aidan46
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| posted on 10/7/12 at 10:29 PM |
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bike turbo running but....
have my kawai turbo bike up and running.......couple of questions that dont make sense.
1. what would the typical map (kpa) reading be at idle... mine seems to be around 99 100 kpa??? (ms2 extra)
2. should there be some boost build at no load ie in neutral gear just reving engine?
3. Where should the boost gauge be taken from, plenum or supply pipe and dose it need a large pipe?
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mark chandler
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| posted on 10/7/12 at 10:40 PM |
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1) Depends on the turbo, a little one may produce a little boost, on mine the vacumn on the inside of the TB's keeps the dump valve slightly
open at idle and I can feel a little positive pressure escaping on the turbo side of the TB's, idle is I think around 46kpa from memory.
2) If you rev hard then snap the throttle shut you will see a little spike of boost, do not expect anyway near full pressure. I stuck the back of mine
on some thick blocks and booted it at full load holding the revs with the brakes for a few seconds which ran the boost up, literally only a couple of
seconds.
3) The gauge should tee in with the MAP sensor, between the TB's and the engine, if you are plugged into the plenum then this explains 100kpa
MAP at idle, you are the wrong side of the throttle spindle, 1/4" pipe BTW.
The wastegate is however plugged into the plenum so you read boost after intercooling and pipework restrictions, before the TB's.
Regards Mark
[Edited on 10/7/12 by mark chandler]
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aidan46
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| posted on 10/7/12 at 10:48 PM |
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Thanks Mark.......I am reading my pressure from above the butterflys in the plenum......thats wrong isnt it?
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matt_gsxr
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| posted on 10/7/12 at 10:59 PM |
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Normal to read pressure after the throttle butterflies. At idle I get around 80kPa.
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aidan46
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| posted on 10/7/12 at 11:10 PM |
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Cheers thanks lads
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mark chandler
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| posted on 11/7/12 at 04:19 PM |
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quote:
Originally posted by aidan46
Thanks Mark.......I am reading my pressure from above the butterflys in the plenum......thats wrong isnt it?
Yes that's wrong, but does explain your issues 
You need to Tee all the inlet runners between the head and the TB's (if you have not got take offs today buy some LPG nozzels and drill and tap)
then take into a 4:1 collector, from this you take a tube to the ECU MAP sensor, one to the dump valve plumbed between the turbo and the intercooler,
and lastly to the vacumn gauge.
Regards Mark
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aidan46
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| posted on 11/7/12 at 10:00 PM |
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Are you guys running pure speed density or is it a hybrid between alpha-n and speed density?. Dose a high idle pressure not limit you in terms of
values to tune with? i.e b/w 70 or 80 kpa at idle to 135 -140 at boost?
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mark chandler
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| posted on 11/7/12 at 10:56 PM |
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I logged the most used values then graphed in excel and grouped around the most used points, you do not need to be linear when setting out as
megasquirt predicts between points.
You can save a bit at the top, I stopped mapping at 12,000 rpm although it can rev higher saving a BIN at the top end.
Mine just runs on speed density and seems to go well enough, was rolling road mapped to finish off, I tried autotune and megatune but struggled to get
a decent map, the RR added 30BHP to my best setting  I was using a JAW wideband which did not help.
Regards Mark
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aidan46
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| posted on 11/7/12 at 11:03 PM |
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Wow 30bhp, that's a lot....would you say more power came from the spark timing or the fueling adjustment? I use a techedge wideband lambda?
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