E30 2.9L Stroker ITBs etc build...

[ForcedFirebird]

Any dyno evidence about this dBilas/RHD comparison ?

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


I have actually dyno'd Extrudabody and RHD on m20's with 272 cams, and the RHD made more power throughout the band. Extrudabody used 45mm throttles like the DBilas, but no air box, just open trumpets...





Here was the same car with RHD after rebuilding the bottom end to a 2.8 (still using a 272 cam)...




As you can see power started falling off at 6500, the car is coming back this summer to install a 284 cam and swapping out the IE valves for SuperTech with the 6mm stems, plus a little more valve seat work with the new cutters I have been using.

[hasa]

Any dyno evidence about this dBilas/RHD comparison ?

[ForcedFirebird]

Fun project!

To get from rwhp to bhp you need to divide by 0.85 assuming 15% losses. The correction for altitude (pressure) is already done by the dyno automatically.

The exhaust design looks ok, you could get more bottom end with longer collectors but there is no guarantee you wont lose from elsewhere in the power band.

You really need to test on the dyno for cam position,the standard position of 288 will probably be ok.

Be aware that MS is notorious for crank sensor issues so it may not have Been a true ignition coil setup problem

15% loss is actually on the high side for a manual BMW. More than likely closer to 10 or 12 - but either way, what is at the wheels is more important.



I haven't had any issues with MS and the stock crank sensors, provided the air gap is correct. The factory ECU doesn't seem to care as much as the MS, so when installing MS, I put the sensor as close to the reluctor wheel as possible without touching - many locals are using them in daily driven cars with no problems.



I do agree with you, though, the RHD ITB's would produce more power. Everything I have read about the DBilas, not many were happy with results. Even FPorro (who works here at the shop with me) had DBilas and switched to RHD on his 3.1L m20 and was much happier.

[mrlucretius]

The exhaust design looks ok, you could get more bottom end with longer collectors but there is no guarantee you wont lose from elsewhere in the power band.

Regarding exhaust design: I recall you showed moving xpipe further back helped bottom end. I think your xpipe was right near the front of the differential? You showed some harmonic calculations, how can I run your model? What tool did you use?

Also, my car is a bit on the loud side. I am tempted to add resonators. Does this help noise wise and does it rob much hp?

I am thinking move xpipe back, either behind or in front of cat, and putting resonators after the headers in the (now lengthened) dual collector pipe section. Similar to your layout on your build thread. Thoughts?

[mrlucretius]

So Digger,

Recalling reading your latest build thread: you like the rhd itbs primarily because they are smaller diameter and longer runners? Second they are layed out to flow a bit better? This is compared to dbilas itbs?

I think you said rhd is 42mm by 300mm?

I think dbilas is 45mm by (unknown to me right now) length?

(This all off the top of my head)...

[digger]

Hey Digger,

You are right. Dyno is corrected for baro. So 211 bhp, seems kind of weak... Let's see what the final tune shows.

We did have crank sensor issues with the megasquirt early on leading to sync lost errors.

A used and then a new crank sensor later, the sync lost errors are gone, based on logs from the dyno pulls.

The wasted spark definitely fixed the missing issues. Pulls hard and smooth to 7krpm+ now on the road. I was confident it was spark since I could adjust the dwell and duration for the stock coil and move the RPM where the missing occured up and down. And also since we are seeing no more sync errors.

So I need to get back on the dyno and finalize tune and accel enrichment. Should get rolling the weekend end of April...

Make sense to work with what you have for now and get everything sorted, though a better intake system would get you to your 250bhp thought not as OEM looking.

[mrlucretius]

California is the worst right?

I'm from Washington after 25 years no emissions..

Montana no emissions.

Colorado always emissions every 2 or 5 years (older than 32 years).

I stupidly thought all states had no emissions after some reasonable age...

It would have been a real issue if this car did not pass. Still not sure how it passed visual under the hood.

