Yet another M50B30 (stroker) Turbo questions

[Vexatus]

Hello to everyone,

That's my first post and I'm starting with tonnes of questions

I'm planning to get a E36 325i and make it a fun car/street racer. Let's leave the chassis and drivetrain for now and focus on the engine. I've read tens of topics and this and other forums. I've came out with the following so far:
M50B25 NV block, head, intake manifold and rods
M54B30 crank and cams
M60 throttle body
RusEFI standalone
Custom exhaust manifold

For the budget reasons I want to do it in few stages:
1. Install stand alone and create the initial maps
2. Build stroker (and remap)
3. Add a turbo

However, as I wouldn't like to do things twice here are some questions:
1. I can't boost it too much with the CR of a "stock" stroker (should be about 10.4:1), so herso what coukd be done:
1a. Spacer
1b. M54 forged, low CR pistons
1c. How about going with M50B25TU block? It has 140 mm rods so with 135 mm rods and M54B30 stock pistons they would be about 6.8 mm bellow the deck. With some block machining a desired CR should be achievable (or not?)
1d. Machine stock M54B30 pistons
2. I know, I'll need to machine the M50B25 block to fit the M50B25 rods with the M54B30 crank, but that's fine.
3. How many WHP will the stock M50B25 rods hold?
4. How many WHP will stock M54B30 pistons hold with the lower CR (1a, 1c or 1d)? Machining the pistons won't make them stronger - that's for sure...

The goal would be about 450 WHP (I think it's a lot for the RWD car that weights just a bit more the a tone) if could be be done with the stock bottom end (and lower CR). Of forged pistons and/or rods are required for the power, then it could go higher, but I'm not after 600+ as it's supposed to be a car I could drive in the street (again - low weight and RWD), not only in a straight line

What turbo would be the best? Spooling early but rather gently (don't want a sudden kick in the back). HX35? HX40? You can get those 2nd hand very cheap here (they go on trucks etc.). Let's say $300 and another $300 to rebuild or get a Chinese one for more or less the same amount.

Thanks for any advice!
Greg

P.S. it'll run RON98 all the time.

[pbonsalb]

Piston pin heights are matched to crank stroke and rod length so you may not be able to mix and match to create the compression you want. Easiest is to do what is certain to work. Lower CR pistons or a thicker HG or a HG plus spacer.

[someguy2800]

Hello to everyone,

That's my first post and I'm starting with tonnes of questions

I'm planning to get a E36 325i and make it a fun car/street racer. Let's leave the chassis and drivetrain for now and focus on the engine. I've read tens of topics and this and other forums. I've came out with the following so far:
M50B25 NV block, head, intake manifold and rods
M54B30 crank and cams
M60 throttle body
RusEFI standalone
Custom exhaust manifold

For the budget reasons I want to do it in few stages:
1. Install stand alone and create the initial maps
2. Build stroker (and remap)
3. Add a turbo

However, as I wouldn't like to do things twice here are some questions:
1. I can't boost it too much with the CR of a "stock" stroker (should be about 10.4:1), so herso what coukd be done:

You could make close to your goal with 10.4:1 compression. You could easily do it with a water meth injection kit.

1a. Spacer
1b. M54 forged, low CR pistons
1c. How about going with M50B25TU block? It has 140 mm rods so with 135 mm rods and M54B30 stock pistons they would be about 6.8 mm bellow the deck

With some block machining a desired CR should be achievable (or not?

The blocks are the same. The only thing different is the rods and pistons

1d. Machine stock M54B30 pistons

Its possible but I wouldn’t

2. I know, I'll need to machine the M50B25 block to fit the M50B25 rods with the M54B30 crank, but that's fine.
3. How many WHP will the stock M50B25 rods hold?

The highest I’ve seen was almost 1000

4. How many WHP will stock M54B30 pistons hold with the lower CR (1a, 1c or 1d)? Machining the pistons won't make them stronger - that's for sure...

a lot more than you want to make

The goal would be about 450 WHP (I think it's a lot for the RWD car that weights just a bit more the a tone) if could be be done with the stock bottom end (and lower CR). Of forged pistons and/or rods are required for the power, then it could go higher, but I'm not after 600+ as it's supposed to be a car I could drive in the street (again - low weight and RWD), not only in a straight line

What turbo would be the best? Spooling early but rather gently (don't want a sudden kick in the back). HX35? HX40? You can get those 2nd hand very cheap here (they go on trucks etc.). Let's say $300 and another $300 to rebuild or get a Chinese one for more or less the same amount.

Thanks for any advice!
Greg

P.S. it'll run RON98 all the time.

Answers in red above.

