[Cadillac Johnson]

Like most stock cars, the N54's rev limiter is set very conservatively. The bore and stroke is 84.1mm/89.7mm. Exactly the same as the E46 330, which isn't a coincidence considering the N54 was based off of it. Doing some calculations, the N54 could rev out to 8350rpm and still stay under 25m/s (meters per second) which is what is recommended to ensure the piston rings seal correctly. I'm sure like most engines it could rev quite a bit higher, but keeping safety and long engine life in mind 8350 should be perfectly safe. For drag applications people could push it close to 10k rpm. The 4g63 (Evo) has an 88mm stroke and those rev past 10k rpm all the time in drag applications and will stay together almost indefinatly if maintained properly.

Now with the stock turbo's there's no point to revving this high. But when the time comes and people are looking into larger turbo upgrades those extra rpms are going to be very valuble.

Anyway, I was curious about how this motor will respond to big turbos and not being able to rev high enough to take advantage of them wouldn't help the cause. Looks like this motor has a ton of potential, and I thought I would share. We still dont know how much the stock bottom end will handle, so this is a bit premature, but I wanted to show that high rpm's are possible with this motor.

[schneid4323]

I wonder how constant boost up to 8k on the stock turbos, with some upgraded cooling, would turn out HP wise. PROcede bump up rev limiter? Seems like some untouched power that is acheivable safely, and virtually making the car into an M motor. Id like to see what shiv thinks.

[Cadillac Johnson]

I was thinking it would be very easy to add a feature to PROcede to raise the rev limiter, but as I said with the stock turbos it wouldn't make any sense. The stockers are so small that they're are maxed out before the factory limit. In stock trim it's probly counterproductive to rev it out to redline, you'll probly go faster by shifting earlier than that. I havent plotted the ideal shift points yet, but by looking at dyno graphs it certainly seems that way.

Now with a 35r or larger, being able to rev to 8k+ would have benefits. But then again it's too early to know how the stock bottom end will respond to high boost and high rpm's. 9k rpms would most likely be safe, but I know BMW owners are pretty conservative and 8350rpm is a nice safe number.

The point of this thread was just to show that the N54 has potential, and could rev high enough to take advantage of large turbos.

[533ogetnom]

wow, what a horrible idea, higher revs are by far the MOST detrimental thing you can do to an engine, and just because the engine shares the bore and stroke of the m3 doesn't mean its anything CLOSE to being the same

[grkm3]

The s54 has solid lifters.anything past 8k on this 335 and you will have valve float and a huge whole in the ALUMINUM BLOCK.The e46 is an IRON BLOCK made to handle the stresses of the high rpms.

Just because it shares the same bore and stroke has nothing to do with the design that went into it.Just the harmonics with those speeds along the boost would blow this thing up.Even the s54 was blowing up engines with its stock redline.

Im not 100% sure but I think the 335 has hydrolic lifters and there springs and not strong enough to rev that high.

A e46 M3 needs a valve adjustment ever 30k miles or so also.

You can be the first to test out that 10krpms you think it can run.go do 80 mph in 3rd gear and down shift to 2nd and see if the engine dosnt blow up.

[BayerischeMW]

N54 is aluminium with cast iron cylinder liners. the S54's that "blew" were pre-2002 and were faulty.

but i agree, it's not possible to say that the N54 can rev this and this high just because the bore/stroke is similiar to the S54.

[Acap14]

if it can rev that high great, but it's pointless if your not makin any real power up there.

[533ogetnom]

Originally Posted by Acap14

if it can rev that high great, but it's pointless if your not makin any real power up there.

yea thats a good point we already know optimal acceleration is derived by shifting before the current limit anyway

[judec]

well, I wouldnt mess with it with stock configuration. It can be really expensive to "test" it w/o former upgrade to lighter forged pistons (stocks are cast), stronger rods, forged valves, stronger valve springs, forged and sharper cams (and what about the vanos this way?) also the hydraulic lifters should be possibly completely removed, as I've seen on other cars using them... ouch, good luck with it

[bnj]

Double the revs -> double the power at a given torque. Revs are the way to power at a given engine size. (+hi flow hi boost turbos in case of fi)
Choke rpm is a function of stroke, inlet valve diameter and inlet valve lift. So you need inlet cam and/or bigger valves. 25m/s does not become a limiting factor in this engine...for a long time. Rev limiter does not matter. It chokes anyway and the gear change should be performed earlier than the limiter in any case.

