High Rev M20B25

[zaq123]

depending on the bearing ratios, temperature has a potential to rise. Pretty much typical forging fluid dynamic of these M20S52 rods. Based on Metric Mechanic tests, 60% of the time it happens every time

[ForcedFirebird]

depending on the bearing ratios, temperature has a potential to rise. Pretty much typical forging fluid dynamic of these M20S52 rods. Based on Metric Mechanic tests, 60% of the time it happens every time

Sorry to be blunt, but MM does not do any flow tests, fluid dynamic tests, and even their customer dynos have come up short of advertised numbers. Anyone who claims results without actual proof is just a salesman.

I may come off as smug and confident in findings, but that's an equation of real world scientific results. I'm not the guy to repeat something read on the internet. If I post x=x, then I am damned sure x=x.

[zaq123]

Sorry to be blunt, but MM does not do any flow tests, fluid dynamic tests, and even their customer dynos have come up short of advertised numbers. Anyone who claims results without actual proof is just a salesman.

I may come off as smug and confident in findings, but that's an equation of real world scientific results. I'm not the guy to repeat something read on the internet. If I post x=x, then I am damned sure x=x.

My post was obviously a joke....fake news

Sent from my VS985 4G using Tapatalk

[cyrmanj]

One of the things that worries me more is the Oil pump, some pumps suffer of cavitation at high RPMS

Do not have experience with high reving M20s, but just throwing the idea around: https://www.crank-scrapers.com/bmw_m20.html + oil pan baffle.

Good luck!

[nando]

depending on the bearing ratios, temperature has a potential to rise. Pretty much typical forging fluid dynamic of these M20S52 rods. Based on Metric Mechanic tests, 60% of the time it happens every time

dude I still can't understand anything you're saying.

forging fluid dynamic?

what happens 60% of the time, every time?

edit: oh I know. 60% of the time, every time I drive my E30, I tag the 7500rpm rev limiter and nothing breaks. ;)

[zaq123]

dude I still can't understand anything you're saying.

forging fluid dynamic?

what happens 60% of the time, every time?

edit: oh I know. 60% of the time, every time I drive my E30, I tag the 7500rpm rev limiter and nothing breaks. ;)

seriously? It was the one of the greatest quotes:

[digger]

you don't need much to rev to 7500. my old little 323i (stock except for modded dizzy) used to do it easily but would valve bounce not long after (they only had the big single spring back then).... its another thing for it to be worthwhile, i.e make power up there.

[jebc125]

Read some interesting stuff here LOL

@ForcedFirebird the recipe you wrote is to make a 2.8 M20 stroker engine, right?

Today I had the visit of the mechanic from the shop who will be building my engine, and discussing about the engine built. He has already a lot of experience building M20 Engines. (The story says 1 m20b25 is reving over 8000 rpms in Costa Rica )

We are not doing an stroker engine, the objetive a engine that produce power at high RPMS. And we ended with this preliminar list (lol trying to look professional and shit ):

-Bimmerheads Super Sport Head with performance valves (according to the site new rocker arms are included)
-Camshaft Schrick 284 or 280 from Bimmerheads (included with the head)
-Set of pistons from IE
-Take out weight of the Crankshaft and balance it (using the one from the engine)
-VAC adjustable pulley
-Oil Pan baffle and crank scrapper
-ECS Performance Water pump kit
-MS2 Management
-ITBs (If I wont the lottery )
-RHD Flywheel
-All the sensors and rubber (already bought that crap from ECS)
-Money

I dont want to take out the calculator :SOS:

[digger]

why pay $700 for stock cast pistons when you can get aftermarket JE etc for ~$900 from?

you could even use the mahle MS IE pistons (a little more) with 140mm m50 vanos rods then a MLS if the 2.05mm HG is a little too thin. this way you can have the valve pockets for a decent cam and CR to match added duration.

i'm also with John a 288 is what you need if you want to rpm and peak the hp past 7000rpm

[TobyB]

...and valve springs- digger & John, what does it take to keep the intakes
from floating at 7500 on overrun with a 288 cam?