If you can find a set of them the pistons out of an M54b25 would be about right. They came with a 75mm crank and 145mm rods so if you do the math they will sit 2.7mm lower than stock with 135mm rods and an m54b30 crank. I can do the math on the compression later. I have a set of them in my shop.

[Vexatus]

Answers in red above.

If you can find a set of them the pistons out of an M54b25 would be about right. They came with a 75mm crank and 145mm rods so if you do the math they will sit 2.7mm lower than stock with 135mm rods and an m54b30 crank. I can do the math on the compression later. I have a set of them in my shop.

I get it, I wasn't aware about longer rods in M50B25TU - this explains a lot. So, ocnsidering tha fact that M54B30 pistons are 1,8 mm bellow the deck, it means it'll give 4,5 mm lower with M54B25 pistons and 135 mm rods. Assuming the piston top would be the same shape (cuts) as M50B25, the CR would be about 7,48:1 - isn't that a bit low? But I know that M54B30 pistons have smaller cuts so it may be somewhere between 7,5-8,0:1 I guess?
In theory: with the same piston shape and 4,5 mm spacing, the combustion chamber is 24,94 ccm larger then in M50B25 and it's 76,66 ccm. The Wiseco forged pistons have 28,3 mm compression height, but the dome volume i -7,3 ccm and they are 9,0:1 CR. But again - M54B30 pistons are 1,8 mm lower on M50B25 then M50B25 stock pistons. I'm confusing myself right now I think :P
Bottom line is - I'd appreciate if you could do the math.

Going back to the other topics:
so if you say that stock pistons (let's say those are M54B25) at CR arround 8:1 will hold what I'm aiming at then potential fail reason could be piston rings spacing I guess?
What about the turbo? What would be big enough to not lose the guts up to at least 6000 RPM, but small enough to spool below 3000 RPM on a stroker like that?

P.S. - I'd prefer good tune/lower CR and be able to run on the RON98 that I can get at any gas station (for just a little bit more then RON95) over using meth.
P.S.S. Here's the sheet I'm using to calculate CR: https://drive.google.com/open?id=1Y-...4RTx4wkqWNT5_D

[someguy2800]

All of these motors have a stock distance between the crank centerline and the head of 211.7mm with a stock gasket. M50’s are 210mm tall with a 1.7mm head gasket, and m52tu and m54 are 211mm with a .7mm head gasket. The compression ratio is determined by different machining of the piston and displacement.

Forget about m54 pistons for a moment. An M54b25 has a 75mm stroke and 145mm rod. Half the stroke is 37.5. So 37.5 + 145 = 182.5mm. This is the height of the connecting rod pin to the top of the block. An M54 is 89.6 stroke and 135mm rod. Half the stroke is 44.8. 44.8 + 135 = 179.8. 182.5 - 179.8 = 2.7mm. So if we use m54b25 pistons and m54 rods and crank the pistons will sit 2.7mm lower than a stock m54b25, but that has nothing to do with what an m54b30 was stock.

So what does this do for compression? BMW lists the stock compression for an m54b25 as 10.5:1.

if we do the math on the bore and stroke this means the volume above the piston must be 34.1cc. But now if we increase the stroke to 89.6 and add 2.7mm to the deck clearance the compression comes out to 9.46:1

The m54b25 pistons are pretty short but any of the stock bmw pistons will be more than strong enough for your power goals. I’ve seen over 1000 whp done on stock pistons. 90% of the time when you see stock pistons break it’s because they didn’t have enough ring end gap and they buckle the rings and break the ring lands off. As for the rods stock m54b30 rods are perfectly fine for 500 whp.

the easiest way is still going to be copper spacer and cutring gasket with stock m54 rods and pistons but I understand budget constraints.

An HX35 will work well, just make sure to get a small turbine housing for it or it will be lazy. A billet compressor wheel works really well on them too. It’s only going to take about 15lbs of boost to hit your goal.

[JOMARO]

I can see that someguy2800 has his valuable input
I can only share my experience , I ve went the m54b30 internals route with 0.140" MLS , with Vanos head and US M3 cams ,
holset hx40 comp/hx35 turbine exh 12 ( equivalent to 60/60 turbo
with 13 psi I had 380-400 whp with 95 ron
full boost was 3400 ( I had some leaks and aluminum intake ) but I had boost instantly and response was great , but turbo felt like falling at high rpm
I think a HXsuper 40 wtih a machined 12 cm turbine housing would be much better

[Vexatus]

All of these motors have a stock distance between the crank centerline and the head of 211.7mm with a stock gasket. M50’s are 210mm tall with a 1.7mm head gasket, and m52tu and m54 are 211mm with a .7mm head gasket. The compression ratio is determined by different machining of the piston and displacement.

