Highly built N/A M50

[exodus454]

So as of now, this is just for discussion.

My friend and I have a shop and we want to turn my 325is into an all-out track car. He's somewhat new to BMW's and is arguing that we could turn the M50 engine into a high-revving ~300hp-ish engine, I've been in the scene for almost 3 years now and know of nobody to do this and I'm very skeptical as to the feasibility of doing such. Now we're not talking about a street-worthy engine here, we're talking full race-spec.

Regardless of whether or not this turns into a high-revving engine, we still plan on doing a killer N/A build on it and have money to spend. So with money not really being an issue, we need to figure out what direction to go on this build. I'm not against try to make it rev high IF it's actually feasible without major mechanical failure occurring in the engine.

I've done some reading on the forum, and one user cited vibratory pressure and deflection from harmonics of the crankshaft causing rod bearing failure. The harmonic is reached between 7200-7400rpm. This is the only substantial reason I've been able to find as to why these things can't rev high, everyone else just said "it can't be done" or it costs too much for the result. :nono

Now, we're talking about building the engine by lightening and balancing everything to zero tolerance, replacing everything with upgraded (forged or hypereutectic) internals and ARP bolts (studs where possible), converting the the hydraulic lifters to mechanical, and upgrading valve springs, retainers, seats, and lighter (possibly oversize) valves, with new cams. Obviously cooling, oiling, fuel and air would be addressed also.

The plan was to go with the stock crank and and maybe offset grind the crankshaft to allow us to shorten the stroke by 2-mm and to bore the engine out to around 90mm to make the engine more oversquare than it already is. I was looking at bore-stroke ratios of high revving engines, and F1 engines have a ratio of 2.5:1. The stock ratio is 1.12:1, and making it more oversquare would result in 1.23:1, which hopefully will help with it's ability to rev.

I don't know if we're on the right path here or not, i know there's more research to be done. Are there any other reasons why these engines can't rev? If we do build the engine all-out, is this feasible? If not, give me some reasons, please! :help:help

[thedude60126]

If you have the money in vest in a 96 and later M3 engine and build that up.

[exodus454]

If you have the money in vest in a 96 and later M3 engine and build that up.

Would you like to back up your statement?

[happycamper]

i think thats what he didn't want to hear i believe u can make a 3.0 stroker using stuff from the m54

[bjh102]

dont see why it couldnt be done. if you can get all the parts to zero tolerance and u build and beef up the parts like you said then it is completely possible. high compression pistons i think would be the best option correct me if i am wrong. also im not sure if the high revving part is the best way to go. higher rvving engines fail easier. but if you have the money you can build it.

[thedude60126]

Well The main reason is the engine size and that it is more performance built than the m50 but if you are rebuilding everything then I retract my statement. I do agree though that a higher reving engine might not be the best thing as they do tend to fail more often. Keep us posted though on it.

[exodus454]

i think thats what he didn't want to hear i believe u can make a 3.0 stroker using stuff from the m54

Yeah, I know you can do that, but it's a completely different game. Higher displacement engines are more difficult to get to rev high, especially a stroked one. We're not trying to go for maximum power possible (if so, I don't think we'd be using the M50), the high-revving thing is the key here.

[happycamper]

prehaps a m3 top end? m3 valve springs and such i believe don't shoot me if im wrong m3's rev up to about 8 grand

[exodus454]

Well The main reason is the engine size and that it is more performance built than the m50 but if you are rebuilding everything then I retract my statement. I do agree though that a higher reving engine might not be the best thing as they do tend to fail more often. Keep us posted though on it.

I agree, they probably aren't as reliable. I think as long as we can get the oiling and cooling up to overbuilt standards and keep everything from getting too hot, we might be okay. If the engine needs to be rebuilt every winter, then so be it.




prehaps a m3 top end? m3 valve springs and such i believe don't shoot me if im wrong m3's rev up to about 8 grand

I'd say the goal here would be at least 9k. If the engine would be completely rebuilt, there's no sense in going with an M3 top end. You're right though, the stock valvetrain is good for 8k before valve float from what I've read.


