M20 "I" head Vs "E" head

[SpecM]

Well, I just dyno'd the 2.7i.

Seems to be running really lean, got to get my wideband installed lol. but it seemed to hover in the high 14's! (stock Motronic 173 DME and injectors)

Made 134.16whp@5500 and 140.1wtq@4000 125+tq after 3000rpm

I will post the graph when I get a chance.

I hate to crap on your really cool build, but most healthy m20b25s lay down 140-145hp.

[ForcedFirebird]

I hate to crap on your really cool build, but most healthy m20b25s lay down 140-145hp.

It's all good. 98 degrees and 33% humidity. Remember, it still has the 25yr old eta exhaust, and the numbers can be skewed by diff ratio since they dyno all cars in 3rd. Also, really lean. All reasons I did it. Now to up the injector size (I have some at the shop, need to look up the parts numbers. I know I have a set of Ford 24# and GM 19#, but will have to calculate what they are with the BMW regulator pressure. I also have a high-flow cat and some spare 2.5" pipe/bends to make a new exhaust, then I will go back :D

Can't wait to build headers for it now!

EDIT: seems to be on target for an untuned build...

http://r3vlimited.com/board/showthread.php?t=139404

http://r3vlimited.com/board/showthread.php?t=97872

http://r3vlimited.com/board/showthread.php?t=39200

I have a few turbos that will compliment it nicely, but not till I'm done playing with it NA.

[DmcL]

im betting it will atleast up to healthy 2.5 numbers even on the 2.93 once the exhaust is changed for something more free flowing along with some injectors and a tune for them.

tbh 24lb would most likely be too big. 19lb may even be to big. 19lb injectors were retardedly rich on my 2.5 even with the MAF and probably the most free flowing of the standard systems. i got the 19lb injectors because everyone was/is ranting and raving about 17lb or 19lb injectors but they are bigger than required unless u have a seriously built NA M20, like headwork and cam, BBTB, full exhaust, etc, etc. having them too big makes tuning alot harder ive found. seems better to stick with a size nearish whats needed tbh, my line of thinking is fot something like 15.5-16lb and an adjustable regulator with gauge when u start needing more fuelling. could even go as low as 14.65lb E36 320i injectors, only a fraction bigger than stock E30 but they are 4 pintle and if u bump up fuel pressure they will flow more. dunno how accurate these calculations would be in practice but its something to think about regarding injector choice.

i think the E36 also uses 3 bar fuel pressure so that would be 14.65lb @ 3 bar for the E36 320i injectors so:

14.65 / 3 = 4.88333333
4.88333333 x 3.5 = 17

so in theory those 14.65lb injectors may as well be 17lb at 3.5 bar fuel pressure. u can work out the same thing for other injectors normally run at 3 bar like E36 323i (also 4 pintle) or whatever other bosch injectors u find.

so far my experience with adjusting fuel pressure vs just fitting larger injectors is that it seems easier to tune (especially without an emulator and tuning program) when installing smaller injectors and increasing fuel pressure if/when necessary as additional mods are done to the engine. i think E36 320i 14.65lb injectors would be ideal for anything from stock to moderately modified. E36 323i injectors are either 15.5 or 16lb at 3 bar so they are a step up and would probably cover minor mods to major mods bepending on the fuel pressure used. without working it out the 323i injectors should be up around 19-20lb @ 3.5 bar.

i dont think theres any need with an NA M20 to go above 19lb either fitting 19lb @ 3 bar injectors or by bumping pressure on slightly smaller ones. maybe the odd exception for very highly modified M20's. 24lb will support 8psi of boost (i have a tune here for 8psi on 24's) so 19lb should be fine if not too much even for a stroker.

with ur standard chip the 19lb and 21lb injectors u have will most likely be too rich and cause cold start problems by choking the engine with fuel. id go for something around 15.5-16lb and if necessary stick a regulator on and up the pressure a little. probably wont be necessary to bump up from 3.0 bar till u do a bit more work tho. a decent chip will also help those numbers.

[ForcedFirebird]

I am running the stock "i" injectors and regulator now, and it's running really lean. I was thinking these injectors I have now from the Vette and the eta 2.5bar regulator might work (19lb), but we will see. Supposedly the m20 likes 12.7-13.2afr for optimal performance, and I was WAYYYY above that, into the 15's several times during the 3 pulls.