Forget about m54 pistons for a moment. An M54b25 has a 75mm stroke and 145mm rod. Half the stroke is 37.5. So 37.5 + 145 = 182.5mm. This is the height of the connecting rod pin to the top of the block. An M54 is 89.6 stroke and 135mm rod. Half the stroke is 44.8. 44.8 + 135 = 179.8. 182.5 - 179.8 = 2.7mm. So if we use m54b25 pistons and m54 rods and crank the pistons will sit 2.7mm lower than a stock m54b25, but that has nothing to do with what an m54b30 was stock.
So what does this do for compression? BMW lists the stock compression for an m54b25 as 10.5:1.

if we do the math on the bore and stroke this means the volume above the piston must be 34.1cc. But now if we increase the stroke to 89.6 and add 2.7mm to the deck clearance the compression comes out to 9.46:1

You're right! I forgot about increased displacement. It would be c.a. 8:1 with the added 2,7 mm of spacer and the same displacement...
So the secon hand B54B25 pistons are cheap as dirt ($15/piece) but 9,5:1 is still a lot.

The m54b25 pistons are pretty short but any of the stock bmw pistons will be more than strong enough for your power goals. I’ve seen over 1000 whp done on stock pistons. 90% of the time when you see stock pistons break it’s because they didn’t have enough ring end gap and they buckle the rings and break the ring lands off. As for the rods stock m54b30 rods are perfectly fine for 500 whp.

Yep, I've mentioned gap on my first post - so what the proper value would be?

the easiest way is still going to be copper spacer and cutring gasket with stock m54 rods and pistons but I understand budget constraints.

You mean O-Ring?
So it would need about 3 mm extra spacer with M54B30 pistons, giving 4,7 mm of the total HG thickness with the M50 block. Seems a lot...
However, with sticking with M54B25 pistons and 3,5 mm HG (2x stock 1,75) would give around 8,23:1.
I'm not sure about endurance, there's a local company known of building a lot of M50Bxx up to 1000+ BHP and they sell a stainless steel spacers which, they claim, will hold up to 600 BHP (over 500 WHP) with two 1,75 mm HG's (Victor Reinz). This sounds reasonable and cheap (those are around $50/piece).

An HX35 will work well, just make sure to get a small turbine housing for it or it will be lazy. A billet compressor wheel works really well on them too. It’s only going to take about 15lbs of boost to hit your goal.

I can see that someguy2800 has his valuable input
I can only share my experience , I ve went the m54b30 internals route with 0.140" MLS , with Vanos head and US M3 cams ,
holset hx40 comp/hx35 turbine exh 12 ( equivalent to 60/60 turbo
with 13 psi I had 380-400 whp with 95 ron
full boost was 3400 ( I had some leaks and aluminum intake ) but I had boost instantly and response was great , but turbo felt like falling at high rpm
I think a HXsuper 40 wtih a machined 12 cm turbine housing would be much better

Other options? GT35R? I've seen people runnig hi HPs (600+) on these but full pressure starting around 4500 RPM - I'd prefer lower. What else is out there?

[someguy2800]

No not orings. With the copper spacer and cutring gasket you lay the copper spacer directly on the block and put the cutring gasket on top of it, so you end up with an extra 1.7mm thickness over stock. Most of the stock motor builds in the US use this and it works great. Available from CES motorsports. For the price though you can nearly buy new forged pistons. I would not have any reservations on trying to make 450 whp on pump gas with 9.4 compression, but it’s your choice.

how thick are the stainless steel spacers you mentioned? They would probably work with just one gasket if you spray it with gasket sealer and put a cutring gasket on it. Then again as Jomaro mentioned you can just try your luck with the .140” mls gasket. They are cheap and some get reasonable life out of them.

[someguy2800]

This is the cutring gasket I’m talking about.

https://www.ebay.com/itm/JE-Cut-Ring-Head-Gasket-For-BMW-E36-M50-m52-2-5l-85mm-Bore-turbo-spacer-328i-325/122286650234?hash=item1c78da337a:g:pOkAAOSwopRYYuA v

[pbonsalb]

The Cometic MLS gaskets come in a few thicknesses. I have use 0.080, 0.098 and 0.140. I think the 0.140 copper spacer and cut ring combination is better at sealing long term. And tougher alloy lowerCR pistons are best.