On a side note, I just found something interesting. The stock bore-stroke ratio of the S2000 F20C (which is limited to 9000rpm) is 1:1.

[bjh102]

im styill confused why you are looking for such a high revving motor? can you explain that please?

[happycamper]

more rev's = more fun

[bjh102]

[quote=exodus454;13659727] If the engine needs to be rebuilt every winter, then so be it.

i think you would need to rebuild it alot more than once a year. you are going to be building a full race motor. look at the race teams with full race motors they rebuild after every race or 2 or they blow up and become unreliable.

[CrazyCoder]

im styill confused why you are looking for such a high revving motor? can you explain that please?

Why not? :shifty


9000RPM should be doable with mechanical lifters, upgrade valve springs to keep them from floating, and balancing. I'd hold off on going 90mm on the bore, that's going to give you some seriously thin cylinder walls, which wouldn't be that good for strength. Keep the stock bore/stroke and go with lightened/forged bits, bump the compression a bit with some pistons maybe.

It should make a beautiful sound.





i think you would need to rebuild it alot more than once a year. you are going to be building a full race motor. look at the race teams with full race motors they rebuild after every race or 2 or they blow up and become unreliable.

Totally different animal, F1 engines (high Revs) are like 20,000RPM low displacement engines. Heck, even NASCAR engines turn 9000-10000RPMs, but they are V style and higher displacement, which isn't as good for high RPMs do to the forces applied on the rotating mass.

Honda S2000s turn something like 9500 RPM, don't they?

[exodus454]

im styill confused why you are looking for such a high revving motor? can you explain that please?

The idea of building a race car for the shop is because we want to get into racing and help promote the shop at the same time. My friend has an E30 M3 which revs like crazy, and lets you hold gears longer through corners and such, so we came up with this idea. If we can be one of the first ones to make a usable high-rev M5xx engine, it would draw good attention to the shop and be a fun and rewarding build. :redspot

There's no "need" for it, really. But if we can, why not? Anyone can stroke an engine or turbo it.

[bjh102]

but if you can get the same hp out of a lower revving more reliable motor why not just put longer gears on it. you may not have the same bottom end but while tracking or racing a caar you arent using low end anyways.

[exodus454]

If the engine needs to be rebuilt every winter, then so be it.

i think you would need to rebuild it alot more than once a year. you are going to be building a full race motor. look at the race teams with full race motors they rebuild after every race or 2 or they blow up and become unreliable.

True, but most race teams run extremely tight tolerances on their engines and most of the frequent rebuilding purpose is more for diagnostic research. Of course you wouldn't build an high-rev engine and forget about it, but if it's built properly then we wouldn't be forced to rebuild that often.

We're also not trying to go for balls to the wall power initially, just something to have fun with in NASA and SCCA racing. "Reliability" is more a concern than power at this point.





Why not? :shifty


9000RPM should be doable with mechanical lifters, upgrade valve springs to keep them from floating, and balancing. I'd hold off on going 90mm on the bore, that's going to give you some seriously thin cylinder walls, which wouldn't be that good for strength. Keep the stock bore/stroke and go with lightened/forged bits, bump the compression a bit with some pistons maybe.

It should make a beautiful sound.

I agree it should be doable. If we do go 90mm or larger (if possible), then the block would be sleeved. 90mm was just a number I pulled out of the air, I just researched it and the maximum bore you can do on these engines is 87mm reliably.

While increasing compression would give more power per stroke, it would also create more heat. We might increase the compression but if temperature is severely affected by it, we might just leave it alone. One of the reasons heat is a major concern is because we're considering using hypereutectic pistons rather than forged, for lightweight and tighter cylinder wall clearances. Considering hypereutectic has a lower tensile strength than forged, piston temperature must be controlled (piston oil sprayer/ceramic coating).



but if you can get the same hp out of a lower revving more reliable motor why not just put longer gears on it. you may not have the same bottom end but while tracking or racing a caar you arent using low end anyways.

Correct! Since we don't want a lot of low end power, that's why we chose to go this route. The lower your engine can rev (if you're making the same power), then the lower in the RPMs your power is - therefore, lower end power. The fact that nobody else has one or has done it is enticing as well.

Also just because an engine doesn't rev as high, does not mean it is more reliable. Higher compression for instance, creates "more heat" per stroke. So throughout the rpm range there is more heat being being produced. where as a stock compression engine that revs higher only makes "more heat" above the originally designed rpm limit. That's why you build engines (whether they rev high or not) to handle and essentially do what you want them to. That is a very simplistic way to look at it, but the point is that we intend to make it reliable.

It's also fun as hell, and like the other guy said -


It should make a beautiful sound.

[LuvMy328is]

2.5 > 2.9 Stroker is available from Zionszille for about $600, parts that is. Drop in Schrick or Sunbelt cams, strengthen up the valve train, run a full exhaust from block to bumper and get a solid tune. I believe AA was making close to 300bhp with a 2.9 stroker :thumbup:
~Phil

[white96850turbo]

[quote=exodus454;13659727] If the engine needs to be rebuilt every winter, then so be it.

i think you would need to rebuild it alot more than once a year. you are going to be building a full race motor. look at the race teams with full race motors they rebuild after every race or 2 or they blow up and become unreliable.

idk about that..... My good friend has a 996 GT3 cup car that he tracks, it is a full blown racecar (ran in the Porsche cup car series for several years before he bought it), and he only has it rebuilt once a year.... And that thing revs high too (not sure what it revs too, would have to ask)....

[bmxludwig]

No offense, but you may want to look into the forced induction forum for more in depth information. They do plenty of head rebuilds and bottom end stuff in a week than the regular e36 forum has ever done.

[exodus454]

No offense, but you may want to look into the forced induction forum for more in depth information. They do plenty of head rebuilds and bottom end stuff in a week than the regular e36 forum has ever done.

I know, I wasn't exactly sure where to post it. I'm kinda surprised this has gotten 18 responses already in the E36 section.

I didn't want to post it there because FI is the opposite of building an N/A engine, but I'm sure there are some more generally knowledgeable people over there.

[bmxludwig]

I know, I wasn't exactly sure where to post it. I'm kinda surprised this has gotten 18 responses already in the E36 section.

I didn't want to post it there because FI is the opposite of building an N/A engine, but I'm sure there are some more generally knowledgeable people over there.


The guys in the FI forum are truly knowledgeable about engines in general. They aren't making 600+ ponies with just turbocharger knowledge. They know all the nooks and crannies of our M5x motors like you wouldn't believe. The tuning aspect of the deal is also covered in great detail there. It seems the e36 forum is simply about intakes and maintenance questions anymore :(

[happycamper]

The guys in the FI forum are truly knowledgeable about engines in general. They aren't making 600+ ponies with just turbocharger knowledge. They know all the nooks and crannies of our M5x motors like you wouldn't believe. The tuning aspect of the deal is also covered in great detail there. It seems the e36 forum is simply about intakes and maintenance questions anymore :(

thanks for summing up the e36 forums thats exactly what it is

[thedude60126]

The guys in the FI forum are truly knowledgeable about engines in general. They aren't making 600+ ponies with just turbocharger knowledge. They know all the nooks and crannies of our M5x motors like you wouldn't believe. The tuning aspect of the deal is also covered in great detail there. It seems the e36 forum is simply about intakes and maintenance questions anymore :(


+1 Its really sad

[thedude60126]

Thats why when I see threads like this come up and I see responses its cool to know which guys on this forum actually know what they are talking about and not just how to put on wheels body kits and smoke lights (though that is cool)

[happycamper]

