E30 Stroker 2.7L CA Smog Questions

[ForcedFirebird]

What is the duty cycle of the stock injectors in the 2.7/2.8 stroker

Hard to say. The stock ECU isn't like MS where you can just click and see the DC. But for an educated guess, I would say it's about 60-70% in stock configuration since the bytes can go to 255 and they max at 140 in the file - but that's just the fuel map, there's also multipliers based on AE, engine temps, air temps etc, would take a fair bit of time with the .bin and math to calculate it accurately (or write a spreadsheet etc). With MS we hardly have done a stock PnP swap, might have some files with that info somewhere, though.

I found the extra power mostly in the timing table. BMW pulled a lot of timing at MBT and that's why you see the dip on most HP graphs for Spec 30 dyno plots (or stock dyno pulls) around 4700rpm. That being said, the race car's tune only required a max of 6% (~12-18bits) additional fuel in MBT, but that was also in part due to the added timing in MBT. I have read many companies chips, and most of them just smooth out that timing curve and touch nothing else! MarkD (EAT), NickG, real JimC and Sssquid are the only commercial chips I have read that actually went through everything.

[Rev Run D]

MarkD (EAT), NickG, real JimC and Sssquid are the only commercial chips I have read that actually went through everything.

What chip and what cam would you recommend on an otherwise stock and/or headered and exhausted m20b25?

[earthwormjim]

Injectors won't change the power output, that's a common misconception. The only reason you should ever need larger injectors is when you reached maximum duty cycle.

Why wouldn't you go with the more modern injectors though? Don't they have a better spray pattern? It's practically the same cost to get M50 ones with refreshed seals and cleaned as it is to clean and refresh your original injectors.

[digger]

I'm sure I could use the stock injectors but I am trying to get as much power out of this car as possible. This will be a forever build and I want to do it right the first time, so spending the extra dough on injectors and a chip isn't a huge deal. But its good to know I can use the stock injectors in case i need to step it back down

If you are going to the expense of buying forged pistons you are better off with a 2.8L and their Mahle ms pistons. Their other custom stuff is inferior.

[ForcedFirebird]

What chip and what cam would you recommend on an otherwise stock and/or headered and exhausted m20b25?

Any of the mentioned chips would work well. They are still "shelf" chips, so unless you have a local tuner to tailor your exact every ounce of power, then go with what's known to be good. As I said previously, I start with a slightly modified stock chip file when tuning (base tune) and it works well, and is very similar to others' good chips. You can only get so much from a stock engine and electronics.

Why wouldn't you go with the more modern injectors though? Don't they have a better spray pattern? It's practically the same cost to get M50 ones with refreshed seals and cleaned as it is to clean and refresh your original injectors.

Define "modern". The m20 is archaic in design, even though it was cutting edge at the time. So, what, you want to implement a dual quad fog spray pattern into a single cam engine? What works, works. The m20 has a single pintle injector that sprays directly on the back of a red hot intake valve. How much more vaporization will you see if you fog before the valve? Does a dual spray pattern actually hep when coating the colder port walls instead of single pintle spraying on a hot valve? Based on my experience with m20's - a fogger 19lb injector will run out of steam before a stock 14lb single pintle will. Duty cycle aside.

If you are going to the expense of buying forged pistons you are better off with a 2.8L and their Mahle ms pistons. Their other custom stuff is inferior.

^^THIS 1000% I can type this stuff until I am blue in the face, but the stock piston shape dominates anything else - enough m20's have been home-brewed by now, it's pretty common knowledge. BMW did a bang up job with the swirl/flow/squish - so much so that the 24v m50nv was barely more powerful, even with all those valves/cams/weight. :P Where the m20 falls short is when you want an off the shelf custom piston that is plug and play, the pent roof design of the 24v makes things cheap to modify. :(

[Rockonp04]

Lots of good stuff here. Lots to consider. I am almost sold on upgrading to 19 lb injectors. I am going to pick IE's brain on what injectors to buy. I've been researching and it seems in the high rpm range, the engine can run lean which is why I am considering the larger injectors. I am going to call Ireland Engineering to pick their brain a little more. Also, there is a tuner in Toronto and from what I understand, can custom tune a chip based on the information I give him. He came highly recommended from IE and has a chip for the upgraded injectors. (http://www3.sympatico.ca/mdsylva/products.htm) I think the custom pistons are the way to go since I can use the rods and block I already have. I just have to pick up an M20B27 crank for around $150. Seems the simplest option since I don't want a mountain of unused parts sitting in my garage and not to mention shopping all over the place finding rare pistons, cranks, and rods. IE has done this setup limitless times and it doesn't seem too complicated. I am going to talk to the machine shop next week to get their $.02 to verify what IE has to offer.

[ForcedFirebird]

Yes, that would be Mark D in Toronto. Very good with tuning, have friended him over the years.

I have built/dyno'd hundreds of m20's, and the only time we run out of injector was when using some fogger type the customer provided, 19lb, and they ran out of steam at 205whp on an ITB m20b28 with all the goodies. It wasn't until they came off the car and went in the injector flow tester that we realized they were spraying erratically with too tight a pulse width.

