M20 fuel system upgrades
 

Hello everyone! So as some of you may know I've been trying to bring my 1990 525i back to its former glory and beyond. I finally have gotten her running just about back to normal, and I'm trying to swap in some performance parts where things need replacing, rather than stock. Currently the car is completely stock except for a 2.7' MAF in place of the AFM.

My fuel pressure regulator was letting a bit of gas into the vacuum line, so I replaced it with the cheapest "OE" part I could find. Come to find out the new regulator is actually not within spec, varying between 38 and 47 psi (should be 40-47). So since the Bosch one is around $100 at the cheapest, I plan on getting the adjustable regulator from IE for $165. I've also been thinking (future) about upgrading from the tiny 1-hole 14lb injectors. Anyway, enough background info.

Questions :dunno:
-What size injector should I be looking at? (I was thinking 4-hole 17 or 19lb)

-Will my O2 sensor be able to cut injector timing enough to keep it from running rich?

-Can I lower fuel pressure to avoid running too rich?


Thanks in advance for your support! :thumbup:

MAF - https://www.millerperformancecars.co...&category_id=6
Regulator - http://www.iemotorsport.com/bmw/E28-...e30adjreg.html
Injectors - http://www.ebay.com/itm/BMW-E36-M3-3...00874888800%26

nvrmnd.

I was going to say m50 swap for all three.
but that would be a bit rude.
If you want to stick with your m20 hopefully someone will answer.
M20s aren't the best option when thinking of refreshing stuff.
Good luck.

try asking on the E30 forum, a lot more people that are keen on tuning the M20 engine there.

Dropping the fuel pressure can affect fuel spray pattern. Extra power is basically flow through of air. Exhaust improvements will give more power than dumping in more fuel.

Unfortunately, I can't afford to just buy a new engine, but I can try to refresh and upgrade the existing one. Hence why we are here today; me asking a question on the engine I currently have, an M20. I was unaware the logical first approach to any engine maintenance was replacement of the engine.

Again I apologize for my response.
Truth is (this is stateside only), the m20b25 is sort of the red headed stepchild of the e34 model. Only second to the m60b30.
Across the pond they have other variants which never arrived on our shores.
Our friends over there may have more to speak of when it comes to not well desired models.

However back to topic.
The m20b25 like it's bigger brother m30b35 can be upgraded in certain areas where they would be more lively.
The basics usually are air filter, coil replacement, plug wires, exhaust changes, etc.
From there a routine valve adjustment and injector replacement (for efficency not performance) are options.

E30/ M20 specific. You can swap heads and blocks.
885 Head (1987-up m20 Head iirc) on a Eta block (1983-1986 m20 block iirc) = a mildly stroked m20

Simply put if your looking for more power and reliability.
You have a decent choice of engine. But its in the wrong chassis to gain any benefit.

IMO do the basics. don't get wild with it. Save your cash and either buy a used m30b35 with 5spd manual trans
to swap in (which aren't expensive or extremely hard to install )or save up for a 525 with a m50 in it.

Well you see, this is my first car, and me being a currently jobless high school student I never dream of this being a race car. I just love to work on it, and see how I can improve it. I spend nearly all my money on it actually. I do plan on changing cars in the future, hopefully staying in the BMW family. As for now though, I just have to work with what I have, and make it perform as well as I possibly can.

So, if I were going to swap out my injectors, what might you suggest?

Understood.
I wish there was a better way to say it but welcome to BMW ownership.
These cars will tap the everliving crap out of your bank account if your careful or not.

That said
R&R and/ or Update all the routine maintenance stuff.
Coil, plug wires, sparkplugs, fluids, filters, distributor cap, rotor button, FPR, etc.

I wouldn't bother dropping coin on injectors unless used and updated version of what's already in the engine.

Depending on your time and skill level: Gasket match inlet and exhaust manifolds, fit 1/2 to 3/4" larger exhaust. Better flow but with out the "Please stop me, Officer' noise. Depending on funds consider a cam re-grind to a mild road profile. I'm sure your local shops or rev heads know who to speak to.

Routine maintenance and following the inspection II to-do list will make the most of the performance of the stock engine. You will also improve reliability so that you can drive the car in college!

The M20 is a very easy engine to work on and is probably a great place to start for someone like you. Have fun working on it.

Since you brought that up, the dash does say it's due for an inspection. I'll have to take a look at that list and see what I haven't already done. I've become almost obsessed with working on the car, everything is fairly straight forward and I learn a lot from it. I've been putting more thought into the exhaust as far as upgrading goes once I get my new regulator, though the only trustworthy headers I can find are the IE ones. I really want to get my hands on some of the Racing Dynamics ones, but that's difficult and expensive.

Racing Dynamics E34 M20 headers
Attachment 360188

Ireland Engineering M20 shorty headers
Attachment 360189