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Title: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 01, 2012, 04:00:06 PM I would like to start a discussion on what is the minimum amount of work required when you change motor (and/or intake manifold) displacement
Displacement (MAF -> load calc)? VE and/or cam overlap (various fueling issues/VVT)? Compression ratio (optimal timing)? Intake mani volume (air mass delay/inertia)? Anybody have experience with tuning a bigger than stock displacement motor? Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: rob.mwpropane on August 01, 2012, 08:23:18 PM I would like to start a discussion on what is the minimum amount of work required when you change motor (and/or intake manifold) displacement Displacement (MAF -> load calc)? VE and/or cam overlap (various fueling issues/VVT)? Compression ratio (optimal timing)? Intake mani volume (air mass delay/inertia)? Anybody have experience with tuning a bigger than stock displacement motor? Here, I kind of ventured down this path before. The deal fell through on the engine, but was interesting stuff. I have no experience though;( maybe one day. http://nefariousmotorsports.com/forum/index.php?topic=1312.0 Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 01, 2012, 09:54:04 PM What I dont get is how intake volume and engine displacement is combined.
shouldn't there be somewhere to put engine displacement separate from intake manifold volume for purposes of converting maf->load? shouldn't that calc be independent of intake volume? Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 01, 2012, 10:02:58 PM I'm thinking KUMSRL is it.
Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 01, 2012, 10:18:18 PM stock kumsrl is .001072 kg/hr / rpm %:
So multiply by 100 for %, and 2 for 2 rotations per cylinder cycle and you get: (((.001072 (kg / hr)) * 1 min) / (1.29 (kg / (m^3)))) * 100 * 2 = 2.77002584 liters HURPMH. Why am I off :) anyway, lets go the other way: (((2.7 liters * (1.29 * (kg / (m^3)))) * 60) / 100) / 2 = 0.0010449 kilograms/hr / rpm % (((3.0 liters * (1.29 * (kg / (m^3)))) * 60) / 100) / 2 = 0.001161 kilograms/hr / rpm % or, maybe .001072 * 3.0/2.7 = 0.001191 Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 01, 2012, 10:24:50 PM Even more interesting: the FR says
KUMSRL: siehe F¨ullungserfassung: V_Hub [l] / 2578 But: 2.7/2578 = .001047 and 2578 * .001072 = 2.764 Go figure. Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: rob.mwpropane on August 02, 2012, 03:52:31 AM (I love how I post, I sleep, you post, and post, and post, I wake, and it's like you never sleep!) At least your posts inform us of your thought process. ;D
The only conclusion that I ever came to was BGSRM>KISRM. And of course KRKTE. I had a quick and rough look at KUMSRL. Looks interesting/worth diving into, but I'm back off to work. FWIW, I know a 2.7 engine is a 2.671 liter engine in reality, so that may throw your math off some. KISRM has input for both intake volume and bore. Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 02, 2012, 09:14:08 AM I don't think displacement really effects krkte. Airmass is airmass, 6 injectors is 6 injectors...
IMO KUMSRL is critical, since it is part of the load calculation, and is exactly proportional to displacement. Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: okkim on August 31, 2012, 12:28:23 AM Any advance in this? I'm also interested since I'm about to build 3.0 liter motor, and maybe some day I know how to make my own tune :)
Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: prj on August 31, 2012, 03:30:24 AM This is pretty much not important, especially if you are underscaling your MAF.
Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: NOTORIOUS VR on August 31, 2012, 06:52:55 AM paging silentbob to the front desk :)
Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: prj on August 31, 2012, 07:51:48 AM The only thing you should verify is that knock control is working well pretty much :)
Title: Re: Stroker/bore engine builds - what has to change when altering displacement Post by: nyet on August 31, 2012, 11:43:03 AM This is pretty much not important, especially if you are underscaling your MAF. I'm thinking that if you are not maxing MAF, you can underscale load via KUMSRL |