[Cadillac Johnson]

Wow, you guys really need to read a little better.. and use some common sense..

All I'm saying is that the N54 has a relatively short stroke, and piston speed would not be a limiting factor as far as high rpms are concerned.

Iron block vs. aluminum block has nothing to do with engine speed. Honda's are aluminum block and they rev WAAYYY past 10k in drag trim.

Revving the stock motor past 8k would be dumb, I said this already, twice actualy. The turbo's are maxxed out before the stock limiter and shifting at redline will make you go slower, I said this twice already too. Bringing up the stock springs is just plain retarded, who would rev a motor that high without valvetrain work? Hydraulic lifters can rev plenty high, 4g63's have hydraulic lifters and rev to 10k+ without swapping them to solid versions. I dont know how well the N54's lifters will work at high rpms, but hydraulic lifters are not always a limiting factor.

My point was, just looking at the bore and stroke, high revs are not out of the question, and gave a limit as to what most people feel is safe when it comes to piston speed. Not that since motor "A" can do this, that motor "B" will do the same. Once people feel the need to tear into their motor, if built properly and tuned correctly, high rpms could be attained with the N54.

I dont have plans to remove the rev limiter and spin it to 10k rpm. I'm saying in the future, looking at piston speed only, this is something that could be possible.

[PresaMat]

I think it would be interesting to see how much higher it could rev. I know that BMW is coming out with kits for the e46 to raise the rev limit like 500rpm.

[Cadillac Johnson]

Turner Motorsports has something that raises it to 8100.

We just need some shops willing to blow up a few motors so we can see what the stock bottom end is capable of handling.

[grkm3]

Go take a look over at bimmerforums and see how many people blew up there e36 M3 engines with minor over revs.can you please stop compairing a ballanced inline 4 to a long crank inline 6,there is a huge difference.The car will need over 5k thrown into it to get it to rev to 8k+.

The 335 engine is not made to rev high,BMW did not balance the crank for it and didnt use solid lifters along with a valve system that can keep up with the rpms up top.

I have over reved my e36 m3 and only hit around 8300 rpm.That was enough to bend all of my exhaust valves and was not a fun process to get fixed.

whats the point of making this turbo engine rev to 8k?why not drop the compression and run a bigger turbo.7.5k is plenty room to make power,even after that high up the head design and flow come into play.

[grkm3]

Originally Posted by Cadillac Johnson

Turner Motorsports has something that raises it to 8100.

We just need some shops willing to blow up a few motors so we can see what the stock bottom end is capable of handling.

see here is the problem,its not the bottom end that we are worried about,Its about all about the top end(valves,retainers,lifters cams and bearings)and maybe a little with the harmonics of the crank.

[Cadillac Johnson]

Yes, and I said;

Originally Posted by Cadillac Johnson

Bringing up the stock springs is just plain retarded, who would rev a motor that high without valvetrain work?

For the third time... I'm not talking about revving a stock motor that high. I'm talking about a built and tuned motor.

[A418t81]

Originally Posted by Cadillac Johnson

Hydraulic lifters can rev plenty high, 4g63's have hydraulic lifters and rev to 10k+ without swapping them to solid versions. .

No, not really. Evos have hydraulic lash adjusters on a "roller rocker" (its not really, but gets the idea across) arm assembly. There's very little between the cam lobe and the valve stem, the hydraulics do not reciprocate. Thats a VERY different setup than a typical hydraulic tappet like a 1.8T and probably the N54 where the entire lifter: tappet, hydraulics and all reciprocate with the valve.

[Cadillac Johnson]

Originally Posted by grkm3

can you please stop compairing a ballanced inline 4 to a long crank inline 6,there is a huge difference.The car will need over 5k thrown into it to get it to rev to 8k+.