We have to stay stock with the Pro3 rules, so I've never looked...

t

[jebc125]

...and valve springs- digger & John, what does it take to keep the intakes
from floating at 7500 on overrun with a 288 cam?

We have to stay stock with the Pro3 rules, so I've never looked...

t

Man good question, I am assuming the ones included with the head are good enough... but what will be a good recommendation, VAC or what brand?

[digger]

...and valve springs- digger & John, what does it take to keep the intakes
from floating at 7500 on overrun with a 288 cam?

We have to stay stock with the Pro3 rules, so I've never looked...

t

schrick springs would be fine and they are only slightly stiffer than stock. i run VAC springs but they are made by Eibach (dont know who makes them now) which are stiffer than the schricks

[ForcedFirebird]

schrick springs would be fine and they are only slightly stiffer than stock. i run VAC springs but they are made by Eibach (dont know who makes them now) which are stiffer than the schricks

I just put some VAC springs on my spring tester. At stock height, the stock dual springs are 60lb at install height, the VAC springs were 55 at stock install height, and weaker throughout. The VAC springs with the VAC retainers is what makes them different. They have thinner coils for a decreased stack height, but the VAC retainers decrease install height (which increases spring rates). The head was for a customer n a tight schedule, so I didn't take the time to measure the install height with the total VAC package.

I would suggest Schrick springs unless you get the whole retainer and spring package from VAC. Otherwise, you are putting weaker spring in with increased lift capability.

[ForcedFirebird]

Read some interesting stuff here LOL

@ForcedFirebird the recipe you wrote is to make a 2.8 M20 stroker engine, right?

Today I had the visit of the mechanic from the shop who will be building my engine, and discussing about the engine built. He has already a lot of experience building M20 Engines. (The story says 1 m20b25 is reving over 8000 rpms in Costa Rica )

We are not doing an stroker engine, the objetive a engine that produce power at high RPMS. And we ended with this preliminar list (lol trying to look professional and shit ):

-Bimmerheads Super Sport Head with performance valves (according to the site new rocker arms are included)
-Camshaft Schrick 284 or 280 from Bimmerheads (included with the head)
-Set of pistons from IE
-Take out weight of the Crankshaft and balance it (using the one from the engine)
-VAC adjustable pulley
-Oil Pan baffle and crank scrapper
-ECS Performance Water pump kit
-MS2 Management
-ITBs (If I wont the lottery )
-RHD Flywheel
-All the sensors and rubber (already bought that crap from ECS)
-Money

I dont want to take out the calculator :SOS:

You don't need to keep the stroke small to make power and rev high. Rama is making something like 275whp at 8000 RPM with an 84mm crank, so please don't dismiss my input.

This car is revving to 7500 and makes 217whp/202wtq, 2.8l with 84.5mm pistons, one of my WOT-Tech cylinder heads (ported and flowed on my bench) and only a small 272 camshaft...

https://www.youtube.com/watch?v=L7UI2UyR91Q

Here is the build...

https://www.r3vlimited.com/board/showthread.php?t=330450

Pics got hosed from photobucket, but you can install a correction in your browser to see them.

[digger]

I just put some VAC springs on my spring tester. At stock height, the stock dual springs are 60lb at install height, the VAC springs were 55 at stock install height, and weaker throughout. The VAC springs with the VAC retainers is what makes them different. They have thinner coils for a decreased stack height, but the VAC retainers decrease install height. The head was for a customer n a tight schedule, so I didn't take the time to measure the install height with the total VAC package.

I would suggest Schrick springs unless you get the whole retainer and spring package from VAC. Otherwise, you are putting weaker spring in with increased lift capability.

in 2008 when i had them tested we had stock, schrick and VAC with stock retainers (they only sold titanium back then no steel aftermarket options were available). i witnessed the test while at the shop and the VAC were noticeably stiffer with appropriate coilbind etc. the website now says they are made in the USA but when i bought them they were reselling eibach brand so they probably changed supplier to make a few extra bucks profit...

mix and match your own.

http://eibach.com/sites/eibach.com.m-america/files/catalogs/evs-catalog.pdf