Buildup: My quest for NA 280 hp

Author Topic: Buildup: My quest for NA 280 hp  (Read 156760 times)

enildeR

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Buildup: My quest for NA 280 hp
« Reply #105 on: September 09, 2010, 12:37:19 PM »
what reason are you going with two stage injection over larger injectors?

build is looking nice. are you going to use MAF, VAF, or MAP with the MS? I haven't looked into MS in years, but I figured by now you'd be able to use MAP.

fabe

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Buildup: My quest for NA 280 hp
« Reply #106 on: September 09, 2010, 10:12:24 PM »
My deduction is that with the injectors placed further away, the engine will get better fuel mixture at high RPM...

I'd do the same if I'm building my high strung 8,500rpm M42...
« Last Edit: September 09, 2010, 10:16:09 PM by fabe »

Boyracer

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Buildup: My quest for NA 280 hp
« Reply #107 on: September 12, 2010, 01:58:55 PM »
There will be (aluminium or composite) airbox that encloses all intake trumpets and cold air will be drawn through cone filter.

Engine load will be establised by new Megasquirt parameter ITB which is basically MAP / Alpha N (TPS) blend. MAP alone will not work because huge pressure pulses from aggressive cams and anyway the intake manifold pressure is near atmospheric when you open the throttles more than little. On the other hand Alpha N does not work on small throttle openings. So you must blend all those together, use MAP on low throttle openings and Alpha N on high throttle openings.

Stock injectors are located only 13 cm away from intake valve. With S50 ITB's and 12 cm long intake trumpets I can locate secondary injectors about 30 cm away from intake valves which is almost 3x the distance and time for fuel and air to mix before it arrives to combustion chamber. This should give some 2-4% increase in top end power.

I am also toying with the idea of variable intake manifold. Secondary set of intake trumpets that are like extensions to fixed trumpets but they can be moved maybe 20 mm forward to allow air to be sucked from shorter path. Easy to control with Mega and also implement but not sure if there is enough space under the bonnet.

romkasponka

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« Reply #108 on: September 12, 2010, 02:29:17 PM »
Hi,

About staged injection. In my opinion primary injectors (stock position) is useless together with secondaries at high rpm and I didn't found function to switch primaries off completely. The only way I now is to use dual table for two banks of injectors. Primaries until 4000rpm and after that secondaries. But not shure about that: stock primaries and secondaries I'm planing 800cc Siemens-deka, low resistance and E85 fuel. Also thinking about cheap and nice composite airbox with posibility to instal secondaries injectors inside. Something like this :) http://www.youtube.com/watch?v=y2iBbwocYZw



Uploaded with ImageShack.us

By the way you can reduce pressure fluctuation for MAP sensor by installing restrictor, or use it for atmospheric pressure and alphaN ;)
« Last Edit: September 12, 2010, 02:58:17 PM by romkasponka »
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enildeR

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« Reply #109 on: September 13, 2010, 12:33:16 PM »
The miata has a variable intake runner design. Could look at that for ideas. I doubt the manifold could be use unless you cut it and you're good at tig welding alum :D

nuvolarossa

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« Reply #110 on: September 13, 2010, 02:18:07 PM »
Quote from: enildeR;96476
The miata has a variable intake runner design. Could look at that for ideas. I doubt the manifold could be use unless you cut it and you're good at tig welding alum :D
well,this image is Mazda VICS, it works like DISA:




but I think Boyracer mean something like this :p


not too difficult to do and use with MS, surely the extra lenght could help for low torque if well calculated ;)

enildeR

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« Reply #111 on: September 14, 2010, 02:49:43 PM »
Yeah. That's pretty badass. I know some of the newer year miatas had the valve closer to the head, but I forget what year they were.

Boyracer

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« Reply #112 on: September 15, 2010, 03:25:17 AM »
Quote from: romkasponka;96457
About staged injection. In my opinion primary injectors (stock position) is useless together with secondaries at high rpm and I didn't found function to switch primaries off completely. The only way I now is to use dual table for two banks of injectors. Primaries until 4000rpm and after that secondaries. But not shure about that: stock primaries and secondaries I'm planing 800cc Siemens-deka, low resistance and E85 fuel. Also thinking about cheap and nice composite airbox with posibility to instal secondaries injectors inside.


Yeah I think primaries always fire and then secondaries start injecting on top of them when certain parameters are met.