The 335 engine is not made to rev high,BMW did not balance the crank for it and didnt use solid lifters along with a valve system that can keep up with the rpms up top.

How do you know that it will need $5k to rev to 8k+?

How do you know how well the crank is balanced?

Since an inline 4 isn't good enough for you, how bout a 2JZ? how bout a RB26? Both are inline 6's, the 2JZ has an 88mm stroke, they rev to 10k in drag trim and I know a guy personally who revs his to 9.5k. RB26's have a shorter stroke, I believe 77mm, they rev even higher. There are limiting parts of any motor when it comes to high rpms, piston speed will not be the issue with the N54, as I've pointed out with numerous examples of similar motors that rev high with similar strokes.

If it takes balancing the crank, forged rods/pistons, head work, valvetrain work etc. Then your saying the motor could rev to 8k+?

If so, that's exactly what I'm saying, it's possible, and piston speed wont be a limiting factor. That's all I'm saying. No where have I said that it will be cheap, or that it happen in stock trim.

Please read a little better next time... and use some common sense.

The point of this thread is to show that piston speed will not be a limiting factor as far as revs are concerned, that's it, nothing more. You keep bringing up stock parts that will not be up to high rpms. Stock parts may or may not be up to high rpms, we dont know yet. But, piston speed will not the the limiting factor. Does that make sense?

[mr2guy]

Someone tell me how the S54 (E46 M3) and N54 have the same bore and stroke?! The S54 is 3246cc while the N54 is 2979cc. The N54 shares it's displacement with the M54B30 from the E46 330i, not the M3. Now the stroke of the N54 is 89.6mm while the S54 is 91mm. The larger stroke decreases the rod ratio, increasing piston speed as well as side load on the cylinder wall. With valvetrain the same, the shorter stroke, bigger rod ratio engine should last longer at the same rpm. Following this, the engine should be able to rev higher without harm to the bottom end. M3's can rev to 9500 with the right parts and so I would assume a similarly built N54 cylinderhead would be able to withstand this as well. I am not saying that the engine needs to rev this high, mainly that it could with the right setup.

[grkm3]

um no read your first post.You are clearly asuming the car can rev like a s54 because it shares the same yadayada and then bring up its bore and stroke bla bla bla insert different engine here and wham this one can do it too.

no where in your first post do you say anything about modding a 335 engine to run higher rpms.

The other cars you mention have no merit.THEY ARE DIFFERENT ENGINES.The 335 is a plane jane 330 engine with direct injection and 2 litttle turbo's.

The S54 was designed from the ground up to to rev like crazzy.

The whole 335 valve train is not made to rev that high,You would need a very light valve train and solid lifters with double springs to be on the safe side.Don't forget your also throwing forced air in to also wich makes things even more unreliable.


take your car to a shop and have them rebuild your whole top end and see how much the bill comes out to.The cams alone would cost you 1500.

[grkm3]

lol turner basically did the r&d for us,you say the raise the limit to 8100?Did you know that they have race programs for the s54 to rev over 8.7kwith the stock valve train and delage motorsports has a kit that revs the car to a whopping 9700rpm on the stock setup also,see what im getting at here?

[Cadillac Johnson]

Maybe I assume your smarter than you are. I wouldn't think anyone would expect the N54 to rev to 8350 in stock trim. That much seems pretty obvious to me.

Once again your reading too much into my comparisons, I'm simply saying that piston speed will not be a limiting factor when it comes to high rpms. How many times do I need to say that? Seriously..

I gave examples of motors with similar strokes that rev high, that's what the comparisons were for.

You bring up the valvetrain again, I'm not advocating revving the stock N54 to 8k+.

Your also assuming the stock motor wont handle it, I agree with you, but until someone tries it we wont know for sure. Your basing your assumption on what you've seen with other motors. I'm basing my assumption about how high this motor can rev based on what I've seen with other motors.

Due to the stroke of the N54, piston speed would not be the limiting factor when it comes to high rpms. How many times do I need to say this?