Need to finally get around to putting the home made WB controller and AFR guage I made a while back into the car.

I have TunerPRO RT, chip burner and my WB controller can log AFR vs RPM, so I should be able to grasp what needs to be done, but I just wanted to see what the hdoge-podge of JY parts would do. I never even put new plugs in it, lol, am running the very ones that were in the head when I pulled it lol.

[DmcL]

if u dont already have the moates ostrich 2.0 emulator i suggest buying one otherwise every time u want to try something u have to burn a chip. ive done in days with the emulator what would take weeks to do by burning chips. ucan take the car out to a quiet road somewhere and try out different ignition/fuelling values on the fly tho when messing with ignition its a wise idea to have a det can on the engine to listen out for knock. i havent had any yet on my low comp 2.5 tho and ive run as high as 39 or 40 deg btdc in the high RPM's. in theory tho as breathing of the engine gets better u will probably want less high RPM advance and more low RPM advance.

i noticed no major difference in pulling power on the butt dyno when running near 13 AFR and running as low as 11.5 AFR. from my own experience id say aim for between 12 and 12.5 AFR.

as for injectors.. u could run injectors that are bigger than needed at a lower pressure but it could have some negative effects on the spray pattern. personally id rather use injectors that are just a tad on the small side and bump pressure up
somewhere between 3 and 3.5 bar, could give fringe benefits of a better spray pattern/better atomisation.

[liv2race]

you may want to finish the port and polish work. it looks like they only did the the port work where you bolt the intake and exhaust manifolds to the head and NOT behind the valves themselves. that's sort of like taking a big dump and not wiping. you didn't finish the job.
if you don't finish the port work you will either see little gain, no gain or less performance than if they had left it alone.

Ill look into it but Leo from Memphis motorworks did the work and from I understand he is the best.

[mkcman17]

i've got a strong 'i' and i'm considering swapping an eta crank when i replace the main seal. are you guys saying i won't get much gain out of it?

[ForcedFirebird]

i've got a strong 'i' and i'm considering swapping an eta crank when i replace the main seal. are you guys saying i won't get much gain out of it?

The torque on my dyno never went below 125. You will feel the difference. I don't know if I would disassemble a block for it without putting in the higher compression pistons, but definitely worth it if you have an assembled eta block ready to go in.

[mkcman17]

well the deal is that i have a spare eta crank, and a main seal leak. i have a buddy that will yank the engine and refresh all the seals/gaskets/bearings in exchange for a set of wheels and a spoiler. eventually i want to M/S5X swap, so i'm not sure i should dump 'money' into my bleeding m20

[mrmckie]

quick newb question, whats is the redline raised to once a 2.7i is put together using factory components

[ForcedFirebird]

If you swap the ECU, then you will have the same rev-limiter as an "i" (~6800rpm)

[eta]

If you have an 325i then you cannot simply replace the crank with the eta crank. You will need to fit the eta conrods and if you use the 325i pistons they will be short of the top of the deck at TDC. Typically you will need to deck the block by a couple of mm. If you do this build and fit a decent cam 200+ hp is feasable but its alot of work. The build that Forced firebird and I and may other have done is much simpler as we started of with an eta motor and bolted a 325i head on. It gives less power but works well.

[Wh33lhop]

If you swap the ECU, then you will have the same rev-limiter as an "i" (~6800rpm)

Stock M20B25 rev limit is 6500. Most aftermarket chips raise it to about 6900.

[mkcman17]

If you have an 325i then you cannot simply replace the crank with the eta crank. You will need to fit the eta conrods and if you use the 325i pistons they will be short of the top of the deck at TDC. Typically you will need to deck the block by a couple of mm. If you do this build and fit a decent cam 200+ hp is feasable but its alot of work. The build that Forced firebird and I and may other have done is much simpler as we started of with an eta motor and bolted a 325i head on. It gives less power but works well.

using which pistons? i was under the impression that swapping out the crank was essentially creating an eta bottom.

[ForcedFirebird]

Stock M20B25 rev limit is 6500. Most aftermarket chips raise it to about 6900.

I thought that was the soft limiter. I have a stock 173 .bin file somewhere and could look at the data from the chip and see...

EDIT: Correct, the soft limit is 6350 + 120rpm for hard limit (6470 to be exact).