[efficient]

To be clear, Colorado is a pain in the ass relative to many states regarding emissions.

even california?
you'd fail automatically just opening the hood.

[mrlucretius]

Hey Digger,

You are right. Dyno is corrected for baro. So 211 bhp, seems kind of weak.. Let's see what the final tune shows.

We did have crank sensor issues with the megasquirt early on leading to sync lost errors.

A used and then a new crank sensor later, the sync lost errors are gone, based on logs from the dyno pulls.

The wasted spark definitely fixed the missing issues. Pulls hard and smooth to 7krpm+ now on the road. I was confident it was spark since I could adjust the dwell and duration for the stock coil and move the RPM where the missing occured up and down. And also since we are seeing no more sync errors.

So I need to get back on the dyno and finalize tune and accel enrichment. Should get rolling the last weekend of April...

[digger]

Yeah 180 x 1.15 drivetrain x 1.20 altitude is about 250hp crank at sea level is what I meant.

I will post a Dyno plot from before I fixed the ignition later. Final Dyno runs will be next weekend hopefully.

I will measure header length too. These are the headers:

http://www.iemotorsport.com/bmw/item/M20STG2.html

Ya I read your stuff about itbs... Sticking with dbilas for now.

What do you think of exhaust design?

Also, can I gain some torque without losing top end by advancing cam?

To get from rwhp to bhp you need to divide by 0.85 assuming 15% losses. The correction for altitude (pressure) is already done by the dyno automatically.

The exhaust design looks ok, you could get more bottom end with longer collectors but there is no guarantee you wont lose from elsewhere in the power band.

You really need to test on the dyno for cam position,the standard position of 288 will probably be ok.

Be aware that MS is notorious for crank sensor issues so it may not have Been a true ignition coil setup problem

[mrlucretius]

Dyno Plot with Ignition Missing Issue

So here is the last dyno pull.

This is at a mile high near Denver... So the air is thin 20% or so.

The stock ignition could not drive the high compression motor over 5200rpm or so where is starts missing as the revs grow.

So the weird dips to the right of 5200rpm is caused by that.

Also the car pulls hard to over 7krpm now, but the dyno quit at 6500 due to missing...

New wasted spark ignition is installed and the problem is resolved just need to get back on the dyno for a final tune.

[mrlucretius]

Yeah 180 x 1.15 drivetrain x 1.20 altitude is about 250hp crank at sea level is what I meant.

I will post a Dyno plot from before I fixed the ignition later. Final Dyno runs will be next weekend hopefully.

I will measure header length too. These are the headers:

http://www.iemotorsport.com/bmw/item/M20STG2.html

Ya I read your stuff about itbs... Sticking with dbilas for now.

What do you think of exhaust design?

Also, can I gain some torque without losing top end by advancing cam?

[digger]

hi post up a dyno sheet? 180 whp is around 210bhp or so.

what is the primary pipe length on those headers? with longer primaries the collector length can be alot shorter....

the best way to gain more would be a RHD ITB setup not that you want to hear that at this point

[mrlucretius]

e30 m20 stroker + schrick 288 emissions

Hi People,

Just wanted to say:

Using MS2PNP, wideband O2, and an oversized cat, schrick 288 cam, I was able to pass emission first try.

Basically for the tune for low loads, low RPM, you aim for stoich AFR.

1.5 out of 2 (limit) HC emissions was the closest fail. Everything else was low.

BTW I am in Boulder County Colorado.

They opened the hood, stared at everything carefully, stared at the exhaust for a while... Scared the shit out of me since I don't recall them opening the hood before... Thought I had failed inspection, the guy came into the booth, and... He shook my hand, and complimented me on the pretty exhaust!

So this is a good data point. Using modern ECU + wideband O2 + big cat + schrick 288... No big deal.

To be clear, Colorado is a pain in the ass relative to many states regarding emissions.

[mrlucretius]

Here is the current exhaust: