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I'm in a little over my head


rstclark

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Hello to all,

Why am I here in the Turbo discussion ? Well because I jumped in to the deep end of the pool and decided to build a turbo project with no experience in fuel injection, turbo chargers or electronic controllers

The basic build will be around a BMW b130  M10 marine engine that is factory new . It was sourced from a boat project that stalled out in the late 1980's and has been sitting ever since

Compression ratio is 8.3 to 1 with flat top pistons so it should be a good candidate for a turbo

 The plan is to use L Jetronic fuel injection and a small turbo with 8lbs. of boost all controlled by a Haltech ecu  It will have a trigger wheel for ignition and some sort of simple signaling device in place of the distributor to act like a cam sensor  so that fuel can be sequential rather that batch 

Somewhere I've seen the ignition curve for the turbo and which had a fairly normal advance curve with 10 degrees of retard under boost  Does anyone have the curve to share  ?  It will help tune the Haltech  

The other thing I'm looking for is info on the turbo oil return line  I know the original was returned to a tap in the front of the oil pan but I think I would prefer a tap in the front timing chair cover

Somewhere in my search I saw a write up of where to place the tap but cant find it now,  Anyone have info and or experience with a return to the front cover ?

 

 Thanks in advance for your help

 

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The BMW 02 turbo was 6.9:1, achieved with a re-worked 121 type cylinder head, thats super low compression and likely influenced the ignition timing used...

 No info on oil return, anywhere which is above the oil level in sump should be adequate

'59 Morris Minor, '67 Triumph TR4A, '68 Silver Shadow, '72 2002tii, '73 Jaguar E-Type,

'73 2002tii w/Alpina mods , '74 2002turbo, '85 Alfa Spider, '03 Lotus Elise

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Okay  I've decider to weld a bung on the front of the oil pan  It seems like the best alternative   Solved

 

Re   the ignition curve,  I just need a baseline that I can adapt to an 8.3 to1 compression using California 91 octane with up to 10% ethanol  The curve will be controlled by the Haltech to be a variable retard depending on the amount of boost

 

A pretty common or even conservative mechanical advance cure can be tuned  but where and when does the boost retard kick in ? 

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After a lot of reading here on the subject of ignition curves, Here is the message I'm getting

 

Build a mechanical curve a lot like a Tii curve but a little more conservative that advances quickly up to about 35 to 38 degrees at 3,500 rpm and flat from there with a progressive retard of 0 to 13 degrees starting at 100 KPa and maxing at 156 KPa

Under full boost the maximum advance should not exceed 25 degrees

This is for a motor with 8.3 to 1 compression

 

Can anyone confirm this plan ?

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why not start with something like this:

 thats a lot more 'modern' and aligned with your Haltech gizmo... back in the day BMW was struggling with the limited ignition system technology that was available...note the pressure range of the original turbo 'boost retard' ...its not what is done today ....

'59 Morris Minor, '67 Triumph TR4A, '68 Silver Shadow, '72 2002tii, '73 Jaguar E-Type,

'73 2002tii w/Alpina mods , '74 2002turbo, '85 Alfa Spider, '03 Lotus Elise

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With low compression you are going to want a fair amount of advance off boost.  You are going to find much better throttle response and lower "boost lag time" if you are up around 32-35 deg of advance. You can also bring it all in very early (2500-3000rpm) and you might even start at 15+ deg at 1000rpm.   Then you can just program a retard based on boost X number of degrees of retard per psi of boost.  I would start at 1.5deg/psi which should be very safe and you can fine tune from there.  

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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Perfect   It's a much earlier ramp up than I would have thought   I'll start here as you have suggested and adjust from there.

I failed to mention that the cam will be a 276 duration with a little extra lift that's not far off the stock cam , so perhaps all the more reason for plenty of early advance

 

Thanks

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