I have several of the dyno graphs posted in one thread, so you can get a feel for how much power the various combinations make (in case you have signatures turned off): https://www.r3vlimited.com/board/for...ad#post9875136 post # 43 had back to back dyno runs of the 2.7 with 2mm shaved blocks, didn't post the AFR's on the graphs, but trust me, stock injectors are fine for this combination - but - will also say that as long as you have a matching chip, the 19lb won't "hurt" anything, either. In fact Mark probably has a chip file already for your intentions.

[earthwormjim]

Define "modern". The m20 is archaic in design, even though it was cutting edge at the time. So, what, you want to implement a dual quad fog spray pattern into a single cam engine? What works, works. The m20 has a single pintle injector that sprays directly on the back of a red hot intake valve. How much more vaporization will you see if you fog before the valve? Does a dual spray pattern actually hep when coating the colder port walls instead of single pintle spraying on a hot valve? Based on my experience with m20's - a fogger 19lb injector will run out of steam before a stock 14lb single pintle will. Duty cycle aside.

So the single pintle design wasn't just a symptom of being an older and worse design, it was intentional for SOHC engines to get the spray where they wanted it? I did not know that, I'm glad I asked.

"Upgrading" to more "modern" multiple pintle injectors seemed like a no brainer. No real cost difference from single pintle designs, and more sprays is better was what I was thinking, for better fuel atomization. I guess that's not necessarily the case.

[digger]

Spray pattern should be a single fairly narrow like 15-20 degrees to not spray on port walls, number of pintles is not what’s important. Once you spray onto walls it gives liquid droplets and atomisation becomes meaningless

[digger]

Lots of good stuff here. Lots to consider. I am almost sold on upgrading to 19 lb injectors. I am going to pick IE's brain on what injectors to buy. I've been researching and it seems in the high rpm range, the engine can run lean which is why I am considering the larger injectors. I am going to call Ireland Engineering to pick their brain a little more. Also, there is a tuner in Toronto and from what I understand, can custom tune a chip based on the information I give him. He came highly recommended from IE and has a chip for the upgraded injectors. (http://www3.sympatico.ca/mdsylva/products.htm) I think the custom pistons are the way to go since I can use the rods and block I already have. I just have to pick up an M20B27 crank for around $150. Seems the simplest option since I don't want a mountain of unused parts sitting in my garage and not to mention shopping all over the place finding rare pistons, cranks, and rods. IE has done this setup limitless times and it doesn't seem too complicated. I am going to talk to the machine shop next week to get their $.02 to verify what IE has to offer.

There’s a difference between a custom piston and a good custom piston for your application.
You can getbetter ( JE ) pistons from top end performance. If you ask for the right things they do the Oem replica dome (8.8 or 9.7 style) and you can request 4032 alloy which will work a whole lot better on the street. There are some various upgrades you can do as well. Eg a total seal conventional ring (not gapless) would be worth the coin.

[Rockonp04]

I am going to stick with the IE pistons. Best fit for my build. I am interested in the model number for the Bosche Mustang 19 lb V8 injectors. I also found someone selling Bosche Gen 3 19lbs injectors off of BMW v8s. I've also heard the mustang injectors do not have notches for installing clips on. I also heard about the M50 injectors. Would these pop in with the clip as well?

[Rockonp04]

Anybody dealt with these injectors? Is this snake oil?

https://www.ebay.com/itm/BMW-E30-M10-M42-S14-19lb-Injector-Upgrade-Genuine-Bosch-Gen-III-gray-/292612092209

[Tinkerer007]

I purchased these from this guy:

https://www.ebay.com/itm/BMW-E30-E34-E36-M20-M30-M50-19lb-injector-upgrade-Genuine-Bosch/292975028671

and got 2 different part numbers that flow slightly differently (3 had the clip slot and 3 didn't). SSSquid did not approve of using different parts.

[digger]

I am going to stick with the IE pistons. Best fit for my build. I am interested in the model number for the Bosche Mustang 19 lb V8 injectors. I also found someone selling Bosche Gen 3 19lbs injectors off of BMW v8s. I've also heard the mustang injectors do not have notches for installing clips on. I also heard about the M50 injectors. Would these pop in with the clip as well?

i highly recommend to stick with their Mahle MS ones in that case, the other 2618 alloys wear poorly, rattle when cold etc due to the low silicon content and associated high expansion. They are actually inferior to stock cast pistons in many ways, most forged pistons are. That's why Andrew (formerly IE) worked with Mahle MS to develop them for the street. if you want something for a non street application or very low mileage or very high boost then 2618 will work but don't fall into the trap that almost everyone else does thinking forged pistons are magic and need no engineering.

[Rockonp04]

i highly recommend to stick with their Mahle MS ones in that case, the other 2618 alloys wear poorly, rattle when cold etc due to the low silicon content and associated high expansion. They are actually inferior to stock cast pistons in many ways, most forged pistons are. That's why Andrew (formerly IE) worked with Mahle MS to develop them for the street. if you want something for a non street application or very low mileage or very high boost then 2618 will work but don't fall into the trap that almost everyone else does thinking forged pistons are magic and need no engineering.

Are you referring to these pistons here? https://www.iemotorsport.com/product...0b25-8-8-1-cr/

If that's the case then I have to find another way to complete my stroker. From what I understand, these are the stock pistons so I would have to find another way to do the stroker. Also, this is just a street car not a performance car and I won't be hauling ass around the track. If I am missing something, enlighten me. I would like to keep the stroker simple with just changing the crank and the piston if possible.