[Vexatus]

No not orings. With the copper spacer and cutring gasket you lay the copper spacer directly on the block and put the cutring gasket on top of it, so you end up with an extra 1.7mm thickness over stock. Most of the stock motor builds in the US use this and it works great. Available from CES motorsports. For the price though you can nearly buy new forged pistons. I would not have any reservations on trying to make 450 whp on pump gas with 9.4 compression, but it’s your choice.

I've never seen this to be honest, but I remember making gaskets of soft copper but those were air cooled engines back then.

how thick are the stainless steel spacers you mentioned? They would probably work with just one gasket if you spray it with gasket sealer. Then again as Jomaro mentioned you can just try your luck with the .140” mls gasket. They are cheap and some get reasonable life out of them.

0.6 and 0.8 mm.

[someguy2800]

Almost forgot there is also a stock gasket that is 2mm thick. That would get it down to 9.2:1 with m54b25 pistons.

[Vexatus]

Cometic is $350 where I live, so compared to a spacer which is $35 as a matter of fact and VR HG for $40/piece... I mean it's half of a price of forged pistons.
The cutring gasket is $250 but does that include everything?

Almost forgot there is also a stock gasket that is 2mm thick. That would get it down to 9.2:1 with m54b25 pistons.

How far boost/HP I could take it with 9.2:1?

[someguy2800]

Cometic is $350 where I live, so compared to a spacer which is $35 as a matter of fact and VR HG for $40/piece... I mean it's half of a price of forged pistons.
The cutring gasket is $250 but does that include everything?


How far boost/HP I could take it with 9.2:1?

i wouldn’t be afraid at all to run that up to 450 whp assuming good exhaust manifold, decent size turbine, good intercooler, good tuning ect... Intake air temps and exhaust back pressure have a huge impact on detonation resistance so it all kind of has to work together as a system.

Can we take a step back and refocus on what your goals are what other stuff your going to put in the car as far as the turbo setup and drivetrain ect... are we still talking about 450 whp max?

[Vexatus]

Yep, around 450 whp, if it'll end up with 480 or 420 with safe timing and EGT then I can live with that as well.
Drivetrain:
- stock transmission and diff (with LSD) - when it explodes I'll start replacing. There's so many Beemas in the junkyards and you can get entire, running E36, E46, E39 for less then $2000, that parts prices are very low so I'm not worried about that.
- M50B20 SMF with M57 pressure plate and custom kevlar friction placte - that should do.

Engine:
- M50B25NV block, rods, head, intake mani, coils
- M54B30 crank, cams
- M60 TB
- Custom exhaust mani, I've been thinking about something like that:



But I need to get on the actual car, measure the space, then I'll 3M model that to get closer to equal lengths, 3D print to make sure it fits, then cut the print in parts and reproduce in metal

- IC like that: https://fmic.eu/fmiceu/89-intercooler-550x180x65mm.html
- 3-3,5" exhaust with some low restriction muffler in the end (it has to be road legal and, trust me - police doesn't like Beemas here, long story)
- RusEFI standalone (as an experiment, it's cheap as dirt and seems to heve it all) or MSIII
- Turbo... well, still no decision made. Yesterday I've been looking at the build with GT35R .63 A/R and it seems to be what I was looking for, it's not insanely powerful, but should handle the power goal and with the stroker should raise bellow 3k RPM
- WG with the GT35R has to be some external + PWM solenoid so I can have EBC and flatten torque (I used to drive a 2.7BiT Audi that has perfectly flat torque 3000-6000 RPM - it's sooo nice to drive!)
- ARPa for head and rods
- HG - well, you say it'll go with 2,05 mm. But if 2x1,75 mm would work then I'd probably sleep better. Victor Reinz I'm thinking here (considered as OEM here)

What else did I missed?

The company I've mentioned yesterday, the one making the HG spacers. They're builind a lot of M50 and M52 cars so from their projects I've seen an 600 BHP (how much whp that could be) M50 with stock bottom and a 550 BHP one with the chineese GT35R .63 A/R (that is I guess pretty close to what I'm after).

[gdavid]

If you haven't bought the car yet, I would suggest picking up a 328 rather than the 325 simply for having a stronger transmission (ZF versus Getrag). The ZF won't be able to handle everything that a turbo can throw at it, but it will withstand it better than the getrag in the 325. The prices for these cars is pretty close anyway. The 325 is more likely to come with a LSD but it may not and it is easier to upgrade than the transmission. 325 used to be preferred for OBD1 tuning but OBD2 tuning is just as supported (maybe more so) at this point.

[Vexatus]

Well, I've been after M50B25 for it's bulletproof iron block, rods and head + intake mani which is know for some good flows and stronger vales. Trasmission is a good point but I've read that M51 TDS transmission is ZF and it's p'n'p from 325TDS and 525TDS - you can get one of these for $80 so I need to do some reserach on that. With $80 price tag I can buy 3 to have a spare and don't even care if it blows or not... But I'll check that...