Thats why when I see threads like this come up and I see responses its cool to know which guys on this forum actually know what they are talking about and not just how to put on wheels body kits and smoke lights (though that is cool)

no its not

[firefirefire90]

This engine is going to sound sweet. That's all I can say. Go for it dude! And make sure to port the fiz-awk out of it ;)

[exodus454]

This engine is going to sound sweet. That's all I can say. Go for it dude! And make sure to port the fiz-awk out of it ;)

Thanks :buttrock

[strogg]

yeah, go for it! i was thinking of doing the same thing with my car in the future. half for the "look it's super powerful NA" factor and half for the "god that sounds hella sick" factor

and yes, it is completely possible. not sure how "safe" it is, but bimmerworld sells a set of sunbelt cams and valvesprings that let you rev to 9000-9500 rpm "safely". they also had for sale at one point a superbly tuned left hand drive euro engine that produced 400bhp. if i had $14k at the time i'd definitely would've bought it.

[NHbmw325I]

9500 rpm safely? Are you kidding me, any US e36 motor crank will not be able to handle anywhere near that.

[ptldM3]

Dont know too much about m50s but a full built m50 should have close to the same potential as moded s50/52s but if money is not the problem i would just get an s50 or s52. Alot of s50s/52s are puting down 240 ish whp w/o cams or any internal work. With cams 260-290 whp is duable, theres a couple members that have minimal modds that are puting down these numbers, cams, headers, track pipe, catback and a really good tune is usually enough to get you around 250-260.

Stock m3s redline at 6500rpm sofware will bump you up to 7000 rpm, sunbelt cams with 276 deg intake and 272 deg exhaust do 7400 rpm on stock interals and 7800rpm with beefed up internals. There is also some 290 deg cams so i would amagine you would be able to go past 8000rpm but there isn't much to gain above 7k.

[Consonance]

Can't bore above 87mm. You will have catastropic failure. M3 Evo is on the limit at 86.4mm.

And yes I do have some knowledge about them, please read...


Bmw E36 Engine Pic 'n Mix List

(V) = Vanos (NV = Non Vanos)

320 has a 66mm stoke length 80mm bore and a rod length of 135mm(NV) or 140mm(V)

323 has a 75mm stoke length 84mm bore and a rod length of 140mm(V)

325 has has a 75mm stoke length 84mm bore and a rod length of 135mm(NV) or 140mm(V)

328 has a 84mm stoke length 84mm bore and a rod length of 140mm(V)

M3 3.0 both Euro and US - has a 85.8 stoke length and a 86mm bore and rod length of 135mm

M3 3.2 Euro and US - stoke of 91mm and a bore of 86.4mm - rod length of 135mm

Euro engines are more powerful because, they use individual throttle bodies worth around 20fwhp on a tuned engine. They have solid lifters which allow the higher redline, a less restrictive intake design and a larger diameter exhuast manifold.

So going on from the other post I did, the best stroker kit to use would be the following.

US M3 3.0 litre crank, US M3 3.0 Rods, the standard pistons, US M3 Cams (or Sunbelt Race Cams if your wealthy and/or mad) , Custom Tune and more depending on your budget.

That setup above would yeild the following equation.

Ba = (B x B x P) / 4

then

Ba x Sl = V (Volume)

then

Ba x Sl = (V) x 6
___________________________________ Resulting in.....

Ba = (8.4 x 8.4 x 3.14159) / 4 = 55.41764cm²

V = 55.41764 * 8.58 = 475.4833512cc

Displacement = (475.4833512 * 6) = 2852.9001072 cc
________________________________

Viola.

Standard = 75mm stoke length 84mm bore and a rod length of 135mm(NV) or 140mm(V)

Stroker = 85.8 stoke length and a 86mm bore and rod length of 135mm

So now we can work out the absolute highest that the piston can go up towards the valves on both setups and then compensate them when we know the results.

Standard Stoke = 75mm. So half its time is spent going up and half its time traveling down.

