best m20 stroker combination.

[Bullet Ride]

If I'm not mistaken, those headers have a 1 3/8 primary, this is NOT ideal in the extreme. 1 3/8 is only ideal on a pretty much stock engine, the reason behind that size is that packaging into the E30 chassis can be pretty tight. You'd be much better off with an 1.5" or maybe 1 5/8".

The OP said he wants a great power band with lots of torque. Based on what the OP wants I'd say that a header with long tubes and a smaller primary diameter would better suit his application. I see and hear people say from time to time that 1 3/8" is too small, but usually they don't provide any evidence to support that (i.e. a dyno plot of the same motor with 1 3/8" primaries vs 1 1/2" primaries).

Generally, primary size affects where peak torque will occur, and primary length affects how much of your torque is above or below your peak torque rpm. There are tools out there that give rough estimates of what your primary diameter should be based on where you'd like your peak torque to be. For example if you were to write the equation on this website (http://victorylibrary.com/mopar/header-tech-c.htm) for a 6-cyl motor you'd have:

OD = (RPM × Motor Size ÷ 415,633)^.5 + .098”

If you plug in 183ci (3L) into that equation you'll see that for a 3500rpm peak torque you'd want a 1.34" primary and that for a 4000rpm peak torque you'd want a 1.43" primary. A 1 1/2" primary would put your peak torque around 4464rpm. When I compare the result that this equation gives to my dyno result I do see a correlation



For a 2.8L (171ci) motor a peak torque at 4000rpm would require a 1.38" primary. I'm running the Bavauto headers which have 1.38" primaries and my peak torque was around 4000rpm. Obviously there are other variables at play such as cam profiles, cam timing, collector design, etc, but generally I haven't seen anything yet to prove that 1 3/8" primaries would be holding back an M20 stroker.

[Chriskbmx]

as far as exhaust im most interested on how the runner lenths change rpm ranges and such?

[tinkerputzer]

If I'm not mistaken, those headers have a 1 3/8 primary, this is NOT ideal in the extreme. 1 3/8 is only ideal on a pretty much stock engine, the reason behind that size is that packaging into the E30 chassis can be pretty tight. You'd be much better off with an 1.5" or maybe 1 5/8".

I agree. A stroker of this magnitude would be better suited with larger primaries. Although I'm running them and still making 210 whp and 218 wtq. The advantage to them is the quality you get for the price.

[F34R]

That is for a turbo kit, not even close to the same thing as a stroker build.

[saurey]

Noob here. What's with those eBay kits? Like this one:
http://www.ebay.com/itm/BMW-325i-3-S...45f8f2&vxp=mtr

Could I just give it to a good shop and say go to town and get results?

[Chriskbmx]

nice. i was thinking about using the ralley for the slightly higher compression and better combustion characteristics.

[RobertC]

what mm pistons did you use? sport or ralley?

86mm Sport

[tinkerputzer]

what mm pistons did you use? sport or ralley?

They look like sport pistons.

[F34R]

???

Was talking about the 3.0 build he has planned. It really did come off as me saying my personal build needed MS. It does not, as I have already drove it on stock management with zero flaws. Could it use it? sure! any tuned MS management is an upgrade to 25+ year old outdated management.

[Chriskbmx]

what mm pistons did you use? sport or ralley?

[RobertC]

Just did a nice stroker build for a customer.

2.7 Eta Crank
S50 135mm Rods
Metric Mechanic Pistons
Metric Mechanic Prepped cylinder head with Race/Rally Cam
Bav Auto style Headers
Stock Intake 19lb injectors
WAR Chip/MAF

With dyno tuning we pulled 197hp to the rear wheels.

[Mr. Burns]

(Mine)
Super ETA

b25(885) head upgrade/intake manifold
-Schrick 288 cam
-Schrick HP dual valve springs
-IE HD Rockers
-IE Adjustable cam gear
-Cometic .70 MLS
-ARP studs
-Guides, valves

There is no way around it, you will need MS if you want to manage this setup. The stock DME cannot handle all that change and run very well. I am sure you know that, just want to make it clear.

