E30 2.9L Stroker ITBs etc build...

[AWDBOB]

I just went through this thread, great stuff. What does your 2.9L setup consist of? Also, that wasted spark setup looks nice.

[digger]

Low 13s is what seems to work well for me. Enrichment that shows a lean spike gives the best response

[ForcedFirebird]

On e30tech there was an extrudeabdoy to RHD dyno posted that showed large gains ill see if i can find the image

That was my post. Same two cars I posted above, but have about 50-70 or so dyno pulls of each, so the ones I posted yesterday may not be the exact ones posted on tech.

How come not the 288?

Haven't decided yet, but it was a race car and the owner cut the cage out, put an interior in it and is daily driving it on nice days. He is a little apprehensive about even going bigger cam at all.

Hi guys,

One more question.

How do I pick a safe afr? My current tune is at 12.8 target for high throttle / high rpm. Clearly I have no knock sensor.

Right now I am driving around with acceleration enrichment disabled due to troubleshooting the ignition stuff.

It seems like I get more power when I get tpsdot stepping on the throttle and the thing leans out a bit (seen in Dyno logs) you can feel momentary extra power.

What do your stroker m20 afr tables look like?

I will post my afr table in a bit. Warning: this is an incomplete tune! Not for reference...

Also there are some internet things suggesting people have added knock sensors to m20s anyone have experience, comments?

I agree with Digger. Mid to high 13's under power is where the m20 is happiest.

[mrlucretius]

Specs

I just went through this thread, great stuff. What does your 2.9L setup consist of? Also, that wasted spark setup looks nice.

Specs:

1989 e30 325is, ~160k miles
m20 stroker 2.9L 10.5:1 CR
+1mm intake valves, mild port + polish
dbilas ITB setup with custom cold air intake
long tube IE headers
full custom SS dual 2.25" exhaust
MS2PNP from DIYAutoTune
Innovate LS2 wideband O2
Schrick 288 with adjustable cam sprocket
wasted spark setup - Bosch coil 0221503002 + DIYAutoTune QuadSpark

I'll see if I can get more specific on the stroker details: pistons, crank, etc.

[mrlucretius]

In my build thread there is a dyno graph showing RHD compared to a dbilas style setup was worth about 25bhp. I modified the dbilas using smaller throttles and made the runners a bit longer. The dbilas still made less torque almost everywhere and only eclipsed the stock one in a narrow band at the topend.

Right now I am going to have to work with the dbilas. This project is over budget by 50% so far and I am feeling broke. :)

What is the chance I can neck down the dbilas trumpets and get more velocity?

I see this is all about gas momentum and friction, and I can see why you like the RHD design.

I wonder how dbilas came up with their design? Aside from being stock-able with the brake booster...

[mrlucretius]

That was my post. Same two cars I posted above, but have about 50-70 or so dyno pulls of each, so the ones I posted yesterday may not be the exact ones posted on tech.


Haven't decided yet, but it was a race car and the owner cut the cage out, put an interior in it and is daily driving it on nice days. He is a little apprehensive about even going bigger cam at all.


I agree with Digger. Mid to high 13's under power is where the m20 is happiest.

So, I am new to the custom ECU / tuning game...

How do I safely increase AFR and avoid predetonation? Maybe it is worth installing a knock sensor + circuit to use manually with headphones during tuning?

And related I have read for spark advance I should just increase timing until torque stops increasing?

To be clear, I am at a mile high, and running 91 octane pump gas...

[hasa]

Well, you could go an purchase both and let us know. ;)

If I had only limited time I would do a comparison of my current 45mm Jenvey setup and a 42mm roller barrel setup I have for spare.

For a stock mild cam 2.5 litre engine it seems obvious that 45mm diameter is too large, but is it for a race prepped 84mm stoker engine too ?

Sorry about messing the thread with own agenda... Nice car anyway!

[digger]

That was my post. Same two cars I posted above, but have about 50-70 or so dyno pulls of each, so the ones I posted yesterday may not be the exact ones posted on tech.

Haven't decided yet, but it was a race car and the owner cut the cage out, put an interior in it and is daily driving it on nice days. He is a little apprehensive about even going bigger cam at all.

I agree with Digger. Mid to high 13's under power is where the m20 is happiest.

There was another on a dyno dynamics, a guy from Melbourne iirc.

288 on itbs ms2 is totally daily driveable, stock manifold motronic yeah is much less so

[nando]

Any dyno evidence about this dBilas/RHD comparison ?

