M20B30 Stroker build in progress

[crappycoco]

[modernist]

Nice! What engine management will you be using? Post videos!

[zoomer]

I am using MS1 Extra.
I was able to start the engine today, but there is some modifications that are needed for the MS.
Also the car has quite alot of work to be done.
So videos soon.

[bmwmaster81]

Im really curious to see this engine Running. I thin the compression ratio will be very high.

Does enyone know how much ccm can be taked out of the 325i cylinder head to make cr lower?

[clarkson]

Looks like a very interesting build. I too want to fit a m54b30 crank in a m20. Good to hear the counter weights don't foul the block, just the rods are close. Easy fix.

I would go with digger on this theory about squish. The 885 head is designed for a dish/dome piston that will direct the compressed mixture around the spark plug. With flat top pistons there is the chance of different flame fronts starting and crashing into each other causing knock.

I built a m20 stroker with m52b28 crank, 130mm rods, m20b25 pistons, the deck shaved .5mm and a 885 head.

A mate at the same time built a stroker with the IE 2.9 kit which had flat top pistons with an 885 head. We both had the Miller war chip and he loaded his already tuned engine map on to my engine on the dyno. Mine made a bit more power with the same timing. I then added a bunch more timing on the road with no knock and increased power. He could not add any more otherwise his would knock. I have been trying to convince him to use a 731 head as the chamber is designed for flat top pistons.

Anyways I hope yours goes well and I look forward to hearing about how it drives. Nice to see someone seeking power from within as opposed to the more popular path of turbo or m5x swap.

[zoomer]

Most likely you guys are correct, regarding the piston shape, however there were number of reasons I went for this piston:

1 - The M54B30 crank requires 135mm rods (currently at BDC there are around 3mm between the counter weights and the piston) as a result you need a piston with very low KH. This gives 2 choices - getting custom pistons which is way out of my budget, or going with the lowest OEM pistons (in this case M54B25)

2 - The 731 head might be designed for flat top pistons, however it flows considerably less. I strongly believe although the miss match between the piston shape and the combustion chamber, the 885 head will produce better results for high volume engine at high rpm.

3 - The combustion chamber volume of the 731 head is considerably smaller, which would result in a considerably higher compression ratio (currently its 11.3:1)

Having in mind the two points above I would say that I either had a choice to use 731 head and port it considerably or use 885 head. At this point I dont have the funds to send the head for port and polish to a proper machine shop and also I dont think I have sufficient skills to do the job myself.

The final reason for going down the N/A road is that I already have another E30 with M20B28 twin turbo and I always wanted to have N/A engine as well.
BTW here is a pic of my twin turbo setup which I am very proud of:

[clarkson]

Wow twin turbo. Now that is different. Looks like it would have very little turbo lag.

I didnt think the 731 head flowed much less than the 885. Will have to revisit and see some figures. But flow is not everything either, you want air speed also. You can easily over port the m20. Some itb kits like Roland or dbilas have too big intake tracts and throttles and make the engine awful in the mid range. On the comp ratio you could've taken more off the pistons or fitted the 2mm head gasket you can buy oem. But the issue in north america is finding a 731. 885s are easy to find.

I am sure with the right tuning it will be a great motor, with heaps of bottom end and decent up top. I would love to build another stroker but I will have to wait till I finish my s14. That could be a while. I would source a m54b30 crank and rods, buy the IE pistons for their 3.1 kit (they now have the correct dish dome design) and fit a 885 head with updated springs and a mildish cam, maybe the 288 schrick.

Budget is always a issue with m20 builds, not many people are willing to throw alot of money into them. Not like s14 people who will go and spend 10k on their head without batting an eyelid.

[digger]

flow is not everything but a bone stock 731 peaks out at 140CFM at only 8mm and flat lines where as the 885 is 170CFM at 10mm and a smoother curve though still does become turbulent at 11mm so even it is not great also considering it has more than enough cross section. the fact that the 731 flat lines VERY abruptly at only 8mm is the bad part it backs up very early before peak lift of most cams and its not good when you start throwing more cubic inches at the bottom end. the head cant take much mass flow before choking to death, it might make a bit more torque at the bottom end but doesnt make hp.

the good news is with the right porter it can be improved alot.

id personally start with a 200 head on a mild size stroker (2.7/2.8L) running flat tops i think the port shape is a better start and might flow the same sort of numbers as 731 with a little bit less cross section but there a fair bit of work in it. with a 3L youre probably going to end up with the same basic port shapes no matter if you start with 200 or 731. if i was building a hot 2.5L id start with a 200 some porting and get the angled squish machined into it to use stock style pistons

[Tinkerer007]

Update?

<Please>

[zoomer]

Its been some time, since I last wrote, but this is because there are no good news to update.
The engine built was complete failure.
200-300km after I assembled it, the oil pressure lamp started to light up at low rpm. Replaced the switch, but the same story. So I opened the sump to check on the condition and it turned out that the oil pump was totally destroyed. As a result the main and rod bearings are gone too. The crankshaft is scourged too. When I opened the head it turned out that the cylinder walls are scourged too. The camshaft was so badly destroyed that I could not remove it from the head.

I havent disassembled the bottom end compleately, but my guess that everything is destroyed, and the whole engine is for the trash.

I've spent alot of time of thinking why did this happen - my first thought was that I did not clean the parts properly and there were some metal chips that destroyed the oil pump.
A bit later, I was about to replace the intake manifold on the turbo, so I was planning to install the one from the NA engine as it looks much better. In the process, I removed the cap where the vacuum outputs are, and found the reason for the engine failure - SAND. The intake manifold was sandblasted before it was powdercoated and the tubes of the manifold were full of sand. Althought I cleaned it it looks like it was not enough. The sand still had a deposit of oil/sand mixture on the inside. I guess I was pretty lucky that I did not install this intake on the turbo engine as well, as this would have resulted in another failure.

[zoomer]

In a month or two I will do another attempt to build the same engine. However I need to spend some time on the turbo e30 that I have (I want to get it ready for the season).

[bmwmaster81]

Too bad, i realy was interested on performance results :-(

[rav320uk]

Hi, read the build so far, thought ths might help.

3.1ltr M20 stroker.

I.E 3.1 kit.

Not sure on all the specs but was hitting 291bhp with about 270 ft/lb torque.

[digger]

Hi, read the build so far, thought ths might help.

3.1ltr M20 stroker.

I.E 3.1 kit.

Not sure on all the specs but was hitting 291bhp with about 270 ft/lb torque.

looks like 277bhp (230whp), 240ft-lb @ fly to my eyes?



Sucks about the sand. i had my rocker cover powder coated and there was traces of sand. i spent ages cleaning it out and when i thought it was clean i cleaned it twice more. i dont see why places cant chemically clean it or atleast clean it properly before giving it back the particles can embed themselves into the soft aluminium casting

[rav320uk]

looks like 277bhp (230whp), 240ft-lb @ fly to my eyes?



Sucks about the sand. i had my rocker cover powder coated and there was traces of sand. i spent ages cleaning it out and when i thought it was clean i cleaned it twice more. i dont see why places cant chemically clean it or atleast clean it properly before giving it back the particles can embed themselves into the soft aluminium casting

It was 291hp, but bought down to a safer level of what you see