I've ever seen is around 350whp, and you're talking big bucks to get there. I just don't think the juice is worth the squeeze.

This is great feedback. Thank you. The fact that you said turbo cars have no soul is what resonates and I completely get what you are saying. Don't get me wrong the 8250 is absolutely satisfying, but 9k+ really gets my juices flowing. I appreciate your constructive feedback sir!

[JeremyJames]

I have a turbo E36 M3 (stg1, 350whp) and a 3.4L stroked E46 M3 (390whp), and I used to have an S/C'd E46 M3 with over 600whp. If you want boost, just get an F8x. Seriously. Great car and you'll get way more out of it for far less than converting an n/a car into a turbo one. I've had fun with my E36 along the way but the S52 was pretty gutless to begin with and nowhere near as satisfying as the S54 out of the box. That being said, I am returning it back to stock if that tells you something... a big boosted M will not be the same car you first fell in love with, and at that point there are better platforms with less compromises to get 500hp.

To get 9500+ out of an S54 you'll have to destroke it and make up the power with other mods. In essence you'll be spending a bunch of money to go in a circle. The RPM 'gains' are pointless, all it does is give you bragging rights and wear the motor out faster. This sounds like a rainy day project/pipe dream at best so the ideal use-case is to leave the motor stock-ish, fortify it for track use and take weight out of the car. You have to ask yourself why are you trying to reinvent the wheel over what you already have? You're already in the sweet spot as far as N/A goes.

This is the type of experience feed back I was seeking. Thank you for taking the time to share my brother.

[George Hill]

I don't know who that is, but it sounds like the same absolute nonsense that comes along every few years from some new 'tuner' who gets everyones hopes up with their bs marketing.

Let me Google that for you.

https://rabidracingdev.com/?srsltid=AfmBOoocuG634s1-GTYsBFZZMyIia8O_ZGi_18PcSPiv6A3eD2pOW6zx

https://www.instagram.com/rabidracingdevelopment/

Michon isn't "new" he's been building ITB swap kits for that engine platform for years now. They are pretty big on the Boosted E36 FB group and have a number of cars running... so IDK?

What about it would you call nonsense though?

[jvit27]

Let me Google that for you.

https://rabidracingdev.com/?srsltid=AfmBOoocuG634s1-GTYsBFZZMyIia8O_ZGi_18PcSPiv6A3eD2pOW6zx

https://www.instagram.com/rabidracingdevelopment/

Michon isn't "new" he's been building ITB swap kits for that engine platform for years now. They are pretty big on the Boosted E36 FB group and have a number of cars running... so IDK?

What about it would you call nonsense though?

ITB swap kits are an instant red flag and do not give anyone credibility, in fact I'd argue they brand you as a n00b because this has happened in all previous versions of the ///Matrix. Since the days of dBilas, people have been trying to justify ITB on M5x based motors. They never ran right due to the MAF placement, and now that people have supposedly gotten them to work with some modern ECU stuff they are realizing what BMW has known/said all along - they don't actually make power, they are for throttle response (and cool factor).

Power gains come from the head design and how much air it can flow. This is why real S5x motors have always reigned supreme. M5x based heads were never designed to rev that high, so sure you can delete the VANOS, increase the CR, do a solid lifter conversion, big cams, and port the head but you've essentially ruined the drivability and made a DIY S5x that has a narrow power band. We've seen it before and those motors have proved time and again to barely crack 300whp. And where are those motors now? There never seems to be anything beyond the first splash. It goes quiet for 5 years and then sometimes you hear how that guy destroyed a bunch of motors and customers were too embarrassed to admit it. Then another kid comes along claiming he did what no one else, including PTG, could do.

Now 400whp from an S52? Here on planet Earth, my stroked S54 barely makes that. What an absolute joke and anyone who believes that is probably paying for it with money from the tooth fairy.

[Nate047]

I don't know who that is, but it sounds like the same absolute nonsense that comes along every few years from some new 'tuner' who gets everyones hopes up with their bs marketing.



