E30 2.9L Stroker ITBs etc build...

[digger]

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.

i actually meant the specs for HASA's engine as he was talking about a race engine and whether 45mm throttles wopuld be better, but a race engine does not mean anything as you can race a stock engine...

with ~180psi realistically you arent near 12:1, 10.5:1 seems like the right ball park. did the pistons come with a cc value?

[mrlucretius]

Exhaust details

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

We measured 34" for the primary pipe length. 1.5" diameter. Then into dual 2.25" diameter.

Can you run a model and tell me what you think regarding the x-pipe location?

I am going to reconfigure the exhaust to add some big resonators to try to quiet it down a bit. Drones pretty hard at 2krpm right now.

[mrlucretius]

Hey people,

Last dyno run made just under 200hp rear wheels on a super flow autodyn 30. The guys call this make/model dyno "the heart breaker" because it measures relatively low compared to other dyno makes and models. Dyno guy says a mustang dyno would have measured over 210hp.

I will update this post with dyno plots later.

Then I need some help with AFR and Spark Advance tables... Will post those too.

Need some MS2PNP tuning feedback. So far I am getting a lot of conflicting information regarding AFRs and how to tune safely.

-mrlucretius

P.S. See you at the RMBMWCCA Driving School this weekend!

[mrlucretius]

Hey Guys,

I was just alerted to the latest from RHD:

http://racehead.com.au/products-page/throttle-body-kits/bmw-m20-itb-kit-e30-cf-plenum/

Works with stock brake booster and comes with plenum...

For my motor / exhaust setup would you go for the 40mm or the 42mm version?

I think next time I have cash to burn I will probably do this upgrade...

Always can use another 20 or 30hp...

[digger]

That's been available for a number of years.

40mm is actually plenty probably oversized for mild engine.

Having said that Im pretty sure that 42mm only means the following changes over 40 as the trumpets are the same
1) manifold is tapered 42mm to the port entry instead of 40 which is a small change
2) Cnc spacer is tapered 42 to 40 to suit 40itb ( 42itb is parallel bore)
3) 42 throttles

That's how it was with old 50mm spacers and gold trumpets, I'm not certain it still is as parts have evolved

This means the loss in midrange will pretty small compared a runner that's 2mm larger over the entire length.

I'd look to 42mm for an engine capable of ~230whp and above or with oversized inlet valve as 40mm throttles are a upstream choke point which is not ideal

[mrlucretius]

Well hell. Per all our discussions I thought RHD was incompatible with brake booster. I guess I could have looked at their website sooner...

Might have to get myself a gift for the holidays!

I emailed RHD, one thing they said was "You MUST run alpha-n or at least a blended strategy combining TPS and MAP" such as ITB mode on the megasquirt... Due to the signal going to atmosphere quickly on open throttle.

What do you think about that statement?

My car is running MAP only right now seems to run fine... However I want to get it right / optimized...

I am still trying to finalize my tune. So far I am not finding anyone local with e30 / m20 experience. I put a call into WOT-tech to see if I can get some consulting from them, maybe some remote tuning perhaps.

Will post dyno plots and tune soon...

[e30RS]

Looking forward to the dyno results!

[mrlucretius]

Ignition Fixed - Dyno Run

Hi,

This is not the best run, I think we saw 196 peak on one.

Also I think there is some room for the tune to be improved.

Enjoy.

[mrlucretius]

MegaSquirt Tune MS2PNP e30 m20 2.9L stroker ITBs

Here is current spark and fuel tables.

Any thoughts / suggestions?

@ForcedFirebird, I want to hire you... Haven't been able to get a hold of you.

[digger]

Well hell. Per all our discussions I thought RHD was incompatible with brake booster. I guess I could have looked at their website sooner...

Might have to get myself a gift for the holidays!

I emailed RHD, one thing they said was "You MUST run alpha-n or at least a blended strategy combining TPS and MAP" such as ITB mode on the megasquirt... Due to the signal going to atmosphere quickly on open throttle.

What do you think about that statement?

My car is running MAP only right now seems to run fine... However I want to get it right / optimized...

I am still trying to finalize my tune. So far I am not finding anyone local with e30 / m20 experience. I put a call into WOT-tech to see if I can get some consulting from them, maybe some remote tuning perhaps.

Will post dyno plots and tune soon...

its really tigtht with the booster and hood depending what engine mounts you have etc.....

Alpha-N improved drievability on mine over MAP. IMO its a better way to go.

the curve atleast has the right shape now, i still thnik you'll seea good uplift across the board if you ever pull the trigger on a RHD setup as the torque is lacking severly.

the tune looks fine, could probably run more timing at cruise

[ForcedFirebird]

@ForcedFirebird, I want to hire you... Haven't been able to get a hold of you.

Replied to your PM just before seeing this post. :/ Only come on this site when working at the shop and we had the long holiday weekend. Email in my signature is always best.



Your AFR's look a little rich, and agree with Digger on timing.

[mrlucretius]

OK People...

I pulled the trigger on the RHD ITB kit.

Anyone want to buy a Dbilas ITB kit?

Stay tuned...

[digger]

Should see good improvement across the board

[bradnic]

SUB'D. I have plenty of dbilas info on my vert build thread. digger will confirm the bores are too big for stock displacement. I'm installing a 3.2 metric mechanic motor in my vert this fall. keeping the dbilas setup for now but if I run into issues RHD with CF plenum will replace it.

[mrlucretius]