Ideal way would be to completely switch over from primaries to secondaries. I have been thinking using relay one output from mega to control solid state relay that would switch between banks, that way only one bank would fire at any given time. Not sure if the switchover from bank to another is a problem, leading to a very short (maybe few milliseconds) lean or rich mixture.

Problem is that I would need 2 x 4 identically sized injectors with flow rate around 500- 550 ccm.

Quote from: romkasponka;96457
By the way you can reduce pressure fluctuation for MAP sensor by installing restrictor, or use it for atmospheric pressure and alphaN ;)


MAP signal is averaged from all four intakes (it is taken from idle/vacuum rail) and there is quite bit of volume in there so maybe the pulses are not that strong. But restrictor will surely help if there is need for more filtering :)

I went to scrapyard yesterday and I purchased some 50 mm diameter aluminium tube for intake trumpets. Also sourced some 16/19/23 mm steel tube for new vacuum and fuel rails. I have whole winter time to build so why not do it properly...

Con rods should be FINALLY ready next week, then I can start measuring bearing clearances with old bearings and then buy new ones. Also ordered some parts for timing case, timing chain guides and oil pan.

romkasponka

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« Reply #113 on: September 15, 2010, 01:04:57 PM »
Do not know what version MS you run, but: http://www.megamanual.com/DT.htm

Independent Injector Bank Settings

Independent injection control for each injector bank which allows completely separate VE entries, kPa and RPM bins, control algorithms, and PWM values. The same enrichments are used for both banks, however you have the option of disabling enrichments for either bank. This means you have independent control of the two injector banks, almost as if you had two MegaSquirts operating them.

and

Zero Pulse

Eric specifically coded into the dual table code that zero VE means exactly no injector pulse at all. So if the VE table returns a zero value, then all other calculations (enrichments, OC time and all that) are ignored, the PW is set to zero, and the injectors do not get a pulse. This feature is essential to prevent secondary injectors (and nitrous systems) from injecting before they are commanded. (Note that in standard MegaSquirt® *****ded code, a zero VE still results in a pulsewidth that includes the injector opening time as well as some enrichments).

So you do not need any SS relay.
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Boyracer

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« Reply #114 on: September 15, 2010, 03:06:04 PM »
There is only four independent injector drivers (two on standard mega...) so if you have two injector banks on four cylinder engine you cannot control each of the eight injectors independently.

You can use semi sequential so both banks are divided to two groups (batch fire like stock motronic/mega but on two banks) but then you lose accurate timing of pure sequential injection and possibility for cylinder specific fuel trim.

Semi sequential might work ok but I am little worried about possible blowback with second bank of injectors shooting down to intake trumpet... With sequential you could perhaps time injections to coincide with stron intake pulse to make sure fuel goes to cylinder, not to airbox walls :)

My ignition & injection driver box and cable trees are designed in a way that each injector control wire comes to the box so for any modifications I just need to rewire the connections inside the box, no need to alter the cabling at all. So I am pretty free to experiment.

romkasponka

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« Reply #115 on: September 15, 2010, 05:26:42 PM »
I am not sure, but seqentional injection is used only for low revs to have better ecology and economy but not for power gain.

http://www.sdsefi.com/techseq.htm

http://www.vems.hu/wiki/index.php?page=PortInjected/SequentialInjection
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« Reply #116 on: September 16, 2010, 04:43:25 AM »
Yes, full sequential mostly improves low end emissions, power and idle quality. But it also offers possibility to use cylinder specific fuel trim in case you can measure EGT's (which I do not have yet...) that works on all revs areas :)

I can give semi sequential two bank solution a shot first to see how it goes.

romkasponka

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« Reply #117 on: September 16, 2010, 04:55:42 AM »
Yes, it's good solution for individual cylinder control and depends what controller you have (MS-III?). I just afraid what it could be overcomplicated. Indvidual: EGT, O2 and smart knock sensing :D
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e21m44

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« Reply #118 on: March 06, 2011, 11:40:24 AM »
:) nice!

wazzu70

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« Reply #119 on: March 18, 2011, 08:02:21 PM »
Won't 50mm throttles be too big and give you poor throttle modulation? Dbilas uses 45mm throttle bodies.

Just curious how you figured 50mm would be suitable.
-Nick
91 E30 M42 with VEMS