Going back to the engine, I forgot about couple of obvious things:
- injectors and fule pump
- intake piping
- BOV
- head - ported and polished

[gdavid]

I misread and assumed you had already had your engine. Also, here in the US the m52's were iron as well so I tend to forget Europe had aluminum blocks.

[Vexatus]

Nope, I'm doing research to pick the best option.
Yep, M52 were aluminium plus I don't want VANOS.

[someguy2800]

Your plans are way overboard for 450 whp. You really don’t need non vanos rods, arp rod bolts, or the non vanos valvetrain. When your really pushing the limits on power and rpms that stuff becomes an issue but for 450 whp your wasting your time and money. With the m54 crank your going to need to keep the rpms to like 7200 and your cams won’t make any power above that anyway so the non vanos valvetrain will be of no benefit to you. I would say the same for porting the head, without bigger cams I don’t think it’s going to make much difference. Also if you want low rpm response from the turbo you will be much better off with a vanos motor. You would get better response with a 2.5l vanos motor than you will from a 3.0l non vanos.

I have never seen someone run two stock headgasket stacked on top of each other but I don’t think that would work without a spacer between them.

[Vexatus]

I honestly believe that 450 whp is more than sufficient for the street car, but you know what they say about the power

But on a more serious note. I tend to overdo things for couple of reasons:
a. I like to do things robust and reliable like a Soviet tank, which very often leads me to a serious overkill, therefore I appreciate voice of reason;
b. VANOS has opinion of being very faulty and unreliable here and I think that's for to reasons: poor service and high mileage, I mean most of these cars are way over 300 000 miles;
c. Local tuners are either idiots that can't do a good tuning or just copy-paste maps and setups found on the internet (not even knowing English well enough to post a question here), because the 600 HP I've mentioned before is known to be the most powerful M50 with stock bottom, in the country, everything else is a low 400ish. And all of them will tell you it's flywheel HP, but measured on a chassis dyno and that is more of thasseography rather then a honest measurement.

Back to the subject:
The plan was to get a 325i (which for some reason can be found much cheaper then a 328i, most likely half of a price) for something like $1500 and an M54B30 engine for another $550. This way I've got most of the parts I've mentioned. Well, besides the M54B25 pistons but these are cheap. That's why I don't agree the NV rods etc. are waste of money.

I'm aware of the rev limitation on a stroker, I was thinking rather like 6800RPM.

As for the HG o guess it's then either M54B25 pistons with 2,05 mm HG and 9,2:1 CR or M54B30 pistons with 2x 1,75 HG and a spacer and CR of about 8,5:1 - despite of the higher CR, the 1st one still seems more robust.

I guess it's all about good tuning, efficient turbo, big IC and correct rings spacing?

[BFresh]

One negative to using non vanos rods with a m54b30 crank is you will have to notch your block a good bit. I’m in the process right now, I’d definitely use m54b30 rods for sub 500whp goals just for the ease of installation.

[Vexatus]

i wouldn’t be afraid at all to run that up to 450 whp assuming good exhaust manifold, decent size turbine, good intercooler, good tuning ect... Intake air temps and exhaust back pressure have a huge impact on detonation resistance so it all kind of has to work together as a system.

With this beeing said I'll go with the big IC, 3,5" exhaust + some good exhaust mani. What kind of "decent" size turbo are we talking here? HX35, GT35R, or rather something HX40-ish?

One negative to using non vanos rods with a m54b30 crank is you will have to notch your block a good bit. I’m in the process right now, I’d definitely use m54b30 rods for sub 500whp goals just for the ease of installation.

I'm aware of the block machinig being required. Could you post any pics of "before and after"?
Another drawback of the NV rods over decent forged ones is that forged are stronger and lighter so the engine can potentially rev higher.

[Vexatus]

I'm looking at those turbos and having an impression that GT35 0.63 A/R may be a bit small for the stroker with it's 2,5" exhaust? Perhaps a GT45 1.05 A/R whould have been better for that? I mean - it's 3,5" V-band... having in mind stock bottom and realtively high CR (9.2:1 let's say with M54B25 pistons), and keeping the heat low.

Thanks!
Greg

[Vexatus]

I've juest realized that right behind Czech border (50 km from my place) i can get E85 in a gas station and it's much cheaper then pump 98 or even 95 here.
This I guess change a lot? What would be optimal CR for E85 then? Perhaps stay with 9.4:1 on M54B25 pistons and have two maps (one for pump 98 and one for E85)?