So the crank only ever travels 37.5mm upwards and the other 37.5mm downwards.

I'll work on the basis of you having a Non vanos car and my car being the vanos version just so there's nothing that isn't covered.

Both Vanos and Non Vanos cars have the same crank length of 75mm, so the above principle applies to both.

The difference is that the non vanos has a conrod that is 5mm shorter than the vanos versions.

So Vanos Max Upward Travel = 37.5 + 140(V) = 177.5mm
So Non Vanos Max Upward Travel = 37.5 + 135(NV) = 172.5mm

So now we work out the Max Upward Travel of the Stroker Parts and if its above the values relating to the respectful versions of engine above, then modification will be needed.

Standard Stroke = 85.8mm. So half its time is spent going up and half its time traveling down.

So the crank only ever travels 42.9mm upwards and the other 42.9mm downwards.

M3 Rods are 135mm so the Max Upward Travel = 42.9 + 135 = 177.9mm

So thats only 0.4mm over, so you need to use a slightly thicker head gasket to make that 0.4mm up in height with the increased height of the cylinder head to stop piston and valves issues and Viola.

Intelligence isn't about knowing just the answers, it's about knowing where and how to find them.

And Link For Gearing Questions...

http://forums.bimmerforums.com/forum/showthread.php?t=1177104:)

Hello, as you asked for some input I will gladly show/tell you what my research and maths has come to after about 3 hours of looking at how to work out engine capacity and CR etc. The maths is quite detailed so I'll try to make it as simple as possible so there won't be anyone scratching their heads after. :)

Calculating Engine Displacement in cc

The volume of a cylinder is calculated by multiplying the area of the bore of the cylinder by the length. In the case of an engine the length is the stroke length. The bore area is calculated as follows;

Bore Area = (Bore x Bore x PI (3.14159) / 4

or

Ba = (B x B x P) / 4

Normally we measure engine volume in cubic centimetres, "cc" although engine dimensions are often shown in millimetres. We need to convert any measurements into centimetres before starting the calculations to simply the operation.

Lets take the example of my 94 325 Vanos. The bore is 84mm and the 75 stroke is mm.

Converting into centimetres we get Bore = 8.4cm, Stroke = 7.5cm.

So my bore area is therefore (8.4 x 8.4 x 3.14159) / 4 = 55.41764 cm²

So the volume of 1 cylinder is the bore area (Ba) x stroke lenght (Sl)

Ba x Sl = V (Volume)

or

55.41764 x 7.5 = 415.6323 cc

That is for 1 cylinder, to work out the exact displacement you need to multiply that singular volume figure by the number of cylinders you have, in my case that is 6.

This means that the calculation would be;

Ba x Sl = (V) x 6

or

55.41764 x 7.5 = (415.6323 cc) x 6 = 2493.7938cc

Compression Ratio Calculation

The compression ratio is defined as ther (Swept Volume (Sv) + Clearance Volume (Cv) ) / Clearance Volume (Cv)

We already know the swept volume of each cylinder from above to be 415.6323 cc so this is how we work out the following for my engine.

Cr = (Sv + Cv) / Cv

or

Compression ratio (Cr) = (415.6323 + 43.75) / 43.75 = 10.5001

This makes it easy to calculate the clearance volume we need in order to obtain a the compression ratio you are after.

What clearance volume do we need if we want to raise the compression ratio of the engine to 11.5? its simple.

We simply divide the swept volume (Sv) by 1.0 less than the compression ratio we need to obtain:

So to simply that paragraph, i will show you an example. If i wanted a 11.5 Cr instead of my current 10.5 Cr I would do the following calculation.

Sv / (The Cr you want to obtain, in my case 11.5) - 1.0) this would look like;

Sv / Cr - 1.0

or

415.6323 / 10.5 = 39.5840 cc for a compression ratio of 11.5.

Thus we need to skim the head or fit higher compression pistons until the clearance volume drops from 43.75cc to 39.5840 cc.