???

[Chriskbmx]

Headers are not something that should be overlooked when building a m20 of this level. I used "bav auto" headers made buy tubular design and have been happy with them. Bullet Ride will be organizing another group buy soon.

I rods and s52 rods are both 135mm. The s52 rods are lighter though.

I'm not sure on using s50 pistons. I think Ixer used some m54 pistons but it requires valve reliefs be machined into them.

Many who have built m20's including myself will tell you if you are building a stroker that requires custom pistons don't go any less than 3L because you'll kick yourself in the end for not going bigger. That metric mechanic catalog that was posted is a good reference for the different combinations.

Imo bigger intake valves aren't necessary but you definitely want a better cam. Schrick 284/272 is a good cam choice if it is to be daily driven.

If you are going through all the work of a building a motor go with an engine management system that will give you full authority like megasquirt. I'm running ms2 pnp from whodwho and am very happy with it.

Here is bullet ride's build which is an excellent resource:

http://www.r3vlimited.com/board/showthread.php?t=243359

My build:

http://www.r3vlimited.com/board/showthread.php?t=265471

Diggers:

http://forums.eurocca.net/showthread.php/20225-E30-331is

Some other good resources:

http://www.flickr.com/photos/peters-...7625008707209/

http://www.msportster.co.uk/m20b28-engine-build/

i just got done reading the metric mechanic link that was listed above and there was alot of good information.
so as far as im thinking looks like my best option for my power goal or even a little more would be this: listed below. now im only gonna use this car for sunday beating, track days, ect. not much dailying.

looks like i would want to go with an 85 or 86 mm piston in the 10.5 to 1 range
deffinitly go with s52 rods or custom rods? according to mm there is a huge benifit for going to longer rods.
89.6mm crank from an s52.
my question about the bottom end is what modifications need to be done to allow me to use the crank and piston combination? some say you need crank machineing ect? also have heard about crank spacers and machined intermediate shafts?
As far as top end goes its looking like this
ie hd rockers
bee hive dual valve springs
284 or 290 cam
obviously fully rebuilt with new guides and such.
anyone have any other options for good headwork?

[SkiFree]

Headers are not something that should be overlooked when building a m20 of this level. I used "bav auto" headers made buy tubular design and have been happy with them. Bullet Ride will be organizing another group buy soon.

If I'm not mistaken, those headers have a 1 3/8 primary, this is NOT ideal in the extreme. 1 3/8 is only ideal on a pretty much stock engine, the reason behind that size is that packaging into the E30 chassis can be pretty tight. You'd be much better off with an 1.5" or maybe 1 5/8".

[tinkerputzer]

Headers are not something that should be overlooked when building a m20 of this level. I used "bav auto" headers made buy tubular design and have been happy with them. Bullet Ride will be organizing another group buy soon.

I rods and s52 rods are both 135mm. The s52 rods are lighter though.

I'm not sure on using s50 pistons. I think Ixer used some m54 pistons but it requires valve reliefs be machined into them.

Many who have built m20's including myself will tell you if you are building a stroker that requires custom pistons don't go any less than 3L because you'll kick yourself in the end for not going bigger. That metric mechanic catalog that was posted is a good reference for the different combinations.

Imo bigger intake valves aren't necessary but you definitely want a better cam. Schrick 284/272 is a good cam choice if it is to be daily driven.

If you are going through all the work of a building a motor go with an engine management system that will give you full authority like megasquirt. I'm running ms2 pnp from whodwho and am very happy with it.

Here is bullet ride's build which is an excellent resource:

http://www.r3vlimited.com/board/showthread.php?t=243359

My build:

http://www.r3vlimited.com/board/showthread.php?t=265471

Diggers:

http://forums.eurocca.net/showthread.php/20225-E30-331is

Some other good resources:

http://www.flickr.com/photos/peters-...7625008707209/

http://www.msportster.co.uk/m20b28-engine-build/