Every single dbilas ITB build I've seen in almost 20 years of E30s has been disappointing. I don't think anyone ever broke 200whp (maybe one guy).

[digger]

Right now I am going to have to work with the dbilas. This project is over budget by 50% so far and I am feeling broke. :)

What is the chance I can neck down the dbilas trumpets and get more velocity?

I see this is all about gas momentum and friction, and I can see why you like the RHD design.

I wonder how dbilas came up with their design? Aside from being stock-able with the brake booster...

You could do anything really if you wanted….epoxy/sleeve the intake manifold, sleeve the throttle bodies, cut off the dbilas runners on the airbox and fab up something using mandrel bends. You can’t really solve the length issue which is at least half the issue.

Dbilas should have went to down the H27SP route with the longer runners IMO.

If I had only limited time I would do a comparison of my current 45mm Jenvey setup and a 42mm roller barrel setup I have for spare.

For a stock mild cam 2.5 litre engine it seems obvious that 45mm diameter is too large, but is it for a race prepped 84mm stoker engine too ?

Sorry about messing the thread with own agenda... Nice car anyway!

What are the exact specs of your engine: bore, stroke, CR, head, cam, exhaust config (lengths & diameter of primary/ secondary) and ITB (size and overall runner length)?

Ultimately it comes down to the hp the engine makes and rpm that is most important

[2mAn]

Specs:

1989 e30 325is, ~160k miles
m20 stroker 2.9L 10.5:1 CR
...
I'll see if I can get more specific on the stroker details: pistons, crank, etc.

very curious how you got to 10.5:1 and 2.9L

Cool project, just keep dumping money in it and enjoy it. Dont stress about the final BHP #, Im sure its a blast

[mrlucretius]

Engine Specs

What are the exact specs of your engine: bore, stroke, CR, head, cam

Maybe I am wrong about 10.5:1 CR. From my expert engine mechanic:


Crankshaft - BMW M52 84mm stroke

Connecting rods - BMW M52 135mm (lighter than 135mm M20)

Pistons - 85mm custom Diamond forgings modifed

Cylinder head - BMW M20 885, custom hand ported, Schrick 288 camshaft, new OEM valve springs, Bimmerheads heavy duty rocker arms, all new OEM associated hardware

Compression ratio - Compression ratio has been estimated by the dynamic compression test pressures recorded, but the definitive result is subject to two unknown factors; the custom piston dome cc volume and cylinder head cc volume (depending on how much the head was milled). Utilizing the basic NOT2FAST calculation program, with the test pressures of 185 psi, the result was 12.5:1. However, there are more detailed programs but they require known piston dome cc volume, combustion chamber cc volume and a few other values. Using a more detailed program, with different published piston dome and head cc volumes, I came up with 12.3:1 to 12.8:1.

Engine displacement - Technically, your motor is 2859.9 cc. Just a tick over-square, which is a great place to be.

[mrlucretius]

Exhaust details

What are the exact specs of your engine: exhaust config (lengths & diameter of primary/ secondary)

I will post exhaust details here and update it when i get some more measurements:

IE Street/Track Long-Tube headers:

1.5" primary tubes - (tbm) length

2.25" custom ss dual exhaust, custom x-pipe, big single chamber cat (dual in dual out), borla xs dual in dual out muffler (in that order see pics here: https://www.r3vlimited.com/board/sho...d.php?t=409986)

[mrlucretius]

ITB specs

What are the exact specs of your engine: ITB (size and overall runner length)?

I believe this is the standard E30 dbilas ITB kit, I will get specs for it.

[mrlucretius]

A little history

To be clear about this project, I did not cobble this together myself. This motor was an un-assembled project design by an experienced enthusiast who was unable to complete the build.

So whatever the reasons were this project was a pile of parts collecting dust for many years. I stumbled upon the opportunity through some good BMW people around my area, and pulled the trigger to bring it to life in my car.

You know you only live once, and the thought of self driving electric cars disgusts me. Might as well burn the gas and have fun with a totally raw car (no auto assist bullshit / self driving / safety "features" like will be mandated for all of the future in the next few years).

Good to have more eyes and questions and answers from you all!

I think after final tune if we can get the AFRs leaner now that ignition issue is fixed (current tune is on the conservative / safe side) we might see a good bump in rwhp... It pulls like hell 4.5k-7krpm. Lower end torque feels (butt dyno) lower than I was imagining it might feel at the moment. Hoping down the road some exhaust reconfig and possibly cam advance may help a bit. Fingers crossed. I will do some experiments over time and get real dyno results for comparison.