what is the maximum HP that an tuned NA M20 can reach

[Ray Smoodiver]

2.8L, 14:1 comp, E85 fuel, peak power at 8000rpm. 259 kw at the wheels, thats 347 whp.


Here's the thread where the builder talks about it, some doubt the dyno results but I didn't read the whole thread to see the outcome.

Link to thread?

[BMW B3 2.5]

i am just curious what number can an NA m20 reach but from what i read over 250 HP is very hard and expensive

[Bimmer_man]

i am just curious what number can an NA m20 reach but from what i read over 250 HP is very hard and expensive

your looking at $2,000 for a 3.0 stroker and about another $1,400.00-$2,000.00 in just head work. Then there is the tuning to take full advantage of the air flow you need to ditch the AFM and get either a Miller WAR chip MAF conversion or Megasquirt and thats another 800. Then the headers and exhaust work about another 1000. Trust me the M20 is a easy and cheap motor to maintain at stock levels but to tune this bitch can get vary vary costly for little gain.

[digger]

You're mistaken. It was 732hp.

well i am dylesic

[ak-]

well i am dylesic

Apogolies

[digger]

it is not that hard all to reach 250hp crank on a big stroker if you do the right things.

you can make circa 330bhp on 98RON/93PON but alot of time/money needs to be invested in the head and intake manifold.

if you want more than 330bhp then you need to use better fuel, alot more compression and more cam duration (non streetable levels) that the higher compression permits

[kistler#7]

Link to thread?

http://speedtalk.com/forum/viewtopic.php?f=1&t=31132&start=15

forgot to copy and paste it

[4x4_e30]

Here's E21jps's build, 293rwhp on 2940cc using an ETA "200" head

http://www.e30tech.com/forum/showpost.php?p=1368911&postcount=131

[digger]

here's e21jps's build, 293rwhp on 2940cc using an eta "200" head
http://www.e30tech.com/forum/showpos...&postcount=131

731

[4x4_e30]

731

When he said he didn't make things any larger than the 731 casting I assumed he used a 200 head.

Did some testing today on a 200 series head and i was even able to take that port out enough to reach my flow target no problems so thats both 731 head and 200 head were fine. So i must have just got unlucky with the AMC due to its large core shift.

Im not making the entry of these ports any larger than a standard 731 casting and even inside they are not huge by any means its more about shape than size. I am a big believer in high velocity and optimum lower lift flow.

[digger]

When he said he didn't make things any larger than the 731 casting I assumed he used a 200 head.

i believe he used either BMW 731 casting or AMC 731 not sure which was used on the engine as he did both. when he means any larger than a 731 im pretty sure he means the port entry size which is about 36/37mm. you dont use 44mm valve without making throat and minimum cross sectional areas larger especially on the 731 where it is tiny at the guide less than D30mm iirc

in either case it bears no resemblance to the original port, many many hrs of labour not your run of the mill port job you get from a random head guy who can do one kind of valve job and just grinds metal for the sake of it due to no experience in these engines. in these parts getting someone to do that is probably 2 to 3k labour and you gotta hope they know what they are doing

[TobyB]

Why bother? If you're racing, you build to the rules. For the street, if you don't go
M52/S52 etc then you're just masochistic.

If it's numbers you care about, that is. If you don't, then you wouldn't ask.

The M20 is the only BMW engine never built for racing (*Wes Hill) and was really built for
the gas crisis of the late '70's. They never built an S20- and there WAS even an S42.

So if you want a nice big number, start with a DOHC engine. You'll START where an M20
starts to get high strung, and you'll have spent a lot more to get there.

t

[SkiFree]

Toby, how is that relevant to the thread? Whether you like the M20 or not, or if its the "right choice" of engine in the first place has nothing to do with what we're talking about. I think you're in the wrong section.

[digger]

not many 24V M50/M54/S52 engine make as much power as the 350rwhp 2.8L and 290rwhp 3L engines above..... you need a proper 24V S50B32 or S54B32 to come remotely close make those numbers not M5x based engines

why would i waste time swapping in crappy M52/S52 engines when LS engines exist......

[TobyB]

I think you're in the wrong section.

That's not the first time that's been said.

t