It's a nice example and I just don't use it much anymore. Time to move on to something else

Interesting, I’ve toyed with the idea of turbocharging my e36 but I don’t think I want the headache. But I know there’s a lot of people who love the M5X as a boost platform.

If my stock motor ever lets go I’ll S54 swap it. I love the character of these engines in the e46 and I know it’s perfectly suited for the e36.

[George Hill]

ITB swap kits are an instant red flag and do not give anyone credibility, in fact I'd argue they brand you as a n00b because this has happened in all previous versions of the ///Matrix. Since the days of dBilas, people have been trying to justify ITB on M5x based motors. They never ran right due to the MAF placement, and now that people have supposedly gotten them to work with some modern ECU stuff they are realizing what BMW has known/said all along - they don't actually make power, they are for throttle response (and cool factor).

Power gains come from the head design and how much air it can flow. This is why real S5x motors have always reigned supreme. M5x based heads were never designed to rev that high, so sure you can delete the VANOS, increase the CR, do a solid lifter conversion, big cams, and port the head but you've essentially ruined the drivability and made a DIY S5x that has a narrow power band. We've seen it before and those motors have proved time and again to barely crack 300whp. And where are those motors now? There never seems to be anything beyond the first splash. It goes quiet for 5 years and then sometimes you hear how that guy destroyed a bunch of motors and customers were too embarrassed to admit it. Then another kid comes along claiming he did what no one else, including PTG, could do.

Now 400whp from an S52? Here on planet Earth, my stroked S54 barely makes that. What an absolute joke and anyone who believes that is probably paying for it with money from the tooth fairy.

When was your S54 built? Time marches on, ideas are tried and improved upon. Partee just made a stroked S54 that on their dyno does over 400whp and they are limiting it to something like 8000rpm. Think about if they turned it up another 500 or more RPM.

If you put a good cylinder head on a 3.2L S52 what is the real difference then? Solid lifter convert the S52 and convert to buckets on the S54 and then add ITBs to the S52 and a good header. They are pretty similar so it doesn't seem to me to be to unrealistic of a claim.

My point is that like you said its all in the cylinder head, cams and tuning. If you just want to poopoo on their ideas because you don't believe it that's fine, but they are doing it and backing it up with data. Even if the data is 10% skewed (because all dynos are different) its still impressive.

And if they are turning them a bunch of RPM that is what the OP wants. He didn't say he wants it to make max torque at 3500rpm and still spin, he said he wants RPM. I'm just offering another avenue. Whether you are on board or not thats fine...

[George Hill]

Then there is this:

https://www.instagram.com/p/CvqSPXWpBnH/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA==

[Slideways]

Boosting an engine that has already been brought to its absolute limit (see CSL and P54 versions) is not a great idea.

The S54 has 4mm of bore spacing. With some quick research, the 2JZ has 7mm and the RB has 10mm. There is a good reason why FI, mainly turbo, was abandoned 10 years ago. The S54 was not designed for boost.

As for NA application, the blueprint is already there:

CSL - airbox, cams, exhaust, software

P54 - all that plus fuel system upgrades and a dry sump oiling system

[Obioban]

Turbo will never be reliable on track.

9500rpm will never be reliable anywhere, or good to drive on the street.

Get a different car, that's turbo or 9500rpm stock.

[JeremyJames]

Turbo will never be reliable on track.

9500rpm will never be reliable anywhere, or good to drive on the street.

Get a different car, that's turbo or 9500rpm stock.

Perhaps my "shoot for the stars" of 9,500rpm was too high, maybe 9,000 is more realistic if balancing reliability. It's also important to know that I enjoy my current NA set up, but this question was pertaining to what to do with my extra S54. I have an extra S54 on the engine stand in the garage. Could be a donor for another platform, but laying out my options so I can understand exactly how I will be rebuilding this engine. I have zero interest in getting a different car, perhaps an additional car, but that's another problem as I currently have 6 in my driveway/garage.

Thanks for the feedback.